Distributed Mode Selection for FDD Communication in Multihop Wireless Networks

We consider a decentralized, multihop wireless network consisting of frequency division duplex (FDD) nodes, which use separate frequency bands for transmission and reception. The use of FDD communication in a multihop wireless network partitions the nodes in two operating modes (or genders), depending on the frequency bands used for the transmission and reception. Since the FDD nodes of the same gender, located in a one-hop neighborhood, cannot communicate with each other, it can limit the availability of communication links between the neighboring nodes and also lead to network partitioning. Therefore, the operating mode of these nodes should be selected such that every node can establish links with its one-hop neighbors. We model the multihop network as a graph and design a novel, distributed bipartite graph coloring scheme, for mode selection of FDD nodes. Unlike the existing graph coloring schemes, which use the entire network topology and yet do not ensure network connectivity, our algorithm requires only the local information of one-hop neighborhood of each node in a distributed manner. The simulation results show that our mode selection algorithm ensures that every FDD node can establish the communication links with approximately half of its one-hop neighbors for omni as well as directional communication, without introducing any disconnected node. This mode selection algorithm also has a lower computational complexity and provides a robust network connectivity, which would help in fault tolerance and establishing stable routes in the network.