.802.16 Guarantee Qos Cross-layer Scheduling Design

The next generation wireless metorpolitan access network(WMAN) technology IEEE802.16d/e has defined a set of specifications to support quality of service (QoS) for heterogeneous services over wireless air interface.At the media access control (MAC) layer, it specifies scheduling services,service flow management,bandwidth request,poiling,grant mechanisms and relevant signaling. However,it doesn't define scheduling algorithms,which are open for developer.Due to beterogeneous services over WMAN, as well as the dynamic variation of wireless transmission channel,the end-to-end QoS guarantee over 802.16 systems requires cooperation across layer,and consequently cross-layer design becomes critical in the futureIn this paper the author studies the existing QoS guarantee mechanism and scheduling algorithm with QoS support,and proposes a cross-layer QoS guarantee and scheduling algorithm for 802.16 system. The proposed scheme at the medium access control (MAC) layer for multiple connections with diverse QoS requirements,where each connection employs adaptive modulation and coding (AMC) scheme at the physical (PHY) layer. Each connection is assigned a priority, which is updated dynamically based on its channel and service quality; and the connection with the highest priority is scheduled each time. Our scheduler provides diverse QoS guarantees, uses the wireless bandwidth efficiently and enjoys flexibility, scalability and low implementation complexity. The performance of our scheduler is obtained by numerical calculation.