Network coding-based 1+N protection scheme in hybrid wireless-optical broadband access networks

In the past decade, network protection which provides resilience against link/node failures has been well studied. Recently, 1+N protection based on network coding has proposed in wireless networks and optical networks respectively to balance the tradeoff between resource utilization and recovery delay, where the receiver can recover the packets from N sources on the fly when there is a single link failure on the paths from N sources to the receiver. This paper will consider 1+N protection in hybrid wireless-optical broadband access networks. We prove that the OLT can recover the N data units even if one of the N+1 combinations is lost, if and only if, any subset of nodes in sources set of size k is connected to at least k + 1 edge-disjoint paths to ONUs, for all values of k, 1 ≤ k ≤ N. We also present a network coding scheme of 1 + N protection in this paper. This paper also points out that our scheme can be used in a more general topology compared with the 1 + N protection scheme used in wireless networks, which is restricted to require that any k clients must be connected to at least k+1 routers in wireless networks. The simulation results show that our solution can achieve higher network throughput than applying the solution used in wireless networks directly in hybrid wireless-optical broadband access networks.