Jyoti Raju

A new approach to on-demand loop-free multipath routing

We present and verify ROAM, an on-demand routing algorithm that maintains multiple loop-free paths to destinations. Each router maintains entries only for those destinations for which data flows through the router which reduces storage space requirements and the amount of bandwidth needed to maintain correct routing tables. In ROAM, routes are established and maintained on demand using diffusing computations. A router does not send updates for active destinations, unless its distance to them increases beyond a given threshold. ROAM maintains a state that informs routers when a destination is unreachable and prevents routers from sending unnecessary search packets attempting to find paths to an unreachable destination. ROAM is shown to converge in a finite time after an arbitrary sequence of topological changes and is shown to be loop-free at every instant. The time and communication complexities of ROAM are analyzed.

Distributed assignment of codes for multihop packet-radio networks

This paper describes and analyzes a distributed algorithm for assigning codes in a dynamic, multihop wireless radio network. The algorithm does not require any form of synchronization and is completely distributed. The algorithm can be used for both the transmitter oriented and receiver oriented code assignment. The algorithm is proven to be correct and its complexity is analyzed. The implementation of the code assignment algorithm as part of the medium access control (MAC) and routing protocols of a multihop packet-radio network is discussed.

A comparison of on-demand and table driven routing for ad-hoc wireless networks

We introduce WRP-Lite, which is a table-driven routing protocol that uses non-optimal routes, and compare its performance with the performance of the dynamic source routing (DSR) protocol, which is an on-demand routing protocol for wireless ad-hoc networks. We evaluate the performance of WRP-Lite and DSR for varying degree of mobility and traffic in a 20-node network. The performance parameters are end-to-end delay, control overhead, percentage of packets delivered, and hop distribution. We show that WRP-Lite has much better delay and hop performance while having comparable overhead to DSR.

Scenario-based comparison of source-tracing and dynamic source routing protocols for ad hoc networks

We present source tracing as a new viable approach to routing in ad hoc networks in which routers communicate the second-to-last hop and distance in preferred paths to destinations. We introduce a table-driven protocol (BEST) in which routers maintain routing information for all destinations, and an on-demand routing protocol (DST) in which routers maintain routing information for only those destinations to whom they need to forward data. Simulation experiments are used to compare these protocols with DSR, which has been shown to incur less control overhead that other on-demand routing protocols. The simulations show that DST requires far less control packets to achieve comparable or better average delays and percentage of packet delivered than DSR, and that BEST achieves comparable results to DSR while maintaining routing information for all destinations.

Efficient on-demand routing using source-tracing in wireless networks

With on-demand routing, a router maintains routing information for only those destinations that need to be reached by the router. The approaches used to date to eliminate long-term or permanent loops in on-demand routing consist of obtaining complete routes to destinations dynamically, or obtaining only the next hops to destinations and validating the information using sequence numbers or internodal synchronization. We present a new approach to on-demand routing, which we call the DST (dynamic source tree) protocol. To eliminate looping, routers in DST communicate paths to destinations; however, only incremental updates to such paths are communicated by specifying the second-to-last hop and distance to each node in the subpath to the destination that must be updated. Simulation experiments are used to show that, in terms of control packet overhead, DST outperforms substantially the dynamic source routing (DSR) protocol which is arguably one of the most efficient on-demand routing approaches to date, while achieving similar performance in terms of the average delay and throughput of data packets.

Scenario-based comparison of source-tracing and dynamic source routing protocols for ad-hoc networks

We present source-tracing as a new viable approach to routing in ad-hoc networks where routers communicate the second-to-last hop and distance in preferred paths to destinations. We use two source-tracing algorithms, a table-driven protocol (BEST) in which routers maintain routing information for all destinations, and an on-demand routing protocol (DST) in which routers maintain routing information for only those destinations to whom they need to forward data. Simulation experiments are used to compare these protocols with DSR, which has been shown to incur less control overhead than other on-demand routing protocols. The simulations show that DST requires far less control packets to achieve comparable or better average delays and percentage of packet delivered than DSR, and that BEST achieves comparable results to DSR while maintaining routing information for all destinations.