dc.description.abstract | The IEEE 802.16 wireless metropolitan area network (WMAN) standard is an advanced wireless communication technology, which is designed to provide ubiquitously and fast communication services for mobile station (MS). In an error-prone wireless environment, receiver is likely to fail to receive data sent from transmitter. To curb this problem, automatic repeat request (ARQ) mechanism is usually adopted to synchronize the reception status between transmitter and receiver. That is, receiver is responsible to report acknowledge information of received data blocks to the transmitter and the transmitter retransmits those erroneous data blocks received by receiver in order to achieve reliable data delivery. Four different ARQ report types have been defined in IEEE 802.16e-2005 standard, and each report type has its specific format, overhead and report capability. The receiver is free to use any ARQ type to indicate which blocks are correct and incorrect. However, from our observations, using improper type to report statuses of blocks may cause extra signal overhead and response time. Unfortunately, the 802.16e-2005 standard does not specify the policy of choosing ARQ report type. As a solution, this thesis proposes a simple policy for optimizing the ARQ report scheme. In order to enhance the efficiency of ARQ mechanism and decrease the number of required report frames, this study focuses on the adaptive and hybrid reporting scheme, which still complies with standard. The concept of adaptive reporting scheme is to dynamically evaluate the most proper method for reporting according to the present statuses of received blocks. Simulation results demonstrate that, with this adaptive reporting scheme, the transmitter could quickly receive the report frame and retransmits data blocks if any.
This thesis will first elaborate and illustrate the operations of ARQ mechanism defined in IEEE 802.16 standard. After then, the proposed scheme is introduced and the performance of proposed scheme will be evaluated by simulations. Simulation results will show that the dynamic choice of report types will obtain the best performance in all cases. | en_US |