To ensure that the final network acceptance can pass, you should strictly monitor the network quality for a period of time after the swap. The tasks involved in network monitoring include online equipment problem handling, network monitoring, and network optimization.
7.1 Online Equipment Problem Handling
7.1.1 Hardware Problem Handling
The hardware problems occurring after swap must be handled immediately; especially the BTSs providing converge for VIP areas should be more carefully monitored.
When the project team handles the coverage problems, such inverse connection of antenna feeder and poor Rxlevel, network optimization supervisor or project supervisor should confirm that the problems are really solved. To solve conversation problem caused by board failure, you need to block the OMC and check the utilization of channels and signaling.
No alarm will be generated if the performance of some hardware decreases. Once discovering such problem, network optimization engineers should solve the problem with the coordination of BSS engineers.
If the traffic volume of a cell is low, the problem may be related to uplink and downlink.
If the channel utilization rate is low, call drop rate is high, and there is great interference, the problem may be related to the decrease of the TRX performance and combiner and divider performance.
7.1.2 Complaint Handling
Users’ complaints must be handled quickly. Generally, complaints can be divided into the following categories:
Voice quality complaints (one way audio, no audio, cross-talking, call drop, echo, noise, etc) Service failure complaints (incoming call failure, outgoing call failure, fax service
unavailable, etc)
PS complaints (slow network connection, GPRS service unavailable, etc)
7.1.3 Alarm Analysis
I. BSS-Focused Abnormal Alarms
The following table lists the alarm names according to BSC32.
Alarm ID Alarm Name Remark
62 Signalling link layer 2 congestion alarm Signaling alarm 65 Destination signalling point unavailable alarm
84 Signalling link layer 3 congestion alarm 86 Signalling link unavailable alarm
107 SCCP remote signalling point failure alarm 113 SCCP destination signalling point forbidden alarm 626 Signalling link service interruption alarm
627 Signalling link location failure alarm
311 Digital relay PCM failure alarm Relay alarm
545 Internal flow class change System load
547 Cell flow control class change Cell load
559 BSC reset alarm Circuit failure
560 BSC reset acknowledgment alarm 562 BSC reset circuit alarm
571 MS reset alarm
572 MSC overload alarm
605 BSC unequipped with circuit alarm 612 MSC unequipped with circuit alarm
695 GCKS clock 10 minutes deviated from reference time Clock source failure 696 GCKS clock 24 hours deviated from reference time
II. Important MSC-Related Alarms
The important MSC-related alarms are A-interface relay circuit alarm, signaling link alarm, BSC overload alarm, and BSC reset alarm.
7.2 Network Monitoring and Optimization
After swapping the network, you should closely monitor the feedbacks from the customers or users. Generally, users are quite sensitive to the network quality several days after the network integration and may put forward subjective feelings. For example, they may complain that they cannot make calls in the rooms where the signals were weak before the network integration. Or they may also complain that there is great noise, the success rate of the fax service is low, and the data service is unavailable. The reasons for the problems are that the coverage sensitive area decreases, or the network parameters are irrationally set, or the cooperation between operators’ parameters are not satisfactory. These problems must be solved as quickly as possible. If the decrease of the coverage area is caused by improper planning, you need to change the planning accordingly immediately. Note that you should pay special attention to antenna adjustment;
otherwise new coverage problem will be introduced. To prevent sensitive problems from causing great negative effect, you need to notify marketing personnel to maintain good customer relationship.
7.2.1 OMC Traffic Statistics Analysis
You can discover the problems of the original network through monitoring and analyzing the daily traffic statistics. During this period of time, you should try to register as much as traffic statistics that are used for network optimization. In addition, you should pay special attention to the traffic statistics related to traffic volume, congestion, call drop, handover, and interference. Furthermore, you also should compare the traffic statistical indicators before and after network swap. If an indicator becomes worse after swap, you should find out the reasons and improve it.
I. KPI Analysis (Voice Service)
In addition to the call drop rate, congestion rate, and handover success rate (for cell-level indicators), you are suggested to pay attention to the following traffic statistical indicators. For TRX-level indicators, you should check the assignment and utilization of SDCCH and TCH in the channel allocation performance measurement and discover the abnormal TRXs immediately. For the statistics in the path balance performance measurement, you need to monitor the uplinks and downlinks of the corresponding TRX.
You should integrate the Rxlevel performance measurement and Rxqual performance measurement into consideration, and can analyze the coverage provided by radio signals and also analyze the interference caused by the radio signals as well.
For the networks with high load, you are suggested to check the signaling link send occupation percentage (%) and signaling link receive occupation percentage (%) in the MTP link performance measurement, because these two items indicate the signaling load at the A-interface. If the values of the two indicators reach 30% respectively, the signaling link will be congested or signaling may be losing. In this case, you should suggest the customer expand the network. In BSC overall performance measurement, if the PCH overload times for circuit service at the Abis interface and the RACH overload times for circuit service at the Abis interface are great, you should consider readjusting the paging parameters or redividing the location areas.
In LAPD performance measurement, if both the pages discarded due to serious LAPD link overload and pages discarded due to slight LAPD overload are not 0, it means that the flow control has been happened during the statistical period.
For the network side, you need to check the following changes.
If the average timeslot occupation time is quite short according to A-interface relay performance measurement, it is likely that the A-interface relay is inversely connected or mismatched. In this case, users cannot hear the opposite party’s voice, and then hang up. Therefore, each conversation only lasts for a short period of time.
The cause values of the inter-BSC outgoing handover failure in cell performance measurement (3) can be divided into multiple types and they can be used for the analysis of inter-BSC handover. II. KPI Monitoring (for Each Swap BTS)
You can use NASTAR to monitor the change of the KPIs before and after swap (the traffic data of the original network should be collected and input into the NASTAR in advance). To discover problem in time and prevent the traffic fluctuation from reducing analysis deviation, you are recommended to use the all-day KPIs (24 hours). And you should pay special attention to the traffic volume, call drop rate, and handover success rate. If there is abnormal case, analyze and handle it immediately. At last, you need to export a KPI monitoring daily report.
III. KPI Analysis (Packet Service)
The daily GPRS network monitoring is responsible for the monitoring of data throughput, transmission performance, accessibility, resource utilization rate, and retain ability. The following table lists the GPRS KPIs.
Data Throughput Downlink NS_PDU mean throughput (kbps)
Transmission performance
Uplink RLC data block retransmission rate (%) Downlink RLC data block retransmission rate (%) Uplink EGPRS RLC data block retransmission rate (%) Downlink EGPRS RLC data block retransmission rate (%)
Accessibility
Uplink assignment success rate Downlink assignment success rate
Mean interval for packet access request initiated on CCCH (s) Uplink TBF congestion rate (%)
Downlink TBF congestion rate (%) Uplink EGPRS TBF congestion rate (%) Downlink EGRPS TBF congestion rate (%)
Resource utilization rate
Uplink PDTCH/PACCH utilization rate Downlink PDTCH/PACCH utilization rate PDCH utilization rate
Success rate for BSC to reclaim overload dynamic PDCH PDCH allocation success rate
Mean downlink throughput per PDCH (kbps) Mean uplink throughput per PDCH (kbps) Retain ability Uplink GPRS TBD call drop rate (%)
Downlink GPRS TBF call drop rate (%) Uplink EGPRS TBF call drop rate (%)
Downlink EGPRS TBF call drop rate (%) For details, refer to GPRS Traffic Statistics Analysis Guide.
7.2.2 Analysis of NSS-Related Radio Indicators
I. Paging Success Rate and Location Update Success Rate
One-time page and subsequent pages cannot be told from each other according to the Abis interface circuit pages measured by BSC, so you are suggested to obtain the one-time paging success rate from the MSC. If the paging success rate is low, you need to check the location update success rate measured by the MSC and perform further analysis.
II. Signaling Load
When analyzing the A-interface signaling load measured by the BSC, you need to check the signaling load measured by MSC. If the load is heavy, you should discuss with the customer on whether to expand the signaling link.
III. Intra-MSC Handover Success Rate
If the inter-BSC handover success rate is low, you need to check the intra-MSC handover success rate or inter-MSC handover success rate.
7.2.3 Analysis of Area DT and CQT and Related Suggestions
The optimized DT lines include but are not limited to the DT lines evaluated before swap. For the convenience of comparison, you are suggested to use the same DT line, test instrument, and vehicles for drive test. Note that the position of MS antenna and that of the vehicle mounted station must keep consistent before and after the swap. In addition, the test should be performed at the same time in a day.
You should perform corresponding optimization according to the drive test, and then compare the final DT results with the predicted results. Finally, you should output a network comparison report.
CQT should be performed for VIP areas and the network quality in the VIP areas must become better after swap. After CQT, you need to further optimize the network.
7.2.4 After-Swap Network Maintenance
NASTAR, GSM network optimization software developed by Huawei, can be used to monitor the daily network performance (it can output daily report, weekly report, half-monthly report, and monthly report). In addition, NASTAR can also be used for frequency analysis, adjacent cell analysis, performance analysis, and geographic location display.
A specialist should be arranged to update the data for NASTAR according to the change of the network, and the specialist should check the data with the customer periodically.
Traffic data should be sent back to the performance service platform of the regional division for analysis and handling.
For details, see NASTAR Operation Guide.
7.2.5 Network Optimization
The following tasks are involved in network optimization: Adjust and optimize BTS coverage area
Adjust and optimize the interference between adjacent cells or frequencies. Set and adjust adjacent cell relationship
1) Adjust and optimize handover parameters
Prepare dialing test for the cells in which frequency hopping is available
2) Register traffic tasks, monitor and optimize network performance after swap, and check the change of KPIs.
7.3 Customer Communication
When analyzing and handling network problems, you need to communicate with customers in time, seek help from them, and notify the results to them in time.