Performance Analysis Of Adaptive ARQ Protocol Base On Broadband Wireless Multimedia Communications

Wireless communication systems have a high error rate because the time-varying nature and multi-path transmission characteristics of the wireless channel and a variety of noise interference. Therefore, effective error control technology is a key issue in wireless communication. Compare with the forward error correction (FEC), the automatic retransmission request (ARQ) error control technology is more reliable, which is one very effective error control technology in wireless high-speed communications.In this paper, some research work about the ARQ error control protocol has be done, the protocol may be used in the infrared communication networks or used in the multimedia communications network. In chapter 2, broadband wireless multimedia communication as the research background, we mainly consider that how to design retransmission scheme to make the reliability and real-time of data reached an acceptable level, when the transmission delay is demanded strictly and the data must be more reliable. An adaptive ARQ protocol (SG-ARQ) which combined ARQ with SR and GBN is proposed for broadband wireless multimedia communication. With using the SG-ARQ protocol, the system delay and packet drop rate are controlled efficiently, the data reliability is improved and system throughput is increased. Besides, the delay of SG-ARQ system is analyzed by using queuing theory, the packet drop rate and throughput is analyzed also, and the general expressions of performance indexes are obtained. Numerical results show that the adaptive ARQ protocol can obtain better performance than any other general ARQ in broadband wireless multimedia communication. In chapter 3, at first, several basic ARQ technology are introduced, the development of infrared communication and its features and principle are described. Following, the GBN-ARQ protocol are analyzed separately when it works in half-duplex communication system and in the duplex communication system, and the similarities and differences are compared. Finally, established vacation queue model for the GBN-ARQ system which work in half-duplex mode using queuing theory, and express the factors which affect the transmission system with proper parameters according the property of half-duplex links, analyze the component of average packet delay by using queuing theory, ordinary expression of average packet delay is obtained, which contain average packet waiting delay and packet service delay. The influence of packet error rate, windows length and data packet length on system delay is analyzed by numerical simulation. The results show that the relations of packet correct rate, packet length, the sending window size have significant impact on the system delay. So, the system transmission efficiency will be improved effectively, if the relationships of the three variables are determined reasonably.