Improve 4G dwell ratio from adjusting RSRQ measurement parameters

Improve 4G dwell ratio from adjusting RSRQ measurement parameters

In order to improve the 4G network occupancy ratio index, combined with the actual situation of the network, some base stations perform adjustments based on RSRQ measurement parameters to trigger A2 events. The author and colleagues have made many attempts. The comparison of the effects before and after adjustment confirms that these methods are effective.

1. Background introduction

4G Residency Ratio Definition: 4G Resident is a ratio of the total traffic generated by a user holding a 4G terminal on the 4G network to the total traffic (2G, 3G, 4G traffic) generated by the 4G terminal. This indicator measures 4G. The user's presence on the 4G network. In the actual assessment, we have a clearer definition of “4G users”.

4G user definition: Users who have used 4G network within 60 days.

At present, the minimum access level, idle state reselection, and redirection mechanism of the current network are implemented based on the RSRP reported by the terminal as the only condition. However, based on the perspective of improving the LTE camping ratio, in many weak coverage scenarios, although the RSRP is poor, the wireless environment is pure, and the terminal can obtain better user perception even in the LTE weak coverage area. A better download rate is obtained, so the dual control based on measurement redirection through RSRQ and RSRP is proposed, which is more conducive to extending the terminal to camp on the LTE network.

2. Principle introduction

The RSRQ (Reference Signal Receiving Quality) indicates the LTE reference signal reception quality. This metric mainly ranks different LTE candidate cells according to the signal quality. This measurement is used as an input to the handover and cell reselection decisions. RSRQ implements an efficient way to report the combination of signal strength and interference.

Relationship between RSRP and RSRQ: RSRQ=N*RSRP/RSSI

Remarks:

N: Measurement bandwidth, mapped to RB number

RSSI: Average of all signals (pilot, data, interference, noise) received in the Symbol

RSRP is the signal receiving power in dbm

RSRQ (dB) reflects the ratio of the CRS signal to all interfering signals, similar to the signal-to-noise ratio

3. Parameter setting strategy

In the LTE system, the inter-frequency handover (1650+500) adopts the A2+A3 algorithm to ensure the road test index in order to obtain a better handover link. This adjustment does not involve inter-frequency handover in the system. For inter-frequency handover in the system, the original decision conditions are still adopted: the A2 event is triggered based on RSRP, the inter-frequency handover is performed by A2+A3, and the system redirection is determined by A2+B2.

This adjustment is for the case where only LTE1650 continuous coverage, no 500 flower arrangement, the use of RSRQ triggered A2 event, while comparing the effect of blind redirection and measurement redirection based on the dwell ratio.

● Blind redirection and comparison based on measurement redirection

Based on the RSR-triggered A2 event, only the source cell RSRQ is used as the sole decision criterion for the blind redirection. When the UE measures the RSRQ ≤ a2ThresholdRsrqPrim of the source cell and satisfies the trigger duration TImeToTriggerA2Prim, the blind redirection is triggered.

Based on the measurement redirection, when the UE measures the RSRQ ≤ a2ThresholdRsrqPrim of the source cell, the A2 event is triggered, and the eNB sends the inter-frequency measurement frequency point. The current connection state priority is set to 4/3G to 6/4, and the UE measures the 3G frequency point and reports the frequency strength of the LTE and W cells.

When the source cell satisfies RSRP≤b2Threshold1Rsrp and the 3G cell RSCP≥b2Threshold2RscpUtra, the trigger is based on measurement redirection.

From the perspective of two redirection modes, the dual control based on measurement redirection through RSRQ and RSRP is more conducive to extending the terminal-resident LTE network.

4. Modify the scene and effect

● Scene:

This adjustment is for the case where only LTE1650 is continuously covered and there is no 500 flower arrangement. All cells do not contain indoor distribution and do not contain inter-frequency neighbors.

● Modify the effect:

After the modification based on RSRQ redirection, the index is stable, and the reverse flow ratio is obviously improved, and the business volume is also improved. Before and after the parameter modification, pull the net comparison:

Access, switch, dropped KPI, CSFB indicators

Backflow ratio, traffic volume, occupancy ratio

It can be seen that the adjusted backflow ratio represented by red is significantly lower than that before the adjustment represented by blue, and there is no degradation effect on other KPI indicators. For details, see the following comparative trend graph.

5. Summary and recommendations

This adjustment parameter is based on RSRQ as the basis for triggering the A2 threshold, and at the same time, it is based on measurement redirection. For areas with strong LTE field strength and weak coverage but good reception quality RSRQ, the A2 event is not triggered, the LTE network is absorbed, the LTE network resident performance is better, and the impact on the daily KPI is not evaluated.

After the parameter adjustment, the local city's 4G network traffic increased by about 1400GB in a single day, an increase of about 7%.

● It is recommended to pay attention to the following points:

1. Parameter adjustment is only applicable to 1650 cells, and there is no inter-frequency neighboring area.

2. After the parameters are modified, it is necessary to pay attention to the fluctuation of the KPI and the quality difference cell. If there is any deterioration, it needs to be analyzed and promptly called back.

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