A performance evaluation of a pre-emptive on-demand distance vector routing protocol for mobile ad hoc networks

WIRELESS COMMUNICATIONS AND MOBILE COMPUTINGWirel. Commun. Mob. Comput. 2004; 4:99–108 (DOI: 10.1002/wcm.167)

A performance evaluation of a pre-emptive on-demanddistance vector routing protocol for mobile ad hoc networks

Azzedine Boukerche*,y and Liqin Zhang

PARADISE Research Laboratory, SITE, University of Ottawa, Canada

Summary

Mobile ad hoc networks are useful for providing communication support where no fixed infrastructure exists or the

deployment of a fixed infrastructure is not economically profitable and movement of communicating parties is

allowed. Therefore, it is not possible to establish a priori and fixed paths for message delivery through the network.

Because of their importance, routing and packets dropped problems, mainly due to the path breaking, are among

the most studied problem in mobile and wireles ad hoc networks. Multi-path protocols can be useful for the

purpose of balancing congestion and decreasing the delay, by routing packets along different paths. However, they

may allow only source-based load balancing decisions. In this paper, we present a pre-emptive ad hoc on-demand

distance vector routing protocol for mobile and wireless ad hoc networks. We present the algorithm, discuss its

implementation and report on the performance results of simulation of several workload models on ns-2. Our

results indicate that a scheme based on scheduling a path-discovery routine before the current in-use link breaks is

feasible and that such a mechanism can increase the number of packets delivered and decrease the average delay

per packet. It also improves the throughput (packet delivered ratio) and balances the traffic between different

source–destination pairs. Copyright # 2004 John Wiley & Sons, Ltd.

KEY WORDS: AODV routing protocol; congestion; mobile ad hoc network; mobile and wireless communiction;

ns-2

1. Introduction

The rapidly expanding wireless LAN and mobile ad

hoc networks coupled with the hardware miniaturiza-

tion and recent proliferation of hand-held portable

(e.g. laptop, palmtop) computers and personal digital

assistants (PDAs) have been the driving forces behind

the field of mobile computing ad mobile ad hoc

networks. Mobile ad hoc networking field has also

the potential to dramatically change the society as

workers become untethered from their information

sources and communication media.

Ad hoc wireless networks are composed of mobile

stations (nodes) communicating through wireless

channels without any fixed backbone support

[11,21]. Mobile hosts (MH) which can receive a

message directly from another mobile, within the

transmission range are said to be neighbors of MH.

A message sent by MH may be received simulta-

neously by all of its neighbors. Messages directed to

mobile hosts that are not within the sender’s transmis-

sion range must be forwarded by neighbors, which

should act as routers. A route may consist of any

number of hops.

*Correspondence to: Azzedine Boukerche, PARADISE Research Laboratory, SITE, University of Ottawa, Canada.yE-mail: [email protected]

Contract/grant sponsor: CRC-Canada Research Program, Canada Foundation for Innovation, and Ontario DistinguishedResearcher Award.

Copyright # 2004 John Wiley & Sons, Ltd.

Ad hoc networks are useful for providing commu-

nication support where no fixed infrastructure exists

or the deployment of a fixed infrastructure is not

economically profitable, and movement of commu-

nicating parties is allowed. Applications of ad hoc

networks include military operations (communication

in a hostile environment), rescue operations (rapid

deployment of a communication network where infra-

structures do not exist or have been damaged) and

sporadic happenings coverage (intense utilization of a

communication network for a very limited time).

Due to node mobility, routes connecting two

nodes may change. Therefore, it is not possible to

establish a priori and fixed paths for message delivery

through the network. Because of its importance, rout-

ing is the most studied problem in ad hoc wireless

networks. To this end, a number of routing protocols

have been proposed for ad hoc wireless networks

[5,6,9,10,14,16,17,19,22], which are derived from

either distance-vector [12] or link-state [13] based

classical routing algorithms.

There exist two broad types of protocols, namely

proactive and reactive. Proactive protocols continu-

ously construct routes so that they are immediately

available when needed. They include the destination-

sequenced distance vector (DSDV) protocol [19,20],

and its Randomized DSDV (R-DSDV) [7], the wire-

less routing protocol (WRP) [17], the temporally

ordered routing algorithm (TORA) [19] and the light-

weight mobile routing (LMR) protocol [22]. On the

other hand, reactive protocols construct routes only

on demand, which include the ad hoc on demand

distance vector (AODV) protocol [17], and the dy-

namic source routing (DSR) protocol [10]. The zone

routing protocol (ZRP) is a hybrid of proactive and

reactive protocols [9].

Due to the frequent changes of topology in the ad

hoc network, minimizing the number of packets

dropped is an important issue. In this paper, we are

concerned with the congestion problem and packets

dropped that are mainly due to the path break in the ad

hoc network where the topology changes frequently,

and the packet delay due to finding a new path and the

transfer time. Multi-path protocols can be useful for

the purpose of balancing congestion and decreasing

the delay, by routing packets along different paths

[11,21]. However, they may allow only source-based

load balancing decisions. Therefore, there may exist

overloaded nodes even if sources equally distribute

their traffic over multiple paths to the same destina-

tion. This situation may be caused by several things

such as asymmetric topologies and asymmetric traffic

flows. Therefore, the use of some protocol may

become necessary in order for an overloaded node

along a path to influence the routing decision taken by

sources of the traffic through that node. The introduc-

tion of such a protocol may involve additional mes-

sage traffic to a node which is already congested, thus

making the scenario even more complicated.

In this paper, we present an extension to the AODV

routing protocol [2,17], which we refer to as PrAODV.

The PrAODV scheme consists of propagating the

route state information if the path is going to break

soon. It invokes a path rediscovery routine from the

source according to the received information about the

path which is contained in the route reply packet or

according to a warning message received at the

source. The purpose of our pre-emptive protocol is

to find a new path before the existing path breaks,

thereby switching to this new path. Our main focus

in this paper is to study the feasibility and the effec-

tiveness of the control mechanism in the proposed

protocol.

The remainder of the paper is organized as follows.

Section 2 presents the basic AODV routing protocol.

In Section 3, we present our PrAODV ad hoc routing

protocol, and outline the congestion control policy

based on the information about the path, followed by a

discussion of methods of how to get the route infor-

mation. In Section 4, we will report the simulation

experiments we have conducted to study the perfor-

mance evaluation of the pre-emptive AODV protocol

followed by a comparative study with the original

AODV protocol [2,17]. Section 5 concludes this

paper.

2. The Basic AODV Protocol

AODV [2,17] uses an on-demand-based protocol to

discover the desired path, while using hello packets to

keep track of the current neighbors. Since it is an on-

demand algorithm, it builds routes between nodes

only upon request by the source nodes. It maintains

these routes as long as they are needed by the sources.

It is loop-free and self-starting. Earlier studies have

also shown that AODV protocol scales quite well

when we increase the number of mobile nodes

[2,3,4]. AODV allows mobile nodes to obtain routes

quickly for new destinations and does not require

mobile nodes to maintain routes to destinations that

are not in active communication. It also allows mobile

nodes to respond to situations associated with broken

100 A. BOUKERCHE AND L. ZHANG

Copyright # 2004 John Wiley & Sons, Ltd. Wirel. Commun. Mob. Comput. 2004; 4:99–108

link and changes in network topology in a timely

manner, as we shall see later.

AODV uses a destination broadcast id number to

ensure loop freedom at all times, since the intermedi-

ate nodes only forward the first copy of the same

request packet. The sequence number is used in each

node, and the destination sequence number is created

by the destination for any route information it sends to

requesting nodes. It also ensures the freshness of each

established route. The route is updated if a new reply

is received with the greater destination sequence or

the same destination sequence number but the route

has fewer hops. Therefore, this protocol will select the

freshest and shortest path at any time.

� Path Discovery: When a route is needed, the source

invokes a path discovery routine. It has two steps:

the source sends out a request and the destination

return a reply. In what follows, we will discuss these

two steps.

� Step 1: Request Phase

When a route to a new destination is needed, the

node uses a broadcast RREQ to find a route to that

destination. A route can be determined when the

RREQ reaches either the destination itself or an

intermediate node with a fresh route to the destina-

tion. The fresh route is an unexpired route entry for

the destination associated.

The important step during the request phase is

that a reverse path from the destination to the source

can be set up. When a source node wants to find a

path to a destination, it broadcasts a route request

packet to its neighbors. The neighbors update their

information for the source node, set up backwards

pointers to the source node in their route tables, and

rebroadcast the request packet.

� Step 2: Reply Phase

When the request arrives at the destination or at an

intermediate node that has a path to that destination

a reply packet is returned to the source node along

the path recorded. While the reply packet propa-

gates back to the source, nodes set up forward

pointers to the destination, and set up the forward

path. Once the source node receives the reply

packet, it may begin to forward data packets to

the destination.

Figure 1 illustrates an example on how this scheme

works. In this example, a path from S to D is desired,

during the request phase, when the request arrives to

node a, it sets up a route entry whose destination is S,

[dest¼ s, next-hop¼ s]; and for b, it sets up for

[dest¼ s, next-hop¼ a]. Let say that b has a route

entry whose destination is D, and it is still active, the

request phase stops at b, and it returns a reply to S flow

the route that just set up, while returning the reply, it

sets up the forward route, for example, at node a, it

sets up the entry [dest¼ d, next-hop¼ b].

� Data Packet Forwarding: After the reply packet

returns from the destination, the source can begin

sending out the packet to the destination via the new

discovery path, or the node can forward any en-

queued packets to a destination if a reverse path is

set up and the destination of the reverse path is the

destination of the path.

A route is considered active as long as there are

data packets periodically traveling from the source

to the destination along that path. Once the source

stops sending data packets, the links will time out

and eventually be deleted from the intermediate

node routing tables.

� Dealing With the Broken Links: If a link breaks

while the route is active, the packets that are

flowing in that path can be dropped and an error

message is sent to the source or a local repair

routine will take over. If the node holding the

packets is close to the destination, this node invokes

a local repair route. It enqueues the packet and finds

a new path from this node to the destination.

Otherwise, the packets are dropped, and the node

upstream of the break propagates a route error

message to the source node to inform it of the

now unreachable destination(s). After receiving the

route error, if the source node still desires the route,

it can re-initiate a route discovery mechanism. How-

ever, we can add a pre-emptive protocol to AODV

and initiate a rediscovery routine before the current

routes goes down. In the next section, we will

discuss this pre-emptive approach in more detail.

Fig. 1. Path discovery.

MOBILE AD HOC NETWORKS 101


3. PrAODV: Adding Pre-emptive Protocolto AODV

In this section, we introduce the pre-emptive protocol

first, then we discuss how this pre-emptive protocol is

added into the original AODV, and finally we compare

the protocol with the original AODV protocol.

3.1. Pre-emptive Protocol

The pre-emptive protocol initiates a route rediscovery

before the existing path breaks. It overlaps the route

discovery routine and the use of the current active

path, thereby reducing the average delay per packet.

During the development of PrAODV development,

we have investigated several pre-emptive mecha-

nisms. In this paper, we will settle on the following

two approaches.

� Schedule a Rediscovery in Advance: In this ap-

proach, when a reply packet returns to the source

through an intermediate node, it collects the infor-

mation of the links. Therefore, when the packet

arrives at the source, the information about the

condition of all links will be known, including the

minimum value of the lifetime of the links. Hence,

we can schedule a rediscovery Trediscovery time

before the path breaks.

� Warn the Source Before the Path Breaks: Some

mechanisms are needed to take care of finding

which path is likely to break. We can monitor the

signal power of the arrived packets as follows:

when the signal power is below a threshold value,

we begin the ping–pong process between this node

and its immediate neighbor nodes. This node sends

to its neighbors in the upstream a hello packet

called ping, and the neighboring nodes will respond

with a hello packet called pong. Such ping–pong

messages should be monitored carefully. In our

approach, when bad packets were received (or we

timeout on ping packets) a warning message should

be sent back to the source during the monitoring

period. Upon receiving a warning message, a path

rediscovery routine is invoked.

3.2. PrAODV Protocol

In our pre-emptive AODV protocol, we combine the

above two pre-emptive mechanisms, and add them to

the original AODV. PrAODV protocol is built based

on the following assumptions. Future work will be

directed to eliminate such assumptions.

� Congestion is Caused Only Due to the Path Breaks:

Other factors such as the limited bandwidth avail-

able on wireless channels and the intensive use of

resources in an ad hoc network cannot affect our

protocol. We assume that the network has enough

bandwidth available, and each node has enough

capacity to hold packets.

� The Route Discovery Time can be Estimated: We

estimate the discovery time by monitoring the

request and reply packets, as the sum of the time

required to process and monitor these two packets.

� We can Detect When a Link Breaks: By monitoring

the transfer time of packets between the two neigh-

boring nodes.

Based on the above assumptions, we present our

PrAODV as the following:

� Schedule a Rediscovery: We have added an addi-

tional field, which we refer to as a lifetime, in the

reply packet to store the information of the links

along the new discovered path. Each link associates

a time-to-live, a parameter that is set up in the

request phase. The lifetime field contains the mini-

mum value of the time-to-live of the links along a

path. The reply packet also has an additional field, a

timestamp, which indicates the time that the request

packet was sent out.

Let us now see how we compute RTT, the esti-

mated time needed to discover a new path. When

the reply packet arrives at the source node, it com-

putes RTT as (arrival time� timestamp), then sche-

dule a rediscovery at time (lifetime�RTT). We use

RTT as our estimated value for the time needed to

discover a new path.

� Warning the Source: Recall that a pre-emptive

protocol should monitor the signal power of the

receiving packet. In our approach, we monitor the

transfer time for the hello packets. According to

Reference [1], Pn ¼ P0=rn, where P0 is a constant

for each link and n is also a constant, we can see

that the distance, which connects to the transfer

time of the packet via each link, has a one-to-one

relationship to the signal power. Thus, by monitor-

ing the transfer time of packets via each link, we

can identify when the link is going to break.

In our protocol, when a node (destination) re-

ceives a real packet other than AODV packets, it

sends out a pong packet to its neighbor (source), i.e.

where the packet comes from. Note that there is no

need to send this pong packet if we can include a

field in the real packet to store the current time the



packet is sent. However, in the original packet, it

does not have such a field, hence, we need an

additional pong packet to get such information. In

both ping and pong packets, we include a field

containing the current time that the packet is sent.

When the source monitoring the transfer time is

greater than some specific value c1, it begins the

ping–pong process. If more than two pong packets

arrived with the transfer time greater than a constant

c2, the node will warn the source of the real packet.

Upon receiving the warning message, the source

checks if the path is still active. This can easily be

done, since each route entry for a destination

associates a value, rt_last_send, which indicates if

the path is in use or not. If the path is still in use, then

a rediscovery routine is invoked.

Theoretically, these two cases can take care of

finding new paths before current paths break. The first

case is quite helpful if the data transmission rate is

slow. If only one data packet is sent out per time-

expired period, then even the current route is still

needed. Note that this entry may not have packets to

go through it during the next time period. This can

happen if the interval between two continuous packets

is greater that the timeout period of the current route.

The second case can be used to find a new path

whenever a warning message is generated. However,

those two cases are also based on some assumptions,

such as the span of a link which can be estimated by

the time out of ping packets and the values of those

constants are accurate. Once we break those assump-

tions, the test results will be unexpected.

3.2.1. Type of Packets in Pr AODV

The packet types in the AODV original protocol are:

route requests, route replies, triggered requests, trig-

gered replies and hello packets. In the PrAODV

protocol, we have added the following packets:

� Pre-emptive Packet: Used to inform the down-

stream nodes that a route rediscovery is needed,

and those nodes will update the information of this

route entry from RTF_UP to RTF_PRE, so that

those entries will be ready for the second request

packet.

� Ping Packet: Generated whenever a node receives a

hello packet which is longer than some value. Once

the ping packet is generated, it will send to the

source of the hello packet. We chose to monitor

periodically the ping–pong process.

� Pong Packets: Response packets sent to the source

of ping packet.

� Warning Packet: Generated during the ping–pong

period as a result of a ping packet timeout.

4. Simulation Experiments

In this section, we present the simulation model and

discuss the simulation experiments we have carried

out to evaluate the performance of the PrAODV

protocol. We have implemented the algorithm using

ns-2, version 2.1b8 [18]. The implementation of Pre-

emptive protocol based on the CMU Monarch exten-

sion. The distributed coordination function (DCF) of

IEEE 802.11 for wireless LANs is used as the MAC

layer. The traffic sources are continuous bit-rate

(CBR). The source–destination pairs are spread ran-

domly over the network. By changing the total amount

of traffic sources, we can get scenarios with different

traffic loads. The mobility models used in our experi-

ments to investigate the effect of the number of nodes

are 670� 670 m field with different number of nodes.

Each node starts its journey from a random location to

a random destination with a randomly chosen speed

uniformly distributed between 0 and 20 m/sec. Once

the destination is reached, another random destination

is targeted after a pause. Varying the pause time

changes the frequency of node movement. In each

test, the simulation time is 1000 s. The experimental

results were obtained by averaging several trial runs.

4.1. Performance Metrics

In order to evaluate the performance of the PrAODV

ad hoc routing protocol, we chose the following

metrics.

� Throughput: (i.e. packet delivered ratio) is a ratio of

the data packets delivered to the destination to those

generated by the CBR sources.

� Average Delay per Packet: This includes all possi-

ble delays caused by buffering during route dis-

covery latency, queuing at the interface queue,

retransmission delays at the MAC and propagation

and transfer time.

� Packet Arrived: This is the number of packets that

are successfully transferred to the destination.

4.2. Simulation Results

In this section, we report on the performance results of

simulation of several workload models of several



scenarios we have used to evaluate the performance

the pre-emptive ad hoc routing protocol.

Before we proceed further, let us first define some

terms we will be using in this paper.

� Traffic Pair: The pair of the source and destination

of a traffic.

� Traffic Rate: The rate of the traffic generated

(packet/s)

� Quiet Time: The time interval between two contin-

uous packets generated at the same source.

In general, in both AODVand PrAODV, the number

of nodes does affect their performance. We have

observed that with the pre-emptive protocol, PrAODV

can significantly improve the performance of the

throughput, the average delay per packet, and the

packet delivered. The pause time and the packet rate

can also affect its performance. In the course of our

experiments, we have observed that PrAODV has

much better performance than AODV when the packet

rate is low.

Let us now turn to our results.

In our experiments, we set the traffic flow to ten-

pairs, the interval traffic rate to 4, and the pause time

to 600. As illustrated in Figure 2 our results indicate

that the number of nodes does not have any effect on

both protocols, AODV and PrAODV. However, the

pre-emptive AODV protocol indicates that it is more

stable than AODV, i.e. when we look closely at the the

standard deviation 9.036961 for AODVand 5.0943 for

PrAODV. This is mainly due to the fact that PrAODV

balances the traffic quite efficiently to a new path

before the current one breaks. The best performance is

observed when the number of nodes is set to 35, as

illustrated in Figure 2. In our experiments, we have

noticed that this type of behavior is always true with

only five traffic pairs as well.

In our next set of experiments, we wish to study the

effect of the number of traffic on the performance of

PrAODV. Based upon our initial experiments, see

above, we choose a scenarios with 35 nodes and five

traffic pairs. We also set the pause time at 600 s. Our

results are as indicated in Figure 3. In both protocols,

we observe an increase of the number of packet

arrivals as we increase amount of traffic. The through-

put obtained with PrAODV is lower when compared to

the AODV protocol, and the delay obtained with the

pre-emptive AODV protocol is lower when compared

to the original AODV. This is mainly due the pre-

emptive paradigm used in PrAODV and the number of

packets that are dropped during the simulation.

In Figure 4, we portray the results we have obtained

when we used 50 nodes, ten (source, destination)

pairs. Our results indicate that the pre-emptive proto-

col can balance quite well the traffic and the perfor-

mance for PrAODV is much more stable when

compared to the AODV protocol, see Table I.

In Figure 5, we portray the results we have obtained

when we use 35 nodes, and when the amount of traffic

Fig. 2. Effect of the number of nodes.



pair is set to five. As we can see, the performance of

the pre-emptive AODV protocol is much better than

AODV. Ths is mainly due to the the pre-emptive

mechanism with PrAODV that finds alternative paths

when links break.

From Figure 6, we portray the results we have

obtained when we vary the value of the interval/traffic

rate, and the interval between two contineous packet

from one source. As we can see from Figure 6, when

the quiet time is longer, the PrAODV has much better

performance than AODV. Since the longer the quiet

time, the more path broken can be rediscovery in

PrAODV protocol, and the performance can be much

better.

Fig. 3. The effect of the amount of traffic pairs.

Fig. 4. Ten traffic pair.



In summary, the pre-emptive AODV invokes the

route rediscovery Tdiscovery before the current active

path breaks, so that we can find a new path before the

old one breaks and switch to it. Therefore, the packets

dropped can be decreased. Since the discovery routine

overlaps the communication process of the current

path, then the total delay will be decreased. After the

path switches to the new one, the packet will be

forwarded by using the new path, therefore, we can

Table I. The standard deviation for ten-pair traffic.

PTYPE Arrived Throughput Delay

AODV 13.768 34 0.910 771 1 0.036 882PrAODV 10.231 22 0.904 51 0.023 925

Fig. 5. The effect of pause time. Fig. 6. The effect of interval/traffic rate.



balance the load from the old path to the new path.

The load will be more balanced in pre-emptive AODV.

The overhead in the new protocol is almost the same

as the old one, except for the k ping–pong packets

monitoring, where k is a constant. Since the new

protocol is more balanced and the overhead is reason-

able, the pre-emptive AODV is easier to scale than

AODV.

5. Conclusion

In this paper, we have presented a pre-emptive on-

demand distance vector routing protocol for mobile

and wireless ad hoc networks. We have discussed the

algorithm and its implementation. We have also

reported a set of simulation experiments to evaluate

the performance of our scheme when compared to the

original AODV on-demand routing protocol.

Our results indicate that both AODV and PrAODV

protocols are easy to scale, and the number of mobile

nodes does not affect the performance of either of the

two protocols. Pre-emptive protocol objectives are to

find a new path before the current in-use path breaks

and switch to it. Therefore, the traffic can be balanced

to the new path. While our results indicate that this

protocol increases the number of arrival packets

within the same simulation time, it decreases the

delay per packet when compared to the original

AODV scheme.

In the future, we plan to extend our simulation

experiments and investigate further improvements of

our scheme and make it efficiently energy aware when

compared to previous protocols. We wish to enhance

our protocol by looking into the QoS parameters

based upon a multipath routing algorithm.

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Fig. 6. Continued.



Authors’ Biographies

Azzedine Boukerche is a CanadaResearch Chair and an AssociateProfessor of Computer Sciences atthe School of Information Tech-nology and Engineering (SITE) atthe University of Ottawa, Canada.He is also the Founding and Direc-tor of PARADISE ResearchLaboratory (PARAllel, Distributedand Interactive Simulation ofLarge Scale Systems and Wireless

Mobile Networking). Prior to this he was an AssistantProfessor of Computer Sciences at the University of NorthTexas, and Director of the Parallel Simulations, Distributedand Mobile Systems Research Laboratory) at UNT. He alsoworked as a Senior Scientist at the Simulation SciencesDivision, Metron Corporation located in San Diego. He wasemployed as a Faculty at the School of Computer Science(McGill University, Canada) from 1993 to 1995. He spentthe 1991–1992 academic year at the JPL-California Instituteof Technology where he contributed to a project centeredabout the Specification and verification of the software usedto control interplanetary spacecraft operated by JPL/NASALaboratory. His current research interests include wirelessand mobile networks, wireless ad hoc and sensor networks,distributed and mobile computing, distributed systems,parallel simulation, large-scale distributed interactive simu-lation, and performance modeling. Dr. Boukerche has pub-lished several research papers in these areas. He was therecipient of the best research paper award at IEE/ACMPADS’97, and the recipient of the 3rd National Award forTelecommunication Software in 1999 for his work on adistributed security systems on mobile phone operations,and has been nominated for the best paper award at IEEE/ACM PADS’99 and at the ACM Modeling, Analysis andSimulation of mobile and wireless systems Conference2001. He served the General co-Chair of the principleSymposium on Modeling Analysis, and Simulation ofComputer and Telecommunication Systems (MASCOTS),in 1998, General Chair of the Fourth IEEE InternationalConf. on Distributed Interactive Simulation and Real TimeApplications (DS-RT2000), General Chair for the 3rd ACMConf. on Modeling Analysis, and Simulation of Wireless

and Mobile Systems (MSWiM’2000), as Program Co-Chairfor the Fifth IEEE International Conference on Mobile andWireless Computing and Communication (MWCN’03),ACM/IFIP Europar 2003, IEEE Wireless Local Networks(WLN’03), the 35th SCS/IEEE Annual Simulation Sympo-sium ANSS2002, and the 10th IEEE/ACM Symposium onModeling Analysis, and Simulation of Computer andTelecommunication Systems (MASCOTS’2002), the thirdInternational Conf. on Distributed Interactive Simulationand Real Time Applications (DS-RT’99), and ACMMSWiM’2000, as a Deputy Vice Chair of Wireless andMobility Access Track for ACM WWW 2002, as a GuestEditor for VLSI Design, the Journal of Parallel and Dis-tributed Computing (JPDC), ACM Wireless Networks(WINET), ACM Mobile Networks and Applications(MONET), and the International Journal of Wireless andMobile Computing. He was the main organizer of a SpecialSession on Performance Analysis of Mobile and WirelessCommunication Systems at the 7th IEEE HiPC Conference.He has been a member of the Program Committee of severalinternational conferences such as ICC, IPCCC, LNC, VTC,ICPP, MASCOTS, BioSP3, ICON, ICCI, MSWiM, PADSand WoWMoM, LWN, networking conferences. Dr. Bou-kerche serves as a Program Co-Chair for IEEE Workshop onWireless, Mobile Ad hoc and Sensor Networks (WMAN2004), and the IEEE Local Wireless Networks (LWCN2004). He also serves as an Associate Editor for the ACM/Kluwer Wireless Networks Journal, for the InternationalJournal of Parallel and Distributed Computing (JPDC), andthe SCS Modeling, Analysis and Simulation TRASNASC-TIONS, and on IEEE Task Force on Cluster Computing(TFCC) Executive Committee. He is a Steering Chair forIEEE DS-RT and ACM MSWiM Symposiums, and a mem-ber of the IEEE and ACM.

Linqin Zhang is a PhD Candidateat the SITE, University of Ottawa.She received her MSc Degree fromthe University of North Texas in2003. Her main research interestsare large-scale distributed systems,wireless and mobile ad hoc net-works.



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