An efficient quality of service routing algorithm for delay-sensitive applications

It is well known that the Delay-Constrained Least-Cost (DCLC) unicast routing problem is NP-complete, hence various heuristic algorithms have been developed for this problem. In this paper, we propose a more efficient distributed algorithm, namely, Selection-Function-based DCLC (SF-DCLC), based on a novel selection function for the DCLC problem. The proposed SF-DCLC algorithm requires limited network state information at each node and is always able to find a loop-free path satisfying the delay bound if such paths exist. Simulation study shows that SF-DCLC is not as sensitive to the delay bound and the size of networks as some other DCLC routing algorithms, and has very low cost-inefficiency compared to the optimal one in various network scenarios we have studied. A noteworthy feature of SF-DCLC is that SF-DCLC has very high probability of finding the optimal solution in polynomial time with low computational complexity and message complexity.