A carrier frequency offset (CFO) estimator was developed based on an interference cancellation scheme for an orthogonal frequency division multiplex access uplink. An initial CFO estimate was first obtained based on the received training signals at each user’s prescribed subcarrier positions. Then, the received training signals were compensated by using the initial CFO estimates in the frequency domain and the multi-user interferences were estimated. Finally, the interference-cancelled training signals were used to reliably estimate each user’s CFO. The CFO estimator performance was evaluated by the bit error rate performances of the CFO compensation-based receivers at the base station. Simulations show that with this optimal interference-cancellation-based CFO compensation receiver, the performance gain with the estimated CFO values is approximately 3 dB better at the 0.1% bit error rate than the initial CFO estimates.

Broadcast delivery of bulk multimedia files is an important wireless LAN application for densely populated scenarios such as inside high-speed train carriages. However, it is a challenge to adapt the broadcast link rate due to heterogeneity and varying channel conditions of the broadcast receivers to achieve both high bandwidth efficiency and fairness. In this paper, the broadcast link rate adaption problem is formulated as a quadratic programming problem with a broadcast link rate adaption algorithm named FBB (Fair and Bandwidth-efficient Broadcast). Simulation results show that the algorithm significantly outperforms fixed rate broadcast with only a small loss compared to its theoretical performance. The algorithm has been successfully applied in a practical wireless LAN access point.