Jeff Boleng

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.

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.

Load balanced parallel QR decomposition on shared memory multiprocessors

Abstract This paper introduces a new parallel QR decomposition algorithm with two key advantages over previous techniques. It is specifically designed to achieve high parallel efficiency on shared memory parallel computers with a modest number of processors, and the novel load balancing method described here considers total computational work as opposed to just balancing Givens rotations. This results in expected efficiencies which approach optimal as problem size grows relative to number of processors. The hybrid nature of the algorithm seeks to maximize computation between communication and synchronization. Implementation results on shared memory multiprocessors track expected performance well up to 12 processors, and initial performance results on a distributed shared memory machine are presented.