ad-hoc networking course instructor: carlos pomalaza-ráez d. d. perkins, h. d. hughes, and c. b....

Ad-Hoc Networking Course

Instructor: Carlos Pomalaza-Ráez

D. D. Perkins, H. D. Hughes, and C. B. Owen: ”Factors Affecting the Performance of Ad Hoc Networks”, in Proc. IEEE International Conference on Communications (ICC’02),

pp. 2048-2052

Sami KoivuCentre for Wireless Communications

[email protected]

© Sami Koivu: Presentation in Ad-Hoc Networking Course 20.1.2004 2(15)

Outline

1. Introduction and Motivation2. Methodology, Simulation, and

Experimental Design3. Performance Metrics and Experimental

Factors4. Simulation Results and Design Analysis5. Summary


Introduction and Motivation

• The goal of mobile ad hoc networks (MANETs) is to provide rapidly deployable means of communication without a pre-excisting infrastructure

• MANETs have a dynamic, multi-hop, and constantly changing structure

• The dynamic characteristics of ad-hoc networks cause great design challenges

• Therefore, the factors that affect the performance of the networks have to be studied


Introduction and Motivation

• In this paper, the impact of five various factors are studied:1. Node speed2. Node pause time3. Network size4. Number of traffic sources5. Routing protocol

• Source vs. distributed

• Additionally, the two-way interactions of these factors are examined, i.e., whether the effect of one factor is dependent on the level of another

• The impact of the factors are studied using a 2kr (k=5, r=4) factorial design


Methodology, Simulation, and Experimental Design

• Since 2kr (k=5, r=4) factorial design is used, 32 separate experiments are done

• Each experiment is replicated 4 times resulting in 128 simulation runs

• Simulation study is carried out using Global Mobile System Simulator (GloMoSim)

• Model is simulated for 200 seconds of simulated time

• Radio transmission range is approximately 250 m, free space propagation model is used

• Channel capacity is 2 Mbits/s


Methodology, Simulation, and Experimental Design

• IEEE 802.11 Medium Access Control Protocol is used as the MAC protocol

• Sources transmit continuously 1024-byte data packets at a constant rate of 4 packets/s

• Utilized routing protocols are: Dynamic Source Routing (DSR, source) and Ad-hoc on Demand Distance Vector (AODV, distributed)– Both the protocols are reactive

• The random waypoint mobility model is used– Each node is placed randomly in the simulated area

(1600m*400m)


Performance Metrics and Experimental Factors

• The studied performance metrics are:1. Throughput

• The effectiveness how well the network delivers the packets from the source to the destination

2. Average Routing Overhead• The average number of control packets (route

requests, replies, and error messages) produced per node

3. Average Power Consumption per node



• The main effect of a factor is the average change in the considered metric when the factor is changed from its level 1 (-) to its level 2 (+)

• The two-way interaction effect is the difference between the average values of a metric when two factors are at the same level and when they are at opposite levels



• The two-way interactions are denoted as label a x label b (for example the two way interaction of node speed and routing is 1x5)


Simulation Results and Design Analysis

• The effects on control overhead– The increase in node speed, number of sources,

and utilization of distibuted routing increase the control overhead

– The two-way interactions of node speed – number of sources, node speed – routing, and number of sources – routing have also strong effects



• The effects on throughput– Node speed, the number of sources, and their two-way

interaction have a strong negative impact (when the factors increase the throughput of the network decreases)

– The increase in network size increases the throughput– The type of routing has little effect on throughput



• The effects on power consumption– Network size has a negative impact– Number of sources has a strong positive impact– Their two-way interaction has small negative

effect



• The importance of each factor is described in Table 2– The proportion of variation in performance metric

that is explained by the factor is presented

• The number of sources is the most important parameter when considering the overall performance of the network

• Node speed and network size are also quite important

• Routing protocol affects significantly only the average control overhead

• The last row includes the proportion of variation of experimental error


Summary

• The effect of five factors (node speed, pause-time, network size, number of sources, and routing protocol) on the performance of ad-hoc network was studied

• Three performance metrics (throughput, average routing overhead, and power consumption) were used

• The number of traffic sources is the most important factor when considering the performance, node speed and network size are also important

• Source routing more efficient than distributed one, because it achieves almost the same performance with much less control overhead

ad-hoc networking course instructor: carlos pomalaza-ráez d. d. perkins, h. d. hughes, and c. b....

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factorial design slide

experimental design

dynamic characteristics