Link Dynamics and Protocol Design in a Multihop Mobile Environment
IEEE Transactions on Mobile Computing
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A routing framework that can be tuned for efficient performance depending on the particular characteristics of the network (such as traffic behavior, device capabilities, mobility patterns, operating environments, etc) is desirable in the versatile ad hoc networking environment. The concept of Zone Routing demonstrates how multi-scoping can provide the basis for a hybrid routing protocol framework. In Zone Routing, each node proactively maintains routing information for a local neighborhood called the routing zone, while reactively acquiring routes to destinations beyond the routing zone. We develop the Independent Zone Routing (IZR) framework which has the capability to form independently sized routing zones. With this capability, each of the nodes in the network can adaptively self-configure its own optimal zone radius in a distributed fashion. We show that the performance of Independent Zone Routing is significantly improved by this ability to provide fine-tuned adaptation to spatial and temporal variations in network characteristics. As a point of reference, through this form of adaptation, we show that the routing overhead in the network can be reduced by an order of magnitude, under some set of parameters' values. Further, automatic and dynamic configuration makes the routing framework truly flexible and robust to frequent changes of the network characteristics and operational conditions. All these factors enhance the scalability of this type of networks. As all the data packets forwarded by the routing protocol goes over the communication links in the network, it is important to get a good understanding of the link dynamics for efficient protocol design. We develop an analytical frame work to investigate the behavior of the communication links of a node in a random mobility environment. Analytical expressions characterizing various properties related to the formation, lifetime and expiration of links are derived. The derived framework can be used to design efficient algorithms for medium access, routing and transport control, or to analyze and optimize the performance of existing network protocols. A number of applications of the characteristics investigated, such as selection of stable routes, route cache lifetime optimization, providing Quality-of-Service (QoS) data communication and analysis of route lifetime are discussed. In particular, we focus on designing an efficient updating strategy for proactive routing protocols based on the derived statistics. Using simulations, we show that the proposed strategy can lead to significant performance improvements in terms of reduction in routing overhead, while maintaining high data packet delivery ratio and acceptable latency. The updating strategy can be used by the proactive component of the IZR framework, further enhancing its performance.