Retransmission 6= Repeat: Simple Retransmission Permutation Can Resolve Overlapping Channel Collisions

Collisions in overlapping channels can be a major problem in thedeployment of high-speed OFDM networks. In this paper, we presentRemap, a simple, novel paradigm for handling collisions in over-lapping OFDM channels. Remap introduces a novel concept ofretransmission permutation that permutes the bit-to-subcarrier as-signment after each transmission, departing from the traditional,simply-repeat paradigm. Remap is simple to implement and ableto exploit collision-free subcarriers to decode frames despite suc-cessive collisions in overlapping channels. We apply Remap to802.11g to demonstrate that the diversity created by remapped framescan substantially improve decoding efficiency and improve wire-less throughput. We implement our technique in software radioand demonstrate that it has potential to be deployed with simplesoftware and firmware updates.