Retransmission rate selection for block-based partial packet recovery

In a Wi-Fi network, partial packets often exist which are packets with some errors. Recent works show that much better efficiency can be achieved by repairing such packets instead of retransmitting such packets. In this paper, we propose a rate selection scheme for the repair packets, refereed to as ReSel. ReSel is developed under the Maranello partial packet recovery framework and is motivated by two observations. First, the repair packet is sent shortly after the original packet and will likely experience similar channel conditions as the original packet. Therefore, given the recent failure on the original packet, a lower data rate should be used for the repair packet. Second, a Maranello receiver will send a NACK packet to the sender, which can be used to carry important information for the selection of the data rate. We build a rate selection table for ReSel with experimental data. We implement ReSel in the firmware and our experiments show that ReSel significantly improves the link throughput and reduces packet jitter. We also find that the repair packet is transmitted only once in the majority of the cases and hence ReSel is capable of selecting the appropriate data rate.