Adaptive puncturing and rate selection in single-codeword turbo-coded OFDMA

This paper proposes using adaptive puncturing for rate-adaptive OFDMA systems utilizing turbo codes. The scheme is based on adaptively puncturing a Single Code Word (SCW) and hence adaptively changing the rate within the codeword. We compare the SCW against the Multiple Code-Words (MCWs) scheme where different rates are obtained by separate encoding, puncturing, and interleaving on a per-tile basis. Noticeable gains are obtained over the MCW scheme due to the use of larger turbo block sizes and hence larger interleavers. The SCW has around 1dB gain in goodput compared to MCWs, with much improved BER performance. We also propose a novel rate selection scheme for the SCW which we call Recursive Mutual Information Effective SNR mapping (R-MIESM) and compare it against the conventional MIESM scheme. The R-MIESM provides further goodput performance gains for the SCW compared to the MIESM method. © 2009 IEEE.