Considerations for wireless network optimization

Wireless network technology is a complicated problem for many network administrators. What are the main problems when we optimize the network? Here is a detailed introduction.

Wireless network optimization has become a daily task, and network optimization technologies and methods are also very advanced. Network parameter optimization has been done in an all-round and meticulous manner, there are already advanced tools and better methods of frequency reuse for frequency optimization. Our current wireless network optimization should be detailed in a base station, a cell, however, some network optimization personnel have little knowledge about the base station hardware, direct station, indoor distribution system, transmission, and antenna feed. These reasons have a great impact on the disconnection, the following typical problems are classified and summarized for reference by network optimization personnel and maintenance personnel.

Wireless Network Optimization 1. disconnection from base station hardware problems

The Base Station hardware involved in the disconnection mainly includes TRU, CDU, DU, FU and related connections.

Due to the decrease in the operating performance of hardware such as TRU, CDU, DU, and FU, the operation is unstable, but the alarm is not displayed. In this case, problems need to be discovered through experience-based optimization statistics.

When there is a TRU problem, the user's call quality on the carrier will be poor and cause the disconnection. Statistics show that the time slot utilization on the carrier is low, and some TRU problems will cause uplink interference, the interference level reaches 4-5. The RLCRP and RXCDP commands can be used to comprehensively check whether the interference time slot is on the same carrier. If the interference time slot is on the same carrier, it can be judged that the TRU has a fault.

When there is a problem with DU, the uplink signal is weak, resulting in many drops, sometimes there will be a Diversity Reception alarm, sometimes there is no such alarm, then you can change the DU and then observe the situation.

When CDU-A, CDU-C + and FU problems will produce the upper and lower line signal weak drop words, sometimes also produce poor quality off words, when there is a problem with the CU, the weak line signal produces a lot of drops.

Direct station and indoor distribution system faults lead to calls out. Due to the performance degradation of the transmitter device, self-excitation sometimes occurs, resulting in calls out. Statistics show that the TA of the base station is frequently dropped, tests show that the coverage distance is approaching, and the call quality is poor.

If a connection error occurs, the RF line connecting the main Cabinet FU to DU is faulty. The FU of the main cabinet should be connected to the RXA port of DU, And the FU of the auxiliary cabinet should be connected to the RXB port of DU, due to the level or negligence of the construction personnel, the auxiliary cabinet FU is also connected to the RXA port of DU, resulting in no diversity reception in the community, resulting in high disconnection, there are four districts in the Heihe region that encounter errors during construction. Three or more carriers of the residential CDU-C + RX receiving line is easy to connect to the wrong, the general error is the first two carriers receive A channel to receive the main, the next one or two carriers are dominated by B-channel reception. In this way, there will be some deviations in the selection of reception signals, which will easily lead to disconnection and affect the success rate of intra-cell switching. This phenomenon is common and cannot be seen in statistics. It can be checked only on the base station side.

If the TRA device on the BSC is poor, it will also lead to disconnection. On the TG data of the base station, if the TRACO is set to SEMI, the time slot of the base station will correspond to the TRA device on the BSC one by one. If the TRA device is faulty, the disconnection rate of the cell connected to the device is high. The TS data is removed and reloaded (the original TRA device is closed at the same time), so that the time slot of the base station is connected to the good TRA device, this problem can be solved.

If the TRACO is set to a POOL on the base station TG data, the base station time slot does not have a one-to-one correspondence with the TRA device. This device is used only when the user calls the device. If the TRA device is faulty, the disconnection generated when the TRA device is used is not fixed in a residential area. In this case, the faulty TRA device should be determined through the software tracking method.

Some of the above hardware causes can be reflected in Ericsson's optimization analysis software, and some may be due to sudden or other reasons, when adjusting power, receiving level, switching, and other related parameters are ineffective, consider whether the disconnection is caused by hardware and related connections.

Optimization of wireless networks 2. disconnection from transmission reasons

The reason for the disconnection is mainly caused by the inconsistency between the grounding of the base station equipment and the grounding of the transmission equipment, poor transmission synchronization, and microwave equipment.

Because some base stations use the leased lines of China Netcom, the mobile companies and China Netcom's protected areas are separated. the grounding of the base station equipment is inconsistent with that of the transmission equipment, when the transmission is connected to the base station equipment, the potential difference is generated, which leads to poor transmission quality, resulting in unstable operation of the base station. In statistics, the disconnection rate of the station is high, and the channel availability rate is often less, however, sometimes the channel availability rate reaches, but the dropped call rate is also high due to the impact of the transmission quality. In the optimization software, there are many sudden dropped calls, however, Ericsson's explanation and analysis of sudden discalls are limited, so there are not many solutions to such discalls. For this reason, zhanhe, erjingzi, and Donggang stations in Heihe have a high drop-down rate. After the station equipment and transmission equipment are unified, the drop-down rate has been significantly improved.

Poor transmission synchronization will also lead to high disconnection from the base station. The RBS200 station of Ericsson has a high requirement on transmission synchronization, and the synchronization of SDH Equipment is slightly drifting. The operation of the 200 station will be affected, the drop-down rate will increase significantly. For some RBS2202 stations, the transmission of Zone B is Cascaded by the transmission of Zone A and Zone C, while that of Zone B cannot be unified, as a result, the operation of cell B of the base station is unstable and the disconnection rate is high, which is difficult to find. The reason is that the transmission of cell B is Cascade transmission and the quality cannot be observed, in statistics, the channel availability rate is also. In this case, you can establish A single level-1 connection between Zone B and Zone A or zone C (for example, if the country transmission time slot is insufficient, the signaling compression method can be used ), in this way, the operation of Zone B can be stable and the phenomenon of high disconnection can be eliminated. This method is used to reduce the number of dropped calls in the 9san station of Heihe region and the B community of Heihe 2nd station.

The Heihe region used a large number of microwave devices after phase IV of the project. These devices are mostly used for some cascade infrastructure stations. When the transmission performance of microwave devices decreases, this will cause unstable operation of the cascade Foundation station and a high disconnection rate. However, the quality of next-level transmission cannot be monitored on the exchange side. In this case, the microwave equipment should be checked and processed in a timely manner. Base stations such as Yinlong River in Heihe region solve their phone disconnection problems by processing microwave devices.

Wireless Network Optimization 3. Out-of-the-box calls

There are many reasons for phone disconnection due to the question of Tianji. Below we will only describe some typical problems.

During the construction of the project, the residential antennas of some targeted stations sometimes receive errors and strings, resulting in a high disconnection rate. In terms of cell errors, we can see that the number of switches is small, the switching failure rate is high, the disconnection rate is also high, and alarms are not collected in ERRORLOG, in this case, the website should conduct DT testing to identify problems. Another case is that there is only one feeder connection string between cells. Statistics show that the uplink signal is weak and there are many reasons for poor quality. In the alarm statistics, there are sometimes alerts for diversity reception, at this time, the community feeder should be proofread and corrected one by one.

Some base stations are selected on the hillside during site selection, and these stations are mostly full-direction base stations, resulting in poor close-range coverage and excessive coverage, statistics show that the uplink signal proportion is relatively high. In this case, the omnidirectional base station should be changed to the targeted base station, which can not only solve the problem of "Black under the light", but also solve the coverage problem, control the disconnection problem.

Statistics show that some base stations have a high percentage of dropped calls due to poor upstream and downstream quality. The day feeder, such as SITEMASTER, is used to test the day feeder. It is found that the standing wave ratio is not high, it is even better than the normal test records in the past. Do not be confused by this phenomenon. By checking the tianfeeder connector, we will find that the connector has been in the water, at this time, the water has penetrated into the feeder. At this time, the traveling wave of the feeder will be better, but the standing wave ratio will be lower, but the transmission performance of the feeder will decrease, resulting in a lot of calls.

In other communities, the uplink interference is found to be more serious, and the interference is more serious during traffic peaks. This is the case for the B community of Beigang station in Heihe region. The disconnection is very serious, it is usually 30-40 times. The interference tester is used for multiple tests, but the external interference sources are not always tested. By changing the transmission and hardware equipment of the residential area, the interference still exists. No problem was found when the antenna tester was used to test the antenna, but the antenna interface of the residential area was cracked when the antenna system was checked, the uplink interference disappears after the antenna is changed, and the disconnection is significantly reduced. Currently, it is within the range of 3-8 normal calls.