MDPSK on frequency-selective Ricean channels with diversity and cochannel interference

The performance of M-ary differential phase shift keying (MDPSK) with diversity combining in frequency-selective slow Ricean fading with and without cochannel interference has been analyzed. The use of L-branch post-detection equal gain diversity combining to mitigate the effects of fading has been investigated. Expressions for the average BER were derived with and without cochannel interference. For the case of cochannel interference, precise average BER results were obtained by using a combination of analysis and simulation. Results obtained using a Gaussian interference model were also obtained. The accuracy of the Gaussian model was assessed by comparing its average BER performance with precise average BER results. The comparative performances of 2DPSK, 4DPSK, and 8DPSK have shown the following. For the same information throughput, it was seen that for small values of the Ricean K-factor (K=0 dB), the best BER performance is obtained in most cases by using 4DPSK. For large values of the Ricean K-factor (K=7 dB), it was seen that the best BER performance in most cases is obtained by using 2DPSK. The results in the paper have also shown that the Gaussian interference model can give an excellent approximation to the precise interference model for the case of no diversity (L=l). For the case of 2-branch postdetection EG combining, it was seen that the Gaussian model gives a good approximation to the precise model for small to medium values of SNR and may underestimate the effects of interference for large values of SNR