Fast Frequency Hopping OFDM with QR-Based Receivers

Fast frequency hopping OFDM (FFH-OFDM) is a recently proposed concept to enhance conventional OFDM performance without using channel coding by fully exploiting frequency diversity available within one OFDM symbol. Previously, a linear receiver of FFH-OFDM requires zero-forcing (ZF) or minimum mean squared error (MMSE) detection algorithm. This paper introduces QR-based receivers for FFH-OFDM systems to further enhance the detection performance. By exploiting a special form of an effective channel matrix with the proposed scheme, a reduced complexity algorithm of QR decomposition is proposed. Simulation results indicate that the QR-based receivers outperform the MMSE and ZF receivers by about 4 dB and more than 5 dB at FER= 10^-2, respectively, in an uncoded case. In a coded case, however, the MMSE receiver has similar performance to the proposed QR-based receivers.