基于IEEE 802.11高速无线局域网的速率自适应MAC协议研究

目前的IEEE 802.11标准在物理层提供了对多种发送速率的支持，然而在MAC层却没有规定速率自适应的方法。该文研究了高速IEEE 802.11 无线局域网中的速率自适应方案。首先，提出了EACK协议，EACK使用基本速率发送MAC头，并在ACK帧中携带信道信息，因而能够较快速地响应信道的变化，同时具有少的开销；其次，在EACK基础上，提出了一种恒定发送时间(CEACK)的策略，CEACK能够克服传统IEEE 802.11 DCF MAC协议的理论吞吐量上限，并且具有更好的时间公平性能，能够应用于高速的无线局域网。

Rate Adaptation MAC Protocol for High Rate IEEE 802.11 WLANs

The current IEEE 802.11 PHYs provide multiple transmission rates, but in MAC layer, the rate adaptation algorithm is not specified. This paper studies rate adaptation schemes for high rate IEEE 802.11 WLANs MAC protocol. Firstly, an Enhanced ACKnowledgement (EACK) rate adaptation protocol is presented. In EACK, the MAC header is transmitted at basic rate and the channel state information is carried by ACK frame. EACK reacts to channel variations quickly while has fewer overheads. Then, a constant transmission duration scheme with EACK (CEACK) is proposed for high rate wireless LANs which can overcome the throughput upper limit of legacy IEEE 802.11 DCF MAC and has better temporal fairness performance in hybrid rates networks.