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Load Balancing, Queueing and Scheduling Mechanisms in Mobile Ad Hoc Networks

Joshi, Avinash
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1004447615

Abstract Details

2001, MS, University of Cincinnati, Engineering : Computer Science and Engineering.
An ad hoc network is a collection of mobile nodes with wireless links that dynamically form a network without the use of any existing network infrastructure or centralized administration. Due to the limited range of the wireless links, multiple network “hops” may be needed for one node to exchange data with another across the network. In recent years, a variety of new routing protocols targeted specifically at this environment has been developed. It is our thesis that capacity of wireless networks being limited, routing performance is heavily influenced by congestion, load imbalance, scheduling priorities and wireless link quality. Our work focuses on developing techniques to address these issues. The overall goal is improved overall routing performance. The following techniques have been studied in connection with on-demand routing protocols, specifically AODV (ad hoc on-demand distance vector routing). Typically, routing protocols discover shortest path route based on number of hops. This routing philosophy can lead to bottlenecks as some links tend to be used by many routes. We present techniques which try to balance the load and avoid such bottlenecks. We use a new routing cost metric which is a function of the current load on each node on a route. The idea of the cost metric is to be able to route around the nodes that are congested for which alternate routes are available. In addition, rerouting is done proactively when any node on an active route starts getting congested. We also investigate efficient queueing paradigms to be used at the radio interfaces for nodes in wireless ad hoc networks. Low bandwidth of wireless links makes queueing paradigms critical for the performance of the network routing protocol. We investigate various packet drop and priority scheduling policies. We demonstrate that effective queueing paradigms can improve routing performance. Unlike wired networks, packets transmitted on wireless channels are often subject to burst errors which cause back to back packet losses. Most link layer protocols recover from packet losses by retransmission. When the wireless channel is in a burst error state, retransmission attempts typically fail, thereby causing poor utilization of the wireless channel. We investigate a channel state dependent scheduling policy where packets are scheduled at the radio interface based on the link quality. Packets seeing a better link quality get higher priority. Conversely, packets seeing weak links are buffered to be transmitted later. We show this technique improves overall channel utilization which in turns improves routing performance.
Dr. Samir Das (Advisor)
65 p.
Computer Science
Mobile Ad Hoc Networks; dropping policies; scheduling policies

Recommended Citations

Citations

  • Joshi, A. (2001). Load Balancing, Queueing and Scheduling Mechanisms in Mobile Ad Hoc Networks [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1004447615

    APA Style (7th edition)

  • Joshi, Avinash. Load Balancing, Queueing and Scheduling Mechanisms in Mobile Ad Hoc Networks. 2001. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1004447615.

    MLA Style (8th edition)

  • Joshi, Avinash. "Load Balancing, Queueing and Scheduling Mechanisms in Mobile Ad Hoc Networks." Master's thesis, University of Cincinnati, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1004447615

    Chicago Manual of Style (17th edition)

ucin1004447615
859
© 2001, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.