A Novel Wavelet Packet Division Multiplexing Based on Maximum Likelihood Algorithm and Optimum Pilot Symbol Assisted Modulation for Rayleigh Fading Channels

Abstract

Wavelet packet division multiplexing (WPDM) is a high-capacity, flexible, and robust multiple-signal transmission technique. In this paper, a novel WPDM system based on optimum pilot symbol assisted modulation (OPSAM) and a maximum likelihood (ML) algorithm is studied for Rayleigh fading channels. The ML detecting algorithm and the new discrete wavelet packet transform structure, which is based on pilot symbol assisted modulation (PSAM) using a least mean squares algorithm, are two novel aspects of the presented system. An expression for the bit error rate of the WPDM scheme on quadrature phase-shift keying (QPSK) is derived in the presence of flat fading and Gaussian noise. It is demonstrated by simulation results that the OPSAM WPDM scheme can provide greater immunity to flat fading channels and Gaussian noise than the OPSAM orthogonal frequency division multiplexing scheme, the differential QPSK WPDM scheme, and the normal PSAM WPDM scheme.