Backbone Construction without a Common Control Channel in Cognitive Radio Networks”

The interference of a single link in traditional wireless networks usually comes from other links. The interfered sender can compete with other nodes fairly, using existing MAC protocols. However, in CRNs, interference to a single link consists of two parts: 1) interference from other SUs; 2) interference from PUs. The interfered nodes in CRNs can compete equally with other nodes for channel access, as is true in other networks. However, they cannot compete with PUs, since the PUs have privileged access on channels. Their data transmission cannot be interfered with by SUs. Therefore, for a single link in CRNs, if it is interfered by a suddenly active PU, it cannot compete with that PU. If the interfered link still wants to transmit on that channel, it has to wait for the PU’s data transmission to be finished. However, the signal duration of PUs usually lasts longer, which means the interfered link is broken for a long time. Therefore, the dynamics of channel availabilities in CRNs are more special than other wireless networks. With virtual backbones, the area routing scheme is implementable and very effective in reducing the influences caused by unpredictable PU activities.