ASSET Technical Reference Guide

ASSET Technical Reference Guide

Software Version 6.1 Reference Guide Edition 1

© Copyright 2008 AIRCOM International All rights reserved ADVANTAGE, ASSET, CONNECT, DATASAFE, DIRECT ENTERPRISE, NEPTUNE, ARRAYWIZARD, OPTIMA, OSSEXPERT, and WEBWIZARD are recognised trademarks of AIRCOM International. Other product names are trademarks of their respective companies. Microsoft Excel , .NET™, Microsoft Office, Outlook , Visual Basic Windows®, Windows XP™, Windows Vista™ and Word are trademarks of the Microsoft Corporation. This documentation is protected by copyright and contains proprietary and confidential information. No part of the contents of this documentation may be disclosed, used or reproduced in any form, or by any means, without the prior written consent of AIRCOM International. Although AIRCOM International has collated this documentation to reflect the features and capabilities supported in the software products, the company makes no warranty or representation, either expressed or implied, about this documentation, its quality or fitness for particular customer purpose. Users are solely responsible for the proper use of ENTERPRISE software and the application of the results obtained. An electronic version of this document exists. This User Reference Guide finalised on 20 May 2008. Refer to the Online Help for more information. This User Reference Guide prepared by: AIRCOM International Ltd Cassini Court Randalls Research Park Randalls Way Leatherhead Surrey KT22 7TW Telephone: Support Hotline: Fax: Web:

+44 (0) 1932 442000 +44 (0) 1932 442345 +44 (0) 1932 442005 www.aircominternational.com

Contents Appendix A Array Descriptions 7 2g and 2.5g (Non-Sim) Arrays

8

Coverage and Interference Arrays (2g + 2.5g) (Non-Sim)

8

GSM (Sim) Arrays

18

Pathloss Arrays Coverage Arrays

18 19

UMTS and CDMA2000 Arrays

20

Pathloss Arrays Pilot Coverage Arrays Handover Arrays Uplink Noise Arrays Downlink Noise Arrays Uplink Coverage Arrays Downlink Coverage Arrays Coverage Balance Arrays Soft Blocking Arrays Hard Blocking Arrays HSDPA Arrays All Servers Array DVB-H C/I Array

21 21 24 25 25 26 27 28 28 28 29 31 32

Fixed WiMAX Arrays

32

General Arrays Thresholded Arrays

33 34

Mobile WiMAX Arrays

34

Pathloss Arrays Preamble Arrays Uplink Coverage Arrays Downlink Coverage Arrays General Arrays

Appendix B About the Prediction Management Algorithm The Prediction Management Algorithm

Appendix C 2g and 2.5g Algorithms

35 35 36 37 39

41 42

45

Interference Table Algorithm

45

Interference and Connection Array Calculations

47

Worst Connection Array Calculation Method Average Connection Array Calculation Method Worst Interferer Array Calculation Method Total Interference Array Calculation Method Table of Default C/I BER Conversion Values

47 48 48 49 49

Frequency Hopping Algorithms Synthesised Hopping Algorithm

50 52

Non-Frequency Hopping Algorithms

52

Automatic Frequency Planning (ILSA)

53

ASSET Technical Reference Guide Version 6.1

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The Cost Function of the ILSA Algorithm

54

MAIO Planning Cost Function

55

GPRS and HSCSD Capacity Calculations

55

TRX Requirement - Circuit Switched Traffic and HSCSD TRX Requirement - Circuit Switched, HSCSD and GPRS Traffic Grade of Service and Data Rate Channel Occupation Table

FCC Calculations

58

Frequency Calculations

60

Appendix D Packet Quality of Service Algorithms

63

Simulation Inputs for QoS Analysis

64

Preliminary Tests

64

Traffic Generator for QoS Analysis

64

Matching Generated Traffic to the Simulator's Mean Number of Served Users WWW Traffic Model Packet Model About the Code Schemes for GPRS QoS Profiles for GPRS

Time Simulator for QoS Analysis

71 71

Results of QoS Analysis

73

Confidence Interval Half Width Simulation Duration Delay and Cumulative Delay Probability Distributions Mean and Standard Deviations of the Queuing Delays 95th Percentile Delay Mean Transmission Time Mean Retransmission Delay

References

Appendix E Static Simulation Algorithms and Outputs

Page 6

65 66 67 68 68

71

System Model for QoS Analysis Simulation Model for QoS Analysis

Index

55 56 56 58

73 74 75 75 76 76 76

77

79

81


APPENDIX A

Array Descriptions This section describes the different types of array available in ASSET. The ranges of arrays available may vary according to which technology you are using, which licences you have, and which processes you have chosen to run. The following types of array are described: Non-Simulation Coverage/Interference Arrays (2g, 2.5g and LMU) Simulation Arrays for GSM, UMTS, CDMA2000, Fixed WiMAX and Mobile WiMAX For information on creating, managing and displaying arrays, see the ASSET User Reference Guide. In addition to this section, there are specialist documents containing more detailed descriptions of the array outputs and algorithms used in the Simulator. For information on how you can obtain these documents, please see Static Simulation Algorithms and Outputs on page 79.

In This Section 2g and 2.5g (Non-Sim) Arrays GSM (Sim) Arrays UMTS and CDMA2000 Arrays Fixed WiMAX Arrays Mobile WiMAX Arrays


8 18 20 32 34

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2g and 2.5g (Non-Sim) Arrays There are a number of different Coverage/Interference arrays that can be generated for 2g and 2.5g, using the Array Creation wizard.

Coverage and Interference Arrays (2g + 2.5g) (Non-Sim) The 2g and 2.5g arrays, generated using the Array Creation wizard, are listed within the Coverage heading in the Map View Data Types.

Example of the 2g/2.5g Arrays under the Coverage heading in the Data Types list

Best Server Array This array displays the signal strength of the best serving cell at each pixel on the Map View. This decision is based on parameters specified in the Site Database window and in the Array Settings dialog box. As with all the arrays, you can change the display settings in the Map View by double-clicking the array in the list of Data Types. For details of how to modify or set up schemas for this array, see the ASSET User Reference Guide.

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This picture shows an example of the Best Server array:

Best Server array

Best Server (GPRS) Array For each pixel, ASSET determines which serving cell layer will be the most likely server of a mobile in that pixel. This decision is based on parameters specified in the Site Database window and in the Array Settings dialog box. The Best Server (GPRS) array is identical to the Best Server array, except that it will exclude non-GPRS sub-cells from the calculation.

Best Server (EGPRS) Arrays Best Server (EGPRS GMSK) Array A subset of the GPRS Best Server array, which only includes EGPRS cells. The EGPRS GMSK array displays the pathloss from the server to that pixel of a signal using Gaussian Minimum Shift Keying (GMSK) modulation. Best Server (EGPRS 8-PSK) Array Covers the same sub-cells as the EGPRS GSK array, but applies the APD to the subcells, making the service area of each sub-cell generally smaller. If the APD is set to 0, then both Best Server EGPRS arrays will be identical. The EGPRS 8-PSK array displays the pathloss from the server to that pixel of a signal using 8-PSK modulation.

Nth Best Server Array For each pixel on the selected cell layer, ASSET determines which serving cell layer will be the most likely server of a mobile in that pixel, plus the next most likely until N. This decision is based on parameters specified in the Site Database window and in the Array Settings dialog box. ASSET Technical Reference Guide Version 6.1

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The difference between Best Server arrays and Nth Best Server arrays is that when creating an Nth Best Server Array, the number of layers is the same as the number of GSM covering cells. You then choose which layer you wish to view.

LMU Arrays Location Measurement Units (LMUs) are used to locate a subscriber and/or their mobile equipment. LMU arrays can indicate geographically where a mobile station can be measured by more than three separately located base stations (through position triangulation). The mobile can only receive effective signals where: 1

The received signal strength at the mobile station is above the signal strength threshold that you have set in the Array Settings dialog box.

2

The total C/I due to inteference from the other cells at the mobile station is above the C/I threshold that you have set.

Therefore, you can create two separate arrays: MS Measured Cells MS Measured Cells (C/I)

MS Measured Cells Array For the MS Measured Cells array, ASSET creates an Nth Best Server array for the selected region based on the selected cells and settings specified in the Array Settings dialog box (including the received signal strength threshold and the timing advance). Only the count of Best Servers are stored, and not the sub-cells.

MS Measured Cells (C/I) Array For the MS Measured Cells (C/I) array, ASSET creates an Nth Best Server array for the selected region, based on a received signal strength threshold of –160dBm, the selected cells and the rest of the settings specified in the Array Settings dialog box. To calculate the C/I for each potential server, ASSET performs the following calculation for each pixel in the Nth best server array: 1

ASSET calculates the worst C/I and the total C/I.

2

ASSET then calculates and stores the worst interfering sub-cell, based on a consideration of every other serving cell entry in the Nth Best Server array for that pixel. The calculations in steps 1 and 2 are based on:

3

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

Each serving cell entry in the Nth Best Server array, where the signal strength is equal to or greater than the received signal strength threshold in the Array Settings dialog box



Each carrier of the serving cell, where the carrier is on a control layer

ASSET then post-processes the array to calculate the average C/I for each pixel, and each serving cell entry in the Nth Best Server array. ASSET Technical Reference Guide Version 6.1

In the Map Information Window (accessed from the View menu in the Map View), if you hover over a cell, the number of cells that could be measured by the LMU is displayed for each array that has been calculated.

Interference Arrays When creating one of the Interference arrays, ASSET requires a Best Server array in memory. If this is not the case, a Best Server array will be automatically created. However, if you later create subsequent Interference arrays after making changes to the network, ASSET does not automatically create a fresh Best Server array. Therefore, in cases where you suspect the Best Server array in memory has become out of date for any reason, you should explicitly create both the Best Server array and the required Interference array when running the Array Creation wizard. For example:

Example of creating Best Server array and required Interference array in the Coverage/Interference wizard

Per Carrier Interference Array For all the interference calculations, ASSET generates an intermediate internal array called a 'per carrier interference array'. For each pixel in the array, the serving sub-cell is determined, and for each carrier of the serving sub-cell the worst carrier to interference (C/I) (lowest numerical value) and the total C/I is calculated, taking into consideration all co- and adjacent carriers from all interfering sub-cells. The total C/I is determined by summing the interfering signals in watts and then later converting back to dB. The result is an array such that for each pixel, a list is obtained of serving carriers plus the worst and total C/I for each carrier. You cannot currently visualise this intermediate array, which no longer exists when all the other selected arrays have been created.


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Worst Connection Array For each pixel, the serving sub-cell is determined, and for each hopping carrier group the average carrier to interference (C/I) is calculated from the corresponding pixel in the 'per carrier interference array', by converting total C/I to BER and calculating the mean. The mean Bit Error Rate is converted back to dB and the hopping carrier group with the lowest resultant C/I is presented, that is, it corresponds to the worst of the mean connection C/I values. For information on the algorithm used for the calculation of this array, see Worst Connection Array Calculation Method on page 47. Worst connection arrays require a Best Server array, which is generated automatically if one does not already exist in memory. If a best server array already exists but its contents are out of date, you will need to recreate it by explicitly selecting to create both the Best Server and Worst Connection arrays in the Array Creation wizard. This interference array type was designed for networks using frequency hopping, although it also works for non-hopping networks. In a non-hopping network, the carrier group can be considered to contain just a single carrier in the above description. This array is not available for AMPS/TDMA networks.

Average Connection Array For each pixel, the serving sub-cell is determined, and for each hopping carrier group the average carrier to interference (C/I) is calculated from the corresponding pixel in the 'per carrier interference array' by converting total C/I to BER and calculating the mean. The mean BER is converted back to dB and the average value for all hopping carrier groups is presented. For information on the algorithm used for the calculation of this array, see Average Connection Array Calculation Method on page 48. Average Connection arrays require a Best Server array, which is generated automatically if one does not already exist in memory. If a best server array already exists but its contents are out of date, you will need to recreate it by explicitly selecting to create both the Best Server and Average Connection arrays in the Array Creation wizard. This interference array type was designed for networks using frequency hopping, although it also works for non-hopping networks. In a non-hopping network, the carrier group can be considered to contain just a single carrier in the above description. This array is not available for AMPS/TDMA networks.

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Worst Interferer Array For each pixel, the carrier with the worst carrier to interference (C/I) is determined from the corresponding total C/I value in the 'per carrier interference array'. The result is the worst C/I and the sub-cell from which the interference originates. For information on the algorithm used for the calculation of this array, see Worst Interferer Array Calculation Method on page 48. Worst Interferer arrays require a Best Server array, which is generated automatically if one does not already exist in memory. If a best server array already exists but its contents are out of date, you will need to recreate it by explicitly selecting to create both the Best Server and Worst Interferer arrays in the Array Creation wizard. This array does not consider frequency hopping, and so can be considered to be an interference calculation for a non-hopping version of the frequency plan.

Total Interference Array For each pixel, the total carrier to interference (C/I) is calculated by summing the total C/I per carrier. This array is applicable to both fully-loaded frequency hopping and non-hopping networks. The calculated C/I is NOT merely as experienced by any individual subscriber, but rather it represents the total of the interference experienced by ALL subscribers at each pixel. For information on the algorithm used for the calculation of this array, see Total Interference Array Calculation Method on page 49. Total Interference arrays require a Best Server array, which is generated automatically if one does not already exist in memory. If a best server array already exists but its contents are out of date, you will need to recreate it by explicitly selecting to create both the Best Server and Total Interference arrays in the Array Creation wizard.

Total Received Power Array This array shows the sum of energy absorbed at any one point from all base stations on a per pixel basis. For each pixel, received power is calculated in dBm from each of the sub-cells. This value is converted to watts, summed and converted back to dBm. When you have determined the total received power, you can use this information for making safety decisions. You can also generate statistical reports showing this information. Each pixel in the area of map you have selected is processed and a list is created of sub-cells that have prediction files overlapping the area. Distributed antenna systems are treated as separate power sources.


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GPRS Data Rate Array The GPRS Data Rate array shows the maximum data rate (in kbits per second) that you can achieve at a particular pixel using GPRS technology. Use the GPRS Data Rate array to see where in a area you will get what performance. This type of array requires a Best Server (GPRS) array, which is generated automatically if one does not already exist. The GPRS Data Rate array determines coverage for cells that support GPRS and includes the effect of Frequency Hopping and DTX. The array calculates a pixel's average C/I value, ignoring the signal (C) from non-GPRS cells but considering interference for all cells, both GPRS and non-GPRS. When the average C/I value for each pixel has been determined, the array converts it from a signal to noise ratio to a data rate per timeslot by referring to the Channel Coding Scheme. For details, see the ASSET User Reference Guide. Only Channel Coding Schemes supported by the best serving sub-cell are included. The data rate is stored in the array. You can specify the cell layer/carrier layer combinations to be considered when calculating the GPRS data rate array by selecting the appropriate combinations in the Interference tab of the Array Settings dialog box. As with other arrays, you can double-click the item from the Data Types list on the Map View to change the displayed colours and categories for the array.

GPRS Average Data Rate per Timeslot Array The GPRS Average Data Rate per Timeslot display uses the serving cell information from the Best Server (GPRS) array. The Average Data Rate per Timeslot array uses the distribution of traffic (Terminal Types/km²) and the data demands of each type. It then calculates an average data rate per timeslot for the cell. This is calculated and stored when the GPRS Data Rate array is produced. It uses the GPRS Data Rate array to give a data rate per timeslot (kb/s). This value is then multiplied by the number of terminals of that type present to get the demand for that pixel for that terminal type. The results for each terminal type for all the pixels within a sub-cell are then divided by the number of terminals of that type with the sub-cell. The result for each terminal type present is then averaged to generate the average data rate per timeslot, which is then stored on the sub-cell. For more details on the calculations, see Grade of Service and Data Rate on page 56. If the traffic array and the GPRS Data Rate array are of different resolutions, the GPRS Data Rate array is interpolated to get the corresponding kb/s for each traffic array pixel.

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To display this on the map, ensure Average Data Rate per Timeslot (GPRS) is selected in the list of data types to display. The area covered by each GPRS sub-cell is displayed on the map in the colour corresponding to its average data rate per timeslot. When displayed on the map, the array has different colours representing the different service levels in a kb/s/timeslot. For example: 

High (Multimedia)

>12kb/s (Red)



Medium (Web access)

7-12kb/s (Green)



Low (e-mail)

2-7kb/s (Blue)

As with other arrays, you can double-click the item from the Data Types list on the Map View to change the displayed colours and categories for the array.

GPRS Service Area Data Rate Array The GPRS Service Area Data Rate array displays the capacity limited GPRS data rate for each serving cell. The data rates are displayed accordingly to chosen categories over the service area of each server. For example, for a server whose capacity limited data rate is 6kb/s, the service area of this server will be displayed as the appropriate category. The default category in this case would be e-mail as according to the default scheme, the data rate range for e-mail is 1-28 kb/s. The service area for this cell would therefore be coloured in the colour for the category e-mail. As with other arrays, you can double-click the item from the Data Types list on the Map View to change the displayed colours and categories for the array.

EGPRS Data Rate Array Use the EGPRS Data Rate array to see where in a area you will get what performance. This type of array requires an EGPRS best server array, which is generated automatically if one does not already exist. The EGPRS Data Rate array is based on the following data: EGPRS-enabled cells EGPRS modulation/coding schemes Frequency hopping LA families supported by the sub-cells The power drop (APD) observed with 8-PSK modulation The EGPRS Data Rate array determines coverage for cells that support EGPRS and includes the effect of Frequency Hopping and DTX. The array calculates a pixel's average C/I value, ignoring the signal (C) from non-EGPRS cells but considering interference for all cells, both EGPRS and non-EGPRS. If you are taking traffic into account for interference and the 8-PSK traffic mix of any sub-cell is greater than zero, ASSET assumes that the percentage of the traffic is 8PSK (which uses less power because of the APD and causes less interference). ASSET Technical Reference Guide Version 6.1

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When the average C/I value for each pixel has been determined, the array converts it from a signal to noise ratio to a data rate per timeslot by referring to the Coding Scheme. For details, see the ASSET User Reference Guide. It works out two of these data rates, one for the best GMSK available, and one for the best 8-PSK available, and then chooses the one that gives the best overall data rate to store. You can specify the cell layer/carrier layer combinations to be considered when calculating the EGPRS data rate array by selecting the appropriate combinations in the Interference tab of the Array Settings dialog box. As with other arrays, you can double-click the item from the Data Types list on the Map View to change the displayed colours and categories for the array.

EGPRS Average Data Rate per Timeslot Array The EGPRS Average Data Rate per Timeslot display uses the serving cell information from the Best Server (EGPRS) array. The Average Data Rate per Timeslot array uses the distribution of traffic (Terminal Types/km²) and the data demands of each type. It then calculates an average data rate per timeslot for the cell. This is calculated and stored when the EGPRS Data Rate array is produced. It uses the EGPRS Data Rate array to give a data rate per timeslot (kb/s). This value is then multiplied by the number of terminals of that type present to get the demand for that pixel for that terminal type. The results for each terminal type for all the pixels within a sub-cell are then divided by the number of terminals of that type with the sub-cell. The result for each terminal type present is then averaged to generate the average data rate per timeslot, which is then stored on the sub-cell. For more details on the calculations, see Grade of Service and Data Rate on page 56. If the traffic array and the EGPRS Data Rate array are of different resolutions, the EGPRS Data Rate array is interpolated to get the corresponding kb/s for each traffic array pixel. To display this on the map, ensure Average Data Rate per Time Slot (EGPRS) is selected in the list of data types to display. The area covered by each EGPRS sub-cell is displayed on the map in the colour corresponding to its average data rate per timeslot. When displayed on the map, the array has different colours representing the different service levels in a kb/s/timeslot. For example: 

High (Multimedia)

>12kb/s (Red)



Medium (Web access)

7-12kb/s (Green)



Low (e-mail)

2-7kb/s (Blue)

As with other arrays, you can double-click the item from the Data Types list on the Map View to change the displayed colours and categories for the array.

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EGPRS Service Area Data Rates Array The EGPRS Service Area Data Rate array displays the capacity limited EGPRS data rate for each serving cell. The data rates are displayed accordingly to chosen categories over the service area of each server. For example, for a server whose capacity limited data rate is 6kb/s, the service area of this server will be displayed as the appropriate category. The default category in this case would be e-mail as according to the default scheme, the data rate range for e-mail is 1-28 kb/s. The service area for this cell would therefore be coloured in the colour for the category e-mail. As with other arrays, you can double-click the item from the Data Types list on the Map View to change the displayed colours and categories for the array.

Co/Adjacent Channel Assignments This feature is not a true array, as it is sensitive to the location of your mouse cursor. As you move your cursor to different cells (with allocated carriers), a set of lines display information about which cells share the co-channels or adjacent channels. As with all the arrays, you can change the display settings by double-clicking the array in the list of Data Types. You can then choose whether to display Co-Channel and/or Adjacent Channels, and you can also distinguish between Control (BCCH) channels and Traffic(TCH) channels, as set in the Carrier Layers.

Service Area (Block, Contour) Service areas enable you to view the information from the Best Server array in terms of the geographical areas where each cell is the Best Serving Cell. It uses the same information as the Best Server array, but displays it in a different way. This picture shows an example of the Service Area Block array:

Service Area Block array


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GSM (Sim) Arrays This is an overview of the GSM arrays generated by the Simulator in ASSET. All arrays are produced on a per cell-layer basis. Many arrays depend on whether the terminal is taken to be indoor or outdoor. Indoor arrays use the in-building parameters for the clutter type at each pixel (that is, indoor loss and indoor shadowfading standard deviation). Coverage arrays can be drawn even if no snapshots have been run, but the user should note that the arrays then refer to coverage in an unloaded system. To obtain coverage arrays for a loaded system the user must run some snapshots; the key purpose of running snapshots is to provide measures of traffic load. The arrays change little after a relatively small number of snapshots have been performed (10s of snapshots in most cases). This is because only a small number of snapshots are needed to get an idea of the average loading on each sub-cell. Here is an example of the GSM arrays you can generate on the Map View when using the Simulator:

Example of the GSM (Sim) arrays appearing in the Map View Data Types

Pathloss Arrays DL Loss & Nth DL Loss Dependencies: Terminal, Cell layer, Indoor These are the lowest (and Nth lowest) downlink losses. They represent average values and are therefore calculated with fades of 0 dB.

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Coverage Arrays These arrays all provide information on coverage levels and coverage probabilities. Best DL Cell by RSS Dependencies: Cell Layer This is the sub-cell that provides the highest RSS for the terminal. Best RSS & Nth Best RSS Dependencies: Terminal, Cell Layer, Indoor These are the highest (and Nth highest) RSS levels. They represent average values and are therefore calculated with fades of 0 dB. RSS Coverage Probability Dependencies: Terminal, Cell Layer, Indoor, Fading This is the probability that the Best DL Cell (by RSS) satisfies the RSS requirement specified on the terminal type. This probability depends on the standard deviation of shadow fading for the clutter type at the pixel. If this standard deviation has been set to zero, then there are only three possible coverage probabilities: 0% if the requirement is not satisfied, 50% if the requirement is satisfied exactly, and 100% if the requirement is exceeded. CINR (Control) Dependencies: Terminal, Cell Layer, Indoor These are the CINR(Control) values corresponding to the best serving sub-cells, i.e. not necessarily the highest CINR(Control) values. CINR (Traffic + Control) & Nth CINR (Traffic + Control) Dependencies: Terminal, Cell Layer, Indoor These are the CINR (Traffic + Control) values corresponding to the best (and Nth best) serving sub-cells, i.e. not necessarily the highest (and Nth highest) CINR (Traffic + Control) values. Achievable Bitrate Dependencies: Terminal, Cell Layer, Service, Indoor This is the highest bitrate that can be achieved by the terminal based on CINR regardless of system loading.


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UMTS and CDMA2000 Arrays This is an overview of the 3g arrays for UMTS and CDMA2000 generated by the Simulator in ASSET. All these arrays are produced on a per carrier basis. Most of them have a dependency on terminal type because body loss and terminal antenna gain are always included in the link budget. Many of them depend on whether the terminal is considered to be indoor or outdoor. Indoor arrays use the in-building parameters for the clutter type at each pixel (that is, indoor loss and indoor shadow fading standard deviation). Indoor terminals are always taken to be slow moving. Coverage arrays can be displayed even if no snapshots have been run, but you should note that in these circumstances the arrays represent coverage in an unloaded network. To obtain coverage arrays for a loaded network, you must run some snapshots. The key purpose of running snapshots is to provide measures of system load. Arrays for coverage tend to have a weak dependence on the number of snapshots run, and the arrays change little after a relatively small number of snapshots have been performed (10s of snapshots in most cases). This is because only a small number of snapshots are needed to get an idea of the average noise rise and average DL traffic power on each cell. Arrays for hard or soft blocking probabilities have a strong dependence on the number of snapshots run. This is because blocking is evaluated by reporting the proportion of snapshots that would block further connections. For example, if only 1 snapshot has been run, then all blocking probabilities will be either 0% or 100%. If 5 snapshots have been run then all blocking probabilities will belong to the set {0%, 20%, 40%, 60%, 80%, 100%}. Here is an example of the 3g arrays you can generate on the Map View when using the Simulator:

Example of the Simulator 3g arrays appearing in the Map View Data Types

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Pathloss Arrays DL Loss Dependencies: Terminal, Carrier, Indoor The lowest downlink loss. Represents average values and is therefore calculated with fades of 0dB. Nth DL Loss Dependencies: Terminal, Carrier, Indoor The Nth lowest downlink loss. Represents average values and is therefore calculated with fades of 0dB.

Pilot Coverage Arrays These arrays all provide information on pilot levels and coverage probabilities. There are 3 types of quantity relating to the pilot (RSCP, Ec/Io, SIR) and there are arrays for all of these. Best DL Cell by RSCP Dependencies: Carrier This is the cell that provides the highest RSCP for the terminal. Best RSCP Dependencies: Terminal, Carrier, Indoor The highest RSCP level. Represents average values and is therefore calculated with fades of 0dB. Nth Best RSCP Dependencies: Terminal, Carrier, Indoor The Nth highest RSCP level. Represents average values and is therefore calculated with fades of 0dB. RSCP Coverage Probability Dependencies: Terminal, Carrier, Indoor This is the probability that the Best DL Cell (by RSCP) satisfies the RSCP requirement specified on the terminal type. This probability depends on the standard deviation of shadow fading for the clutter type at the pixel. If this standard deviation has been set to zero, then there are only three possible coverage probabilities: 0% if the requirement is not satisfied, 50% if the requirement is satisfied exactly, and 100% if the requirement is exceeded.


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RSCP Coverage OK Dependencies: Terminal, Carrier, Indoor This is a thresholded version of the RSCP Coverage Probability array and has just 2 values (Yes/No). It has the advantage of being quicker to calculate than the RSCP Coverage Probability array. A value of “Yes” means that the RSCP coverage probability meets the coverage reliability level specified in the Sim Display Settings tab of the Array Settings dialog box. Number of RSCP OK Dependencies: Terminal, Carrier, Indoor This is the number of covering cells with a satisfactory RSCP. A cell is counted as having a satisfactory RSCP if its RSCP coverage probability meets the coverage reliability level specified in the Sim Display Settings tab of the Array Settings dialog box. Pilot Ec/Io & Nth Best Pilot Ec/Io Dependencies: Terminal, Carrier, Indoor These are the highest (and Nth highest) Ec/Io values. They represent average values and are therefore calculated with fades of 0dB. Pilot Ec/Io Coverage Probability Dependencies: Terminal, Carrier, Indoor This is the probability that the Best DL Cell (by RSCP) satisfies the Ec/Io requirement specified on the terminal type. This probability depends on the standard deviation of shadow fading for the clutter type at the pixel. If this standard deviation has been set to zero, then there are only three possible coverage probabilities: 0% if the requirement is not satisfied, 50% if the requirement is satisfied exactly, and 100% if the requirement is exceeded. Pilot Ec/Io Coverage OK Dependencies: Terminal, Carrier, Indoor This is a thresholded version of the Pilot Ec/Io Coverage Probability array and has just 2 values (Yes/No). It has the advantage of being quicker to calculate than the Pilot Ec/Io Coverage Probability array. A value of “Yes” means that the pilot Ec/Io coverage probability meets the coverage reliability level specified in the Sim Display Settings tab of the Array Settings dialog box.

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Number of Pilot Ec/Io OK Dependencies: Terminal, Carrier, Indoor This is the number of covering cells with a satisfactory pilot Ec/Io. A cell is considered as having a satisfactory pilot Ec/Io if its pilot Ec/Io coverage probability meets the coverage reliability level specified in the Sim Display Settings tab of the Array Settings dialog box. Pilot SIR Dependencies: Terminal, Carrier, Indoor This is the best Pilot SIR value. It represents an average value and is therefore calculated with fades of 0dB. Pilot SIR Coverage Probability Dependencies: Terminal, Carrier, Indoor This is the probability that the Best DL Cell (by RSCP) satisfies the pilot SIR requirement specified on the terminal type. This probability depends on the standard deviation of shadow fading for the clutter type at the pixel. If this standard deviation has been set to zero, then there are only three possible coverage probabilities: 0% if the requirement is not satisfied, 50% if the requirement is satisfied exactly, and 100% if the requirement is exceeded. Pilot SIR Coverage OK Dependencies: Terminal, Carrier, Indoor This is a thresholded version of the Pilot SIR Coverage Probability array and has just 2 values (Yes/No). It has the advantage of being quicker to calculate than the Pilot SIR Coverage Probability array. A value of “Yes” means that the pilot SIR coverage probability meets the coverage reliability level specified in the Sim Display Settings tab of the Array Settings dialog box. Number of Pilot SIR OK Dependencies: Terminal, Carrier, Indoor This is the number of covering cells with a satisfactory pilot SIR. A cell is considered as having a satisfactory pilot SIR if its pilot SIR coverage probability meets the coverage reliability level specified in the Sim Display Settings tab of the Array Settings dialog box.


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Handover Arrays The aim of the following arrays is to provide the planner with an idea of potential handover areas, and to indicate areas of pilot pollution. All arrays are based on mean Pilot Ec/Io levels calculated with fades of 0dB. Available Soft/Softer Cells Dependencies: Terminal, Carrier, Indoor This is the number of suitable HO candidates for the Best DL Cell (by RSCP). If the Ec/Io level of the best DL cell is below the Ec/Io requirement on the terminal type, then no result is given. Otherwise all the other cells are checked to see if their pilot Ec/Io levels make them suitable HO candidates. Available Soft Cells Dependencies: Terminal, Carrier, Indoor This is the number of suitable soft HO candidates for the Best DL Cell (by RSCP). If the Ec/Io level of the best DL cell is below the Ec/Io requirement on the terminal type, then no result is given. Otherwise all the other cells (on different sites to the best cell) are checked to see if their pilot Ec/Io levels make them suitable HO candidates. Available Softer Cells Dependencies: Terminal, Carrier, Indoor This is the number of suitable softer HO candidates for the Best DL Cell (by RSCP). If the Ec/Io level of the best DL cell is below the Ec/Io requirement on the terminal type, then no result is given. Otherwise all the other cells (on the same site as the best cell) are checked to see if their pilot Ec/Io levels make them suitable HO candidates. Active Set Size Dependencies: Terminal, Carrier, Indoor This is the potential size of the active set. It is related to the Available Soft/Softer Cells array by: Active Set Size = min (1 + Available Soft/Softer Cells, Max Active Set Size). Pilot Polluters Dependencies: Terminal, Carrier, Indoor If the Pilot Pollution Threshold specified in the Simulation Wizard is XdB then: For UMTS, the number of pilot polluters at a location is: The number of cells that are not in the active set, but provide an Ec/Io level within XdB of the best Ec/Io in the active set. Therefore the pilot pollution threshold in UMTS is a relative quantity. A typical value for UMTS is 6dB. Page 24


For CDMA2000, the number of pilot polluters at a location is: The number of cells that are not in the active set, but provide an Ec/Io level higher than XdB. Therefore the pilot pollution threshold in CDMA2000 is an absolute quantity. A typical value for CDMA2000 is -15dB.

Uplink Noise Arrays UL Load Dependencies: Carrier This is the uplink cell load of the Best DL Cell (by RSCP). Note that for OTSR cells, there can be a different uplink load on each antenna used by the cell (just as in the uplink simulation reports for OTSR cells). UL FRE Dependencies: Carrier This is the uplink frequency re-use efficiency of the Best DL Cell (by RSCP). Note that for OTSR cells, there can be a different uplink FRE on each antenna used by the cell (just as in the uplink simulation reports for OTSR cells).

Downlink Noise Arrays DL Io Dependencies: Terminal, Carrier, Indoor This is the total downlink power spectral density. It represents an average value and is therefore calculated with fades of 0dB. DL Iother/Iown Dependencies: Carrier This is the ratio of downlink power received from other cells, to downlink power received from own cell, where “own cell” is the Best DL Cell (by RSCP). DL FRE Dependencies: Carrier This is the downlink frequency re-use efficiency at a pixel and it is related to DL Iother/Iown as follows: DL FRE = 1 / ( 1 + Iother/Iown ).


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Uplink Coverage Arrays Uplink coverage arrays are available for each bearer at different speeds. Best UL Cell Dependencies: Terminal, Carrier, Indoor, Service, UL Bearer, Speed This is the cell requiring the minimum uplink transmit power. For UMTS bearers, the only real dependence is on the carrier used. However, for CDMA2000 bearers, the Best UL Cell must have an RC type that is supported by the terminal type. UL Eb/No Margin Dependencies: Terminal, Carrier, Indoor, Service, UL Bearer, Speed This is how much we exceed the uplink Eb/No requirement by on the Best UL Cell, assuming the terminal transmits at full power. UL Coverage Probability Dependencies: Terminal, Carrier, Indoor, Service, UL Bearer, Speed This is the probability of satisfying the uplink bearer Eb/No requirement on the Best UL Cell, assuming the terminal transmits at full power. This probability depends on the standard deviation of shadow fading for the clutter type at the pixel. If this standard deviation has been set to zero, then there are only three possible coverage probabilities: 0% if the requirement is not satisfied, 50% if the requirement is satisfied exactly, and 100% if the requirement is exceeded. UL Coverage Probability OK Dependencies: Terminal, Carrier, Indoor, Service, UL Bearer, Speed This is a thresholded version of the UL Coverage Probability array and has just 2 values (Yes/No). It has the advantage of being quicker to calculate than the UL Coverage Probability array. A value of “Yes” means that the uplink coverage probability meets the coverage reliability level specified in the Sim Display Settings tab of the Array Settings dialog box. Achievable UL Bearer Dependencies: Terminal, Carrier, Indoor, Service, Speed The purpose of this array is to provide a composite coverage plot for the uplink bearers of a service. The array shows the highest priority uplink bearer with acceptable uplink coverage, that is, with UL Coverage Probability meeting the coverage reliability level specified in the Sim Display Settings tab of the Array Settings dialog box.

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Downlink Coverage Arrays Downlink coverage arrays are available for each bearer at different speeds. Best DL Cell Dependencies: Terminal, Carrier, Indoor, Service, DL Bearer, Speed This is the cell requiring the minimum downlink transmit power. For UMTS bearers, the only real dependence is on the carrier used, and so this array is exactly the same as the Best DL cell by RSCP. However, for CDMA2000 bearers, the Best DL Cell must have an RC type that is supported by the terminal type. DL Eb/No Margin Dependencies: Terminal, Carrier, Indoor, Service, DL Bearer, Speed This is how much the downlink Eb/No requirement has been exceeded, assuming that the link powers of cells in the active set are at maximum allowed levels. DL Coverage Probability Dependencies: Terminal, Carrier, Indoor, Service, DL Bearer, Speed This is the probability of satisfying the downlink bearer Eb/No requirement, assuming that the link powers of cells in the active set are at maximum allowed levels. This probability depends on the standard deviation of shadow fading for the clutter type at the pixel. If this standard deviation has been set to zero, then there are only three possible coverage probabilities: 0% if the requirement is not satisfied, 50% if the requirement is satisfied exactly, and 100% if the requirement is exceeded. DL Coverage Probability OK Dependencies: Terminal, Carrier, Indoor, Service, DL Bearer, Speed This is a thresholded version of the DL Coverage Probability array and has just 2 values (Yes/No). It has the advantage of being quicker to calculate than the DL Coverage Probability array. A value of “Yes” means that the downlink coverage probability meets the coverage reliability level specified in the Sim Display Settings tab of the Array Settings dialog box. Achievable DL Bearer Dependencies: Terminal, Carrier, Indoor, Service, Speed The purpose of this array is to provide a composite coverage plot for the downlink bearers of a service. The array shows the highest priority downlink bearer with acceptable downlink coverage, that is, with DL Coverage Probability meeting the coverage reliability level specified in the Sim Display Settings tab of the Array Settings dialog box.


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Coverage Balance Arrays Coverage Balance Dependencies: Terminal, Carrier, Indoor, Service, Speed The purpose of this array is to provide a composite uplink/downlink coverage plot for a service. The uplink is deemed to have coverage if any of the uplink bearers on the service have UL Coverage Probability meeting the coverage reliability level specified in the Sim Display Settings tab of the Array Settings dialog box. Similarly, the downlink is deemed to have coverage if any of the downlink bearers on the service have DL Coverage Probability meeting the coverage reliability level specified in the Sim Display Settings tab of the Array Settings dialog box. This array also considers (where appropriate) HSDPA downlink bearers.

Soft Blocking Arrays UL Soft Blocking Probability Dependencies: Terminal, Carrier, Indoor, Service, UL Bearer, Speed This is the probability of uplink soft blocking on the Best UL Cell. Uplink soft blocking occurs if an additional connection with the uplink bearer would cause the noise rise limit to be exceeded. The uplink soft blocking probability is determined by examining the proportion of snapshots that would block a connection with the uplink bearer in this way. Note that for OTSR cells, the noise rise is measured on a per antenna basis (as in the simulation reports), so the soft blocking probability depends on the antenna that covers the pixel. DL Soft Blocking Probability Dependencies: Terminal, Carrier, Indoor, Service, DL Bearer, Speed This is the probability of downlink soft blocking on the Best DL Cell. Downlink soft blocking occurs if an additional connection with the downlink bearer requires more power than is available on the cell. The downlink soft blocking probability is determined by examining the proportion of snapshots that would block a connection with the downlink bearer in this way.

Hard Blocking Arrays There a two types of hard blocking arrays for each uplink and downlink resource type. The exception is the HSDPA resource type used to represent HSDPA codes. This does not have a “primary” blocking array because there are no “primary” limits for HSDPA codes. Hard Blocking Probability Dependencies: Terminal, Carrier, Indoor, Service, Bearer, Speed

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This is the probability of hard blocking on the Best DL Cell because of lack of resources. This type of blocking occurs if an additional connection with the bearer requires more resources than are available. The blocking probability is determined by examining the proportion of snapshots that would block a connection with the bearer in this way. Hard Blocking Probability – Primary Dependencies: Terminal, Carrier, Indoor, Service, Bearer, Speed This is the probability of hard blocking on the Best DL Cell because of lack of primary resources. This type of blocking occurs if an additional connection with the bearer requires more primary resources than are available. The blocking probability is determined by examining the proportion of snapshots that would block a connection with the bearer in this way.

HSDPA Arrays HSDPA - Best DL Cell by SINR Dependencies: Carrier This is the cell that provides the highest SINR level for the terminal. HSDPA - SINR Dependencies: Terminal, Carrier, Indoor This is the highest SINR level. It represents an average value and is therefore calculated with fades of 0dB. HSDPA - DL Eb/No Margin Dependencies: Terminal, Carrier, Indoor, Service, HSDPA Bearer, Speed This is the extent to which the Eb/No requirement of the HSDPA bearer is exceeded. The cell of interest is chosen by examining the SINR levels of cells that support the HSDPA bearer, and choosing the cell with the largest level. HSDPA - DL Coverage Probability Dependencies: Terminal, Carrier, Indoor, Service, HSDPA Bearer, Speed This is the probability of satisfying the Eb/No requirement of the HSDPA bearer. The cell of interest is chosen by examining the SINR levels of cells that support the HSDPA bearer, and choosing the cell with the largest level. The probability depends on the standard deviation of shadow fading for the clutter type at the pixel. If this standard deviation has been set to zero, then there are only three possible coverage probabilities: 0% if the requirement is not satisfied, 50% if the requirement is satisfied exactly, and 100% if the requirement is exceeded.


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HSDPA - DL Coverage Probability OK Dependencies: Terminal, Carrier, Indoor, Service, HSDPA Bearer, Speed This is a thresholded version of the HSDPA - DL Coverage Probability array and has just 2 values (Yes/No). It has the advantage of being quicker to calculate than the HSDPA - DL Coverage Probability array. A value of “Yes” means that the coverage probability meets the coverage reliability level specified in the Sim Display Settings tab of the Array Settings dialog box. HSDPA - Achievable DL Bearer Dependencies: Terminal, Carrier, Indoor, Service, Speed The purpose of this array is to provide a composite coverage plot for the HSDPA bearers of a service. The array shows the highest priority HSDPA bearer with acceptable coverage. i.e. with HSDPA - DL Coverage Probability meeting the coverage reliability level specified in the Sim Display Settings tab of the Array Settings dialog box. HSDPA - Offered Load Dependencies: Carrier, This is the offered HSDPA load on the Best DL Cell by SINR. Note that the offered load is calculated for each HSDPA resource pool in the network. Therefore, if the HSDPA resources have been pooled on a site, all HSDPA cells on that site will show the same offered load. HSDPA - Effective Service Rate (Unloaded) Dependencies: Terminal, Carrier, Indoor, Service, Speed This is the bitrate that the user experiences at a location when there is no queuing delay on the cell. It is calculated by multiplying the bitrate of the HSDPA - Achievable DL Bearer by its activity factor. HSDPA - Effective Service Rate (Loaded) Dependencies: Terminal, Carrier, Indoor, Service, Speed This is the bitrate that the user experiences at a location when there is queuing delay on the cell. The rate drops to zero as the HSDPA load on the cell approaches 100%. HSDPA - Effective Cell Service Rate (Unloaded) Dependencies: Carrier, Service This is the total amount of data in a service session (bits) divided by the mean service time per user on the cell (seconds), assuming there is no queuing delay.

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HSDPA - Effective Cell Service Rate (Loaded) Dependencies: Carrier, Service This is similar to the HSDPA - Effective Cell Service Rate (Unloaded) array, except that the mean service time per user on the cell is increased because of queuing delay. As the offered HSDPA load on the cell approaches 100%, the queuing delay approach infinity and the Effective Cell Service Rate (Loaded) drops to zero.

All Servers Array This feature is not a true array, since it is sensitive to the location of your mouse cursor. It is a more basic version of the Pixel Analyser tool (for more information on the Pixel Analyser, see the ASSET User Reference Guide). It displays information about which cells are "covering" each pixel. A set of lines is drawn between all possible serving cells to the simulation pixel where the mouse cursor is located. For pixels with more than one covering cell, the line thickness increases proportionally. This array enables you to identify distant servers so that you can optimise your network design by lowering, moving or reducing the pilot power of problematic sites. The covering cells are shown in order of either: Best Servers by Pilot Strength (according to the threshold set in the Array Settings dialog box). This will work even if you have not yet run any snapshots because it relates to the power in the cell and path loss, not to any simulation results. Best Servers by Ec/Io. This requires snapshots to have been run because it relates to attempted connections. Lines are only drawn if a terminal has been served on that pixel. This picture shows an example of the All Servers array:

All Servers array


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DVB-H C/I Array This array is exclusively for DVB-H analysis. The array shows combined C/I value for DVB-H at each pixel, calculated from the DVB-H parameters set in the Simulator wizard. When you display the results of a DVB-H simulation on the Map View, you should ensure that you set the array display properties to display appropriate ranges of values, in accordance with the values for your network. You should also add appropriate descriptive labels for each range, using the mapping relationship between C/I and Throughput, as described in the DVB-H section of the ASSET User Reference Guide. As with all arrays, you can customise the display properties by double-clicking on the array heading.

Fixed WiMAX Arrays This is an overview of the Fixed WiMAX arrays generated by the Simulator in ASSET. All arrays are produced on a per carrier basis. Most arrays have a dependency on the terminal type because terminal antenna gain is always included in the linkloss. Many arrays depend on whether the terminal is taken to be indoor or outdoor. Indoor arrays use in-building parameters for the clutter type at the given pixel. Coverage arrays can be drawn even if no snapshots have been run. Here is an example of the Fixed WiMAX arrays you can generate on the Map View when using the Simulator:

Example of the Fixed WiMAX arrays appearing in the Map View Data Types

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General Arrays Achievable UL Bearer This array shows the highest priority UL bearer with acceptable UL coverage. The array is based on the UL CINR value. Achievable DL Bearer This array shows the highest priority DL bearer with acceptable DL coverage (based on the CINR). DL RSS This array represents the DL RSS at a given point. Calculated with fades of 0 dB as it represents an average value. Best Server by DL RSS This array represents the service area of each WiMAX sector based on DL RSS. CPE Azimuth This array displays the CPE azimuth required in order to connect to the best server (server with the highest signal strength). DL Loss This array represents the lowest DL losses. Calculated with fades of 0 dB as it represents an average value. DL CINR This is the best C/(I+N) in the DL. The C/(I+N) is calculated by taking into account the signal strength from the reference base station and signal strength from all interfering base stations. UL Required TX Power This array displays the UL required TX power for a given receiver sensitivity (specified in the Site Database). UL CINR This array displays the CINR in the UL.


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Thresholded Arrays DL CINR OK DL RSS OK UL CINR OK UL RSS OK These are thresholded versions of their corresponding arrays. They have just 2 values (Yes/No), and have the advantage of being quicker to calculate than their corresponding arrays. A value of “Yes” means that the probability meets the reliability level specified in the Sim Display Settings tab of the Array Settings dialog box.

Mobile WiMAX Arrays This is an overview of the Mobile WiMAX arrays generated by the Simulator in ASSET. All arrays are produced on a per carrier basis. Most arrays have a dependency on terminal-type because body loss and terminal antenna gain are always included in the linkloss. Many arrays depend on whether the terminal is taken to be indoor or outdoor. Indoor arrays use the in-building parameters for the clutter type at each pixel (i.e. indoor loss and indoor shadow-fading standard deviation). Indoor terminals are always taken to be slow moving. Coverage arrays can be drawn even if no snapshots have been run, but the user should note that the arrays then refer to coverage in an unloaded system. To obtain coverage arrays for a loaded system the user must run some snapshots. Remember that the key purpose of running snapshots is to provide measures of system load. Arrays for coverage tend to have a weak dependence on the number of snapshots run, and the arrays change little after a relatively small number of snapshots have been performed (10s of snapshots in most cases). This is because only a small number of snapshots are needed to get an idea of the average noise rise and average DL traffic power on each cell.

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Here is an example of the Mobile WiMAX arrays you can generate on the Map View when using the Simulator:

Example of the Mobile WiMAX arrays appearing in the Map View Data Types

Pathloss Arrays DL Loss Dependencies: Terminal, Carrier, Indoor These are the lowest downlink losses. They represent average values and are therefore calculated with fades of 0 dB.

Preamble Arrays Best Server by Preamble RSS Dependencies: Carrier This is the cell that provides the highest Preamble RSS for the terminal. Preamble RSS and Nth Best Preamble RSS Dependencies: Terminal, Carrier, Indoor This is the highest (and Nth highest) RSS levels. They represent average values and are therefore calculated with fades of 0 dB. The preamble power (that is, the TX power for the cell in the site database) is boosted by the preamble boosting factor specified in the Site Database.


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Preamble RSS OK Dependencies: Terminal, Carrier, Indoor This array has two values (Yes/No). A value of “Yes” means that the RSCP coverage probability (the probability that the Preamble RSS satisfies the RSS requirement in the terminal dialog) meets the coverage reliability criteria specified in the Sim Display Settings tab of the Array Settings dialog box. The coverage probability depends on the standard deviation of shadow fading for the clutter type at the pixel. Preamble CINR Dependencies: Terminal, Carrier, Indoor This is the best preamble CINR. It represents an average value and hence is calculated using fades of 0 dB. Sectors on the same site are not considered as interferers because such sectors will be allocated different segments.

Uplink Coverage Arrays UL PUSC CINR Dependencies: Terminal, Carrier, Indoor, speed The calculation of the UL PUSC CINR assumes that the terminal is transmitting over all available data subcarriers. Best Server by UL PUSC CINR Dependencies: Terminal, Carrier This is the cell that provides the highest CINR at a given pixel. UL Achievable Bearer Dependencies: Terminal, Carrier, Indoor, Service, Speed This array shows the combined coverage plot for the UL bearers of the service. The array shows the highest priority bearer with acceptable UL coverage, that is, where the UL coverage probability meets the reliability level specified in the Sim Display Settings tab of the Array Settings dialog box. UL AMC CINR Dependencies: Terminal, Carrier, Service, Indoor, Bearer This array displays the UL CINR in the AMC zone. For the uplink CINR analysis, the signal from the connected terminal is the server signal and the signal from all other terminals are the interferers. The power transmitted by the terminal can be assumed to be the power specified in the terminal type dialog. The UL CINR represents an average value (with fades set to 0 dB).

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UL OPUSC CINR Dependencies: Terminal, Carrier, Service, Indoor, Bearer This array displays the UL CINR in the OPUSC zone. For the uplink CINR analysis, the signal from the connected terminal is the server signal and the signal from all other terminals are the interferers. The power transmitted by the terminal can be assumed to be the power specified in the terminal type dialog. The UL CINR represents an average value (with fades set to 0 dB). Best Server by UL OPUSC CINR Dependencies: Terminal, Carrier, Service, Indoor, Bearer This array displays the cell with the highest UL OPUSC CINR. Best Server by UL AMC CINR Dependencies: Terminal, Carrier, Service, Indoor, Bearer This array displays the cell with the highest UL AMC CINR.

Downlink Coverage Arrays DL PUSC CINR Dependencies: Terminal, Carrier, Indoor, speed DL FUSC CINR Dependencies: Terminal, Carrier, Indoor, speed Best Server by DL PUSC CINR Dependencies: Terminal, Carrier This is the cell that provides the highest CINR at a given pixel, for the PUSC zone. Best Server by DL FUSC CINR Dependencies: Terminal, Carrier This is the cell that provides the highest CINR at a given pixel, for the FUSC zone. DL Achievable Bearer Dependencies: Terminal, Carrier, Indoor, Service, Speed This array shows the combined coverage plot for the DL bearers of the service. The array shows the highest priority bearer with acceptable DL coverage, that is, where the DL coverage probability meets the reliability level specified in the Sim Display Settings tab of the Array Settings dialog box.


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DL FUSC Worst Interferer Array Dependencies: Terminal, Carrier This array displays the worst interferer at each pixel. The pixel ownership is determined by the Best Server by DL FUSC CINR array. DL PUSC Worst Interferer Array Dependencies: Terminal, Carrier This array displays the worst interferer at each pixel. The pixel ownership is determined by the Best Server by DL PUSC CINR array. DL OPUSC Worst Interferer Array Dependencies: Terminal, Carrier This array displays the worst interferer at each pixel. The pixel ownership is determined by the Best Server by DL OPUSC CINR array. DL AMC Worst Interferer Array Dependencies: Terminal, Carrier This array displays the worst interferer at each pixel. The pixel ownership is determined by the Best Server by DL AMC CINR array. DL AMC CINR Dependencies: Terminal, Carrier, Service, Indoor, Bearer This array displays the DL CINR in the AMC zone. For the downlink CINR analysis, the CINR is calculated by taking into account the level from the connected BS (reference base station) as server and the level from all other sites as interferers. The CINR represents an average value (with fades set to 0 dB). DL OPUSC CINR Dependencies: Terminal, Carrier, Service, Indoor, Bearer This array displays the DL CINR in the OPUSC zone. For the downlink CINR analysis, the CINR is calculated by taking into account the level from the connected BS (reference base station) as server and the level from all other sites as interferers. The CINR represents an average value (with fades set to 0 dB).

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General Arrays Throughput Array Dependencies: Terminal, Carrier The throughput array displays the information displayed in the Simulator throughput report in a graphical format. The throughput for a given sector is presented within the region specified by the Best Server by Preamble RSS array. The throughput is summed for all services. UL Required TX Power Dependencies: Terminal, Carrier, Indoor This array displays the minimum UL required TX power for a given receiver sensitivity (specified in the Site Database). CPE Azimuth Array Dependencies: Carrier This array displays the azimuth that the directional CPE should point to in order to connect to the best server.


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APPENDIX B

About the Prediction Management Algorithm Prediction files contain data that can be freshly regenerated at any time, but, as this process takes time, it is more efficient to store the files on the disk when they are created, and manage them as a cache of precalculated data. Therefore, in ENTERPRISE 6.0 onwards, the concept behind the storage of the prediction files is that they are stored on disk and remain stored, even if they become 'invalid' due to changes to the cell parameters or locations. The major benefit of this is that they can be reused whenever they become 'valid' again. It is evident from this that at some stage the disk might become full and consist of many unwanted prediction files. For this reason, these files are automatically managed within ENTERPRISE by a new caching algorithm, which can dispose of unwanted files on the basis of specific criteria, based on a 'least-used' algorithm. As a vital input to this algorithm, you need to specify the maximum disk space for the storage of these files, on a per prediction folder basis. This limit is specified on the User Data Directories tab of the Project Settings (Modify Project) dialog box, and is described in the ENTERPRISE User Reference Guide.

Example of Setting Maximum Disk Space for Prediction File Storage in the Modify Project dialog box

Overview of Algorithm The settings for maximum disk space specified, as described above, are stored in a configuration file in the root of the prediction folder. The prediction management algorithm is designed to manage the files as a cache, using a „weighting‟ function to determine which files are to be removed whenever the cache exceeds its maximum space. In order to monitor this, a statistics file is updated at the end of every prediction creation session.


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The weighting function takes the following factors into consideration for each prediction file (most important first) : The elapsed time since the file was last used The amount of time that was needed to perform the pathloss calculation The number of times the file has been loaded If a "disk full" error occurs during prediction creation, then the file management system may be automatically invoked early to try to provide some space for the prediction that has just been calculated. If this fails to provide enough space then a "disk full" error is written to the message log. The prediction management algorithm only monitors files generated by ENTERPRISE, and ignores any other files.

In This Section The Prediction Management Algorithm

42

The Prediction Management Algorithm Whenever necessary, the prediction management system gathers information about the prediction files from the statistics file. It uses the information to generate an ordered list of the files, prioritised for deletion. From the top of this list, the system deletes the files until the required disk space requirements have been satisfied. To determine a file‟s position in this prioritised list, the following formula is used: Position = ( Now – Last Loaded Time ) × modifier

A file with a large 'position' has more chance of being deleted than one with a small 'position'. The basic concept is as follows: The most important factor used in determining the position of a file in the list is the elapsed time since the file was last loaded. The position can also be influenced by a modifier weighting:

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

Files that were 'quick to create' are more likely to be deleted



Files that have been 'loaded many times' are less likely to be deleted


Modifier Calculation 1

2

The time taken to create the prediction is recorded and will result in an initial modifier as follows: Creation Time

Modifier

0-10s

1.2

10s-20s

1.15

20s-40s

1.1

40s-1.5m

1.05

1.5m-2.5m

1

2.5m-5m

0.95

5m-10m

0.9

10m-20m

0.85

20m-40m

0.8

40m+

0.75

The number of times a file has been loaded is recorded and then used to adjust the modifier, as follows: Number of loads

Add to modifier

0

+0.05

1-5

0

5-10

-0.03

10-20

-0.06

20-40

-0.09

40-80

-0.12

80-160

-0.15

160-320

-0.18

320-640

-0.21

640+

-0.24

All the above values are stored in the configuration file in the root of the prediction folder, and can be modified by your administrator if necessary.


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APPENDIX C

2g and 2.5g Algorithms This section contains information about the algorithms and calculations that ASSET uses in relation to 2g and 2.5g network planning. For information on the GSM Simulator algorithms and outputs, please see Static Simulation Algorithms and Outputs on page 79.

In This Section Interference Table Algorithm Interference and Connection Array Calculations Frequency Hopping Algorithms Non-Frequency Hopping Algorithms Automatic Frequency Planning (ILSA) MAIO Planning Cost Function GPRS and HSCSD Capacity Calculations FCC Calculations Frequency Calculations

45 47 50 52 53 55 55 58 60

Interference Table Algorithm The Interference Table stores the following four values for any pair of sub-cells A and B. These relate to the region where A is the best server. Field Name

Description

Co-channel Traffic

The amount of traffic served by cell A that would be affected by interference if A and B were to be assigned the same carrier.

Co-channel Area

The area served by cell A that would be affected by interference if A and B were to be assigned the same carrier.

Adjacent Channel Traffic

The amount of traffic served by cell A that would be affected by interference if A and B were to be assigned adjacent carriers.

Adjacent Channel Area

The area served by cell A that would be affected by interference if A and B were to be assigned adjacent carriers.

The values for area are obtained by averaging the probability of interference over the region where A is the best server. The average is taken over all pixels in the appropriate coverage array.


Page 45

For traffic, the value to be averaged is the probability of interference x the traffic (in mE) at that pixel. Thus it is necessary to have a traffic raster available to make this calculation. The probability of interference at a given pixel is calculated using a standard statistical technique based on a C/I signal threshold value and a standard deviation. The assumption is that a difference in signal level between server and interferer exactly equal to the threshold value would give rise to a 50% chance of co-channel interference. For more information on how these values can be specified, see the ASSET User Reference Guide. By default, a -18dB offset is used for the adjacent channel interference, relative to the co-channel interference. This means that if, for example, the co-channel C/I threshold value is set at 9dB, a signal difference of -9dB between server and adjacent channel interferer would give rise to a 50% chance of adjacent channel interference. The C/A offset can be modified in the Array Settings dialog box. All signal differences are converted into probabilities of interference. The following graph displays the spread of probabilities for both C/I and C/A based on the default Interference Weights. Here, the C/I signal threshold value is 9dB, using a standard deviation of 7.78dB.

C/I and C/A weights curve

An example of an Interference Table can be found, along with a description of its File Format, in the ENTERPRISE Technical Reference Guide.

Page 46


Interference and Connection Array Calculations This table shows the different interference analyses that are possible: Field Name

Description

Worst Connection C/Ic

Determines the co-channel C/I levels for all of the possible interfering frequencies that may be used by the MS-BTS connection. Each pixel presents the worst C/Ic level and frequency.

Worst Connection C/Ia

Determines the adjacent channel C/I levels for all of the possible interfering frequencies that may be used by the MS-BTS connection. Each pixel presents the worst C/Ia level and frequency.

Worst Connection C/(Ic+Ia)

Determines the combined co-channel/adjacent channel C/I levels for all of the possible interfering frequencies that may be used by the MS-BTS connection. Each pixel presents the worst C/I level and frequency.

Average Interference C/Ic

Sums the co-channel C/I levels for all possible interfering frequencies and presents the average C/Ic level.

Average Interference C/Ia

Sums the adjacent channel C/I levels for all possible interfering frequencies and presents the average C/Ia level.

Average Interference C/(Ic_Ia)

Sums the combined co-channel and adjacent C/I levels for all possible interfering frequencies and presents the average C/(Ic_Ia) level.

Worst Interference C/Ic

For non-frequency hopping networks sums all of the co-channel C/I levels for an interfering frequency. Each pixel presents the total C/I level, server and interfering sub-cells and interfering frequency.

Worst Interference C/Ia

For non-frequency hopping networks sums all of the adjacent channel C/I levels for an interfering frequency. Each pixel presents the total C/I level, server and interfering sub-cells and interfering frequency.

The worst connection and the worst interferer calculations are the same in the case of a non-frequency hopping network.

Worst Connection Array Calculation Method In the Worst Connection Array calculation, the connection refers to the carrier(s) corresponding to a single call: In the case of hopping frequencies, it corresponds to the entire group of hopping frequencies In the case of non-hopping frequencies, it corresponds to a single frequency The Worst Connection Array calculates the C/I per connection, summing over all interferers, and then selects the connection with the lowest C/I. The algorithm for this is as follows:

Where: For each non-hopping carrier fi in the serving sub-cell, C/I(fi) is calculated. ASSET Technical Reference Guide Version 6.1

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For the hopping frequency group in the serving sub-cell, a single C/I(FH) is calculated.

Average Connection Array Calculation Method The Average Connection Array calculates the C/I per connection, summing over all interferers, and then calculates the average of those. The algorithm for this is as follows:

(2) Where: is the averaged C/I for the hopping carriers. is the number of hopping frequencies. is the number of non-hopping frequencies. is frequency Diversity Gain. is the fractional loading, calculated as follows:

, where

is the number of hopping TRX.

are the non-hopping frequencies. For each non-hopping carrier fri in the serving sub-cell, C/I(fri) is calculated. For the hopping frequency group in the serving sub-cell, a single C/I(FH) is calculated. The denominator in the equation above can never be zero ( and cannot both be 0 at the same time). This is because ASSET does not allow you to set the total number of TRX allocated to a sub-cell to zero, if at least one carrier layer is allocated.

Worst Interferer Array Calculation Method The Worst Interferer Array calculates the C/I per frequency, summing over all interferers, and selects the frequency with the lowest C/I. It also finds the interferer that causes the most interference on that frequency. This array does not take into account fractional loading. The most interfered frequency and its corresponding C/I are calculated as follows: If

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, then


If

, then

Where: For each (non-hopping) carrier f1 in the serving sub-cell, C/I(f1) is calculated. The worst interferer is calculated as follows:

Total Interference Array Calculation Method The Total Interference Array calculates the C/I per frequency, summing over all interferers, and then sums the C/I for each frequency at the serving cell. This array does not take into account fractional loading. The total interference is calculated as follows:

Where: For each (non-hopping) carrier fi in the serving sub-cell, C/I(fi) is calculated.

Table of Default C/I BER Conversion Values This table shows the Default C/I BER Conversion Values in ASSET: C/I (dB)

Bit Error Rate

-10

0.5000000000

-9

0.4880000000

-8

0.4650000000

-7

0.4300000000

-6

0.3880000000

-5

0.3500000000

-4

0.3200000000

-3

0.3000000000

-2

0.2700000000

-1

0.2500000000

0

0.2200000000

1

0.2000000000

2

0.1700000000

3

0.1500000000

4

0.1200000000

5

0.1000000000


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C/I (dB)

Bit Error Rate

6

0.0900000000

7

0.0780000000

8

0.0660000000

9

0.0550000000

10

0.0450000000

11

0.0370000000

12

0.0300000000

13

0.0260000000

14

0.0200000000

15

0.0150000000

16

0.0120000000

17

0.0080000000

18

0.0060000000

19

0.0040000000

20

0.0020000000

21

0.0007000000

22

0.0001000000

23

0.0000070000

24

0.0000004000

25

0.0000000100

26

0.0000000001

27-45

0.0000000000

Frequency Hopping Algorithms The algorithms used for frequency hopping cells are as follows:

1 is used if

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, α is used if

, 0 is used otherwise


Where: C/I(i)

=

C/I ratio for frequency i

SSC(i)

=

Signal strength from frequency i for serving cell

i,j

=

A particular frequency

N

=

Number of interfering cells

n

=

Number of frequencies in serving cell

m

=

Number of frequencies in interfering cell K

SIC(K,i)

=

Signal strength from frequency i for interfering cell K

K

=

Interfering cell

L(K,j)

=

Load in interfering cell K on frequency j

V(K,j)

=

DTX factor in interfering cell K on frequency j

f (i)

=

Fractional loading for frequency i for interfering cell

α

=

Adjacent interference factor

Each C/I(i) is converted to a Bit Error Rate, BER(i) The following graph shows the relationship between the Probability of Bit Error and the C/I:


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BERAV(serving cell) is calculated as the average BER(i) for all frequencies in the cell:

Where: x Number of FH frequencies per TRX mFH

Number of FH frequencies/serving cell

nTRX

Number of TRX/serving cell

BERAV(serving cell) is then converted back to dB to give C/I (FH)(serving cell). If frequency diversity gain GFDIV(m) is enabled, you also need to add a given gain figure to the hopping C/I. For more information on this, see the ASSET User Reference Guide.

Synthesised Hopping Algorithm For synthesised hopping carrier layers, fractional loading is calculated as follows:

Where: is the number of TRX allocated to the hopping carrier layers is the number of hopping carriers

Non-Frequency Hopping Algorithms The calculations for non-frequency hopping are as follows:

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1 is used if

, α is used if

, 0 is used otherwise

P(i) = f(C/I(i)) P(i) is the Probability of interference, and is calculated from the cumulative normal distribution of combined standard deviation of serving and interfering cell models.

and PTOT = Average of all P(i) in the cell The following picture shows an example conversion curve:

Example C/I/Probability Curve

Automatic Frequency Planning (ILSA) ILSA (Intelligent Local Search Algorithm) is ASSET's frequency planning tool. Using an advanced heuristic algorithm, incorporating the latest techniques in combinatorial mathematics, ILSA searches for improvements based on user-specified criteria, and greatly speeds up the frequency planning process. Search algorithms specialise in looking for solutions to problems that have too many possible solutions to allow a simple solution. Advanced heuristic search algorithms use the algorithmic equivalent of taking the path that “looks like the best one”, They use a 'cost' function to determine the most desirable next state, which typically will be the state with the lowest cost. ILSA initialises with a random frequency plan (unless the option is chosen to load the current plan from the database). This means that for any two runs of ILSA, the results may not be the same. Moreover, certain starting frequency plans can allow ILSA to make either more rapid initial improvement or allow a much better plan to be found within a reasonable period of time.


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ILSA (as its 'Local Search' name implies) reduces the number of options it has for new states derived from a current state. ILSA can give special attention to areas of high cost within the network (analogous to areas of high interference), temporarily ignoring lower cost areas. This allows ILSA to make very rapid initial progress. For example, if ILSA is attempting to plan for a network requiring 60 carrier allocations, with 20 available carriers, and identifies a subset of 10 high cost carrier allocations, then the maximum number of new states that ILSA needs to consider has been reduced from 3.8*1025 to 6.1*1012. Random changes can be made by ILSA if only low improvement rates are being achieved, or if a dead end is reached. The algorithm monitors its own progress and will behave differently depending on how quickly the cost is decreasing at a given time. This intelligent behaviour enables it to continue finding improvements over long periods of time. The principle behind ILSA's algorithm is that a single number (the cost) measures the effectiveness of any particular frequency plan. The algorithm then tries to minimise the cost over the set of all possible plans. The cost function measures how much interference exists in the network, and what separations have been broken, while taking account of any user-specified 'importance' weightings for different sub-cells. As an optional add-on to ASSET, ILSA is licensed separately.

The Cost Function of the ILSA Algorithm The principle behind the algorithm used in the frequency planning tool is that the effectiveness of any particular frequency plan is measured by a single number (the cost). The algorithm then tries to minimise the cost over the set of all possible frequency plans. The cost function measures how much interference there is in the network, and also allows for the different weights that you may have imposed. For a given frequency plan the value of the cost function is given by the formula:

Where:

Page 54

=

The adjacent channel interference caused on allocation i by allocation j (Units: 200*mE or 20,000*km²)

=

The co-channel interference caused on allocation i by allocation j (Units: 200*mE or 20,000*km²)

=

The frequency allocated at allocation i

=

Members of the set of all frequency allocations

=

The retune cost associated with allocation i

=

The fixed or forbidden carrier cost associated with allocation i

=

The separation costs (from equipment, neighbours, exceptions or close separations) between allocations i and j

=

The handover count and intermodulation interference costs associated with allocation i


=

The weighting factor applicable to carrier allocation i

MAIO Planning Cost Function The cost function for MAIO planning is an aggregate of C/I and C/A separation counts generated by per cell pair frequency combinations, based on MAIO step and offset values, and weighted by the interference matrix. It has the following form:

Where: are sub-cells

and and

are traffic and area percentages are traffic and area associated with sub-cell c and

are interference matrix coefficients

is the C/I or C/A separation count for all TRX combinations on subcells

GPRS and HSCSD Capacity Calculations This section describes GPRS and HSCSD capacity calculations, as follows: TRX Requirement - Circuit Switched Traffic and HSCSD TRX Requirement -Circuit Switched, HSCSD and GPRS Traffic Grade of Service and Data Rate Channel Occupation Table

TRX Requirement - Circuit Switched Traffic and HSCSD The number of TS required ( ) for the CS traffic load ( Grade of Services and a choice of Erlang table.


) given specified two

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The number of TRX required is determined using the Channel to Transceiver Map by increasing the number of TRX from 1 until the map‟s and

is equal to or greater than

is greater than or equal to

.

TRX Requirement - Circuit Switched, HSCSD and GPRS Traffic For cells where GPRS is enabled, the number of TS required from the shared traffic channels for the GPRS ( average GPRS data rate per TS (

) traffic load (

) can be determined using the

):

The total number of TS required for CS and GPRS traffic (

) can then be

determined using the average Circuit Switched TS requirement channel occupation efficiency (e) as follows:

and the

Where: is total shared traffic channels required is average (long term) number of TS required for Circuit Switched traffic (= is average (long term) number of TS required for HSCSD traffic (=

) )

The channel occupation efficiency (e) is determined by first calculating ( ) without dividing by e and then using the result to look up e in the Channel Occupation table. The number of TRX required and are determined using the channel to transceiver map by increasing the number of TRX from the result of the previous section until the number of available TS for traffic (NCS allocation) is equal to or greater than

.

Grade of Service and Data Rate Circuit Switched Traffic This section presents the calculation for the blocking for the current allocation of TRX for CS and for each HSCSD multi-slot type traffic (%). It has been assumed throughout that CS traffic and HSCSD traffic will take precedence over GPRS traffic and therefore the Grade of Service for CS and HSCSD will not be affected by the GPRS load. Calculate the blocking for the CS traffic given the traffic load ( current allocation of TRX using the selected Erlang table.

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) the


HSCSD Blocking Blocking is calculated from Erlang B or C using the number of HSCSD TS currently allocated to the cell and the HSCSD load in timeslot Erlangs. = HSCSD traffic load =timeslots allocated to CS = number of CS timeslots that may be allocated to HSCSD Erl = Erlang B or C functions returning blocking given traffic and channels

Summary blocking is the average of the four separate blocking values weighted by the known distribution. GPRS Data Rate The GPRS data rate for the current allocation of TRX is determined by first calculating the number of TS required for CS and HSCSD. The remaining TS are available for GPRS. That is:

Where: e

is the efficiency from the Channel Occupation table determined from N is the number of TS from the Channel Carrier Map for the current allocation of TRX


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Channel Occupation Table A table (similar to the one shown below) is used to relate the number of timeslots available to the channel occupancy for GPRS capacity calculations. The table is stored in the database and you can edit the occupancy values.

Example of Channel Occupation Table, for Illustrative Purposes Only

FCC Calculations This section describes the algorithms used to calculate the data provided in the FCC report. Antenna Height AAT The Antenna Height AAT is calculated in metres. The calculation is: Antenna height + Site ground height + Radial average terrain elevation The Radial average terrain elevation is the average ground height mapped along a radial of between 3 km and 16 km from the site. If the mapping data prevent this then it will not be calculated and this will be flagged in the FCC report. Feature height data and clutter heights are ignored in the calculation. The best available resolution of the map data is used for this calculation. If the best map data is 1000 m resolution then you will receive a warning noting that the map data is of insufficient resolution for the FCC form.

Page 58


Used Antenna Height The Used Antenna Height AAT (metre) is subject to some minimum values according to the FCC category and, the ERP. Category

ERP (if necessary)

Minimum

32dBu Served

N/A

Minimum of 30 metres

32dBu Unserved

ERP>=10 W

Minimum of 30 metres

ERP<=10 W

Minimum of 3 metres

N/A

Minimum of 8 metres

Gulf of Mexico

You will receive a warning if the Average Radial distance exceeds 40.2 km (79.1 km for Gulf of Mexico cells). Transmitting ERP Watts The transmitting ERP for a cardinal radial is the radiated power in Watts taking into account the antenna gain for the azimuth, the downtilt and the base station powers/losses. You will receive a warning if the ERP exceeds 500W. Used ERPS This is the value of the transmitting ERP which is used in the calculations, it is the Transmitting ERP subject to certain minima. Used ERP is the maximum of: 0.1 W Maximum ERP/500 Transmitting ERP for the radial Area within the Service Area Boundary This will be calculated by finding the distance to the SAB for each degree by linear interpolation of distance as a function of angle, hence dividing the area into triangular sectors, joining at the site. The total area is then calculated by adding up the areas of each of the triangles. Heron's Formula for calculation of area of scalene triangle: A = SQR(S (S-a) (S-b) (S-c)) SQR - Square Root a, b, c – sides of the triangle S – half the perimeter of triangle, that is (a+b+c)/2


Page 59

Distance to Service Area Boundary The distance to the SAB is calculated as shown here: For:

The distance to the SAB is:

32dBu Served

D = 2.531 x Used Antenna Height(m) ^ 0.34 x Used ERP for Radial in Watts ^ 0.17

and 32 dBu Unserved Gulf of Mexico

Subject to a minimum distance of 5.4 km D = 6.895 x Used Antenna Height(m) ^ 0.30 x Used ERP for Radial (W) ^ 0.15 There is no minimum distance for this SAB

Frequency Calculations Two frequency calculations are used when you create a Frequency Plan report. Effective Frequency Re-use The effective frequency re-use is an approximate indication of the quality of the hopping network. It can be calculated for each sub-cell and also the average of these calculated to give a figure for the network as a whole.

Where: REFF is the Effective Frequency Re-use for a sub-cell NF is the total number of carriers available to hopping TRX on the sub-cell (note: this is not the MA list length) NTRX is the number of hopping TRX on the sub-cell Frequency Load The average frequency load is another approximate indication of the quality of the hopping network. It can be calculated for each sub-cell and also the average of these calculated to give a figure for the network as a whole.

Page 60


Where: LFREQ is the Frequency Load of a sub-cell LFRACTION is the Fractional Load of a sub-cell LHW is the Hardware Load of a sub-cell NTRX is the number of hopping TRX on the sub-cell NMA is the MA list length (i.e. all carriers assigned to hopping carrier layers on the subcell) E is the traffic that could be carried by the timeslots of hopping TRX on the sub-cell, at a user specified Grade of Service (GoS), i.e. NCSTS is the total number of timeslots installed – this value is derived from the Carrier to Timeslot map using NTRX.


Page 61

Page 62


APPENDIX D

Packet Quality of Service Algorithms This section details the Packet Quality of Service algorithms used in ASSET, and therefore explains the associated reports generated by the QoS analysis. The packet QoS analysis feature is a downlink cell level simulation, with 10 ms (single radio frame) resolution. It is a trace-driven queuing simulation, the packet transmission delays through a cell are modelled by a queuing system, which has a time-series of packet traffic offered to it. It is based on the www traffic model and multiple, prioritised services can be specified. The simulation is run for a calculated period of time, then the results are presented on the summary page of the QoS Analysis wizard as a spread sheet and graphs. The results can be saved as an Excel workbook containing graphs and spreadsheets, or the raw the raw data saved in text or comma separated variable (csv) format. The graphs include the cumulative delay distributions of the packet services on each cell, enabling you to view percentile delays. The Excel workbook contains the following data per service, per carrier and, per cell: Mean and standard deviations of the queuing delays 95th percentile delay Confidence interval half width Mean transmission time Mean retransmission delay Total transmission delay ( mean queuing delay+mean transmission time+mean retransmission delay Graphs for each cell and carrier giving the cumulative queuing delay probability distributions

In This Section Simulation Inputs for QoS Analysis Traffic Generator for QoS Analysis Time Simulator for QoS Analysis Results of QoS Analysis References ASSET Technical Reference Guide Version 6.1

64 64 71 73 77 Page 63

Simulation Inputs for QoS Analysis Most of the packet QoS analysis parameters are input when you configure the network design, ready for the simulation. The site/cell, carrier, terminal type and service type parameters are configured at this stage, and the QoS analysis uses these parameters later to deduce: The number of queues to model The parameters of the traffic streams to generate Priorities of the service types, before the time simulation You then need to run at least two snapshots of the simulation, although at least 100 snapshots are recommended to produce statistically valid inputs to the QoS analysis. The simulation calculates the mean blocking probability for each packet service type, on each carrier, on each cell in the simulation in the simulation and the mean number of terminals connected to each cell, per carrier, per service, and per bitrate. The mean blocking probability and mean number of terminals are then used as inputs to the QoS analysis.

Preliminary Tests Some conclusions can be deduced from the input data without running the simulation at all. These are: 100% blocking on any service will result in delays building up to infinity Zero traffic on all services will result in zero delays Zero blocking on all services will result in zero delays These results are immediately updated on the summary page of the QoS Analysis dialog box.

Traffic Generator for QoS Analysis This section describes the traffic generation processes: Matching Generated Traffic to the Simulator's Mean Number of Served Users WWW Traffic Model Packet Model About the Code Schemes for GPRS QoS Profiles for GPRS

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Matching Generated Traffic to the Simulator's Mean Number of Served Users The Simulator calculates the number of users which can be served for each service, by each cell and carrier in every snapshot. The mean is then calculated over the total number of snapshots run in the simulation. This figure is the starting point for the QoS analysis; it provides the mean number of users for each packet service in each cell and carrier in the simulation. The traffic generator generates a time series of packet sessions for each service in a cell and carrier, which matches the mean number of users over time, as shown in the following diagram:

The red line represents the mean number of users input from the simulation. The orange blocks represent the number of users varying over time. The blue blocks represent the holding times of the packet sessions produced by the traffic generator. Little‟s theorem gives us the relation between the arrival rate of packet sessions, the mean number of users in the cell and their mean session holding time. Let = mean session arrival rate

T = mean session holding time = mean number of users in the cell Little‟s result says that:

N

.T


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The traffic generator therefore generates sessions with mean arrival rate calculated from the mean number of users in the cell, and the mean session holding time, which is determined using the WWW traffic model.

WWW Traffic Model The WWW traffic model is used to generate the activity of each packet session. The following diagram shows a typical WWW browsing (packet service) session, which consists of a sequence of packet calls. The user initiates a packet call when downloading a WWW document and during a packet call, several packets may be generated. After the document has completely arrived, the user requires reading time to study the information. The following diagram shows packets from a source, which may be at either end of the link, but not both ends simultaneously.

The model requires the generation of six random variables: Session arrival process - The arrival of session set-ups to the network is modelled as a Poisson process. For each service there is a separate process. Number of packet calls per session, Npc - A geometrically distributed random variable* is used, with a mean number of packet calls of 5. Reading time between packet calls, Dpc - A geometrically distributed random variable* is used, with a mean reading time of 4 to 12 s. Number of packets per packet call, Nd - A geometrically distributed random variable* is used, with a mean number of packets of 25. Size of packet, Sd - A Poisson distributed random variable is used, with a mean size of 480 Bytes. Page 66


Inter arrival time between packets, Dd - A geometrically distributed random variable* is used. * (In other words, a discrete representation of the exponential distribution.) The session holding time is modelled implicitly by the number of events during the session. Using the WWW traffic model, the mean holding time of a packet session T is given by:

T

( N pc 1)D pc

N pc ( N d 1)D d

Packet Model The traffic generator uses the session arrival and WWW models to produce a list of packets for each service type, for each cell, for each carrier, lasting the duration of the simulation. Each packet is stamped with its arrival time at the cell, and also keeps a record of when it gets transmitted (its departure time), and its randomly generated size. The packet service type lists are then merged and sorted in arrival time order, to produce a single list of packets offered to the cell carrier:

In the diagram, the data contained in the packet boxes is the arrival time, the departure time and the packet size. Initially, the packet‟s departure time is set to be the same as its arrival time. The departure time is updated each time step the packet is queued, until it is successfully transmitted. A histogram of the generated traffic is displayed for each service on each cell and carrier in the graphs tab of the QoS Analysis dialog box.


Page 67

About the Code Schemes for GPRS The peak throughput and block size in GPRS is determined by the coding scheme and, in EGPRS, by the coding and modulation scheme, as shown in the following table: System

Scheme

GPRS

CS - 1

EGPRS

Link Adaption Family

Modulation

Peak Rate per Slot Blocks Per (kb/s) 20 ms

RLC Block Size (bits)

GMSK

9.05

181

1

CS - 2

13.4

268

CS - 3

15.6

312

CS - 4

21.4

428

8.8

176

MCS - 1

C

GMSK

MCS - 2

B

11.2

224

MCS - 3

A

14.8

296

MCS - 4

C

17.6

352

MCS - 5

B

MCS - 6

A

29.6

MCS - 7

B

44.8

MCS - 8

A

54.5

1090

MCS - 9

A

59.2

1184

8 - PSK

22.4

1

448 592

2

896

In order to calculate the block size, the coding scheme allocated to each connection needs to be input from the simulation (a mean number of MS connections per coding scheme, per bearer, per service type, per sub-cell array will be required as input). The block size can be inferred directly from the GPRS coding schemes, however, the following mapping is used to calculate the block size for the first transmission attempt for the link adaptation families: A – 592 bits B – 448 bits C – 352 bits There are no default BLER versus C/I curves for MCS – 7, 8 and 9. In the retransmission model, the lower bitrates of the link adaptation families are used.

QoS Profiles for GPRS GPRS defines several different QoS Profiles which consist of four components: Precedence class Delay class Reliability class Throughput class

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Precedence Class Traffic is given a precedence of 1 (premium), 2 (standard) or 3 (best effort), with a precedence of 1 being highest. This precedence is similar to the service type priorities set in the QoS Analysis wizard in ASSET, however the number of priorities needs to be restricted to three and different service types can have equal priorities. The precedence class is used to prioritise the queues. For more information, see Simulation Model on page 71.

Delay Class GPRS has four different traffic classes. The following table shows the parameters that specify the related QoS requirements: Traffic Class

Medium

Application

Data Rate (kbit/s)

One-way Delay

Conversational

Audio

Telephony

4-25

<150ms

Data

Telnet

<8

<250ms

Audio

Streaming (HQ)

32-128

<10s

Video

On-way

32-384

<10

Data

FTP

-

<10s

Audio

Voice messaging

4-13

<1s

Data

Web browsing

-

<4s/page

Streaming

Interactive

For background traffic, only bit integrity is required. 3g service types have traffic classes and are used in the packet service types dialog box in 3g to set default www parameters and delay targets. In the ASSET QoS Analysis the achieved 95th percentile delay per service type, per carrier, per cell is compared with the target 95th percentile delay. Traffic class is used to prioritise the queues. For more information, see Simulation Model on page 71.

Reliability Class Applications can request different reliability classes, depending on their ability to handle corrupt and duplicated blocks. The following table shows the reliability classes that can be selected: Reliability Class

Lost Block Probability

1

10

2

10

3

10


Page 69

Reliability is only considered in terms of the retransmission delay formula used in ASSET. This uses the block error rate (BLER) to analytically calculate the retransmission delay for packet services. A different approach is proposed for GPRS. The BLER can be calculated using the Average Data Throughput per Timeslot vs Average Connection C/I curves. The formula is:

where: Throughput(C/I) = throughput in kb/s read off the throughput per timeslot graph for the C/I achieved by the link

PeakDataRatePerSlot = peak rate per slot for the given coding scheme (the asymptote of the throughput per timeslot graph BLER(C/I) = block error rate for the C/I achieved by the link The mean BLER over all the connections made per service type, per sub-cell is required as an input from the simulation, and is reported in the QoS Analysis spreadsheet. Block errors also have implications for the retransmission model. For more information, see Mean Retransmission Delay on page 76.

Throughput Class Applications can request different mean and peak throughputs, in order to request the desired throughput for bursty IP traffic. Peak throughput applies to short intervals where the transfer rate is at a maximum. Mean throughput describes the data transfer rate over an extended period of time, which could involve many idle periods. Peak throughput class

Peak throughput (kb/s)

Mean throughput class

Mean throughput (bytes per hour)

1

8

1

100

2

16

2

200

3

32

3

500

4

64

4

1 000

5

128

5

2 000

6

256

6

5 000

7

512*

8

1024*

17

20 000 000

9

2048*

18

50 000 000

*Data rate only reachable 31 with UMTS or EDGE

Best Effort

In GPRS, the peak throughput is determined by the peak data rate per slot achievable by the coding scheme, and the number of timeslots for which the MS is enabled. The peak throughput is calculated as follows:

PeakThroughput

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PeakDataRatePerSlot * BlocksPerFrame * MaxNumberOfSlots


The coding scheme is identified by the bearer allocated to the connection during the simulation and the maximum number of timeslots enabled on the MS will be a parameter set on the terminal type. It is therefore possible to do a preliminary check prior to running the GPRS QoS analysis to determine the peak throughput achievable for each service type on each sub-cell. The peak throughput is reported in the QoS Analysis spreadsheet. The mean throughput is logged as successful transmissions are made from the queue in the QoS analysis, and are reported in the QoS Analysis spreadsheet.

Time Simulator for QoS Analysis This section describes the time simulation processes and assumptions: System Model Simulation Model

System Model for QoS Analysis The call admission manager monitors the system's available capacity and accommodates new packet transmission requests, at the same time ensuring the QoS of existing connections. This may be situated at the BSC in a 2g network or the RNC in a 3g network. The steps of a connection admission procedure are: A new packet transmission request is received by the call admission manager The capacity of the destination cell is monitored The system either accepts or blocks the new connection If the QoS of an existing connection is degraded, it is dropped

Simulation Model for QoS Analysis The simulation models the connection admission procedure by making the following assumptions: The call admission manager monitors the cell capacity in every radio frame, that is every 10ms The cell capacity for each service type is generated using the blocking probability input from the simulation The blocking decision is prioritised to accept new connections in the priority order of their services The dropping of existing connections is not modelled The cell capacity for each service is determined in each frame by generating a uniformly distributed random number for each packet held in a queue. If the random number is greater than the blocking probability, the packet starts transmission in that frame. If the random number is less than of equal to the blocking probability, the packet is delayed in the queue until the next frame. ASSET Technical Reference Guide Version 6.1

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If the packet call mode is selected instead of the packet mode, connection admission decisions are taken on a packet call, instead of an individual packet basis. The service prioritisation is modelled in the simulator. All the packets awaiting transmission through a cell are stored in a set of queues, one for each service type. A diagram of the queuing model which would be used for three packet services being transmitted through a cell is shown here:

Queuing Model - example

The rule is then applied that if admissions for each service are considered in priority order, and that if any higher priority packets remain queued, no lower priority packets are admitted. By the end of the simulation, the simulator will have produced a list of transmitted packets, each stamped with its arrival and departure times from the cell. A histogram of the queue length throughout the simulation is displayed for each service on each cell and carrier in the graphs tab of the QoS Analysis dialog box.

Packet QoS Session Timeout Calculation for CDMA2000 The main limitation on capacity on CDMA systems is the forward link PA power available. The simulator provides us with data on the total available transmit power on the sector carrier (minus noise contributions) and the average transmit power required per sector, service , carrier or bearer for each user.

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When a terminal is connected and active, and there is no data to transmit, it uses a fundamental and supplemental channel. For example, in between packets it uses a 1/8th rate fundamental channel. This means that a terminal is still consuming transmit power between packet calls. The session timeout parameter was added to prevent all the available power being consumed by terminals transmitting at 1/8th rate, which would mean that no packet data could be transmitted. The session timeout parameter is employed to kill any sessions which have been active for longer than the session timeout, thus freeing up transmit power and allowing packets or packet calls to be transmitted.

Results of QoS Analysis This section describes the analysis results: •

Confidence Interval Half Width

•

Simulation Duration

•

Delay and Cumulative Delay Probability Distributions

•

Mean and Standard Deviations of the Queuing Delays

•

95th Percentile Delay

•

Mean Transmission Time

•

Mean Retransmission Delay

Confidence Interval Half Width The performance measure of the simulation is the mean delay of the first service on the cell. An estimate of the length of time for which a queue simulation should be run has been obtained by setting up a simulation for an M/M/1 queue, for which analytical results for the mean delay can be obtained, and experimentally determining how long the simulation should be run to obtain results of a given accuracy. To get an accuracy of 10% at a 95% confidence level, the following procedure has been recommended: 1

Set the basic run length to ensure at least 1000 or 2000 packet admission requests are made to the cell for each service.

2

Repeat the run (replicate) 5 times and calculate the confidence interval half width H5.

3

If the confidence interval is less than 10% of the mean delay, the desired accuracy has been obtained.

The confidence interval half width H5 is calculated by repeating runs, using a different random number stream for each run (3). Suppose we make k runs (replications), each generating m sample values of the packet delay, Y. Let Y1, Y2, Y3,…, Yk be the mean values of the k runs. The mean values are independent, since a different random number stream was used for each run and, for a sufficiently large m, it will be approximately normally distributed. The confidence interval half width Hi is then calculated from the sample mean ASSET Technical Reference Guide Version 6.1

, and variance σ . 2

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k Y i k i 1

Y

k

2

i 1

(Yi Y) 2 (k 1)

2. m

Hi

Simulation Duration This is calculated for each cell and carrier. The value depends on the parameters that you have set for the services supported by that cell, and carrier, and the mean number of users of those services input from the simulation. Using the same notation as the www traffic model section, plus the following definitions:

N req

= required number of packets

S req

= number of sessions required to generate

Treq

= time until the

S req

N req

packets

session arrives

D = recommended simulation duration Each session contains

S req

N pc .N d

packets, so

N req N pc .N d

(1)

The session arrivals are modelled as a Poisson process, and so the expected time until the

Treq

S req

session arrives is:

S req (2)

Substituting Little's law and equation (1) and (2),

Treq

N req .T N pc .N d .N

Adding the duration of the

D

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N req N .N pc .N d

S req

session itself, the simulation duration is:

1 .T


Delay and Cumulative Delay Probability Distributions Graphs of the delay probabilities and the cumulative delay probabilities are produced for each service, on each cell and carrier. The delay probability graphs are the most easily understood. It will be apparent that the highest priority service should have a delay distribution, which peaks before the next highest priority service, and so on. However, the cumulative delay probability graphs are more useful, because you can read any percentile delay from them. The data for these graphs will be collected by maintaining counts during the simulation. For example, when a packet which has been queued for 4 frames is finally transmitted, the count in the 4 frame bin will be incremented. If there are N bins, each bin represents a delay of F frames, and c is the count in a bin at the end of the simulation, their state can be represented by this table: Bin

Delay

Count

0

0.F

C0

1

1.F

C1

2

2.F

C2

...

...

...

N

n.F

Cn

...

...

...

N

N.F

CN

Total number of packets transmitted during the simulation: N

TP

ci i 0

Delay probability of n.F frames:

P ( n)

cn TP

Cumulative delay probability of n.F frames: n

ci CP(n)

i 0

TP

Mean and Standard Deviations of the Queuing Delays The following are the mean and standard deviations of the queuing delays:

N D Mean delay


F.

n.P(n )

n 0

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N Standard deviation

(F.n n 0

D ) 2 .P(n )

95th Percentile Delay The 95th percentile is calculated from the cumulative delay graph, and compared with the target 95th percentile delay, that you originally set in the Packet Service dialog box. If the delay calculated from the graph is greater than the target, a „QoS target failed‟ message is generated, listing the services which have failed on a particular cell and carrier. If the delay is less than the target, a „QoS target achieved‟ message is displayed in the QoS Analysis summary page.

Mean Transmission Time This is calculated using a running mean of the transmission time of each packet transmitted by the simulation. The packet transmission time is calculated from the mean packet size Sd (Bytes), (a Poisson distributed random variable, with the mean size set in the Packet Service dialog box), and the service bitrate b (kbs-1)

).

Transmission time:

Ttrans

8. S d 1000.b

Mean Retransmission Delay Error detection and correction across the air interface is handled by the Radio Link Control (RLC) sublayer, and is described in UMTS Standard TS 25.301. Packets are segmented by the RLC into equal sized blocks for transmission across the air interface. The block size and bearer rate determine the number of blocks which are transmitted per radio frame. The RLC then transmits the blocks, detects dropped or corrupted blocks and guarantees their delivery by retransmission. The retransmission protocol can be configured to provide different levels of QoS. The retransmission protocol which is modelled in the calculation of the retransmission delay is Stop-andWait ARQ (Automatic Repeat reQuest). This has the following features: One block is received and handled at a time The receiver acknowledges each correctly received block If a block is corrupted, the receiver discards it and sends no acknowledgement The sender uses a timer to determine whether or not to retransmit The sender keeps a copy of each transmitted block until its acknowledgement has been received Finally, the blocks are put back into order and reassembled into packets by the RLC at the receiver

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In order to calculate the average retransmission delay, the block error rate (BLER) at which the system will operate is required as an input. A typical value of 10% is set as the default. You also need to set the re-transmission timeout in units of radio frames. The BLER can then be used to calculate the increase in traffic through the link caused by retransmission, and the mean or median retransmission delay:

Mean retransmission delay

0.01. rt

BLER 1 BLER

1 seconds

References The following are documents that have been referred to throughout this chapter: “Selection procedures for the choice of radio transmission technologies of the UMTS” TR 101 112 v3.2.0, p.34 “Quality of Service for Multimedia CDMA”, N. Dimitriou, R. Tafazolli, G. Sfikas, IEEE Communications Magazine, July 2000 “Simulating Computer Systems”, M.H. MacDougall, MIT Press, p.114 “Introduction to Mathematical Statistics”, R.V. Hogg and A.T. Craig, CollierMacmillan Ltd, p.193


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APPENDIX E

Static Simulation Algorithms and Outputs The Simulator in ASSET enables you to perform static simulations for your network (depending on your licence). The following technologies are supported: GSM UMTS (FDD) GSM/UMTS (joint) CDMA2000 EV-DO Fixed WiMAX Mobile WiMAX There are technology-specific documents available which contain comprehensive details of all the algorithms and outputs related to the Simulator. If your company is registered for a customer web account, and you know the login password, you can download these specialist documents. To do this, log in to the Support website, click the „User Reference Guides‟ link, and then click the link named „Static Sim‟ (Static Simulation Algorithms and Outputs).


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F Frequency Planning automatically using ILSA • 53

Index

G GPRS algorithms • 45 arrays • 14, 15 GSM algorithms • 45

A Algorithms FCC calculations • 58 Frequency hopping • 50 Frequency Re-use and Load • 60 GPRS and HSCSD capacity • 55 ILSA cost function • 54 Interference arrays • 47 Interference Tables • 45 MAIO planning cost function • 55 Non-Frequency hopping • 52 Packet QoS • 63 Prediction file caching algorithm • 41 Arrays 2g (GSM Sim) • 18 2g and 2.5g (Non-Sim) • 8 3g (UMTS and CDMA2000) • 20 best server • 8, 9, 17 CDMA2000 • 20 descriptions • 7 GSM (Sim) • 18 HSDPA • 29 interference (2g Non-Sim) • 11 LMU • 10 measured cells (LMU) • 10 pilot coverage • 21 types available • 7 UMTS • 20 WiMAX (Fixed) • 32 WiMAX (Mobile) • 34 Assignments, carriers • 53

B Best Server arrays • 8, 9

C Caching algorithm for predictions • 41 Carriers assignments • 53

H HSCSD algorithms • 45

I iDEN algorithms • 45 ILSA about • 53 cost function • 54 Interference arrays • 8, 11, 12, 13

L LMUs arrays • 10

M Measured cells, arrays • 10

P Packet Quality of Service algorithms • 63 Planning frequency • 53 PMR algorithms • 45 Prediction file management • 41 Predictions file caching system • 41 file management algorithm • 41

Q QoS algorithms • 63

E

S

ECSD algorithms • 45 EGPRS arrays • 15, 16, 17

Serving Cell arrays descriptions • 8, 9


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ASSET Technical Reference Guide

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