Technical Support - Welcome to Huawei.com

Title: High RSSI Value of the Antenna System of the CDMA450 Base Station Caused by Engineering Quality Problems ID: SE0000369962

Update Time: 2009-01-14 09:59:10

Views:

Author: c60028130

Product Family: Antenna Feeder Product: Antenna & Feeder

Fault Type: Others

Keywords: VSWR RSSI feeder connector engineering quality

Digest:

Phenomenon Description:

The customer A in country M uses the CDMA450 system. After the CDMA450 equipment is running for several months, suddenly, the main RSSI values of the base stations in sites Sabkha and Zatar are high. The customer cannot confirm whether the abnormal RSSI occurs after the base station is running or occurs recently. By observing on site, find that the main RSSI values of the three sectors in the two base stations range from -70 dB to -80 dB, which is overlarge. The diversity RSSI lower than -100 dBm is a normal case.

Alarm Information: None.

Cause Analysis:

The two base stations with high RSSI values use the S3/3/3 configuration. The CDDU of each sector provides the TRX and RX ports. The fact that the RSSI value at TRX ports is large and the RSSI at RX ports is normal indicates that interference does not exist. The fault may be caused by faulty hardware and signal transmitting paths. The field engineers do not have relevant experiences in solving this kind of problems. Therefore, the troubleshooting takes a long time. For details, see the following handing process.

Handling Process:

1. Use the YBT250 to test interference at night and in day under blocked and unblocked conditions. No interference is detected. 2. Use the Sitemater to test the VSWR and DTF of the feeder and find that the VSWR and DTF of the feeder are abnormal. (The feeder is found normal falsely during the on-site test.) 3. Remake the antenna jumper and feeder connector. The RSSI value improves but does not achieve a normal range. 4. Block carriers in turns and observe the change of the RSSI value. No rules are found. 5. The problem is not solved and antenna is falsely regarded as faulty. Contact the headquarters to deliver a new antenna for replacement. 6. The HQ analyzes the problem, and asks field engineers to analyze and locate problems by exchanging feeder parts. The antenna is found functional and the connection between the feeder and jumper is found faulty, which can influence the RSSI value. 7. Contact experienced engineers to remake feeder connectors and replace feeders on site. Then, continuously observe the RSSI values of two base stations in four days and find that the RSSI values are stable. The fault is cleared.

Suggestions and Summary:

1. Wireless network engineers should be skilled in making feeder and jumper connectors that meet the specifications and be able to quickly troubleshoot some simple engineering quality problems. 2. Wireless network engineers should be skilled in using the Sitemaster to analyze problems and to locate fault causes. What we can learn from the case: some of our engineers ignore some basic acknowledge and skills although they master some high-level product skills. Therefore, they fail to locate some simple engineering quality problems on site. The problem location takes more than one month. It is a waste of resources and influences the quality of network running.

Attachments: DTFdata.JPG

Related Document Link No Related Documents.

[Close] Huawei Technologies Co.,Ltd Copyright 1998-2006,All rights reserved

file:///E|/EDOCs/Huawei/Huawei%20problems%20(Case%20Studies)/antenna%20feeder/SE0000369962/SE0000369962.html (1 of 2) [5/12/2010 2:00:48 AM]

Local DiskTechnical Support - Welcome to Huawei.com