Robust rate adaptation for 802.11 wireless networks

Abstract

Rate adaptation is a mechanism unspecified by the 802.11 standards, yet critical to the system performance by exploiting the multi-rate capability at the physical layer. In this paper, we conduct a systematic and experimental study on rate adaptation over 802.11 wireless networks. Our main contributions are two-fold. First, we critique five design guidelines adopted by most existing algorithms. Our study reveals that these seemingly correct guidelines can be misleading in practice, thus incur significant performance penalty in certain scenarios. The fundamental challenge is that rate adaptation must accurately estimate the channel condition despite the presence of various dynamics caused by fading, mobility and hidden terminals. Second, we design and implement a new Robust Rate Adaptation Algorithm (RRAA) that addresses the above challenge. RRAA uses short-term loss ratio to opportunistically guide its rate change decisions, and an adaptive RTS filter to prevent collision losses from triggering rate decrease. Our extensive experiments have shown that RRAA outperforms three well-known rate adaptation solutions (ARF, AARF, and SampleRate) in all tested scenarios, with throughput improvement up to 143%.

ERA: Effective Rate Adaptation for WLANs

“…The scheme dubbed Robust Rate Adaptation Algorithm (RRAA) by Wong, et al [8] is a frame loss rate driven scheme with loss differentiation. It keeps track of short term frame loss rates, and accordingly adapts the rate.…”

“…So far, RTS/CTS frames were used [7,8] to probe the channel and/or alleviate congestion to yield efficient rate adaptation schemes. However, since RTS/CTS control frames may represent a significant overhead and are usually not used, it is particularly desirable, though challenging to develop, such a rate adaptation scheme without using RTS/CTS frames.…”

“…Thus, in recent years, researchers designed second generation rate adaptation schemes that diagnose the cause of a loss and appropriately react [7,8]. But these schemes require the use of RTS/CTS control frames that are pure overhead.…”

Enhanced Rate Adaptation Schemes with Collision Awareness

“…However, as pointed out in [4], CARA-BASIC might suffer from RTS oscillation, which alternates in turning on and off the RTS frame transmission.…”

Rateless spinal codes

“…The link and subnetwork layers implement bit rate adaptation policies to dynamically select and configure the discrete choices and parameters provided by the PHY. The selection of a suitable bit rate is made by observing channel conditions, such as the signal-to-noise ratio (SNR) from a preamble [7,8] or pilot tones, interference-free bit error rate [19], dispersion in the constellation space [13], frame loss rate [20], or the time taken to successfully transmit a frame [2].…”