Bandwidth and power efficiency considerations for optimal training in OFDM

Orthogonal frequency division multiplexing (OFDM) has been adopted by many high speed transmission standards. Pilot tone assisted modulation (PTAM) is a well known technique to estimate the channel state information (CSI) in OFDM but is not bandwidth efficient. To achieve high bandwidth efficiency, we propose to carry out superimposed training with techniques described in this paper to improve the quality of the CSI estimate. It is well known that OFDM signals have high peak-to-average power ratios (PARs) and are thus not power efficient. To improve the power efficiency, we employ a blind selected mapping (SLM) PAR reduction method in conjunction with superimposed training. Simulation results demonstrate that under medium to low SNR conditions, combining superimposed training with PAR reduction yields BER performance that is comparable with PTAM; the benefit of the former is that bandwidth efficiency is preserved