A study into the use of polarisation diversity in a dual band 900/1800 MHz GSM network in urban and suburban environments

This paper details a diversity performance study undertaken by Mason Communications, on behalf of Omnitel Pronto Italia (OPI), to investigate the use of dual polarisation antennas for cellular base stations within a dual band GSM900/1800 network. Extensive radio measurements for both uplink and downlink were taken using horizontally separated vertically polarised antennas, horizontally/vertically (H/V) polarised diversity antennas and /spl plusmn/45/spl deg/ polarised diversity antennas, in urban and suburban environments and in both the 900 and 1800 MHz bands. An analysis of the measurements was undertaken to find the gross mean and local mean of the signals received, and hence the branch imbalances, the correlation between the voltage envelopes of the signals, and the diversity gains achieved through the use of maximal ratio combining (MRC). The results of this analysis suggest that, in both environments and at both 900 and 1800 MHz, horizontally separated spatial diversity outperforms both /spl plusmn/45/spl deg/ and H/V polarisation diversity. However, the results indicate that /spl plusmn/45/spl deg/ polarisation provides a better performance than H/V polarisation at both frequencies and within both environments considered.