Dynamic Joint Switching Point Configuration and Resource Allocation in TDD-OFDMA Wireless Networks

The development of the Time Division Duplexing (TDD) mode in next generation OFDMA-based wireless standards has brought some major advantages but at the same time raised several critical design requirements. Among others, the introduced flexibility in splitting resources between the uplink and downlink directions makes of the uplink/downlink switching point configuration a major design problem, especially that it is directly connected to other design aspects such as resource allocation and interference mitigation. In this paper, we propose a dynamic joint uplink/downlink resource allocation and switching point configuration algorithm. The proposed algorithm is channel-aware, traffic-aware, and service-aware. The resource allocation problem is formulated as an optimization problem that captures the different network parameters. Resulting instantaneous uplink and downlink rates are utilized in a dynamic estimation of the uplink and downlink time shares. A fast implementation using sequential quadratic programming is presented. Simulation results demonstrate the efficiency of the proposed approach in responding dynamically to varying network conditions and the improved performance when compared to fixed uplink/downlink switching point configurations.