Performance of combined diversity reception and convolutional coding for QDPSK land mobile radio

Diversity reception and error correction coding are powerful techniques to combat multipath fading encountered in mobile radio communications. In order to improve the transmission performance of the π/4-shift QDPSK signal in mobile radio channels, the authors propose a new scheme of combined coding and diversity reception, i.e., combination of diversity reception employing code combining (CC) and convolutional coding employing error-and erasure correction Viterbi decoding. They also consider another combination scheme, i.e., combination of diversity reception employing postdetection maximal ratio combining (MRC) and convolutional coding employing hard decision Viterbi decoding. They theoretically analyze the performance of the schemes taking into account the additive white Gaussian noise (AWGN), random FM noise, co-channel interference (CCI), and intersymbol interference (ISI) due to multipath propagation delay spread. Numerical calculations are presented for the required average signal energy per bit-to-noise power spectral density ratio (E_b/N₀), required average signal-to-interference power ratio (SIR), tolerable maximum Doppler frequency, and tolerable rms delay spread needed to achieve a certain average BER. The spectrum efficiency of the cellular system is also calculated