Receiver Assisted Rate Adaptation in Wireless Networks

Abstract

The IEEE 802.11 wireless local area network (WLAN) standard, especially 802.11a re- mains the most popular way to exchange data over wireless links. The major requirement is to adapt to highly dynamic channel conditions with minimum overhead and ensure robustness and speed of transmission. To this end, we propose a novel rate adaption scheme NARC (Neighbor Aware Rate Control). Firstly, our key contributions include exploiting the more precise channel estimation of SNR based rate adaptation coupled with estimating the channel condition at the receiver and nally sending this estimated information to the transmitter with minimum overhead. We use acknowledgment rates to serve this feedback purpose. Our feedback mechanism also allows for optimal rate switch rather than sequential one that most of the existing methods support. Secondly, we address the stale feedback problem that the SNR based methods mainly su er from and provide a unique solution to overcome this. To the best of our knowledge no works have addressed the solution to this problem. The stale feedback problem was mitigated by a prediction mechanism using linear regression on the observed rates on sender side and feedback rates from the receiver side. Besides, we di erentiate the cause of frame loss as either due to channel error or collision using RTS/CTS but in an adaptive fashion to minimize overhead but at the same time ensure that rate is not falsely changed due to frame loss caused by collision. NARC exploits the best of SNR based approaches and provides channel condition at the receiver to the transmitter with minimum overhead thereby ensuring optimal rate switching decision aided by sender side prediction mecha- nism to tackle against stale feedback problem. Moreover use of Adaptive RTS provides robustness to our method.