Space-Time Processing for Wireless Communications
ICASSP '97 Proceedings of the 1997 IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '97) -Volume 1 - Volume 1
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This paper presents the performance of adaptiveantennas in a 1/3 reuse frequency hopping GSM networkusing conventional beamforming. It mainlyfocuses on C/I improvement for the purpose of capacityenhancement. The performance evaluation has beenconducted by means of network computer simulations,where measured time-space radio channel impulseresponses are applied for the desired user in thenetwork. Measurements with an M = 8 element uniformlinear array were conducted in the cities ofAarhus, Denmark, and Stockholm, Sweden. The simulatedC/I improvement shows an almost 10 * log10(M)behavior for low azimuth spread values. For largevalues of azimuth spread (relative to the antennabeamwidth), the performance gain is reducedsignificantly. For an azimuth spread of10°–12°, which has been measured inurban macro-cellular environments, the C/I gain forM = 8 is reduced to approx. 5.5–7.5 dB (which should becompared to the theoretical value of 9 dB for a pointsource). The designed DoA algorithm is very robust toco-channel interference and only a small degradationin performance is observed for single element C/I downto approx. –8 dB. We conclude that the designedbeamforming implementation facilitates a potentialcapacity gain of ×3 in a 1/3 reuse FH-GSM network foran array size of M = 4–6.