Smart Retransmission and Rate Adaptation in WiFi

Transmission failures are common in wireless networks due to dynamic channel conditions and unpredictable interference. To efficiently recover from failures, we proposea smart retransmission scheme where the receiver combines information received from multiple failed transmissions associated with the same frame. The smart retransmission has two distinguishing features: (i) it can simultaneously supportpartial retransmission and combines bits with low confidence, and (ii) it has the first combining-aware rate adaptation scheme, which selects the data rates for all transmissions associated withthe same frame to maximize overall throughput. We find thatcombining-aware rate adaptation is essential to harnessing thecombining gain. Using trace-driven simulation and USRP testbedexperiments, we demonstrate the feasibility and effectiveness ofour approach, and show it significantly out-performs the existingschemes, such as WiFi, partial packet recovery (PPR), andSOFT in terms of both throughput and energy.