Space-time block coding with symbol-wise decoding for polynomial phase modulated signals

Abstract

Polynomial phase modulation (PPM) has been shown to provide improved error rate performance with respect to conventional modulation formats under additive white Gaussian noise and fading channels in single-input single-output (SISO) communication systems. In this paper, we evaluate the performance of systems with two and four transmit antennas using PPM as the modulation format. In both cases we employ full-rate space-time block codes in order to take advantage of the multipath channel. For two transmit antennas, we use the orthogonal space-time block code (OSTBC) proposed by Alamouti and perform symbol-wise decoding by estimating the phase coefficients of the PPM signal using three different methods: maximum-likelihood (ML), sub-optimal ML (S-ML), and the high-order ambiguity function (HAF). In the case of four transmit antennas, we employ the full-rate quasi-OSTBC (QOSTBC) proposed by Jafarkhani. Then, in order to perform low-complexity symbol-wise decoding, we find a decoupling matrix for the Jafarkhani scheme and apply a technique known as quasi-zero forcing (ZF). After that, the PPM signal parameters are estimated just as in the two-antenna case using ML, S-ML, and HAF. We show that the proposed systems using PPM and ML outperform OSTBC and ZF-QOSTBC using M-ary PSK as their modulation format.