4 Location Area Planning ISSUE1.00

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Location Area Planning


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Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Confidential Information of Huawei. No Spreading Without Permission

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Definition of Location Area z

GSM mobile communication network is divided into multiple service areas according to the codes of location areas.

z

Location area is the basic unit of paging areas in GSM system. The paging message of a subscriber is sent in all cells of a location area.

z

A location area contains one or more BSCs, but it belongs to one MSC only.


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Definition of Location Area


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Location Area Code（LAC） z

Definition

To locate the location of MS, the whole area covered by each GSM PLMN is divided into different location areas. LAC is used to identify different location areas.

z

Format

LAI contains LAC, which is composed of two bytes. LAC adopts hexadecimal coding. The available range is from 0001H to FFFEH. The code 0000H and FFFFH cannot be used (please refer to specification GSM0303, 0408, and 1111). One location area can contain one or more cells.


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z

When MS is powered on or LAC of current cell is found to be different from its originally stored contents, MS will inform network of the current location area via location update, and the network uses the LAI for paging. Generally the allocation and coding of LAC is set at the early stage of network construction, and seldom modified during the operation.

z

The size of location area (LA) is one of key factors in the system. If the LA coverage is too small, the chances for MS to update location increase, and this will increase the signaling load in the system. If the LA coverage is too large, when network conducts paging to the MS, the same paging information will be transmitted in a large number of cells, and this will lead to the heavy load on CCCH. The adjustment of LA size has no unified standard. Operating departments can decide whether to adjust the size according to the currently running network. If the CCCH signaling load is heavy because of too big LA coverage, then reduce the size of LA, and vice versa. It is generally recommended to set the LA as large as possible. The calculation of LA is related with the paging strategies of different manufacturers. If Huawei equipment is employed, it is recommended to set the TRX number within the range of 300 in one location area. In the early stage of network construction, the traffic is not heavy, so the TRX number in one LA can be larger than this value. It is necessary to monitor the PCH load and the increase of traffic in a long term. If necessary, PCH capacity can be increased by adding one extended BCCH channel.

z

While making LA planning, try to make use of the geographical distribution and behaviors of mobile subscribers to allocate the LA, so as to achieve the objective of reducing the times of location update at the boundary between location areas. Please note that LAC in cell parameters must be in consistent with that in MSC. Otherwise, call setup failure will occur.


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Location Update z

Purpose of location update:

To inform the system the LA in which the MS is to facilitate paging

z

When need the MS perform location update？

Getting into a new LA

Periodical location update


z

z

z

z

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First of all, we should know the purpose of location update: To inform the system the LA in which the MS is to facilitate paging. When need the MS perform location update? There are two cases: The first one: Getting into a new LA. This type of location update is called forced location update. The second one: regular update, it is also called periodical location update. Even if the MS doesn’t enter a new location area, GSM system will also require the MS to perform regular location update, thus to grasp the MS current status. The location update signaling be sent on SDCCH channel.


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Size of location areas z

The size of a location area, plays a key role in a GSM system.

z

If the size of location area is too big, the paging traffic will be higher, perhaps PCH will be congestion.

z

If the size of location area is too small, the MS will occur more location update process. The signaling traffic is higher, SDCCH channel perhaps be congestion.


z

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If the coverage area of a location area is too small, the mobile station will perform frequent location update. In this case, the signaling flow in the system will increase. If the coverage of a location area is too larger, however, the network will send a paging message in multiple cells until the mobile station is paged. In this case, the PCH will be overloaded and the signaling flow at the Abis interface will increase.


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Paging VS Location update Traffic signaling traffic

Paging

Location update optimum number of cells in Loc. area

# of cells in Loc. area

minimize signaling traffic optimum varies with network evolution


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Division of location areas z

If two or more location areas are present in a big city of great traffic, the landforms, such as mountains and rivers within this city can be used as edges of the location areas.

z

If no such landforms available within this city, the areas (such as streets and shopping centers) with great traffic cannot be used as edges of the location areas.

z

In the intersected areas of urban areas and suburban areas, to avoid frequent location update, should design the edges of location areas near the outer base stations.


z

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If two or more location areas are present in a big city of great traffic, the landforms, such as mountains and rivers within this city can be used as edges of the location areas. In this case, the overlapped depth between the cells of the two location areas can be reduced.


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Location Area Design For Dual-band z

If 1800 MHz cells and 900 MHz cells are under the control of two MSCs respectively, their location areas are different.

z

Related parameters should be set to maintain the mobile stations stay in the 1800 MHz cells where the traffic is absorbed. In this case, the times for the mobile station to handover between the two bands and reselect cells will decrease.

z

Designing signaling channels, fully consider the load resulted from location update.


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If 1800 MHz cells and 900 MHz cells share a MSC, at the early network construction stage, they are suggested to use the same location area without affecting the network capacity.

z

If the restriction on paging capacity is present, two location areas must be divided for them either in terms of band or geographic location, as shown in Figure .


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Location Area Design For Dual-band


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Location Area Design For Dual-band


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If the location is divided in terms of geographic location, the frequent location updates resulted from inter-band handover and cell reselection can be avoided.

z

However, need to modify the related data of the original 900 MHz network. In addition, at the edges of the location areas, because the location updates caused by intra-band and inter-band handover and cell reselection is present simultaneously, the signaling flow is huge at these edges. As a result, carefully design the edges of the location areas.


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Physical Combination of Logical Channel 26-frame multi-frame TCH/F+SACCH/F (full-rate TCH) TCH/H+SACCH/H (half-rate TCH)

51-frames multi-frame FCCH+SCH+BCCH+CCCH (main BCCH) FCCH+SCH+BCCH+CCCH+SDCCH/4+SACCH/4 (combined BCCH) BCCH+CCCH (extended BCCH) SDCCH/8+SACCH/8 (main SDCCH)


z

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As shown above, CCCH=PCH+RACH+AGCH; downlink CCCH=PCH+AGCH; and uplink CCCH=RACH. In the above combinations, combination 3 and 4 must be allocated to slot 0 of the BCCH carrier configured for the cell; while combination 5 must be allocated to timeslots 2, 4 and 6 of the BCCH carrier. The FACCH works in the frame stealing mode, for which no fixed time sequence will be allocated. In addition, the cyclic multiframe period of SACCH/C4 and SACCH/C8 is 102 frames.


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Structure of Main BCCH 1 multi-frame (51TDMA Frames) 235.38ms Downlink Group3,4

Group

Group1

Group2

(same as

Grpup5

Group2)

Channel Frame Number

F 0

S 1

BX4 2-5

CX4

F

6-9

10

S

CX4

CX4

1

12-

16-

1

15

19

…… 20-39

F

S

4

4

0

1

CX4

CX4 46-

42-45

I 50

49

1 multi-frame (51TDMA Frames) 235.38ms Uplink Channel Frame Number

R

R

R

R

R

R

R

R

R

R

R

R

R

R……R

R

0

1

2

3

4

5

6

7

8

9

10

11

12

13-46

47

R

R

4

4

8

9

R

50

F:FCCH; S:SCH; B:BCCH; C:CCCH; I:IDLE; R:RACH Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

z

z

z

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The TDMA/FDMA multiplexing is used in GSM, the information needed in the synchronization between MS and BTS is provided by FCCH+SCH. The MS determines the frequency of the BCCH carrier by searching for the frequency correction Burst transmitted via FCCH; then it finds the SCH (synchronization channel) according to the relationship between SCH and FCCH and decodes the current frame number and BSIC for synchronization with BTS. Furthermore, it determines whether the cell is barred or not and decodes the system information on BCCH. In the structure diagram of extended BCCH, except that the F and S timeslots are replaced by Idle timeslots, the rest of the structures are the same as that of the main BCCH.


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Structure of Combined BCCH 1 multi-frame (51TDMA Frames) 235.38ms Downlink Group

Group1

Channel

F

Channel

F

Frame

0

Number

S

S

1

Group2

B

C

×

×

4

4

B

C

×

×

4

4

2-

6-

5

9

F

F

10

S

S

11

Group3

C

C

×

×

4

4

C

C

×

×

4

4

12

16

-

-

15

19

F

F

20

S

S

21

Group4

D0

D1

×

×

4

4

D0

D1

×

×

4

4

22

26

-

-

25

29

F

F

30

1 multi-frame (51TDMA Frames) 235.38ms

S

S

Grpup5

D2

D3

×

×

4

4

D2

D3

×

×

4

4

32

36

-

-

35

39

31

F

A0

A1

×

×

4

4

A2

A3

×

×

4

4

42

46

S

F

S

40

41

-

-

45

49

I

I

50

Uplink

Channel

D3×4

R

R

A2×4

A3×4

R……R

D0×4

D1×4

R

R

D2×4

Channel

D0×4

R

R

A0×4

A1×4

R……R

D0×4

D1×4

R

R

D2×4

Frame Number

0-3

4

5

6-9

10-13

14-36

37-40

41-44

45

46

47-50

F:FCCH; S:SCH; B:BCCH; C:CCCH; D:SDCCH ;A:SACCH; I:IDLE; R:RACH Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

z

z z

z z

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It is used in the configuration of cells of low traffic density and small capacity. The Combined BCCH is only configured at timeslot 0. Channel combination: FCCH＋SCH＋BCCH＋CCCH+SDCCH/4+SACCH/4 SDCCH/4: Stand-alone dedicated control channel. Each TDMA multiframe with 51 frames has 4 SDCCH; SACCH/4: Slow SDCCH/4 associated control channel; Compared with the main BCCH channel, 4 signaling channels are added to the 51 frames. The functions of these 4 signaling channels are the same as those of the SDCCH8 channel. Therefore, this channel combination can be taken as a combination of the functions of the above two channels. This combination take effect on two aspects: first, this reduced the quantity of AGCH+PCH on CCCH and only a small-capacity system is provided; second, this combination provides a certain quantity of signaling channels in timeslot 0. Thus, it is unnecessary to assign SDCCH8 channels in a small-capacity system. This channel suitable for small-capacity systems. And it is also an example of the flexible GSM network configuration.


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Structure of Logical Channel Combination Frame-Main SDCCH 1 multi-frame (51TDMA Frames) 235.38ms Downlink Channel

Channel Frame Number

D0

D1

D2

D3

D4

D5

D6

D7

A0

A1

A2

A3

×4

×4

×4

×4

×4

×4

×4

×4

×4

×4

×4

×4

D0

D1

D2

D3

D4

D5

D6

D7

A4

A5

A6

A7

×4

×4

×4

×4

×4

×4

×4

×4

×4

×4

×4

×4

0-3

4-7

8-11

12-

16-

20-

24-

28-

32-

36-

40-

44-

15

19

23

27

31

35

39

43

47

I

I

I

I

I

I

4

5

9

0

48

1 multi-frame (51TDMA Frames) 235.38ms Uplink Channel

A5 ×4

A6 ×4

A7 ×4

I

I

I

D0 ×4

D1 ×4

D2 ×4

D3 ×4

D4 ×4

D5 ×4

D6 ×4

D7 ×4

A0 ×4

Channel

A1 ×4

A2 ×4

A3 ×4

I

I

I

D0 ×4

D1 ×4

D2 ×4

D3 ×4

D4 ×4

D5 ×4

D6 ×4

D7 ×4

A4 ×4

Frame Number

0-3

4-7

8-11

12

13

14

1518

1922

2326

2730

3134

3538

3942

4346

4750

D:SDCCH; A:SACCH; I:IDLE Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

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Channel combination: SDCCH/8+ SACCH/C8 z SDCCH/8: Stand-alone dedicated control channel. Each TDMA multiframe with 102 frames has 8 SDCCH. z SACCH/C8: Slow SDCCH/8 associated control channel. z


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ATT z

Value range: Yes, No

z

Content：It is used to inform MS whether IMSI attach-detach is allowed in this cell. If it is set to “Yes”, the network will not process the connection to the called mobile subscriber when MS is power-off. Thus network processing time and radio resources are saved. Otherwise the network will process the connection even though the MS has been powered off.

z

Recommendation：Yes


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Detach process (IMSI) refers to the process that MS informs the network that it is shifting from working state to non-working state (usually a power-off process), or the SIM card is being taken out from MS. Upon receiving the notice from MS, the network knows that the IMSI subscriber is in non-working state. Therefore, if the MS is called, the call connection will be implemented.

z

IMSI attach process is opposite to detach process. It is the process that MS informs the network it has entered the service area (usually a power-on process) or SIM card has been inserted into MS. After entering service state again, MS will test whether the current location area (LAI) is the same with the latest LAI recorded in MS. If yes, MS will start IMSI attach process. Otherwise MS will start location update process, upon receiving the location update or IMSI attach process, the network will indicate that this IMSI subscriber is in working state.

z

Note that ATT configuration of different cells in the same LAI must be the same. It is because IMSI detach process will be started when MS is power-off in the cell with ATT set as yes. The network will record that this subscriber is in non-working state and reject all the called connection requests to this subscriber. When MS is power-on again, if it is in the same LAI as it was power-off (thus the LAI update process will not be started) but in another cell, and ATT of the cell is set as no, then the MS will not start IMSI attach process. In this case, this subscriber can not be called normally until the MS starts the location update process.

z


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CCCH_CONF z

Value range: 1 Non-Compounding CCCH, 1 Compounding CCCH, 2 NonCompounding CCCHs, 3 Non-compounding CCCHs, 4 Non-compounding CCCHs.

z

Content: It is “Common Control Channel Configuration”. CCCH configuration determines the capacity of PCH, AGCH and RACH. This parameter can be automatically configured by the BSC Data Auto Configuration System according to the TRX channel configuration.

z

Recommendation: When there is one TRX in the cell, one combined CCCH is recommended (in a system with few paging messages in location area). For others, it is configured according to the number of TRX in the cell.


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In GSM system, the downlink common control channel mainly includes Access Granted Channel (AGCH) and Paging Channel (PCH). It serves to send the access granted (immediate assignment) and paging messages. CCCH is shared. According to the configuration of traffic channel and traffic model, CCCH can be carried by either one or multiple physical channels. Moreover, CCCH and SDCCH can share one physical channel. The MS needs to know how the CCCH(s) is/are configured, so that it can find and select one to listen to. The CCCH_CONF is just used to tell the MS about this matter.

z

When CCCH is a physical channel which combined with SDCCH, the capacity of CCCH is the lowest. When CCCH is a physical channel which is not combined with SDCCH, the capacity is higher. For other cases, the more the physical channels are used as CCCH, the higher the CCCH capacity is.

z

Configuration of CCCH_CONF is specified according to the traffic model. This model is closely related to the cell location and environment. According to experiences, when TRX quantity in the cell is 1 or 2, it is recommended to use a combined CCCH as the common control channel. When TRX quantity in the cell is 3 or 4, it is recommended to use a noncombined CCCH as the common control channel.

z

zCurrently CCCH can be configured according to actual traffic load. If the paging load is very heavy, the paging traffic of cell should be distributed via multiple CCCH physical channels other way. Special attention should be paid to PCH in CCCH. Generally PCH capacities of various cells under one LAC must be the same.


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BS_AG_BLKS_RES z

Value range: 0~2 (1 combined CCCH), 0~7 (others)

z

Unit: Block

z

Content: It is also called Access Granted Blocks Reserved. It is the number of CCCH channel message blocks that are reserved in one multi-frame for access granted channels (AGCH).

z

Recommendation: 2 (non-combined CCCH)


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As downlink CCCH includes both AGCH and PCH, it is necessary to set the number of blocks, which are reserved for AGCH among CCCH message blocks. To let MS know such configuration information, the system information of each cell includes a configuration parameter, which is the number of access granted blocks reserved (BS_AG_BLKS_RES). This parameter actually assigns the proportion of AGCH and PCH on CCCH. It affects the time of MS’s response to the paging.

z

The network operator can adjust this parameter to balance the traffic of AGCH and PCH by referring to the following principles:

z

1. Principle for BS_AG_BLKS_RES: make this parameter as small as possible without causing overload of AGCH, so as to increase the capability of paging and improve the system performance. ٛ2. Generally it is recommended to select 1 (when CCCH_CONF is 1 combined CCCH), 2 or 3 (when CCCH_CONF is one of other values) for BS_AG_BLKS_RES. ٛ3. During operation, observe the statistics of AGCH overload and adjust BS_AG_BLKS_RES properly. ٛ

Note: In Huawei system, when AGCH has been all occupied, if PCH is free, it can be used to send the immediate assignment command. If AGCH blocks reserved is set as 0, the immediate assignment would be sent only when there is free PCH channel. Therefore, a fixed capacity reserved for AGCH is necessary.

ٛ


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BS_PA_MFRAMES z

Value range: 2～9

z

Unit: Multi-frame period (51 frames)

z

Content: It is Paging Channel Multi-frames. It defines the number of multi-frames used as a cycle of paging sub-channels.

z

Recommendation: 2


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This parameter specifies the number of paging sub-channels that are assigned in a cell. In the network, MS only monitors the paging sub-channel it belongs and ignores the content of the others. When this parameter is set larger, there will be more paging subchannels in the cell and accordingly there will be less MS in each paging sub-channel. Therefore, the bearing capability of PCH will be more (theoretically the capacity of each PCH does not increase, but the buffer that buffers paging message in each BTS is increased, which makes the sending of paging messages more even in the time domain), and the lifetime of MS battery will be longer. The value of this parameter should be as small as possible under the condition that the overload on PCH does not occur. In the operation, the PCH load should be measured regularly and the value of this parameter should be adjusted properly according to the PCH load. In a location area, paging is sent in all the cells. Therefore, all cells in the same location area should have the same or nearly the same PCH capacity (number of paging sub-channels). In the area where the PCH bears a medium or large load, it is suggested to be set as 6 or 7 (6 or 7 multi-frames are used as a cycle of paging). For the area with a small load, it is set as 4 or 5. Besides, it is often set as 2. zNote: z1. One CCCH block (four consecutive CCCH timeslots) can bear the information of two IMSI pagings or four TMSI pagings or two AGCH immediate assignments. z2. In idle mode MS camps in a cell. The DSC is initialized to the integer part of 90/N (N is BS_PA_MFARMES, with the value range: 2~9). when MS can successfully decode the message on paging sub-channel, DSC will increase by 1, but it will not exceed initially value. If decoding fails, DSC will decrease by 4. If DSC<=0, the downlink signaling link fails, resulting in cell reselection. z


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T3212 z

Value range: 0~255

z

Unit: 6 minutes

z

Content: It is the Periodic Location Update Timer. It defines the interval of periodic location update.

z

Recommendation: 30 (for urban area), 20 (for suburban area)


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MS will make location update when detecting the change of location. Besides, MS will make periodic location update controlled by parameter T3212. Once MS read T3212 from system information, it will store it in SIM card. When the time reaches T3212 value, the location update process will be triggered. The shorter the period is, the better the performance is. But it will bring more signaling load for system. On setting of this parameter, the processing capability of MSC and BSC, the flux of A interface, Abis interface and Um interface, the flux of HLR and VLR should be considered. Generally this parameter is set as a larger value for urban area and smaller for suburb, countryside or the place with poor coverage.

z

Large T3212( 16 hours 20 hours) is recommended for the area with heavy traffic, and small T3212 (3 hours, 2 hours) for the area with normal traffic. For the area where the traffic exceeds the system capacity, it is recommended to set T3212 as 0 (no periodic location update). To set the value of T3212 properly, it’s necessary to conduct long-term measurement on the processing capability and flux of each entity in the system. If any overload occurs, increase the value T3212.

z

Note that this value should be smaller than the period by which the network queries the IMSI attached subscriber. Otherwise, the following situation occurs: When MS has not done any operation in a certain time, and it is not yet the time for periodic location update, the network will set IMSI flag of MS as detached, because its query result shows that MS has not done any operation. Thus, the network will not process the paging of this MS. So, before MS initiates another round of periodic location update, once there is a call to the MS, the network will voice the calling party that the called MS is has been powered off. As usual, the T3212 is set smaller than one third of the MSC’s check time.

z

When MS reselects a cell in a different location area, it will make a non-periodic location update and reset T3212 in the new cell. If it reselects in the same location area, then the timer value will be remainder of the original one divided by the new T3212.

z


P-23


CRH z

Value Range: 0~14, the step size is 2dB

z

Unit: dB

z

Default Value: 6

z

Description: Cell Reselection Hysteresis. It is the parameter used when cell reselection happens between two location areas.

z

Location: Cell Attributes/Idle Mode/Basic Idle Parameters


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This parameter aims to prevent the frequent location update that may increase the network signaling flow and to reduce the possibility of paging message loss. If the value of this parameter is too small, the location update will have “ping-pong” effect and the signaling load on SDCCH will increase. Moreover, the call setup successful rate of the system will become lower because MS will not respond paging during location update. When it is too large, the cell where MS resides for a long time may not be the best when MS enters a new location area. When MS reselects a cell from a different location, MS will start a location update. Due to the fading of radio channel, C2 values of two cells at the their edges will fluctuate, which causes MS to reselect frequently. To reduce the influence, GSM specifications define a parameter called cell reselection hysteresis. It is required that MS start cell reselection only when C2 value of the adjacent cell (in a different location area) is greater than that of serving cell and their difference is greater than the value of reselection hysteresis.

z

Appropriate cell reselection hysteresis is important for network optimization. Usually it is recommended to be 8~10dB and can be adjusted in the following cases: zWhen the traffic of an area is very heavy and the signaling overload often occurs, it is recommended to increase the value of cell reselection hysteresis of the adjacent cells belonging to different LACs. ٛWhen the overlapping coverage of the adjacent cells belonging to different LAC are wide, it is recommended to increase the value of cell reselection hysteresis. z


P-24


TCH Immediate Assignment z

Value Range: Yes, No

z

Default Value : No

z

Description: Option "Yes" means that TCH channel can be immediately assigned as signaling and traffic channel when SDCCH has no available resource. The option "No" means that only SDCCH can be assigned.

z

Location: Cell Attributes


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Calculating For Location Area z

Generally, the capacity of a location area is calculated as follows: The number of paging blocks sent in each second × the number of paging messages sent in each paging block = the maximum paging times in each second.


z

z

z

z

Page25

As a result, the number of paging times in each hour, the traffic allowed in each location area, and the number of carriers supported in each location area can be deducted. The calculation of location areas varies with the paging strategies designed by different carriers. During early network construction stage, the traffic is not great, so a location area can accommodate more TRXs. However, it is still necessary to monitor the PCH load and traffic growth. When the traffic grows great, enhance the PCH capacity by adding a BCCH to the system, but the number of TCH channels is reduced by one .


P-26


Calculating For Location Area The number of paging blocks sent in each second 1 frame = 4.61ms, 1 multiframe = 51 frames = 0.2354s;


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suppose the number of access grant blocks is AGB, the number of blocks, the number of paging blocks sent in each second is calculated by the following formulas:

For non-combined BCCH, the number of paging blocks sent in each second = (9 – AGB)/0.2345 (paging block/second).

For non-combined BCCH, the AGB is 2 according to Huawei BSC. Therefore, the number of paging blocks sent in each second is 29.7 (paging block/second).


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suppose the number of access grant blocks is AGB, the number of blocks, the number of paging blocks sent in each second is calculated by the following formulas:

For combined BCCH, the number of paging blocks sent in each second = (3 – AGB)/0.2345 (paging block/second).

For combined-BCCH, the AGB is 1, so the number of paging blocks sent in each second is 8.5 (paging blocks/second).


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P-29



The number of paging messages sent in each paging block (X)

According to protocols, each paging block has 23 bytes, and can send 2 IMSI pages, or 2 TMSI and 1 IMSI pages, or 4 TMSI pages.

According to the paging strategies of Huawei MSC, if the IMSI paging mechanism is adopted, the number of paging messages sent in each paging blocks is 2 (paging times/paging block); if the TMSI paging mechanism is adopted, it is 4 (paging times/paging block)


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P-30



If the IMSI paging mechanism is adopted, for non-combined BCCH when AGB = 2, P = 59.47 (paging times/second);

z

For combined-BCCH when AGB = 1, P = 16.99 (paging times/second);


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P-31



If the TMSI paging mechanism is adopted, for non-combined BCCH, when AGB = 2, P = 118.95 (paging times/second);

z

For combined BCCH, when AGB = 1, P = 33.98 (paging times/second);


z

Page31

According to the previous analysis, the paging capacity under IMSI paging mechanism is half of that under TMSI paging mechanism.


P-32



Paging Capability (Hour)= [(CCCH CONF-BS AG BLKS RES)×Paging Strategy×3600] / [51×TDMA period ×(1+Sencond Paging Ratio)]

z

Paging Strategy: IMSI paging or TMSI paging


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LAC Capability (ERL)= [(CCCH CONF-BS AG BLKS RES)×Paging Strategy× Average Holding Time ×Average Paging Load at BTS ] / [51×TDMA period×(1+Sencond Paging Ratio) × MTC Ratio]

z

Paging Strategy: IMSI paging or TMSI paging


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LAC Capability (TRX)= LAC Capability (ERL) / Average Traffic Volume per TRX × (1+TCHH Ratio) ]


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Calculating For Location Area CCCH CONF

Main BCCH

BS AG BLKS RES

5

Sencond Paging Ratio

15%

Paging Strategy


TMSI

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Calculating For Location Area CCCH CONF

9

BS AG BLKS RES

2

BS PA MFRMS

2

Sencond Paging Ratio

15%

MTC Ratio

50%

Average Paging Load at BTS

50%

TCHH Ratio

70%

Average Holding Time Paging Strategy

58 TMSI

Average Traffic Volume per TRX


4.8

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Calculating For Location Area Paging Capability (Hour) =

LAC Capability (ERL) =

[(9 - 2) × 2 × 4 × 3600] = 372813 51× 0.00461× 2 × (1 + 0.15)

[(9 - 2) × 4 × 58] × 0.5 = 6006 51× 0.00461× (1 + 0.15)× 0.5

LAC Capability (TRX)= 6006 / 4.8 × (1+ 0.7) ] =736


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Thank you www.huawei.com


4 Location Area Planning ISSUE1.00

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