Implementation and Evaluation of Cooperative Routing in Software Defined Wireless Networking

In a mesh network, not all WiFi APs are always taken part in the actual packet transmission which makes network resources redundant. A same packet is usually received by more than one node even though they are not on this packet’s original transmission path. These nodes can be chosen to forward the packets to the destination node, which improves the bandwidth of the designated link in a cooperative routing path. However, due to the transmission and computation overhead on WiFi APs, the cooperative routing is difficult to be implemented in traditional wireless networking. The centralized architecture of software defined wireless networking (SDWN) makes it convenient to select helper nodes effectively and globally for a cooperative routing. This paper proposes a cooperative routing algorithm in SDWN. In this algorithm, routing discovery is performed on WiFi APs while the global and computation intensive tasks such as the route validation, the helper node selection and the interferences update are completed by the controller. By extending OpenFlow protocol, the proposed cooperative routing has been implemented and evaluated on a test bed. The evaluation indicates that our QoS oriented SDWN-based cooperative routing achieves greater bandwidth and less packet transmission delay than traditional wireless protocols.