08 WCDMA RNO Coverage Problem Analysis WCDMA Coverage Problems AnalysisWCDMA Coverage Problems Analysis Course ObjectivesCourse Objectives � Analyze problems of pilot coverage and service coverage, an[.]
WCDMA Coverage Problems Analysis Course Objectives After learning the course, you can: Analyze problems of pilot coverage and service coverage, and then solve them Measure the coverage performance of a network Know coverage enhancement technology Contents Coverage problems classification Coverage analysis flow Coverage enhancement technology Typical coverage problems analysis Key items at each stage of network optimization Training.huawei.com Coverage Problems Classification Signal dead zone Coverage void Cross-cell coverage Pilot pollution Imbalance of uplink and downlink Coverage Problems Classification Signal dead zone In the zone, pilot signal is lower than the minimum access threshold of mobile phone For example, RSCP threshold is -115 dBm, and Ec/Io threshold is -18 dB, such as valley, opposite of the sidehill, elevator well, tunnel, underground garage or basement, and inside of the high buildings Solutions: Construct a new NodeB Add coverage areas Use RRU and repeaters Use leakage cable and micro cell Use indoor distributed coverage system Coverage Problems Classification Coverage void In the area, pilot signal is lower than minimum requirement in full-coverage areas (such as Voice, VP, PS128K), but better than the minimum access threshold of mobile phone Solutions Construct micro NodeBs or repeaters Use high-gain antenna, increase antenna height, reduce the mechanism tilt angle of antenna Optimize power configuration of full-coverage services (in scenes without large capacity requirements Coverage Problems Classification Cross-cell coverage Coverage areas of some NodeB are beyond the planned range, and forms pilot areas satisfying full-coverage services in coverage areas of other NodeBs Solutions: Adjust tilt angel and azimuth of antenna Avoid antenna propagation directed to the road Use the shield effect of peripheral buildings Adjust pilot power, and reduce coverage areas of NodeB Coverage Problems Classification Pilot Pollution Multiple pilot signals are received in one point, but there is primary pilot strong enough If over three pilots meet CPICH _ RSCP > −95dBm and (CPICH _ RSCP1st − CPICH _ RSCP4th ) < 5dB, there is pilot pollution Solutions: Consider pilot pollution at planning stage to facilitate later network optimization Adjust distribution and antenna parameters Lower pilot power Merge NodeB sectors or remove redundancy sectors without affecting capacity Coverage Problems Classification Imbalance of uplink and downlink In target coverage areas, uplink coverage is limited (the transmit power of UE is maximum but cannot meet uplink BLER requirements), or downlink coverage is limited (the transmit power of downlink dedicated channel code is maximum but cannot meet downlink BLER requirements) Imbalance of uplink and downlink due to uplink interference Imbalance of uplink and downlink due to limited downlink power Contents Coverage problems classification Coverage analysis flow Coverage enhancement technology Typical coverage problems analysis Key items at each stage of network optimization Training.huawei.com Coverage Void Problems Caused by Improper Site Planning Irregular mesh structure causes coverage void Cross -cell Coverage Problems caused by Cross-cell Improper Site Selection Case If a site is over high, cross-cell coverage occurs easily, so intrafrequency interference to other sites occurs Red indicates cross-cell coverage areas by the first sector of Road 27 Site Cross -cell Coverage Problems caused by Cross-cell Improper Site Selection Solution Increase mechanism tilt angle and adjust direction angle to solve cross-cell coverage problems for high sites Red indicates Part cross-cell coverage areas in Wenhua Rd by the first sector of Rd 27 Site Coverage Restriction Problems Caused by Improper Installation of Antennas Case The Pilot Network: 701070_ParkLaneHotel site of S project covers the Victoria Park and the antenna is mounted on the platform (10 meters high), as shown in this picture At the optimization phase after the network construction, before the traffic light under the antenna, Video Phone mosaic adds and image quality is worse and PS 384K service is reactivated Call drop occurs easily by traffic lights New 3G antenna Existing 2G antenna Coverage Restriction Problems Caused by Improper Installation of Antennas Analysis From the perspective of planning, 3G network and 2G network co-locate Compared with 2G coverage test data, 2G network has not large signal fluctuation under the road and site, that is, if the antennas of 3G network and 2G network are in the same location, the road’s 3G coverage is performed by 701070_ParkLaneHotel_Podium site The problem lie in than 3G antenna is so close to the platform that the wall blocks the signal and installation conditions of antenna are not met Meanwhile, 2G antenna and installation components affect the 3G antenna pattern Solution Change least without affecting the 2G coverage, connect the transceiver feeders of 3G and 2G respectively with two ports of external broad frequency polarization antenna, and connect other transceiver feeders of 3G and 2G with two antennas of internal broad frequency antennas Coverage Restriction Problems Caused by Incorrect Installation of Antennas Case In the Pilot network of S project, 701640_ElzHse1 site has only one cell and combines transmitter A, B and C (It is not OTSR, but the combination of three antenna receiving signals and distribution of NodeB transmission signal) During the antenna installation at the NodeB construction phase, all the transmission feeders are combined to sector A by mistake, so sector B and C have no signals to transmit and the coverage effect is worse The problem is found after RF engineers test RTWP interference at the site Before the problem is found, the single site test is passed The problem even remains in the later network optimization test until RF engineers identifies it during testing RTWP interference Coverage Restriction Problems Caused by Incorrect Installation of Antennas The figure shows the comparison of pilot RSCP before and after the antenna installation correction After antenna is corrected… Before antenna is corrected… Coverage Restriction Problems Caused by Incorrect Installation of Antennas Analysis The pilot RSCP before the antenna correction in the previous figure shows that the signals close to the bottom of the site are below -76 dBm Comparing the coverage of three sectors, obviously, you can find that the coverage of sector A is 20 dB stronger than that of sector B and sector C From the perspective of current single site test Checklist, it is difficult to find the pilot RSCP is larger than -85 dBm, especially for the micro-cellular site Most sites of S project share 2G sites location or sector Therefore, use the 2G coverage distribution to check whether the 3G coverage is normal For example, compare the distribution area ranging from -90 dBm to 80 dBm Currently, the minimum work level of 2G network is about -60 dBm, and only when the minimum working level at the bottom of 3G sites also should reach about -60 dBm, the sites are basically normal Contents Coverage problems classification Coverage analysis flow Coverage enhancement technology Typical coverage problems analysis Key items at each stage of network optimization Training.huawei.com Single Site Test Stage Signal dead zone Concern the major coverage target of each transmitter and confirm whether the signal dead zone is present based on the specified target Coverage void Concern whether the continuous coverage of full-coverage service can be guaranteed Planning verification Concern the difference between the digital map and actual environment, and perform a comparison and verification between the coverage prediction and actual drive test data Evaluation Stage before Optimization Uplink and downlink interference Concern the change of uplink RTWP of each cell, Scanner in the drive test or RSSI of UE Ec/Io mean Under the unloaded downlink and loaded downlink, concern whether the areas less than the mean value affects continuous coverage of full-coverage service RSCP mean Concern whether areas with the mean value affect seamless coverage of full coverage service RF Optimization Stage Cross-cell coverage Concern the repeated coverage due to inconsistent height of sites Pilot pollution Concern whether the ping-pong handover exists in the soft handover area to reduce the intra-frequency interference Over large areas of soft handover Concern volume restriction due to over large areas of soft handover Network Optimization Project Acceptance Stage Traffic measurement indexes Concern the inconsistency between the specified coverage target and actual user traffic distribution Summary The network optimization can improve quality of the whole network used by the mobile users and use network resources more effectively Although the coverage indexes are not reflected in the KPI, the coverage optimization is the basic requirement for improving the network performance The radio performance optimization can take effect only based on the coverage optimization Thank you!