On the spectral efficiency of shared wireless channels

A new mathematical model is presented for the analysis of interference in wireless systems sharing a common frequency band. It is applied to a random access environment, whereby a random number of users transmitting BPSK narrowband signals share a common wideband wireless channel, and the carrier frequency of each signal is randomly selected over the common frequency band. Based on this model, a new bit error rate analysis is derived and used to investigate the spectral efficiency of shared wireless channels. It is shown that the shape of the baseband pulse plays an important role. Specifically, numerical results suggest that the spectral efficiency of the shared wireless channel is increased when a rectangular waveshape is used instead of half-sine or raised-cosine.