Diversity multiplexing tradeoff analysis of coded OFDM systems with linear precoding and linear receivers

In this paper, we investigate coded OFDM systems with linear constellation precoding and linear receivers. A prominent example of such systems is the DFT-Spread-OFDM uplink in the 3GPP LTE based cellular network. We adopt the diversity multiplexing tradeoff framework and show that, in the presence of an ideal outer code, precoding does not improve the diversity order obtained using the optimal decoder. On the other hand, in the presence of an ideal outer code precoding can be detrimental from a diversity order perspective when linear receivers are used. In the latter case, we show that a simple way to guarantee improved diversity orders is to optimize the symbol loading. Finally, we extend our analysis to the multiuser case and propose an algorithm to optimally divide the available subcarriers among the multiple active users.