无线信道固有的特点,使得无线局域网面临比有线局域网更多的困难。发展合适的介质访问控制协议(MAC)是无线局域网一个关键,而其中退避算法又是 MAC 协议考虑的重点。本文介绍了退避机制在 IEEE802.11MAC 层中的作用,指出了二进制指数退...无线信道固有的特点,使得无线局域网面临比有线局域网更多的困难。发展合适的介质访问控制协议(MAC)是无线局域网一个关键,而其中退避算法又是 MAC 协议考虑的重点。本文介绍了退避机制在 IEEE802.11MAC 层中的作用,指出了二进制指数退避算法存在的不足。对当前已提出的多种典型退避算法进行了介绍,对各类算法的设计思想进行了分类。最后阐明了退避算法研究的发展趋势。展开更多
In contention-based satellite communication system, collisions between data packets may occur due to the randomly sending of the packets. A proper delay before each＇ transmission can reduce the data collision rate. A...In contention-based satellite communication system, collisions between data packets may occur due to the randomly sending of the packets. A proper delay before each＇ transmission can reduce the data collision rate. As classical random multiple access protocol, the slotted ALOHA （S-ALOHA） reduces the data collision rate through time slot allocation and synchronous measures. In order to improve the stability and throughput of satellite network, a backoff algorithm based on S-ALOHA will be effective. A new adaptive backoff algorithm based on S-ALOHA using grey system was proposed, which calculates the backofftime adaptively according to the network condition. And the network condition is estimated by each user terminal according to the prediction of the channel access success ratio using the model GM （1,1） in grey system. The proposed algorithm is compared to other known schemes such as the binary exponential backoff （BEB） and the multiple increase multiple decrease （MIMD） backoff. The performance of the proposed algorithm is simulated and analyzed. It is shown that throughput of the system based on the proposed algorithm is better than of system based on BEB and MIMD backoff. And there are also some improvements of the delay performance compared to using BEB. The proposed algorithm is especially effective for large number of user terminals in the satellite networks.展开更多
文摘无线信道固有的特点,使得无线局域网面临比有线局域网更多的困难。发展合适的介质访问控制协议(MAC)是无线局域网一个关键,而其中退避算法又是 MAC 协议考虑的重点。本文介绍了退避机制在 IEEE802.11MAC 层中的作用,指出了二进制指数退避算法存在的不足。对当前已提出的多种典型退避算法进行了介绍,对各类算法的设计思想进行了分类。最后阐明了退避算法研究的发展趋势。
文摘In contention-based satellite communication system, collisions between data packets may occur due to the randomly sending of the packets. A proper delay before each＇ transmission can reduce the data collision rate. As classical random multiple access protocol, the slotted ALOHA （S-ALOHA） reduces the data collision rate through time slot allocation and synchronous measures. In order to improve the stability and throughput of satellite network, a backoff algorithm based on S-ALOHA will be effective. A new adaptive backoff algorithm based on S-ALOHA using grey system was proposed, which calculates the backofftime adaptively according to the network condition. And the network condition is estimated by each user terminal according to the prediction of the channel access success ratio using the model GM （1,1） in grey system. The proposed algorithm is compared to other known schemes such as the binary exponential backoff （BEB） and the multiple increase multiple decrease （MIMD） backoff. The performance of the proposed algorithm is simulated and analyzed. It is shown that throughput of the system based on the proposed algorithm is better than of system based on BEB and MIMD backoff. And there are also some improvements of the delay performance compared to using BEB. The proposed algorithm is especially effective for large number of user terminals in the satellite networks.
