Tracy Camp

Comparison of broadcasting techniques for mobile ad hoc networks

Network wide broadcasting in Mobile Ad Hoc Networks provides important control and route establishment functionality for a number of unicast and multicast protocols. Considering its wide use as a building block for other network layer protocols, the MANET community needs to standardize a single methodology that efficiently delivers a packet from one node to all other network nodes. Despite a considerable number of proposed broadcasting schemes, no comprehensive comparative analysis has been previously done. This paper provides such analysis by classifying existing broadcasting schemes into categories and simulating a subset of each, thus supplying a condensed but comprehensive side by side comparison.The simulations are designed to pinpoint, in each, specific failures to network conditions that are relevant to MANETs, e.g., bandwidth congestion and dynamic topologies. In addition, protocol extensions using adaptive responses to network conditions are proposed, implemented and analyzed for one broadcasting scheme that performs well in the comparative study.

MANET simulation studies: the incredibles

Simulation is the research tool of choice for a majority of the mobile ad hoc network (MANET) community. However, while the use of simulation has increased, the credibility of the simulation results has decreased. To determine the state of MANET simulation studies, we surveyed the 2000-2005 proceedings of the ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc). From our survey, we found significant shortfalls. We present the results of our survey in this paper. We then summarize common simulation study pitfalls found in our survey. Finally, we discuss the tools available that aid the development of rigorous simulation studies. We offer these results to the community with the hope of improving the credibility of MANET simulation-based studies.

Location information services in mobile ad hoc networks

In previous years, many location based routing protocols have been developed for ad hoc networks. Some of these protocols assume a location service exists which provides location information on all the mobile nodes in the network. We evaluate three location service alternatives. One is a reactive protocol; the other two are proactive protocols. Of the proactive protocols, one sends location tables to neighbors and the other sends location information to all nodes. In our evaluation, one proactive protocol proved to have the best performance overall. Thus, we also evaluate the main input parameter associated with this protocol for optimal performance.

Performance comparison of two location based routing protocols for ad hoc networks

Many location based routing protocols have been developed for ad hoc networks. This paper presents the results of a detailed performance evaluation on two of these protocols: location-aided routing (LAR) and distance routing effect algorithm for mobility (DREAM). We compare the performance of these two protocols with the dynamic source routing (DSR) protocol and a minimum standard (i.e., a protocol that floods all data packets). We used NS-2 to simulate 50 nodes moving according to the random waypoint model. Our main goal for the performance investigation was to stress the evaluated protocols with high data loads during both low and high speeds. Our performance investigation produced the following conclusions. First, the added protocol complexity of DREAM does not appear to provide benefits over a flooding protocol. Second, promiscuous mode operation improves the performance of DSR significantly. Third, adding location information to DSR (i.e., similar to LAR) increases both the network load and the data packet delivery ratio; our results conclude that the increase in performance is worth the increase in cost. Lastly, our implementation of DREAM provides a simple location service that could be used with other ad hoc network routing protocols.

An ACM-W literature review on women in computing

The pipeline shrinkage problem for women in computer science is a well-known and documented phenomenon where the ratio of women to men involved in computing shrinks dramatically from early student years to working years [19, 22, 23, 32, 42, 93, 112], also see this issue [24]. During the last decade, considerable research ensued to understand the reasons behind the existence of the shrinking pipeline and in some cases to take action to increase the numbers of women in computing. Through the work of a National Science Foundation funded project [56], ACMs Committee on Women in Computing (ACM-W) has taken a first step towards pulling this research together. A large number of articles was gathered and processed on the topic of women in computing and the shrinking pipeline. The committee created a publicly available online database to organize the references of this body of work by topic, author, and reference information. The database, constantly being updated, is accessible through ACM-Ws website ⟨http://www.acm.org/women⟩. A final report is also available via the ACM-W website which covers current statistics on women in computing, summaries of the literature in the database, and a set of recommendations.The following discussion is a brief synopsis of a subset of the literature review as of August 2001. In addition, you can find statistics on women in computing and recommendations throughout this special issue.

A taxonomy of distributed termination detection algorithms

Abstract An important problem in the field of distributed systems is that of detecting the termination of a distributed computation. Distributed termination detection (DTD) is a difficult problem due to the fact that there is no simple way of gaining knowledge of the global state of the system. Of the algorithms proposed in the last 15 years, there are many similarities. We have categorized these algorithms based on the following factors: algorithm type (e.g., wave, credit-recovery), required network topology, algorithm symmetry, required process knowledge, communication protocol (synchronous or asynchronous), communication channel behavior (first-in first-out (FIFO) or non-FIFO), message optimality, and fault tolerance. This methodology is intended to guide future research in DTD algorithms (since research continues on these algorithms) as well as to provide a classification survey for this area.

An adaptive mesh-based protocol for geocast routing

This article concerns a variation on multicasting, called geocasting, for an ad hoc network. The goal of a geocast routing protocol is to deliver packets to a group of nodes that are within a specified geographical area, i.e., the geocast region. This paper presents a Geocast Adaptive Mesh Environment for Routing (GAMER) which provides geocast communication in an ad hoc network. GAMER adapts to the current network environment by dynamically changing the density of the mesh. Thus, when nodes are highly mobile, a dense mesh is created; when nodes are moving slowly, a sparse mesh is created. We compare the performance of GAMER with non-adaptive mesh-based geocast routing protocols in an ns-2 simulated ad hoc network. We also compare two versions of GAMER; one version is more active than the other in adapting to the current network environment. We conclude that both versions of GAMER improve the transmission accuracy significantly, without increasing the load on the network significantly, when compared to non-adaptive mesh-based geocast routing approaches.

Trace-based mobility modeling for multi-hop wireless networks

Realistic and scenario-dependent mobility modeling is crucial for the reliable performance evaluation of multi-hop networks. In the last decade, a significant number of synthetic mobility models have been proposed. However, only a few of these models have been validated by realistic movement traces. In the last few years, several of such traces have been collected, analyzed, and made available to the community. This paper provides a comprehensive and up-to-date survey of (1) available movement traces, (2) modeling/analyses of these traces, and (3) synthetic mobility models. The focus of the paper is on mobility traces/models that include position information. The contribution of this paper is to summarize the research that has been done in the area of mobility modeling over the last few years and present challenges for future work.

Mesh-based geocast routing protocols in an ad hoc network

This paper concerns the development and performance evaluation of protocols that provide geocast communication in an ad hoc netw ork. The goal of a geocasting protocol is to deliver pac kets to a group of nodes that are within a speci ed geographical area, i.e., the geocast region. The geocast group consists of the nodes within this region at a given time. We present three di erent approaches for delivering packets to the geocast group and then evaluate these approaches via simulation. In addition, we consider the e ect the random waypoint mobility model has on the performance evaluation of an ad hoc netw ork protocol in general.

Adaptive location aided mobile ad hoc network routing

We combine location information and mobility feedback to create an innovative mobile ad hoc network (MANET) routing protocol which we demonstrate is effective over a wide range of mobility conditions typical in a MANET. We use link duration as our mobility feedback metric, and we demonstrate that mobility feedback using link duration effectively enables adaptive MANET protocols. Using our mobility feedback agent, we develop a hybrid MANET routing protocol which adapts between two MANET routing protocols in order to combine the strengths of both component protocols while avoiding their weaknesses. Our hybrid, adaptive protocol achieves data packet delivery ratios above 80% in VERY demanding network mobility conditions (i.e. link durations less than 4 seconds). In more stable networks (i.e., link durations more than 15 seconds), our protocol achieves data packet delivery ratios above 90%. While other existing MANET routing protocols can achieve similar data packet delivery ratios in stable networks, no other existing MANET routing protocol can achieve such high performance in unstable networks.