Cognitive radio on TV bands: a new approach to provide wireless connectivity for rural areas

Employing wireless technologies to provide connectivity for rural areas is an active topic in the academic and industrial communities. In this article we begin by discussing the challenges of rural communications and reviewing existing wireless technologies that have been proposed or implemented for this market. We then focus on an emerging technology, cognitive radio, that promises to be a viable solution for rural communications. The most notable candidate for rural cognitive radio technology is the IEEE 802.22 standard that is currently being developed and is based on time division duplexing, orthogonal frequency division multiple access, and opportunistic use of the VHF/UHF TV bands. We address two important issues that can affect the success of IEEE 802.22 technology in rural deployments, namely, to: 1) Provide suitable service models 2)Overcome the problem of long TDD turnaround time in large rural cells For the first issue, we introduce a service model that combines TV broadcasting and data services to facilitate service adoption. For the second issue, we propose an adaptive TDD approach that effectively eliminates the requirement for long TDD turn-around time and thus, increases the efficiency of large-coverage rural networks.