Network Coding Based Cooperative Peer-to-Peer Repair in Wireless Ad-Hoc Networks

Cooperative Peer-to-Peer Repair (CPR) has been proposed to recover from packet losses incurred during 3G broadcast. CPR leverages the increasing presence of multi-homed mobile devices having both 3G cellular and IEEE 802.11 wireless interfaces. Mobile devices can, therefore, draw upon IEEE 802.11 peering links to cooperatively achieve out-of-band repair of 3G broadcasting losses. This paper considers the problem of employing Network Coding (NC) to exploit the broadcast nature of the wireless medium towards enhancing the efficiency of CPR. We show that the minimum latency scheduling problem for NC based CPR (NC-CPR) is NP-Hard. We present heuristics for NC-CPR that assume a priori topology and packet loss information. Insights gained from our heuristics are leveraged to propose NC-DCPR, a fully distributed protocol for NC-CPR. We conduct extensive simulation experiments under realistic network conditions. Our results show that employing network coding significantly improves the efficiency of CPR.