Cognitive radios (CR) technology enables wireless devices to dynamically switch between channels in a wide range of frequency bands and utilize unused parts of licensed and unlicensed frequency bands. The CR-enabled devices can either form a stand-alone multi-hop wireless network or form a multi-hop wireless backbone network that can connect different types of devices together. In a multi-hop wireless network composed of CR-enabled devices the number and the set of available channels vary from one node to another. This is in contrast to the existing multi-hop wireless mesh networks where all the nodes have the same set of channels available. In this paper we present a CSMA-based MAC protocol for CR-based multihop network. This protocol is based on the channel segregation technique proposed for cellular networks. Simulation results indicate that the protocol incurs low latency and achieves reasonable throughput.

Cognitive radios (CR) have the ability to dynamically adapt to local spectrum availability. In a multi-hop wireless network comprised of CR-enabled devices, medium access control (MAC) layer scheduling for data communication involves assignment of timeslots and channels to either links or nodes in the network. The number of channels available and the channel identities vary from one node to another within the CR network. This is in contrast to the existing use of multiple channels where all the nodes have the same set of channels available (for example in IEEE 802.11 networks). In this paper, we present an integer linear programming (ILP) formulation for the MAC-layer scheduling problem and find an optimal schedule. We also propose a simple and efficient distributed heuristic for MAC-layer scheduling. Simulation results indicate that the proposed distributed heuristic provides near optimal schedule

A Mobile Ad hoc NETwork (MANET) is a group of mobile nodes that form a multihop wireless network. The topology of the network can change randomly due to unpredictable mobility of nodes and propagation characteristics. Previously, it was assumed that the nodes in the network were assigned IP addresses a priori. This may not be feasible as nodes can enter and leave the network dynamically. A dynamic IP address assignment protocol like DHCP requires centralized servers that may not be present in MANETs. Hence, we propose a distributed protocol for dynamic IP address assignment to nodes in MANETs. The proposed solution guarantees unique IP address assignment under a variety of network conditions including message losses, network partitioning and merging. Simulation results show that the protocol incurs low latency and communication overhead for an IP address assignment.

No abstract available.