A mobile ad hoc network consists of wireless hosts that may move often. Movement of hosts results in a change in routes, requiring some mechanism for determining new routes. Several routing protocols have already been proposed for ad hoc networks. This paper suggests an approach to utilize location information (for instance, obtained using the global positioning system) to improve performance of routing protocols for ad hoc networks. By using location information, the proposed Location-Aided Routing (LAR) protocols limit the search for a new route to a smaller “request zone ” of the ad hoc network. This results in a significant reduction in the number of routing messages. We present two algorithms to determine the request zone, and also suggest potential optimizations to our algorithms. 1

Mobile ad hoc networks have gained a lot of attention lately as a means of providing continuous network connectivity to mobile computing devices regardless of physical location. Recently, a large amount of research has focused on the routing protocols needed in such an environment. In this two-part report, we investigate the effects that link breakage due to mobility has on TCP performance. Through simulation, we show that TCP throughput drops significantly when nodes move because of TCP's inability to recognize the difference between link failure and congestion. We also analyze specific examples, such as a situation where throughput is zero for a particular connection. We introduce a new metric, expected throughput, for the comparison of throughput in multi-hop networks, and then use this metric to show how the use of explicit link failure notification (ELFN) techniques can significantly improve TCP performance. In this paper (Part I of the report), we present the problem and an analysis of our simulation results. In Part II of this report, we present the simulation and results in detail.

Abstract. Mobile ad hoc networks are characterized by multi-hop wireless links, absence of any cellular infrastructure, and frequent host mobility. Design of efficient routing protocols in such networks is a challenging issue. A class of routing protocols called on-demand protocols has recently found attention because of their low routing overhead. We propose a technique that can reduce the routing overhead even further. The on-demand protocols depend on query floods to discover routes whenever a new route is needed. Our technique utilizes prior routing histories to localize the query flood to a limited region of the network. Simulation results demonstrate excellent reduction of routing overheads with this mechanism. This also contributes to a reduced level of network congestion and better end-to-end delay performance of data packets.

In this paper, we present the MCEDAR (Multicast Core Extraction Distributed Ad hoc Routing) multicast routing algorithm for ad hoc networks. MCEDAR is an extension to the CEDAR architecture and provides the robustness of mesh based routing protocols and the approximates the efficiency of tree based forwarding protocols. It decouples the control infrastructure from the actual data forwarding infrastructure. The decoupling allows for a very minimalistic and low overhead control infrastructure while still enabling very efficient data forwarding.

Sensor networks can be considered distributed computing platforms with many severe constraints including limited CPU speed, memory size, power, and bandwidth. Individual nodes in sensor networks are typically unreliable and the network topology dynamically changes, possibly frequently. Sensor networks can also be considered a form of ad hoc network. However, here also many constraints in sensor networks are different or more severe. Sensor networks also differ because of their tight interaction with the physical environment via sensors and actuators. Due to all of these differences many solutions developed for general distributed computing platforms and for ad hoc networks cannot be applied to sensor networks. Many new and exciting research challenges exist. This paper discusses the state of the art and presents the key research challenges to be solved, some with initial solutions or approaches.

Recent advances in wireless sensor networks have led to many new routing protocols specifically designed for sensor networks. Almost all of these routing protocols considered energy efficiency as the ultimate objective in order to maximize the whole network lifetime. However, the introduction of video and imaging sensors has posed additional challenges. Transmission of video and imaging data requires both energy and QoS aware routing in order to ensure efficient usage of the sensors and effective access to the gathered measurements. In this paper, we propose an energy-aware QoS routing protocol for sensor networks which can also run efficiently with best-effort traffic. The protocol finds a least-cost, delay-constrained path for real-time data in terms of link cost that captures nodes ’ energy reserve, transmission energy, error rate and other communication parameters. Moreover, the throughput for non-real-time data is maximized by adjusting the service rate for both real-time and non-real-time data at the sensor nodes. Simulation results have demonstrated the effectiveness of our approach for different metrics. 1.

This article is the first in a series intended to chronicle the status of work underway within the

Mobile ad hoc networks are characterized by multi-hop wireless links, absence of any fixed networking infrastructure, and a dynamic network topology. Routing protocols for such networks typically use exchanges of control packets, either at fixed intervals of time or in response to a requirement, to adapt to the changing network topology. Balancing the optimality of the routes used in an ad hoc network as well as the overhead incurred from transmissions of routing packets is a challenging task. In this paper, we propose a hybrid routing scheme that combines proactive route optimization to a reactive routing protocol, for reducing the average end-to-end delay in packet transmissions without exceeding the routing overhead. The proposed scheme uses a pre-emptive route discovery to replace an existing route by a shorter route when the route has been used for a given interval of time. The optimum time for making the pre-emptive search is obtained by studying the statistical distributions of the link and route lifetimes. The preemptive search is restricted within a limited distance from the old route by using a query-localization method. Performance evaluations of the proposed hybrid scheme in comparison with a purely on-demand routing protocol are presented.

Location-Aided Routing (LAR) [14] algorithm is an approach to utilize location information for mobile hosts, with the goal of decreasing routing-related overhead in mobile ad hoc networks. A number of optimizations are possible to improve performance of the basic LAR protocols. This paper mainly focuses how the basic operation of LAR can be improved by applying those optimization schemes. 1 Introduction The issue of developing efficient routing algorithms is a challenging problem in the area of mobile ad hoc networking (MANET). Many different protocols have been proposed to achieve a given level of routing performance for MANET [1, 2, 4, 5, 6, 8, 9, 14, 15, 18, 19, 20, 22, 23]. Among those protocols, Location-Aided Routing (LAR) algorithms we proposed [11, 12, 14] attempt to reduce routing discovery overhead incurred with some flooding based approaches, such as Dynamic Source Routing (DSR) [9, 10] and Ad hoc On demand Distance Vector routing Research reported is supported in part b...

Ad hoc networks are peer to peer, autonomous networks comprised of wireless mobile devices. The ease and speed of deployment of these networks makes them ideal for battlefield communications, disaster recovery and other such applications where fixed infrastructure is not readily available. Limited bandwidth, energy constraints and unpredictable network topologies pose difficult problems for the design of applications for these networks. The last couple of years has seen renewed research in this field. Specifically in unicast and multicast routing and security issues. In this thesis, we address the multicast routing problem for ad hoc networks. We present a novel multicast routing protocol called the source grouped floodingprotocol. The protocol creates multicast routes between the source and group members based on hop count distance constraints. We also propose a probabilistic data forwarding mechanism to achieve efficient data dissemination. We present simulation results that capture the performance of our protocol against parameters