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DSR: The Dynamic Source Routing Protocol for Multi-Hop Wireless Ad Hoc Networks”, in Ad Hoc Networking, edited by Charles E.

by David B Johnson , David A Maltz , Josh Broch - Perkins, Chapter , 2001
"... Abstract The Dynamic Source Routing protocol (DSR) is a simple and efficient routing protocol designed specifically for use in multi-hop wireless ad hoc networks of mobile nodes. DSR allows the network to be completely self-organizing and self-configuring, without the need for any existing network ..."
Abstract - Cited by 764 (8 self) - Add to MetaCart
Abstract The Dynamic Source Routing protocol (DSR) is a simple and efficient routing protocol designed specifically for use in multi-hop wireless ad hoc networks of mobile nodes. DSR allows the network to be completely self-organizing and self-configuring, without the need for any existing network infrastructure or administration. The protocol is composed of the two mechanisms of Route Discovery and Route Maintenance, which work together to allow nodes to discover and maintain source routes to arbitrary destinations in the ad hoc network. The use of source routing allows packet routing to be trivially loop-free, avoids the need for up-to-date routing information in the intermediate nodes through which packets are forwarded, and allows nodes forwarding or overhearing packets to cache the routing information in them for their own future use. All aspects of the protocol operate entirely on-demand, allowing the routing packet overhead of DSR to scale automatically to only that needed to react to changes in the routes currently in use. We have evaluated the operation of DSR through detailed simulation on a variety of movement and communication patterns, and through implementation and significant experimentation in a physical outdoor ad hoc networking testbed we have constructed in Pittsburgh, and have demonstrated the excellent performance of the protocol. In this chapter, we describe the design of DSR and provide a summary of some of our simulation and testbed implementation results for the protocol.

The Node Distribution of the Random Waypoint Mobility Model for Wireless Ad Hoc Networks

by Christian Bettstetter, Giovanni Resta, Paolo Santi , 2003
"... The random waypoint model is a commonly used mobility model in the simulation of ad hoc networks. It is known that the spatial distribution of network nodes moving according to this model is, in general, nonuniform. However, a closed-form expression of this distribution and an in-depth investigation ..."
Abstract - Cited by 377 (10 self) - Add to MetaCart
The random waypoint model is a commonly used mobility model in the simulation of ad hoc networks. It is known that the spatial distribution of network nodes moving according to this model is, in general, nonuniform. However, a closed-form expression of this distribution and an in-depth investigation is still missing. This fact impairs the accuracy of the current simulation methodology of ad hoc networks and makes it impossible to relate simulation-based performance results to corresponding analytical results. To overcome these problems, we present a detailed analytical study of the spatial node distribution generated by random waypoint mobility. More specifically, we consider a generalization of the model in which the pause time of the mobile nodes is chosen arbitrarily in each waypoint and a fraction of nodes may remain static for the entire simulation time. We show that the structure of the resulting distribution is the weighted sum of three independent components: the static, pause, and mobility component. This division enables us to understand how the model’s parameters influence the distribution. We derive an exact equation of the asymptotically stationary distribution for movement on a line segment and an accurate approximation for a square area. The good quality of this approximation is validated through simulations using various settings of the mobility parameters. In summary, this article gives a fundamental understanding of the behavior of the random waypoint model.
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On-demand Multipath Distance Vector Routing in Ad Hoc Networks

by Mahesh K. Marina, Samir R. Das - in Proceedings of IEEE International Conference on Network Protocols (ICNP , 2001
"... We develop an on-demand, multipath distance vector protocol for mobile ad hoc networks. Specifically, we propose multipath extensions to a well-studied single path routing protocol known as Ad hoc On-demand Distance Vector (AODV). The resulting protocol is referred to as Ad hoc Ondemand Multipath Di ..."
Abstract - Cited by 360 (3 self) - Add to MetaCart
We develop an on-demand, multipath distance vector protocol for mobile ad hoc networks. Specifically, we propose multipath extensions to a well-studied single path routing protocol known as Ad hoc On-demand Distance Vector (AODV). The resulting protocol is referred to as Ad hoc Ondemand Multipath Distance Vector (AOMDV). The protocol computes multiple loop-free and link-disjoint paths. Loopfreedom is guaranteed by using a notion of "advertised hopcount." Link-disjointness of multiple paths is achieved by using a particular property of flooding. Performance comparison of AOMDV with AODV using ns-2 simulations shows that AOMDV is able to achieve a remarkable improvement in the end-to-end delay --- often more than a factor of two, and is also able to reduce routing overheads by about 20%. 1
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Mobile ad hoc networking: imperatives and challenges

by Imrich Chlamtac , Marco Conti , Jennifer J.-N. Liu , 2003
"... Mobile ad hoc networks (MANETs) represent complex distributed systems that comprise wireless mobile nodes that can freely and dynamically self-organize into arbitrary and temporary, "ad-hoc" network topologies, allowing people and devices to seamlessly internetwork in areas with no pre-exi ..."
Abstract - Cited by 317 (8 self) - Add to MetaCart
Mobile ad hoc networks (MANETs) represent complex distributed systems that comprise wireless mobile nodes that can freely and dynamically self-organize into arbitrary and temporary, "ad-hoc" network topologies, allowing people and devices to seamlessly internetwork in areas with no pre-existing communication infrastructure, e.g., disaster recovery environments. Ad hoc networking concept is not a new one, having been around in various forms for over 20 years. Traditionally, tactical networks have been the only communication networking application that followed the ad hoc paradigm. Recently, the introduction of new technologies such as the Bluetooth, IEEE 802.11 and Hyperlan are helping enable eventual commercial MANET deployments outside the military domain. These recent evolutions have been generating a renewed and growing interest in the research and development of MANET. This paper attempts to provide a comprehensive overview of this dynamic field. It first explains the important role that mobile ad hoc networks play in the evolution of future wireless technologies. Then, it reviews the latest research activities in these areas, including a summary of MANET's characteristics, capabilities, applications, and design constraints. The paper concludes by presenting a set of challenges and problems requiring further research in the future.

Performance Comparison of Two On-demand Routing protocols for Ad Hoc Networks

by Charles Perkins, Charles E. Perkins Nokia, Elizabeth M. Royer, Samir R. Das, Mahesh K. Marina , 2001
"... Ad hoc networks are characterized by multihop wireless connectivity, frequently changing network topology and the need for efficient dynamic routing protocols. We compare the performance of two prominent on-demand routing protocols for mobile ad hoc networks: Dynamic Source Routing (DSR) and Ad Hoc ..."
Abstract - Cited by 255 (1 self) - Add to MetaCart
Ad hoc networks are characterized by multihop wireless connectivity, frequently changing network topology and the need for efficient dynamic routing protocols. We compare the performance of two prominent on-demand routing protocols for mobile ad hoc networks: Dynamic Source Routing (DSR) and Ad Hoc On-Demand Distance Vector Routing (AODV). A detailed simulation model with MAC and physical layer models is used to study interlayer interactions and their performance implications. We demonstrate that even though DSR and AODV share similar ondemand behavior, the differences in the protocol mechanics can lead to significant performance differentials. The performance differentials are analyzed using varying network load, mobility, and network size. Based on the observations, we make recommendations about how the performance of either protocol can be improved.

ATCP: TCP for Mobile Ad Hoc Networks

by Jian Liu, Sun Microsystems, Suresh Singh - IEEE Journal on selected areas in communications , 2001
"... Transport connections set up in wireless ad hoc networks are plagued by problems such as high bit error rates (BER), frequent route changes and partitions. If we run TCP over such connections, the throughput of the connection is observed to be extremely poor because TCP treats lost or delayed ACKs a ..."
Abstract - Cited by 251 (1 self) - Add to MetaCart
Transport connections set up in wireless ad hoc networks are plagued by problems such as high bit error rates (BER), frequent route changes and partitions. If we run TCP over such connections, the throughput of the connection is observed to be extremely poor because TCP treats lost or delayed ACKs as congestion. In this paper we present an approach where we implement a thin layer between IP and standard TCP that corrects these problems and maintains high end-to-end TCP throughput. We have implemented our protocol in FreeBSD and in this paper we present results from extensive experimentation done in an ad hoc network. We show that our solution improves TCP's throughput by a factor of 2 { 3. 1
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Stochastic properties of the random waypoint mobility model

by Christian Bettstetter, Hannes Hartenstein - Wireless Networks
"... Abstract | The random waypoint model is a commonly used mobility model for simulations of wireless commu-nication networks. In this paper, we present analytical derivations of some fundamental stochastic properties of this model with respect to: (a) the length and duration of a movement epoch, (b) t ..."
Abstract - Cited by 202 (3 self) - Add to MetaCart
Abstract | The random waypoint model is a commonly used mobility model for simulations of wireless commu-nication networks. In this paper, we present analytical derivations of some fundamental stochastic properties of this model with respect to: (a) the length and duration of a movement epoch, (b) the chosen direction angle at the beginning of a movement epoch, and (c) the cell change rate of the random waypoint mobility model when used within the context of cellular networks. Our results and methods can be used to compare the random waypoint model with other mobility models. The results on the movement epoch duration as well as on the cell change rate enable us to make a statement about the \degree of mobility " of a certain sim-ulation scenario. The direction distribution explains in an analytical manner the eect that nodes tend to move back to the middle of the system area.
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The Impact of Multihop Wireless Channel on TCP Performance

by Zhenghua Fu, Haiyun Luo, Petros Zerfos, Songwu Lu, Lixia Zhang, Mario Gerla , 2004
"... This paper studies TCP performance in a stationary multihop wireless network using IEEE 802.11 for channel access control. We first show that given a specific network topology and flow patterns, there exists an optimal window size W # at which TCP achieves the highest throughput via maximum spatia ..."
Abstract - Cited by 199 (12 self) - Add to MetaCart
This paper studies TCP performance in a stationary multihop wireless network using IEEE 802.11 for channel access control. We first show that given a specific network topology and flow patterns, there exists an optimal window size W # at which TCP achieves the highest throughput via maximum spatial reuse of the shared wireless channel. However, TCP grows its window size much larger than W # , leading to throughput reduction. We then explain the TCP throughput decrease using our observations and analysis of the packet loss in an overloaded multihop wireless network. We find out that the network overload is typically first signified by packet drops due to wireless link-layer contention, rather than buffer overflow-induced losses observed in the wired Internet. As the offered load increases, the probability of packet drops due to link contention also increases, and eventually saturates. Unfortunately, the link-layer drop probability is insufficient to keep the TCP window size around W # . We model and analyze the link contention behavior, based on which we propose Link RED that fine-tunes the link-layer packet dropping probability to stabilize the TCP window size around W # . We further devise Adaptive Pacing to better coordinate channel access along the packet forwarding path. Our simulations demonstrate 5% to 30% improvement of TCP throughput using the proposed two techniques.
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ATP: A Reliable Transport Protocol for Ad-hoc Networks

by Karthikeyan Sundaresan, Vaidyanathan Anantharaman, Hung-Yun Hsieh, Raghupathy Sivakumar , 2003
"... Existing works have approached the problem of reliable transport in ad-hoc networks by proposing mechanisms to improve TCP's performance over such networks. In this paper we show through detailed arguments and simulations that several of the design elements in TCP are fundamentally inappropriat ..."
Abstract - Cited by 170 (2 self) - Add to MetaCart
Existing works have approached the problem of reliable transport in ad-hoc networks by proposing mechanisms to improve TCP's performance over such networks. In this paper we show through detailed arguments and simulations that several of the design elements in TCP are fundamentally inappropriate for the unique characteristics of ad-hoc networks. Given that ad-hoc networks are typically stand-alone, we approach the problem of reliable transport from the perspective that it is justifiable to develop an entirely new transport protocol that is not a variant of TCP. Toward this end, we present a new reliable transport layer protocol for ad-hoc networks called ATP (ad-hoc transport protocol). We show through ns2 based simulations that ATP outperforms both default TCP and TCP-ELFN.
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Smooth is Better than Sharp: A Random Mobility Model for Simulation of Wireless Networks

by Christian Bettstetter , 2001
"... This paper presents an enhanced random mobility model for simulation-based studies of wireless networks. Our approach makes the movement trace of individual mobile stations more realistic than common approaches for random movement. After giving a survey of mobility models found in the literature, we ..."
Abstract - Cited by 167 (2 self) - Add to MetaCart
This paper presents an enhanced random mobility model for simulation-based studies of wireless networks. Our approach makes the movement trace of individual mobile stations more realistic than common approaches for random movement. After giving a survey of mobility models found in the literature, we give a detailed mathematical formulation of our model and outline its advantages. The movement concept is based on random processes for speed and direction control in which the new values are correlated to previous ones. Upon a speed change event, a new target speed is chosen, and an acceleration is set to achieve this target speed. The principles for a direction change are similar. Moreover, we propose two extensions for modeling typical movement patterns of vehicles. Finally, we consider strategies for the nodes' border behavior (i.e., what happens when nodes move out of the simulation area) and point out a pitfall that occurs when using a bounded simulation area.