Inter-RAT CS Threshold Trial for RSCP and EcNo

Introduction

OVSF codes are shared between HSDPA and R99 (CS+PS) service with high priority for CS voice service. If CS traffic is high on any cell, it will occupy more codes resulting in fewer codes for HSDPA leading to low HSDPA throughput. In order to increase cell throughput, it was proposed to shift 3G voice traffic to 2G.

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2G TCH TrafficAround 20 Erlang increase

• Traffic shifted in 3G2G from -Δ of traffic 50 erlang in 3G +Δ of Traffic to 20 Erlang in 2G.• 1 Erlang in GSM equals around 3 Erlang in WCDMA as 3 RSL are connected in active State .

KPI Benchmark

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3G Voice Traffic

ParameterChanged

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HSDPA Throughput(Kbit/S)ParameterChanged

Throughput remains improved after changing

Throughput got improved as now more code are being assigned to Data services

KPI Benchmark

Increase in CS IRAT which was expected . IRAT HOSR is in trend.

KPI Benchmark

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CS IRATParameterChanged

CELLNAME CELLIDInterRATCSThd2DEcNo InterRATCSThd2FEcNo InterRATCSThd2DRSCP InterRATCSThd2FRSCP TargetRATCSThd

Current Proposed Current Proposed Current Proposed Current Proposed Current Proposed

QTA2018H_0_MEZNCHK 3018 -16 -6 -14 -4 -100 -60 -97 -57 26 16

QTA2018H_1_MEZNCHK 13018 -16 -6 -14 -4 -100 -60 -97 -57 26 16

QTA2018H_2_MEZNCHK 23018 -16 -6 -14 -4 -100 -60 -97 -57 26 16

QTA2018H_3_MEZNCHK 33018 -16 -6 -14 -4 -100 -60 -97 -57 26 16

QTA2018H_4_MEZNCHK 43018 -16 -6 -14 -4 -100 -60 -97 -57 26 16

QTA2018H_5_MEZNCHK 53018 -16 -6 -14 -4 -100 -60 -97 -57 26 16

Current and Proposed Parameter

Parameter ID InterRATCSThd2DEcN0Parameter Name Inter-RAT CS Measure Start Ec/No THD

Meaning Threshold of triggering inter-RAT measurement for CS services when measurement quantity is Ec/No. The threshold of triggering the inter-RAT measurement (the threshold of enabling the compressed mode) is a key parameter in the inter-RAT handover policy. The setting of this parameter affects the proportion of the UEs in compressed mode in a cell and the success rate of the hard handover

Unit dBm

Actual Value Range -24~0

Default Value -14

Impact on Radio Network Performance

The setting of this parameter affects the proportion of the UEs in compressed mode in a cell and the success rate of the hard handover. If this parameter is set to a greater value, hard handover is likely to be triggered, but ping-pong handover may occur. If this parameter is set to a smaller value, hard handover is unlikely to be triggered, but call drops may occur.

Parameter Detail

Parameter ID InterRATCSThd2FEcN0Parameter Name Inter-RAT CS Measure Stop Ec/No THD

Meaning Threshold of stopping inter-RAT measurement for CS services when measurement quantity is Ec/No. The threshold of stopping the inter-RAT measurement (the threshold of disabling the compressed mode) is a key parameter in the inter-RAT handover policy. The setting of this parameter affects the proportion of the UEs in compressed mode in a cell and the success rate of the hard handover.

Unit dBm

Actual Value Range -24~0

Default Value -12

Impact on Radio Network Performance

The setting of this parameter affects the proportion of the UEs in compressed mode in a cell and the success rate of the hard handover. If the threshold for event 2F is set to a larger value, more UEs will enter compressed mode, thus affecting user experience. If the threshold for event 2F is set to a smaller value, it becomes difficult for UEs to trigger inter-RAT measurement, thus decreasing handovers.

Parameter Detail

Parameter ID InterRATCSThd2DRSCPParameter Name Inter-RAT CS Measure Start RSCP THD

Meaning Threshold of triggering inter-RAT measurement for CS services when measurement quantity is RSCP. When RSCP is used as the measurement quantity for CS services, the UE reports event 2D when the measured RSCP value is lower than this threshold. Then, the RNC sends the signaling to enable the compressed mode and start the inter-RAT measurement. To enable the compressed mode earlier, increase the threshold of triggering event 2D; otherwise, decrease the threshold of triggering event 2D. To prevent the frequent enabling and disabling of the compressed mode, increase the difference between the thresholds of triggering event 2D and event 2F. In most cases, users want to be maintained within a 3G network. Therefore, the start threshold of the inter-RAT measurement is set smaller than that of the inter-frequency measurement in order to trigger inter-frequency easily. In scenarios where inter-frequency neighboring cells are unavailable or where inter-frequency coverage is insufficient, the inter-RAT measurement start threshold should be set relatively larger in order to trigger inter-RAT measurement easily, thus reducing call drops..

Unit dBm

Actual Value Range -115~-25

Default Value -100

Impact on Radio Network Performance

The setting of this parameter affects the proportion of the UEs in compressed mode in a cell and the success rate of the hard handover. If this parameter is set to a greater value, hard handover is likely to be triggered, but ping-pong handover may occur. If this parameter is set to a smaller value, hard handover is unlikely to be triggered, but call drops may occur

Parameter Detail

Parameter ID InterRATCSThd2FRSCPParameter Name Inter-RAT CS Measure Stop RSCP THD

Meaning Threshold of stopping inter-RAT measurement for CS services when measurement quantity is RSCP. When RSCP is used as the measurement quantity for CS services, the UE reports event 2F when the measured RSCP value is larger than this threshold. Then, the RNC sends the signaling to disable the compressed mode and stop the inter-RAT measurement.

Unit dBm

Actual Value Range -115~-25

Default Value -97

Impact on Radio Network Performance

If the threshold for event 2F is set to a larger value, more UEs will enter compressed mode, thus affecting user experience. If the threshold for event 2F is set to a smaller value, it becomes difficult for UEs to trigger inter-RAT measurement, thus decreasing handovers.

Parameter Detail

Parameter ID TargetRatCsThdParameter Name Inter-RAT CS Handover Decision THD

Meaning Quality requirement for the cell of another RAT during inter-RAT handover for CS domain services. For CS services, if the value of "Inter-RAT Reporting Mode" is set to "EVENT_TRIGGER", this parameter is used to set the criterion for triggering event 3A. That is, event 3A is triggered only when the quality of the target frequency is higher than this threshold and the measurement quality of the current CS services is lower than the quality of the currently used frequency. If the value of "Inter-RAT Reporting Mode" is set to "PERIODICAL_REPORTING", this parameter is used to evaluate inter-RAT coverage handovers at the RNC. Note that 0 means a value smaller than -110 dBm. If the value of "Inter-RAT Reporting Mode" is set to "PERIODICAL_REPORTING", this parameter is used for the assessment of inter-RAT coverage handover. That is, Tother_RAT in the following formulas. This parameter is the absolute threshold of the cell of another RAT (Received Signal Strength Indicator: RSSI) for the inter-RAT handover decision. If the quality of the cell of another RAT in the inter-RAT measurement report fulfils the following criterion: Mother_RAT + CIO >= Tother_RAT + H/2 Then, the system starts the trigger timer, and makes the handover decision after the timer expires. If the quality of the cell of another RAT fulfills the following criterion before timeout: Mother_RAT + CIO < Tother_RAT - H/2 The RNC stops the timer and waits for another inter-RAT measurement report. Here, Mother_RAT is the measurement result of the GSM RSSI. Tother_RAT is the inter-RAT handover decision threshold. Cell Individual Offset (CIO) is the offset for the cell of another inter-RAT. H represents the hysteresis, the setting of which can reduce wrong decisions caused by signal jitters. The sensitivity of a GSM mobile phone is -102 dBm. Considering a margin of 3 dB for compensation of fast fading, 5 dB for compensation of slow fading, 2 dB for compensation of interference noise, and 2 dB for compensation of ambient noise, the outdoor reception level should not be lower than -90 dBm. The parameter value can vary with the handover policy. To have UEs handed over only to GSM cells of high quality, the inter-RAT handover decision threshold can be set to a comparatively large value, for example -85 dBm.

Unit dBm

Actual Value Range lower than -110, -110~-48(Actual value meets the condition: Actual Value = GUI Value - 111

Default Value 16

Impact on Radio Network Performance

The setting of this parameter affects number of hard handovers. If this parameter is set to a smaller value, hard handover is likely to be triggered, but ping-pong handover may occur. If this parameter is set to a greater value, hard handover is unlikely to be triggered, but call drops may occur

Parameter Detail

Drive Test Results:

PRE D.T POST D.T

Static testing was done Pre and Post changes to check on field Throughput during BH. Significant improvement observed after changing parameters

Drive Test Results:

During drive testing high number of UE mean observed due to which throughput is low on all sectors.

During drive testing high number of UE mean observed due to which throughput is low on all sectors.

Drive Test Results: