Performance evaluation of different antenna array approaches for 3G CDMA uplink

One approach to solve the coverage problem in 3(rd) generation CDMA macro cells is to increase the number of receiving antennas at a base station. Antenna gain, diversity gain or both can be increased compared to conventional solutions. In this paper the relative performance of maximal-ratio combining, MRC, interference-rejection combining, IRC, fixed beam method (analog beamforming) and higher-order sectorization were studied. It was found out that the link level performance of different approaches depends mainly on the radio channel characteristics and on the particular multiple access interference scenario. In case of a large number of low-bit-rate users sectorization performs best in the macro cell channel giving 2.7-5.3 dB gain compared to 2-antenna MRC with 4 - 8 antennas. If only very few high-bit-rate interfering users are present and fractional loading is 50%, IRC gives best results giving a relative gain of 2.5 - 4.8 dB.