Maximizing Network Coding Opportunity through Buffer Management in Wireless Networks

Due to asynchronous packet transmissions and rate mismatch among different coding flows in existing opportunistic network coding architectures, such as COPE, the amount of packets which can be coded together may be insufficient and thus the performance gain of network coding cannot be fully exploited. One feasible solution for this problem is to make coding nodepurposely delay some packet transmissions so as to increase more coding opportunities. However, extra delay could be introduced and it will impose an adverse influence on delay-sensitive applications, such as video streaming. In this paper, we propose to use buffer management to maximize the coding opportunity while meeting the delay constraints of traffic flows. We formulate the design of delaying policy as an optimization problem. Based on the model, the network-coding-aware buffer management policy (NBM) consists of packet delaying and scheduling mechanisms, and each node independently decides whether and for how long to delay a packet. Numerical results validate our analytical model and show that NBM can substantially improve the performance gain of network coding compared with COPE.