On The Research Of Radio Resource Allocation And Energy-saving Strategy Based On IEEE802.16

As one of the most promising technology in the next generation communication network, BWA (Broadband Wireless Access) has drawn much attention and became a hot spot of researching. The IEEE 802.16 standard is proposed as a world standard of BWA.Our work is based on IEEE 802.16 standard. To enhance the system performance to confront the challenge of supporting more users and providing higher rate and multiple services in future networks, we make research in perspective of radio resource management, mainly on two spots: resource allocation and energy conserving.IEEE 802.16 specifies several physical layer modes, among which, OFDM and OFDMA modes are both based on OFDM technology. In this work, we first investigate downlink resource allocation problem in OFDMA mode. According to present algorithms, to improve system capacity, the base station may adaptively allocate subcarrier, bit, and power to users based upon their Quality of Service (QoS) requirement and channel conditions. The resulted OFDM signals are more subject to non-linearity which may cause signal amplitude clipping and degrades all users' QoS granted by the radio resource allocator. This work will study the influence of non-linearity on the final SNR performances in such a system, and propose a novel resource allocation algorithm considering the non-linearity of practical transmitting system. The system performance is simulated and compared with that of an ideal system which has no non-linearity.Another major issue in today's wireless networks is the limited energy of the communication devices. In this work, an energy-conserving protocol which complies with TDD mode of IEEE 802.16 standard is proposed. This protocol is applicable to downlink data service. The base station buffers data packets for each mobile station (MS), and pages them on paging channel. As soon as the MS wakes up from sleeping mode, it turns on receiver. If there is a piece of information for that MS, it tries to access the network and receive packets. When there is no packet left in buffer queue, the MS switches to sleeping mode. This protocol may save energy at expense of packet delay performance and the probability of queue overflow. By setting the sleeping time properly, the overflow probability can be reduced to a required limit. Simulation proves the analytical results and shows a significant improvement of energy-consuming performance.