An Optimal Network Control Framework for Wireless SDN: From Theory to Implementation

Software Defined Network (SDN) has emerged as a new programmable network paradigm that facilitates flexibility in robust control and management. Current routing protocols deployed in SDNs are based on quasi-static shortest path algorithms and operate much below the throughput capacity of the network. Though throughput-optimal and well-established in the literature, the Back-Pressure (BP) algorithm is not compatible with wireless SDN architecture. In contrast, the recently developed Universal Max-Weight (UMW) policy also achieves throughput-optimality, yet permits algorithmic structure more congruent with SDN's requirements. Unlike BP, UMW pre-computes a fixed route per-packet upon a packet arrival, which can be integrated with the flow installation phase of SDN, and uses novel easy-to-track virtual queues in place of physical queues (of backlogged packets), whose operations are not supported by SDN switches. In this paper, we propose a UMW-based routing framework for wireless SDN that achieves the full network capacity and supports an arbitrary mix of multi-type traffic. In order to improve robustness in dynamic wireless environments, we modify the UMW algorithm to enable re-routing around failed links. Finally, we develop a Mininet-based implementation of our framework to validate and evaluate its performance. Our simulation results demonstrate that, compared against the conventional SDN shortest path routing, UMW improves throughput by over 100% and significantly reduces average per-packet delay in high-throughput regime. In the presence of dynamic link failures, our results show only marginal loss in throughput, further validating UMW's effectiveness in dynamic wireless environments.