Constellation-rotated vector OFDM and its performance analysis over Rayleigh fading channels

  • Authors:

  • Chenggao Han;Takeshi Hashimoto;Naoki Suehiro

  • Affiliations:

  • Department of Electronic Engineering, University of Electro-Communications, Chofushi, Tokyo, Japan;Department of Electronic Engineering, University of Electro-Communications, Chofushi, Tokyo, Japan;Graduate School of Systems and Information Engineering, University of Tsukuba, Tsukuba-shi, Ibaraki, Japan

  • Venue:
  • IEEE Transactions on Communications
  • Year:
  • 2010

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Abstract

Although the single antenna vector OFDM (VOFDM) proposed by Xia shows performance robust to channel spectral nulls, it does not necessarily attain full diversity for multi-path fading channels. It is known that the degradation in diversity order is sometimes rescued by the rotation of constellation. A simple application of constellation rotation to the V-OFDM system does not, however, improve its performance. In this paper, we discuss the sub-channel spectral structure of the V-OFDM signal and give upper bounds on its pairwise error probability over multi-path Rayleigh fading channels and propose a novel constellation-rotated V-OFDM (CRV-OFDM) with improved diversity. To this end, we design rotation angles for sub-channel symbols to minimize upper bounds on BER. Simulation results show that the proposed CRV-OFDM attains diversity order min{M,P} for the vector length M and the number of paths P. As the results, for BER 10-4, CRV-OFDM improves the performance of V-OFDM by 2dB for both BPSK and QPSK modulation when M is 2, and, for M = 4, the improvement factor is about 1.3dB. We also discuss the effects of M on the transmitter and receiver complexities and on the peak-to-averate power ratio. Finally, we compare several methods for rotational angle determination.