Revisiting partial packet recovery in 802.11 wireless LANs

Abstract

In wireless LANs, partial packets are often received which usually contain only a few errors. According to the current 802.11 standard, such packets have to be retransmitted. Much effort has been invested recently in repairing such packets without retransmitting the entire packet, e.g., by using error correction (EC) code or retransmitting only the corrupted blocks. In this paper, we revisit this problem, and propose Unite, a framework for more efficient partial packet recovery. Unite is motivated by two key observations. First, the two repair methods, i.e., the EC-based and block-based, are not mutually exclusive and can be combined to achieve higher performance. Second, the recently introduced error estimators can be utilized to determine the optimal repair method depending on the condition of each partial packet. The combined method should achieve better performance than each individual method; in addition, it should remain low in complexity because the EC-based and block-based method are both simple in nature. Unite uses AMPS, a recently proposed estimator, for error estimation. We implement Unite on the Madwifi open source driver, and our experiments show that Unite outperforms other recovery schemes.