Work flow of interference investigation of base station


Because of the difference between LTE system and traditional frequency division system, there is no experience in field interference screening. There are some problems such as blindness and difficulty in locating interference source. The interference processing time cannot be guaranteed and the user satisfaction is seriously affected.


1、 Interference check of macro station

Macro station troubleshooting is mainly divided into two parts: background operation and field frequency scanning. Through background operation, the efficiency of on-site inspection can be effectively improved, and the interference source can be accurately located by field inspection.

1. Check whether there are important alarms and recover, check whether there is any abnormality in the time slot ratio and frame offset parameter setting of the station and surrounding base stations;

2. Restart RRU for real-time observation, compare the low-noise changes before and after restart to determine whether it is caused by equipment reasons;

3. Reduce the cell transmit power to 0, and observe the average bottom noise value of Rb in 15 to 30 minutes. Objective: to determine whether RB reception will cause interference without transmitting power.

If interference exists, it may be external interference; if interference disappears, it may be interference of hardware class;

4. Whether the isolation degree of the upper station is insufficient with other heterofrequency (GSM, DCS, telecom and Unicom) antenna is insufficient. If there is insufficient isolation degree of mobile, it can be verified by short blocking background observation + field frequency scanning. If other operators go to step 5;

5. Observe and check external interference at 90 ° and 180 ° of torsion antenna. Objective: to determine the direction of interference from, the larger the scope of macro station, the higher the difficulty of interference detection, and to reduce the scope of the investigation can improve efficiency; after adjusting the azimuth angle, contact the background to check the interference bottom noise value, and the direction of the highest bottom noise is the direction of the interference source.

6. If the interference caused by equipment and isolation degree is still existing, it is necessary to scan frequency on site to find out the interference source. Note that the antenna of frequency sweep instrument and base station should be on the basic equal level (it must be on the base station sky plane) when sweeping frequency. Determine which direction of interference bottom noise is the highest, and then follow the track to sweep through. The interference source is found by three-point positioning method.

2、 Room interference check

1. Check whether the cell frame offset parameter setting is abnormal;

2. Check whether there are important alarms and recover them;

3. Restart RRU for real-time observation;

4. Lock WLAN AP to make it have no signal transmitting or field shake off WLAN coupler, observe background index;

5. The DCS1800 was locked for bottom noise observation, and then GSM900 cell was blocked;

6. Cascade multiple rrus are turned off gradually to check whether the equipment is faulty;

7. Use frequency sweep to check external interference (common ones include mobile phone signal jammer, mobile phone shield, etc.), and electronic equipment EMI such as wireless monitoring equipment, NFC, elevator induction door, etc.);

8. Connect mushroom head directly to output port of RRU equipment to observe bottom noise, connect each connector step by step to observe and check component faults;