A scalable rate adaptation mechanism for IEEE 802.11e wireless LANs

Although many rate adaptation schemes have been introduced to efficiently utilize the multiple transmission rates of the IEEE 802.11 standard, Automatic Rate Fallback (ARF) is the most widely implemented scheme on the market because of its simplicity. Our study reveals that the ARF malfunctions severely when it is used over IEEE 802.11e WLANs. The reason is that the intolerably shortened range of contention window for voice access category induces frequent collisions even when a small number of users contend. This paper demonstrates the inefficiency of the ARIF using an analytic model and proposes a new rate adaptation scheme that maintains scalability. Simulation reveals that our scheme performs consistently well compared to the ARF scheme.