A pruning scheduler for multi-user clustered OFDM systems

Multi-user diversity is meant to work in a cell with several active users, relying on the increased probability that at least one of the users will have a high SNR. When using clustered OFDM with multi-user diversity, the system can admit too many users, defeating the multi-user effect. We present a scheduling scheme that overcomes this disadvantage by using a simple on-off waterfilling. We analyze the performance of the system when the feedback is not reliable and the average SNR is very low (0 dB). Our proposed scheduling algorithm increases the number of successful users by a factor of three over a coded system with one user per OFDM symbol.