On Design of TDD for Joint Uplink and Downlink Resource Allocation in OFDMA-Based WiMax

In this paper, the authors study the joint design of uplink and downlink resources in OFDMA-based systems. They first analyze the interactions between uplink and downlink, due essentially to the usage of Time Division Duplexing (TDD) and the TCP ACKs. This analysis is based on analytical models for interference and throughputs that they develop for both directions. They next study the capacity of the system using a Markovian analysis and matrix geometric solutions. Their performance analysis study allows one to determine the optimal proportion of resources that has to be allocated to the uplink so as to minimize blocking.