how to solve congestion using outgoing ho when multiple rate is maxed out

8/10/2019 How to Solve Congestion Using Outgoing HO When Multiple Rate is Maxed Out

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[Huawei Technologies]|How to solve Congestion using Outgoing HO when Multiple Rate is maxed out 1

Case Name:

How to solve Congestion using Outgoing HO when Multiple Rate is maxed out

Phenomenon Description:

Cell 42862 had a big TCH congestionevery day especially at busy hour that can reach sometimes to 5% as seen

below in the figure, so more investigation is needed to solve the problem

Alarm Information:

None

Cause Analysis:

1)

Cell 42862 had high TCH congestion especially at busy hour, the problem is that I couldntmake Half Rate

in the cell more dominant than the FR as already TCH Traffic Busy Thresholdand AMR TCH/H Prior Cell

Load parameters are found as 20% and 10%, so already the HR is the one that is assigned preferably than

the FR, although of this still there is TCH congestion, and I didnt want to make it 1% and 0% as this willdegrade the voice quality in the cell as this means that allthe calls will be assigned HR preferably

2)

So there was no solution except solving it from HO angleand not Multiple Rate Adaptationangle

3)

I monitored KPISs for Outgoing Inter-Cell HOfrom this celland found following:

o I found out what cells that our cell 42862 HO to them the mostand doesnt have TCH congestion

on themand can handle more traffic in it to relief traffic from our cell. I found following:C42862,

C4863, R25422and 42863 (C means the DCS of the sector, as the sector is made out of 2 cells:

GSM and DCS). HO requests to them are in thousands per day and they have no congestion:


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42862Cell C42862: I found that most HO Requests in them are Better Cell HO, so it

means Layer HOas they are in differentband, so I changed parameter Adjacent Cell

Inter-Layer HO Hysteresis from 67 to 60 to this neighbor only as this parameter is added

per neighbor (per relation)


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42862Cell C42863: I found that most HO Requests in them are Better Cell HO, so it

means Layer HOas they are in differentband, so I changed parameter Adjacent Cell

Inter-Layer HO Hysteresis from 67 to 60 to this neighbor only as this parameter is added

per neighbor(per relation)

42862Cell R25422: I found that most HO Requests in them are Better Cell HO, so it

means PBGT HOas they are in sameband, so I changed parameter Inter-Cell HO

Hysteresis from 68 to 64 and PBGT HO Thresholdfrom 68 to 64 to this neighbor only

as this parameter is added per neighbor, and I changed both as changing one of them will

have no effect as PBGT HO takes the bigger from them

42862Cell 42863: I found that most HO Requests in them are Better Cell HO, so it

means PBGT HOas they are in sameband, so I changed parameter Inter-Cell HO

Hysteresis from 68 to 64 and PBGT HO Threshold from 68 to 64 to this neighbor only

as this parameter is added per neighbor, and I changed both as changing one of them will

have no effect as PBGT HO takes the bigger from them


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Handle Process:

I would like to speed up the outgoing HO from our cellso that calls doesnt maintain the call that muchon our

cell to lower traffic and remove congestion

Parameter Name Old Value New Value

[Adjacent Cell Inter-Layer HO Hysteresis]42862(serving) C42862(neighbor) 67 60

[Adjacent Cell Inter-Layer HO Hysteresis]42862(serving)C42863(neighbor) 67 60

[Inter-Cell HO Hysteresis]42862(serving)R25422(neighbor) &42862(serving) 42863(neighbor) 68 64

[PBGT HO Threshold]42862(serving)R25422(neighbor) &42862(serving) 42863(neighbor) 68 64

Result:

1)

After changing parameter, I monitored KPIs (TCHcongestion) in next day especially busy hour and found

that the problem is solved and we relieved traffic to other cell without affecting their TCH congestion, so

the congestion was solved and traffic in cell was decreased a little bit


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4) LAYER HO:


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[Inter-layer HO Threshold]

Value Range: 0~63

Recommended Value: 25

Description: In BSC handover algorithm, the M criterion is used to rank the handover

candidate cells. The M criterion includes 16 bits. This parameter is one bit of the 16 bits and it

affects the rank of a candidate cell. When the downlink level of a cell is lower than this

threshold, the cell takes low priority as far as comprehensive sequence is concerned.

Remarks: Make sure that the receive level of the destination cell is higher than this threshold

in inter-layer handover or load handover. Otherwise, the MS may be handed from a cell with

heavy load and high level (high priority cell) to a cell with light load and low level (low priority

cell), thus leading to call drops.

[Inter-layer HO Hysteresis]


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Value Range: 0~63


Description: This parameter indicates the hysteresis of an inter-layer or inter-priority

handover. It is used to avoid inter-layer ping-pong handovers.

Actual Inter-layer HO Threshold of a serving cell = Inter-layer HO Threshold - Inter-

layer HO hysteresis

[Adjacent Cell Inter-layer HO Hysteresis]

Value Range: 0~63


Description: This parameter indicates the hysteresis of an inter-layer or inter-priority

handover. It is used to avoid inter-layer ping-pong handovers.

Actual Inter-layer HO Threshold of a neighboring cell = Inter-layer HO Threshold +

Adjacent Cell Inter-layer HO Hysteresis

5) PBGT HO:


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[PBGT HO Threshold]

Value Range: 0~127 (-64 dB to +63 dB)


Description: A threshold in PBGT handover algorithm used to judge whether to perform PBGT

handover. When PBGT Handover Allowed is set to Yes and Inter-cell HO Hysteresis > PBGT HO

Thresh., the Inter-cell HO Hysteresis will act instead of the PBGT HO Thresh. When this parameter

is assigned with a value smaller than 64, MS can hand over to a lower level neighboring cell. 68 for

popular urban areas, 72 for suburbs.

Remarks: When PBGT handover is enabled, and Inter-cell HO Hysteresis > PBGT HO Thresh, the

Inter-cell HO hysteresis instead of the PBGT HO Thresh works. PBGT HO Thresh must be adjusted

as per handover performance statistic result and actual network.

how to solve congestion using outgoing ho when multiple rate is maxed out

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