Multi-dimensional adaptation and multi-user scheduling techniques for wireless OFDM systems

This paper considers techniques to increase the performance of the broadband wireless OFDM system through adaptation in both the time and frequency domains. System throughput estimates are provided for frequency non-selective coding and frequency selective coding for single antenna, Alamouti, and selective closed-loop MIMO configurations. Additional gains from performing multi-user frequency-domain scheduling are achieved and determined using proportional fair and maximum C/I schedulers. The performance gains of multi-dimensional adaptation and scheduling techniques are contrasted with the amount of feedback required. Measured data from a 20 MHz experimental system and turbo coding simulations are used to estimate the size of each feedback report, and an accepted user speed distribution is used to estimate an appropriate feedback rate.