Dynamic downlink and uplink subframe boundary adjustment for capacity improvement and QoS support in mobile WiMAX

Mobile WiMAX is a promising broadband access technology providing wireless last mile connectivity. In the Time Division Duplex (TDD) mode, a WiMAX frame is divided into two parts: downlink and uplink subframes. The subframe division ratio is normally set to a fixed value, resulting in under-utilization of the downlink or uplink subframes. In this paper, we propose a dynamic downlink and uplink subframe boundary adjustment scheme in which the downlink and uplink subframe ratio is dynamically adjusted upon the usage statistics. It consequently improves the frame utilization efficiency, system capacity as well as QoS support.