Design tradeoffs in OFDMA traffic channels

This paper studies uplink traffic channel design tradeoffs for broadband OFDMA systems. For fixed and portable users, where the propagation channels are semi-static, we show that the uplink capacity can be maximized when user traffic channels are configured with the maximum frequency selectivity. For mobile services on the other hand, we show that the optimality depends on the outage threshold associated with the "outage capacity." In the low outage probability region, the outage capacity is maximized when the traffic channels are configured with the maximum frequency diversity. The opposite is true for the high outage probability region. Using the results presented, designers of OFDMA system can determine the optimum traffic channel configuration based on the types of services supported by the network.