A multiconstraint QoS routing scheme using the depth-first search method with limited crankbacks

We propose a multiconstraint QoS routing scheme using the DFS (depth-first search) method to sequentially search for a feasible routing path. Although the standard sequential search approach has several advantages, it has not been explored for multiconstraint QoS routing in the literature due to its asymptotic exponential worst-case time complexity. Our scheme limits the number of crankbacks per node (crankback degree) to control the worst-case time complexity. The scheme uses a metric, called the normalized margin, to reduce the average-case time complexity by first exploring the paths that are most likely to be feasible. We further tune the crankback degree based on correlation coefficients between QoS attributes to reduce the worst-case time complexity. We use simulations to show that our scheme solves multiconstraint QoS routing problems with a small probability of missing a feasible path while keeping the average-case time complexity low.