aircominternational-casestudy-ltesmallcellplanningusingasset

Case Study LTE Small Cell planning using ASSET

AIRCOM International International Cassini Court, Randalls Way, Leatherhead, KT22 7TW United Kingdom www.aircominternational.com

Copyright 2012 AIRCOM International - All rights reserved. No part of this work, which is protected by copyright, may be reproduced in any form or by any means - graphic, electronic or mechanical, including photocopying, recording, taping or storage in an information retrieval system – system – without the written permission of the copyright owner.

Table of Contents 1 2 3

4

5

6

7 8 9

Executive Summary ......................................................... ................................................................................ ........................................... .................... 3 Introduction .......................................... ................................................................. ............................................. ............................................. ......................... 4 Configuration ............................................ .................................................................. ............................................ ........................................... ..................... 4 3.1 Analysis Area ............................................ .................................................................. ............................................ ................................... ............. 4 3.2 Propagation Modelling .......................................... ................................................................. ............................................. ........................ 4 3.3 Macrocell Layer ............................................................... ...................................................................................... ................................... ............ 5 3.4 Small Cell Layer............................................ ................................................................... ............................................. ............................... ......... 5 3.5 Traffic Model ................................................ ...................................................................... ............................................ ................................ .......... 5 3.6 Traffic Raster ............................................ .................................................................. ............................................ ................................... ............. 5 Coverage Analysis ............................................. ................................................................... ............................................ ................................... ............. 6 4.1 Coverage with Building Vectors Vect ors displayed ............................................ ............................................................ ................ 7 4.1.1 LTE Macrocell Best RSRP ........................... ................................................. ............................................. ................................ ......... 7 4.1.2 LTE Small Cell Best RSRP ................................................ ....................................................................... ................................ ......... 7 4.1.3 Combined LTE Macrocell & Small Cell Best RSRP.......................... RSRP............................................... ..................... 8 4.2 Coverage Statistics ........................................... .................................................................. ............................................. ........................... ..... 8 Interference/Quality Analysis ........................................... .................................................................. ........................................... .................... 9 5.1 Interference/Quality with Building Vectors displayed ............................................ .............................................. 9 5.1.1 LTE Macrocell Best RSRQ ........................................................... ................................................................................ ..................... 9 5.1.2 LTE Small Cell Best RSRQ ............................................. .................................................................... ................................. .......... 10 5.1.3 Combined LTE Macrocell & Small Cell Best RSRQ (Single Carrier) ..................... 10 5.1.4 Combined LTE Macrocell & Small Cell Best RSRQ (Two Carriers) ...................... ...................... 11 5.2 Interference/Quality Statistics .......................................... ................................................................. ................................. .......... 11 Failure rate and failure reasons analysis ........................................... .................................................................. .......................... ... 12 6.1 Failure Rate Arrays .................................... .......................................................... ............................................. ................................. .......... 12 6.1.1 LTE Macrocell Failure Rate ........................................... .................................................................. ................................. .......... 12 6.1.2 LTE Small Cell Failure Rate ........................................... .................................................................. ................................. .......... 13 6.1.3 Combined LTE Macrocell & Small Cell Failure Rate (Single (Si ngle Carrier) ................... 13 6.2 Failure Reason Arrays ................................... ......................................................... ............................................. .............................. ....... 14 6.2.1 LTE Macrocell Failure Reason ............................................................. ........................................................................ ........... 14 6.2.2 LTE Small Cell Failure Reason .......................................... ................................................................. .............................. ....... 15 6.2.3 Combined LTE Macrocell & Small Cell Failure Reason (Single (Si ngle Carrier) ............... 15 6.3 Simulation Statistics........................... Statistics................................................. ............................................. ......................................... .................. 16 Conclusion ............................................ ................................................................... ............................................. ............................................ ...................... 17 Glossary ............................................ .................................................................. ............................................ ............................................. .......................... ... 18 Appendix A - About the Products and modules used used in this application note ................. 19 9.1 ASSET 8.0......................................... ............................................................... ............................................ ......................................... ................... 19 9.2 Myriad .......................................... ................................................................. ............................................. ............................................ ...................... 19

LTE Small Cell planning using ASSET

© AIRCOM International, International, 2012

Page 2 of 20

1 Executive Summary With wireless data already predicted to exceed wired data in the next few years and network capacity demands to increase 20-40 fold over the next 5 years, mobile operators are under pressure to dramatically increase their network capacity and maintain data throughput rates, in a cost effective manner. Embracing a Small Cell strategy seems to be the most common approach to achieve this across the World’s operators. Small Cell technology (which includes femto, pico and micro cells) is currently in use by 67% of operators according to the Small Cell Forum and usage will increase from 4.3 million small cells to 36.8 million by 2016. Operator needs a planning strategy to ensure capacity issues are addressed and throughput rates are maintained for continued positive customer experience. Small cells can solve the data bandwidth issues and provide improved indoor coverage but careful planning is critical to ensure they do not introduce additional network interference and degrade overall network performance. A case study will be presented on how LTE Small Cells can be planned with ASSET 8.0 using a high-traffic, high-density area of central London, in the United Kingdom, which contains both Small Cells and Macro cells. We will demonstrate how to setup a Small Cell LTE layer on top of an LTE Macrocell layer in AIRCOM’s ASSET Radio Network Planning tool and how the Coverage, number of served users, throughput and quality improve significantly by doing so. It will also show that the introduction of Small Cells provides the biggest benefit in terms of improving the number of successfully served terminals and that having separate carriers for the macro and small cell layers helps in reducing failures further particularly those due to capacity problems.



Page 3 of 20

2 Introduction This document demonstrates how LTE Small Cells can be planned with ASSET v8.0. For this case study we are using a high-traffic, high-density area of central London, in the United Kingdom, which contains both Small Cells and Macro cells. The Macrocell sites locations are real ones obtained from the UK’s regulator’s published data. We will show the configuration in ASSET, the Coverage (RSRP) and Interference (RSRQ) analysis, as well as the number of Served Terminals Macrocell layer alone, for the Small Cells alone and for the combined Macro + Small cell layers using a single carrier and then using separate carriers. Details of the configuration and of the reports run can be obtained by contacting your local AIRCOM representative. We will demonstrate how to setup a Small Cell LTE layer on top of an LTE Macrocell layer in AIRCOM’s ASSET Radio Network Planning tool and how the Coverage, number of served users, throughput and quality improve significantly by doing so. It will also show that the introduction of Small Cells provides the biggest benefit in terms of improving the number of successfully served terminals, but that having separate carriers for the macro and small cell layers helps in reducing failures further particularly those due to capacity problems.

3 Configuration 3.1 Analysis Area Area The Analysis Area covers a dense urban area of central London that includes Covent Garden and Holborn and is bounded by Soho, Leicester Square and Tottenham Court Road.

3.2 Propagation Modelling A MYRIAD propagation model was was configured using Height data to create Facets, Clutter data to create Morphologies and Building Vectors to create Graphs along the streets. For the configuration of the Myriad model, please contact your AIRCOM local representative.



Page 4 of 20

Predictions for both Macrocells and Small Cells were calculated usi ng the MYRIAD Model with a Prediction Resolution of 5m (even though the highest Map Data resolution was 50m) and Prediction Radius of 3km.

3.3 Macrocell Layer The LTE Macrocells of UK Operators, for the central London area, have been created and used to generate Macrocell Coverage. They have been configured to use a single 10MHz Carrier with a Max TX Power of 10W (40dBm). From the report below containing the antenna configur ation of the Macrocells in and surrounding the Use Case Area it can be seen that t hey are all three sector sites with antenna heights ranging from 19-100m with an average height of 32.5m, total downtilts range from 3 14o with an average downtilt of 7.2 o.

3.4 Small Cell Layer Twenty LTE Small Cells were manually added using a Template in an area of poor Macrocell Coverage, as per the initial results from analysing the Macrocell layer. The Small Cell Template was designed to model a deployment utilizing street furniture i.e. lamp posts, traffic lights, etc. so the configuration included the following: 

   

Three Sector Sites with Antenna Azimuths of 0, 120 & 240 o and Azimuths separation fixed at 120o Antenna Height of 4m Fixed Total Downtilt of 0o Single 10MHz Carrier Max TX Power of 1W (30dBm)

The majority of Small Cell Sites have been positioned on street corners or junctions, although there are a few in squares. If necessary the antenna azimuths have been adj usted from the default (0, 120 & 240 o) but the azimuth separation has been fixed at 120 o to model the use of a fixed antenna housing.

3.5 Traffic Model An LTE real time data terminal was used for the simulation. simulation. This used the default StreamingQCI-4 Service available in ASSET v8.0 that is configured to provide an UL GBR of 500kbps and DL GBR of 1000kbps. 1000kbps. The terminal’s RF Parameters were configured as follows: Parameter Max Tx Power (dBm) Tx Dynamic range (dB) Req. RSRP (dBm) Req. RSRQ (dBm) Req. BCH/SCH SINR (dB) RC combining gain (dB)

Value 23 70 -122 -18 -15 0

Parameter Antenna gain (dBi) Horiz. Beamwidth (deg) Body Loss (dB) Noise figure (dB) Background Noise (dBm/Hz)

Value 0 360 1 7 -167

3.6 Traffic Raster A traffic raster was created for the Test Area by specifying 200 Terminals to be distributed within the Small Cell Area polygon. As the majority of the area consisted of urban, dense



Page 5 of 20

urban and high-rise building clutter all cutter types were equally weighted to provide a uniform traffic weighting of 1. This produced a traffic density of 349.34 Terminals per km2. As the highest resolution of Clutter Data was 50m the Traffic Raster was created at 50m Resolution, however thi s traffic was used to run the simulator at 5m resolution.

4 Coverage Analysis The following Best RSRP Arrays are for outdoor coverage i.e. no Indoor Losses defined in the LTE Clutter Parameters have been considered, but indoor losses have been calcul ated for areas inside the Building Vectors using the MYRIAD Building Calculation options. Coverage Arrays are displayed for the Macrocells only, Small Cells Cells only and Combined Macrocells/Small Cells both with Building Vectors to highlight outdoor street level coverage and without Building Vectors show areas of indoor coverage. The Best RSRP Schema is as follows:

Coverage Statistics were also calculated for the Small Cell Area polygon for Macrocells only, Small Cells only and Combined Macrocells/Small Cells.



Page 6 of 20

4.1 Coverage with Building Vectors displayed 4.1.1 LTE Macrocell Best RSRP

From this picture, it can be seen that the areas in orange and red are areas with poor coverage. 4.1.2 LTE Small Cell Best RSRP

From this picture, it can be seen that the small cells coverage is very focused on the vicinity of the cells themselves.



Page 7 of 20

4.1.3 Combined LTE Macrocell & Small Cell Best RSRP

When combining the coverage from the two layers, it can be seen that the orange and red areas previously seen on the Macrocell-only coverage have turned to Green, or good coverage, by adding the Small Cells layer.

4.2 Coverage Statistics The Best RSRP Array Statistics, obtained from ASSET, can be compared in t he table and reports below. RSRP Thresholds

-120.00 <= x < -115.00 dBm -115.00 <= x < -110.00 dBm -110.00 <= x < -105.00 dBm -105.00 <= x < -100.00 dBm -100.00 <= x < -95.00 dBm -95.00 <= x < -90.00 dBm -90.00 <= x < -85.00 dBm -85.00 <= x < -80.00 dBm -80.00 <= x < -75.00 dBm -75.00 <= x < -70.00 dBm -70.00 <= x < -65.00 dBm -65.00 <= x < -60.00 dBm -60.00 <= x < 0.00 dBm

Macrocells Only Small Cells Only

92.041% 84.319% 73.934% 63.434% 54.844% 44.771% 31.126% 18.779% 11.233% 6.618% 3.984% 2.055% 0.974%

96.837% 93.938% 89.699% 84.073% 76.884% 68.239% 57.043% 45.754% 36.125% 28.839% 23.431% 17.991% 9.986%

Combined Macrocell & Small Cells 99.912% 99.420% 97.672% 94.045% 88.693% 81.392% 71.717% 58.253% 45.290% 34.873% 27.327% 20.045% 10.960%

From these statistics, it is clear that the coverage statistics are much better for the combined Macro and Small cells network than for the Macro net work alone.



Page 8 of 20

5 Interference/Quality Interference/Quality Analysis The following Best RSRQ Arrays are for outdoor interference/quality and were generated from a simulation using the Traffic Raster and snapshots. RSRQ Arrays are displayed for the Macrocells only, Small Cells only, Combined Macrocells/Small Cells (with a single Carrier assigned to Macro and Small Cells) and Combined Macrocells/Small Cells (with two Carriers, one assigned to Macrocells and another assigned to Small Cells). Arrays are available with Building Vectors and without Bui lding Vectors. The Best RSRQ Schema is as follows:

Best RSRQ Array Statistics were also calculated for the Small Cell Area polygon for Macrocells only, Small Cells only, Combined Macrocells/Small Cells (with a single Carrier) and Combined Macrocells/Small Cells (with two Carriers).

5.1 Interference/Quality Interference/Quality with Building Vectors displayed 5.1.1 LTE Macrocell Best RSRQ

From this picture, it can be seen that the areas in orange represent poor quality (mostly indoors), whilst yellow is acceptable.



Page 9 of 20

5.1.2 LTE Small Cell Best RSRQ

From this picture, it can be seen that the small cells quality is very good (green) on the vicinity of the cells themselves.

5.1.3 Combined LTE Macrocell & Small Cell Best RSRQ (Single Carrier)

When combining the coverage from the two layers, it can be seen that the orange areas previously seen on the Macrocell-only plot have t urned to Green, or good quality, by adding the Small Cells layer.



Page 10 of 20

5.1.4 Combined LTE Macrocell & Small Cell Best RSRQ (Two Carriers)

Having separate carriers has a positive effect on quality, altho ugh hard to visualise. A clearer picture in terms of statistics is presented further on this document.

5.2 Interference/Quality Interference/Quality Statistics The Best RSRQ Array Statistics, obtained from ASSET, can be compared in the table and reports below.

RSRQ Thresholds

-30.00 <= x < -27.00 dB -27.00 <= x < -24.00 dB -24.00 <= x < -21.00 dB -21.00 <= x < -18.00 dB -18.00 <= x < -15.00 dB -15.00 <= x < -12.00 dB -12.00 <= x < -9.00 dB -9.00 <= x < -6.00 dB -6.00 <= x < -3.00 dB -3.00 <= x < 0.00 dB 0.00 <= x < 3.00 dB

Macrocells Only

Small Cells Only

100.000% 100.000% 99.981% 99.814% 99.045% 93.651% 50.851% 1.359% 0.000% 0.000% 0.000%

100.000% 99.995% 99.963% 99.879% 99.541% 98.646% 88.646% 38.152% 2.240% 0.000% 0.000%

Combined Macrocell & Small Cells (Single Carrier) 100.000% 100.000% 100.000% 100.000% 100.000% 99.977% 94.351% 65.113% 15.769% 0.320% 0.000%

Combined Macrocell & Small Cells (Two Carriers) 100.000% 100.000% 100.000% 100.000% 100.000% 100.000% 99.606% 84.579% 32.253% 1.373% 0.000%

From these statistics, it is clear that the quality statistics are much better for the combined Macro and Small cells network than for the Macro net work alone.



Page 11 of 20

6 Failure rate and failure reasons analysis Monte Carlo simulations were run in ASSET to assess the Failure Rate and the Failure Reasons using the Traffic Raster and multiple simulatio n snapshots. The Failure Rate and Failure Reason Arrays are displayed for the Macrocells only, Small Cells only and Combined Macrocells/Small Cells (with a single Carrier assigned to Macro and Small Cells). Simulation Composite Report Statistics were also calculated for Macrocells only, Small Cells only, Combined Macrocells/Small Cells (with a single Carrier) and Combined Macrocells/Small Cells (with two Carriers).

6.1 Failure Rate Arrays The Failure Rate Schema is as follows:

6.1.1 LTE Macrocell Failure Rate

From this picture, it can be seen that the orange and red dots signal high failure rates.



Page 12 of 20

6.1.2 LTE Small Cell Failure Rate

From this picture, it can be seen that the small cells result in very low failure rates on the vicinity of the cells themselves.

6.1.3 Combined LTE Macrocell & Small Cell Failure Rate (Single Carrier)

When combining the two layers, the orange and red dots disappear, leaving an all-green area with very low failure rates.



Page 13 of 20

6.2 Failure Reason Arrays The Failure Reason Schema is as follows:

6.2.1 LTE Macrocell Failure Reason

From this picture, it can be seen that the non-green signal a number of failure reasons, which translate to high failure rates in the areas further away from the macro cells.



Page 14 of 20

6.2.2 LTE Small Cell Failure Reason

From this picture, it can be seen that the small cells result in very low failure rates on the vicinity of the cells themselves.

6.2.3 Combined LTE Macrocell & Small Cell Failure Reason (Single Carrier)

When combining the two layers, the multi-coloured dots disappear, leaving an all-green area with very low failure rates.



Page 15 of 20

6.3 Simulation Statistics The Simulation Composite Report Statistics, obtained from ASSET, can be compared in the table and reports below.

Simulation Statistic

Mean Attempted Mean Served Mean Failed Mean Served (%) Mean Failed (%) DL RSRP RSRQ DL BCH/SCH SINR UL SINR DL SINR UL Capacity DL Capacity User Limit No valid connection scenarios No pathloss data

198.960 188.420 10.540 94.70% 5.30% 81.78% 24.67% 5.60% 3.32% 1.90% 0.00% 10.72% 2.28%

Combined Macrocell & Small Cells (Single Carrier) 198.280 196.790 1.490 99.25% 0.75% 55.03% 2.68% 0.67% 4.70% 7.38% 0.00% 32.89% 0.00%

Combined Macrocell & Small Cells (Two Carriers) 199.040 197.890 1.150 99.42% 0.58% 86.09% 7.83% 0.87% 4.35% 0.00% 0.00% 7.83% 2.61%

0.00% 0.00%

0.00% 0.00%

0.00% 0.00%

Macrocells Only

Small Cells Only

200.090 145.340 54.750 72.64% 27.36% 25.70% 5.92% 0.55% 14.74% 2.23% 0.00% 41.11% 22.76% 0.00% 0.00%

From these statistics, it is clear that the success rate (Mean Served terminals) statistics are much better for the combined Macro and Small cells network than for the Macro network alone. It is also clear that the areas on which having separate carriers help, are in helping reduce failures due to poor coverage, poor quality, poor SINR and low capacity.



Page 16 of 20

7 Conclusion This Use Case has shown that LTE Small Cells can be effectively planned and analysed in ASSET. As the majority of Small Cells will be deployed deployed in dense urban and urban environments it is highly recommended that Building Vector data and a semi-deterministic, such as MYRIAD, or a deterministic propagation model is used. Considering the low antenna height of 4m and low TX Power of 1W (30dBm) the Small Cells provide impressive improvements in both outdoor (street level) and indoor coverage in the vicinity of each Small Cell location. Because o f the low antenna height which is well below the building height in dense urban and urban e nvironments the interference is controlled for the Small Cells when compared with the higher Macrocells which tend to be at or above building height. The number of Terminals Served, in this case for a guaranteed UL Throughput of 500kbps and DL Throughput of 1000kbps, is significantly better for the Combined Macrocell and Small Cell scenario than for the Macrocell only scenario . This is primarily due to improved indoor in door coverage and the capacity provided by the addition of the Small Cells. Having separate carriers for the Macro and the Small cells networks provides additional benefits; mainly in terms of reduce failures due to poor coverage, poor quality, poor SINR and low capacity. Geolocated traffic and Network optimization tools, such as Symena Capesso, could be used t o select the best Small Cell locations and to optimise the antenna azimuths whilst maintaining the azimuth separation of 120o.



Page 17 of 20

8 Glossary LTE - Long Term Evolution, a technology from the 3GPP industry group RSRP - Reference Signal Received Power RSRQ - Reference Signal Received Quality Streaming-QCI-4 - A type of data streaming service which complies with 3GPP’s QCI (Quality Control Indicator) category 4 UL - Uplink, referring to the direction from the User Equipment to the Base transmitting station, or eNodeB for LTE GBR GBR - Guaranteed Bit Rate RF - Radio Frequency SINR SINR - Signal to Interference Noise Ratio



Page 18 of 20

9 Appendix A - About the Products Products and modules used used in this application note 9.1 ASSET 8.0 ASSET is the world’s most popular Radio Network Planning tool. It is used by over 250 customers and it allows you to:    

Plan and Optimise the Radio Network Configuration Perform Coverage and Interference Planning Perform Traffic and Capacity Analysis Perform financial analysis on your radio network

ASSET’s capability can be summarised as follows: follows: Master Site Database   

Keep an accurate list of all RAN elements Maintain key planning parameters Act as the focal point of network management applications

Coverage Planning   

Predict radio propagation Analyse outdoor and indoor network coverage & quality Create coverage maps by Service, UE and technology type

Neighbour & Resource Planning   

Plan relations between cells Plan IRAT handovers Plan frequencies, scrambling codes, etc.

Traffic & Capacity   

Model the performance of new Services prior to implementation Perform traffic forecasting and capacity impact Plan network expansion and run “What if” scenarios

ASSET is a product with excellent security, data integrity and open interfaces. A product that can work in very large corporate environments, but can also be very user-friendly at an individual level.

9.2 Myriad The Myriad propagation model is a Productivity Pack of the ASSET Radio Network Planning tool. Myriad is a universal propagation model which can be used for: All main technologies: 

o



Any kind of cell type: o



DVB, GSM, EDGE, GPRS, UMTS, WIMAX and LTE

Micro-Cells, Mini-cells, Smalls-cells and Macro-cells.

Any kind of environment:



Page 19 of 20

o

 

Dense Urban, Urban, Suburban, Rural, Open, Seaside, Mountainous, etc.

Frequency range: 200 MHz to 5 GHz. Use different geographical data: o

Height, Clutter and Building raster.

o

Building Vectors (VBF and MapInfo TAB format).

o

Line Vectors (MapInfo TAB format for the train opt ion).

The Myriad model features a realistic channel modelling, which accounts for vertical diffraction, horizontal guided propagation and mountainous area reflection.

Figure: Myriad’s channel modelling

Other key features of Myriad include: 

    

Pre-processing of specific geographical data, such as Morphologies (from Clutter Data), Facets Facets (from Height Data) and Graphs (from Building Vectors) in order to save on overall processing time Penetration component both automatic and manual Railway component Antenna location correction Speed Accuracy



Page 20 of 20

aircominternational-casestudy-ltesmallcellplanningusingasset

Recommend Documents