| A wireless ad hoc network has been popularly researched for several decades. They support many various applications like Internet backbone, contents distribution, sensor network and vehicular communication, which encourage to build the ad hoc networks especially in urban areas. However, the deployment in unlicensed bands of dense urban areas imposes many challenges. The unlicensed bands have heavy interference from various wireless devices such as Wi-Fi, Bluetooth, Zigbee, etc. Previous researches about spectral diversity to enlarge channel capacity mostly focus on multi-channel allocation among nodes to avoid inter or intra-flow interferences within the networks. As cognitive radio technology utilizing spectrum holes on licensed bands attracts many attentions, however, we propose a new system model for cognitive multi-hop ad hoc networks in the urban unlicensed bands, borrowing cognitive radio concept, which avoids external interference from incumbent users as well as the internal interference simultaneously. Here our contributions are designing and developing new unicast and multicast routing protocols for the cognitive multi-hop ad hoc networks based on a cross-layer scheme. In detail, we develop a novel unicast routing protocol and forwarding schemes in urban wireless mesh networks, Urban-X. Also, we develop a new unicast and multicast routing protocols for cognitive vehicular ad hoc networks, Co-Vanet under traffics from the external incumbent users in urban areas. From many simulations, we demonstrate feasibility of our cognitive network model in unlicensed bands by showing that our protocols are robust to variation of channel environment and outside traffics. |
