A Survey on Coexistence in Heterogeneous Wireless Networks in TV White Spaces

With the advent of analog to digital transition in TV broadcasting, a substantial amount of spectrum has become available in TV bands. To take advantage of this, the idea for cognitive radios was introduced for two major reasons: better utilization of spectrum in urban areas and facilitation of wireless connectivity in rural areas. To achieve these two goals, however, many challenges have to be addressed first. Considering that these frequencies are commonly licensed, besides primary user detection, a serious challenge remains the detection and identification of other secondary devices and networks. The problems arising from this issue concern the coexistence problems happening from having several primary and secondary networks of different technologies cohabiting the same licensed spectrum simultaneously and from many secondary systems/users coexisting at the same place while using identical or different technologies. In this survey we provide a review of existing works and outline new challenges regarding coexistence and self-coexistence in heterogeneous wireless networks in TV White Spaces including a comparative analysis between selected coexistence mechanisms.