19 research outputs found
Self-stabilizing cluster routing in Manet using link-cluster architecture
We design a self-stabilizing cluster routing algorithm based on the link-cluster architecture of wireless ad hoc networks. The network is divided into clusters. Each cluster has a single special node, called a clusterhead that contains the routing information about inter and intra-cluster communication. A cluster is comprised of all nodes that choose the corresponding clusterhead as their leader. The algorithm consists of two main tasks. First, the set of special nodes (clusterheads) is elected such that it models the link-cluster architecture: any node belongs to a single cluster, it is within two hops of the clusterhead, it knows the direct neighbor on the shortest path towards the clusterhead, and there exist no two adjacent clusterheads. Second, the routing tables are maintained by the clusterheads to store information about nodes both within and outside the cluster. There are two advantages of maintaining routing tables only in the clusterheads. First, as no two neighboring nodes are clusterheads (as per the link-cluster architecture), there is no need to check the consistency of the routing tables. Second, since all other nodes have significantly less work (they only forward messages), they use much less power than the clusterheads. Therefore, if a clusterhead runs out of power, a neighboring node (that is not a clusterhead) can accept the role of a clusterhead. (Abstract shortened by UMI.)
Modular expansion and reconfiguration of shufflenets in multi-star implementations.
by Philip Pak-tung To.Thesis (M.Phil.)--Chinese University of Hong Kong, 1994.Includes bibliographical references (leaves 57-60).Chapter 1 --- Introduction --- p.1Chapter 2 --- Modular Expansion of ShuffleNet --- p.8Chapter 2.1 --- Multi-Star Implementation of ShuffleNet --- p.10Chapter 2.2 --- Modular Expansion of ShuffleNet --- p.21Chapter 2.2.1 --- Expansion Phase 1 --- p.21Chapter 2.2.2 --- Subsequent Expansion Phases --- p.24Chapter 2.3 --- Discussions --- p.26Chapter 3 --- Reconfigurability of ShuffleNet in Multi-Star Implementation --- p.33Chapter 3.1 --- Reconfigurability of ShuffleNet --- p.34Chapter 3.1.1 --- Definitions --- p.34Chapter 3.1.2 --- Rearrangable Conditions --- p.35Chapter 3.1.3 --- Formal Representation --- p.38Chapter 3.2 --- Maximizing Network Reconfigurability --- p.40Chapter 3.2.1 --- Rules to maximize Tsc and Rsc --- p.41Chapter 3.2.2 --- Rules to Maximize Z --- p.42Chapter 3.3 --- Channels Assignment Algorithms --- p.43Chapter 3.3.1 --- Channels Assignment Algorithm for w = p --- p.45Chapter 3.3.2 --- Channels Assignment Algorithm for w = p. k --- p.46Chapter 3.3.3 --- Channels Assignment Algorithm for w=Mpk --- p.49Chapter 3.4 --- Discussions --- p.51Chapter 4 --- Conclusions --- p.5
An Energy-Based Comparison of Long-Hop and Short-Hop Routing in MIMO Networks
This paper considers the problem of selecting either routes that consist of
long hops or routes that consist of short hops in a network of multiple-antenna
nodes, where each transmitting node employs spatial multiplexing. This
distance-dependent route selection problem is approached from the viewpoint of
energy efficiency, where a route is selected with the objective of minimizing
the transmission energy consumed while satisfying a target outage criterion at
the final destination. Deterministic line networks and two-dimensional random
networks are considered. It is shown that when 1) the number of hops traversed
between the source and destination grows large or 2) when the target success
probability approaches one or 3) when the number of transmit and/or receive
antennas grows large, short-hop routing requires less energy than long-hop
routing. It is also shown that if both routing strategies are subject to the
same delay constraint, long-hop routing requires less energy than short-hop
routing as the target success probability approaches one. In addition,
numerical analysis indicates that given loose outage constraints, only a small
number of transmit antennas are needed for short-hop routing to have its
maximum advantage over long-hop routing, while given stringent outage
constraints, the advantage of short-hop over long-hop routing always increases
with additional transmit antennas.Comment: 27 pages, 12 figures, submitted to IEEE Transactions on Vehicular
Technology in March 2009, revised in July 200
Random hierarchies that facilitate self-organization
©2002 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.Since it is widely accepted that self-organization is difficult to achieve using constructive or centrally run algorithms a random hierarchy is proposed that intrinsically facilitates self-organization. The random hierarchy consists of each node in the network independently choosing a rank at random such that a mean 2(\Delta-1)\Delta^{i-1} nodes have rank i, where \Delta is a network wide hierarchy parameter. Each node of rank i chooses the nearest node of rank i-1 as its leader which forms the hierarchy. The mean and variance of the relevant properties is derived, for example it is shown that each leader has a mean \Delta followers. Simulations were used to demonstrate the effectiveness of the proposed hierarchy and a "bare-bones" set of procedures where provided that may be used to implement the hierarchy over a network of autonomous nodes in a robust way.Aaron Harwood, Hong She
Performance analysis of the carrier-sense multiple access protocol for future generation wireless networks
Ankara : The Department of Electrical and Electronics Engineering and the Graduate School of Engineering and Science of Bilkent University, 2013.Thesis (Ph. D.) -- Bilkent University, 2013.Includes bibliographical references leaves 115-127.Variants of the carrier-sense multiple access (CSMA) protocol has been employed
in many communications protocols such as the IEEE 802.11 and Ethernet standards.
CSMA based medium access control (MAC) mechanisms have been recently
proposed for other communications scenarios such as sensor networks and
acoustical underwater networks. Despite its widespread use, the performance
of the CSMA protocol is not well-studied from the perspective of these newly
encountered networking scenarios. We here investigate the performance of the
CSMA protocol from the point of three different aspects: throughput in networks
with large propagation delay, short-term fairness for delay sensitive applications
in large networks and energy efficiency-throughput trade-off in networks with
battery operated devices.
Firstly, we investigate the performance of the CSMA protocol for channels
with large propagation delay. Such channels are recently encountered in underwater
acoustic networks and in terrestrial wireless networks covering larger areas.
However, a mathematical model of CSMA performance in such networks is not
known. We propose a semi-Markov model for a 2-node CSMA channel and then
extend this model for arbitrary number of users. Using this model, we obtain the
optimum symmetric probing rate that achieves the maximum network throughput
as a function of the average propagation delay, ¯d, and the number of nodes
sharing the channel, N. The proposed model predicts that the total capacity
decreases with ¯d
−1 as N goes to infinity when all nodes probe the channel at the
optimum rate. The optimum probing rate for each node decreases with 1/N and
the total optimum probing rate decreases faster than ¯d
−1 as N goes to infinity.
Secondly, we investigate whether the short-term fairness of a large CSMA network degrades with the network size and density. Our results suggest that (a)
the throughput region that can be achieved within the acceptable limits of shortterm
fairness reduces as the number of contending neighboring nodes increases for
random regular conflict graphs, (b) short-term fair capacity weakly depends on
the network size for a random regular conflict graph but a stronger dependence is
observed for a grid topology. We also present related results from the statistical
physics literature on long-range correlations in large systems and point out the
relation between these results and short-term fairness of CSMA systems.
Thirdly, we investigate the energy efficiency of a CSMA network proposing a
model for the energy consumption of a node as a function of its throughput. We
show that operating the CSMA network at a very high or at a very low throughput
is energy inefficient because of increasing carrier-sensing and sleeping costs, respectively.
Achieving a balance between these two opposite operating regimes, we
derive the energy-optimum carrier-sensing rate and the energy-optimum throughput
which maximize the number of transmitted bits for a given energy budget. For
the single-hop case, we show that the energy-optimum total throughput increases
as the number of nodes sharing the channel increases. For the multi-hop case, we
show that the energy-optimum throughput decreases as the degree of the conflict
graph of the network increases. For both cases, the energy-optimum throughput
reduces as the power required for carrier-sensing increases. The energy-optimum
throughput is also shown to be substantially lower than the maximum throughput
and the gap increases as the degree of the conflict graph increases for multi-hop
networks.Köseoğlu, MehmetPh.D
Mobile Ad Hoc Networks
Guiding readers through the basics of these rapidly emerging networks to more advanced concepts and future expectations, Mobile Ad hoc Networks: Current Status and Future Trends identifies and examines the most pressing research issues in Mobile Ad hoc Networks (MANETs). Containing the contributions of leading researchers, industry professionals, and academics, this forward-looking reference provides an authoritative perspective of the state of the art in MANETs. The book includes surveys of recent publications that investigate key areas of interest such as limited resources and the mobility of mobile nodes. It considers routing, multicast, energy, security, channel assignment, and ensuring quality of service. Also suitable as a text for graduate students, the book is organized into three sections: Fundamentals of MANET Modeling and Simulation—Describes how MANETs operate and perform through simulations and models Communication Protocols of MANETs—Presents cutting-edge research on key issues, including MAC layer issues and routing in high mobility Future Networks Inspired By MANETs—Tackles open research issues and emerging trends Illustrating the role MANETs are likely to play in future networks, this book supplies the foundation and insight you will need to make your own contributions to the field. It includes coverage of routing protocols, modeling and simulations tools, intelligent optimization techniques to multicriteria routing, security issues in FHAMIPv6, connecting moving smart objects to the Internet, underwater sensor networks, wireless mesh network architecture and protocols, adaptive routing provision using Bayesian inference, and adaptive flow control in transport layer using genetic algorithms
Simulation-based Performance Evaluation of MANET Backbone Formation Algorithms
As a result of the recent advances in the computation and communications industries,
wireless communications-enabled computing devices are ubiquitous nowadays.
Even though these devices are introduced to satisfy the user’s mobile computing
needs, they are still unable to provide for the full mobile computing functionality
as they confine the user mobility to be within certain regions in order to benefit
from services provided by fixed network access points.
Mobile ad hoc networks (MANETs) are introduced as the technology that potentially
will make the nowadays illusion of mobile computing a tangible reality.
MANETs are created by the mobile computing devices on an ad hoc basis, without
any support or administration provided by a fixed or pre-installed communications
infrastructure.
Along with their appealing autonomy and fast deployment properties, MANETs
exhibit some other properties that make their realization a very challenging task.
Topology dynamism and bandwidth limitations of the communication channel adversely
affect the performance of routing protocols designed for MANETs, especially
with the increase in the number of mobile hosts and/or mobility rates.
The Connected Dominating Set (CDS), a.k.a. virtual backbone or Spine, is
proposed to facilitate routing, broadcasting, and establishing a dynamic infrastructure
for distributed location databases. Minimizing the CDS produces a simpler
abstracted topology of the MANET and allows for using shorter routes between
any pair of hosts. Since it is NP-complete to find the minimum connected dominating
set, MCDS, researchers resorted to approximation algorithms and heuristics
to tackle this problem.
The literature is rich of many CDS approximation algorithms that compete in
terms of CDS size, running time, and signaling overhead. It has been reported
that localized CDS creation algorithms are the fastest and the lightest in terms of
signaling overhead among all other techniques. Examples of these localized CDS
algorithms are Wu and Li algorithm and its Stojmenovic variant, the MPR algorithm,
and Alzoubi algorithm. The designers of each of these algorithms claim
that their algorithm exhibits the highest degree of localization and hence incurs the lowest cost in the CDS creation phase. However, these claims are not supported
by any physical or at least simulation-based evidence. Moreover, the cost of maintaining
the CDS (in terms of the change in CDS size, running time, and signaling
overhead), in the presence of unpredictable and frequent topology changes, is an
important factor that has to be taken into account -a cost that is overlooked most
of the time.
A simulation-based comparative study between the performance of these algorithms
will be conducted using the ns2 network simulator. This study will focus
on the total costs incurred by these algorithms in terms of CDS size, running time,
and signaling overhead generated during the CDS creation and maintenance phases.
Moreover, the effects of mobility rates, network size, and mobility models on the
performance of each algorithm will be investigated. Conclusions regarding the pros
and cons of each algorithm will be drawn, and directions for future research work
will be recommended