Performance analysis of cellular digital mobile radio systems including diversity techniques

Abstract

The performance of cellular digital mobile radio systems is investigated using quadrature amplitude modulation (4-QAM) and differential phase shift keying (DPSK) in a frequency nonselective Rayleigh fading environment with lognormal shadowing, including the effects of (white) Gaussian noise, narrow-band impulsive noise/interference (Middleton's Class A model), and cochannel interference. The performance is analyzed in terms of probability of bit error. The UHF groundwave propagation law is introduced by considering the local mean power to be inversely proportional to the fourth power of propagation distance. To investigate the improvement in performance the influence of selection diversity and maximal ratio combining on the bit error probability is analyzed. It has been found that shadowing significantly affects the bit error performance. Application of selection diversity or maximal ratio combining results in important improvement of system performance. Selection diversity gives better results than maximal ratio combining for low signal-to-noise ratios. Results of our analysis show maximal ratio combining is not that sensitive to unequal branch signal-to-noise-plus-interference ratio.