RODMAC: A RObust and Distributed MAC protocol for efficient use of white spaces

We describe the design, implementation and evaluation of a RObust and Distributed MAC (RODMAC) protocol for cognitive radio networks which exploit spectrum white spaces for communication. RODMAC incorporates two novel features. These are a robust design resilient to node failure and a scheme for on-demand channel hopping. Other features include a fully distributed architecture and incorporation of Forward Error Correction (FEC) for better performance. RODMAC allows any pair of nodes requiring dedicated bandwidth for communication between them to request exclusive use of a free channel. Besides improving the QoS for communication between this pair of nodes, this mechanism also improves the overall efficiency of bandwidth resource usage. RODMAC can serve as the basis for building MAC protocols for applications which include device-to-device (D2D) communication, tele-medicine or military communication in a jamming environment. Our design has been implemented on the Wireless Open Access Research Platform (WARP) of Rice University. For this purpose, we have established a test bed of 4 WARP nodes. This design has been validated by careful analysis and repeated experiments over a 6 month period. We have analyzed our results for jitter, throughput and loss for different bandwidths. Our results for these parameters show an improvement in loss percentage of about 70% for a 5 Mbps link with video streaming on different channels using our novel on-demand channel hopping scheme as compared to simultaneous video streaming on the same channel.