Mitigation of Intermodulation Effects Due to Co-Existence Of GSM 900 And CDMA 2ooo 1x Systems Using Antenna Isolation Technique
Okorogu Victor N · 2013
The major drawback of shared sites is the increased level of interference, analysis on intermodulation interference and the effect of noise on Receiver sensitivity of the CDMA System due to interference from GSM System in co-site cells showed that the Signal –to –Interference–plus–Noise Ratio (SINR) of Networks when operating separately in different sites is better than in co-site arrangement. This work adopted the Antenna Isolation technique as a viable option to minimize the interference level, in order to ensure harmony and co-existence of shared Networks based on a physical optimization of antenna systems that could be understood as a physical symmetry rotation in space, to vary the antenna tilt and azimuth. The approach independently reduces the interference effects on the distance between the base station antennas. This research analyzes the interference between co-site CDMA2000-800MHz (CDMA2000 1x/UMTS800) and GSM900MHz Base Station Systems due to spurious emission, intermodulation effects and blocking. Received Signal Strength (RSS) measurements were gathered in Enugu from Mobile Telecommunications of Nigeria (MTN) Network (GSM900) and Visafone Network (CDMA2000 1x) in sites where each Network operates alone and where both Networks shared sites (co-site or coexistence), while Antenna Isolation measurements were practically demonstrated in Huawei Laboratory so as not to disrupt traffic on Operators Networks, using token antennas and calibrated cables.