pi/4-DQPSK signaling with baseband zero-crossing demodulator

The recently developed zero-intermediate frequency zero-crossing demodulator (ZIFZCD) can be employed for both narrowband and wideband angle modulated mobile communication systems. The digital implementation of the ZIFZCD offers low power consumption, small size and ease of manufacturing compared to conventional analog hardware and digital signal processor implementation. En this paper, the ZIFZCD is applied to pi/4-differential quadrature phase shift keying (pi/4-DQPSK), and the bit error rate (BER) performance of the ZIFZCD under static channel is compared with three conventional detection schemes. The simulation results show that the BER performance of 8-axes ZIFZCD is almost 2 dB worse than that of the limiter discriminator integrate and dump (LDI). This is mainly due to the nonconstant envelope property of the pi/4-DQPSK. However, if the ZIFZCD is applied to the constant envelope angle modulation e.g., minimum shift keying (MSK) and Gaussian minimum shift keying (GMSK), then the BER of the ZIFZCD is comparable with conventional detection schemes.