A Study based analysis of destination sequence distance vector

Document Sample
A Study based analysis of destination sequence distance vector Powered By Docstoc
					A comparison based overview of destination distance sequence vector routing (DSDV) and mobile ad
hoc on demand data delivery protocol (MAODDP)

                           Humayun Bakht
                           School of Computing and Mathematical Sciences
                           Liverpool John Moores University
                           Byrom Street, Liverpool L3 3AF, UK


Mobile ad hoc network is an autonomous system          networks are known as base stations. As the
of mobile nodes establishing ad hoc or short live      mobile travels out of range of one base station
network without the intervention of any fixed          and into the range of another, a “handoff” occurs
infrastructure. Routing in these types of network      from the old base station to the new, and the
is an unresolved issue. Effort is going on to          mobile is able to continue communication
establish an effective routing mechanism for           seamlessly throughout the network. Typical
mobile ad hoc networks. Proposed protocols for         applications of this type of network include
mobile ad hoc network can be categorized into          office wireless local area networks (WLAN).
two types i.e. table‟s driven and on-demand
routing protocols.                                     The second type of mobile wireless network is
Destination sequence distance vector routing is        mobile ad-hoc network or infrastructure-less
one of tables driven earliest proposed algorithms.     mobile networks. A mobile ad-hoc network is a
DSDV maintains the consistent overview of the          collection of wireless mobile nodes dynamically
network. DSDV requires participating nodes             forming a temporary network without the use of
broadcast updates after a regular interval of time.    any existing network infrastructure or centralized
Most of the tables driven type protocol is either a    administration[4, 5]. Mobile ad-hoc networks are
extension or modified form of DSDV.                    deployed in applications such as disaster
Mobile ad-hoc on demand data delivery protocol         recovery and distributed collaborative computing
follows an intermediate approach in compression        where routes are mostly multi-hop and network
with tables driven and on demand routing               hosts communicate via packet radios[6].
protocols. The key feature of MAODDP is to             Examples include infrared, wireless RF,
establish the route and deliver the data               Bluetooth, ad-hoc sensor networks[7] or even
simultaneously at the same time one after the          wired based transceivers used when emulating ad
other.                                                 hoc networks. There is current and future need
This paper is an effort to describe the detail         for dynamic ad hoc networking technology [8].
functioning of these protocols. This paper also        The emerging field of mobile and nomadic
covers an analytical and discussion section to         computing, with its current emphasis on mobile
compare the various aspects of these protocols         IP operations should gradually broaden and
with each other.                                       require highly-adaptive mobile networking
                                                       technology to effectively manage multi-hop,
                                                       mobile ad-hoc network clusters which can
1. Introduction                                        operate autonomously or, more than likely, be
                                                       attached at some point to the bigger network
With the advancement in radio technologies like        such as the Internet.
Bluetooth[1], IEEE 802.11 or Hiperlan, a new
concept of networking has emerged which make           Most of the existing Internet protocols were
wireless networks increasingly popular in the          designed to aid routing in a network with fixed
computing industry[1, 2]. This is particularly         infrastructure. These protocols therefore are not
true within the past decade which has seen             considered good enough to support routing in an
wireless networks being adapted to enable              ad-hoc networking environment[9]. One of the
mobility. There are currently two variations of        first routing solutions was based on the idea of
wireless networks[3]. The first is known as            considering each mobile nodes of an ad hoc
Infrastructure networks i.e. those networks with       network as a router and running some
fixed and wired gateways. The bridges for these        conventional routing protocol[10]. However This
scheme was not very successful as mobile ad-hoc
network suffers from frequent topology changes               Mobile ad-hoc on demand data delivery
which results a large number of packets to be
dropped or lost[11]. Later on numbers of                   Bandwidth                                Security
different protocols have been proposed as a                Constraint
routing solution for mobile ad hoc networks.
These can be classified as either tables
driven[12] or on-demand protocol[13] types.                                      Routing

Pro-active protocols follow an approach similar
to the one used in wired routing protocols. By
                                                             Multicasting                        Battery Life
continuously evaluating the known route and
attempting to discover new routes, they try to
maintain the most up-to-date map of the                    Figure 1 Model of MAODDP
network. This allows them to efficiently forward
packets as the route is known at the time when
the packet arrives at the node. Pro-active or
table-driven protocols, in order to maintain the     MAODDP uses destination sequence numbers to
constantly changing network graph due to new         ensure loop free routing. The primary concerns
moving or failing nodes require continuous           in mobile ad-hoc networks are bandwidth
updates which may consume large amounts of           limitations and unpredictable topology changes.
bandwidth. In contrast, reactive protocols           Thus, efficient utilization of routing packets and
determine the proper route only when required.       immediate recovery of route breaks are critical in
Therefore, when a packet needs to be forwarded       routing and multicasting protocols. MAODDP
In this instance the node floods the network with    intial specification taken into account these two
a route-request and builds the route on demand       factors besides number of other factors.
from the responses it receives. This technique       MAODDP could proved to be an effective
does not require constant broadcasts and             solution particularly in terms of minimizing
discovery, but on the other hand causes delays       bandwidth consumption and maximizing battery
since the routes are not already available.          life of the mobile nodes in an ad hoc network.
Additionally, the flooding of the network may
lead to additional control traffic, again putting    Rest of the paper is organized as follows in
strain on the limited bandwidth.                     section 2 we discuss routing problems in mobile
                                                     ad hoc networks, section 3 and 4 covers details
Mobile ad-hoc on Demand Data Delivery                functioning of destination sequence distance
protocol (MAODDP) follows a centralized              vector routing and mobile ad hoc on demand on
approached figure 1 is based on the idea of          demand data delivery protocol, analysis and
accomplishing route discovery and data delivery      discussion is given in section 5 while references
simultaneously at the same time one after the        are listed in section 6.
other. It is an on-demand routing protocol type it
builds routes between nodes only as desired by
source nodes. MAODDP offers loop-free routing        2. Routing in mobile ad hoc network
with the help of sequence number, self-starting.
MAODDP offers quick adaptation to dynamic            Despite the numerous advantages and potential
link conditions, low processing and memory           application possibilities[8], ad-hoc networks are
overhead, low network utilization, and               yet far from being deployed on large-scale
determines routes to destinations within the         commercial basis. To enable communication
mobile ad-hoc network.                               within a MANET, a routing protocol is required
                                                     to establish routes between participating nodes.
                                                     Because of limited transmission range, multiple
                                                     network hops may be needed to enable data
                                                     communication between two nodes in the
                                                     network. Since MANET is an infrastructure less
                                                     network, each mobile node operates not only as a
                                                     host but also as a router, forwarding packets for
                                                     other mobile nodes in the network.
There are frequent unpredictable topological         node. As the number of nodes in the network
changes in these networks, which makes the task      grows, the size of the routing tables and the
of finding and maintaining routes are                bandwidth required to update them also grows.
difficult[14-16]. Conventional routing protocols     This overhead is considered to be the main
based on distance vector algorithms are not very     weakness of DSDV.
suitable for such situations as the amount of
routing related traffic would consume a large        3.1 Overview
portion of the wireless bandwidth, and such
discovered routes would soon become crucial          Every mobile node in the network maintains a
due to mobility of nodes. Although good              routing table, as shown in figure 1 in which all of
numbers of routing protocols are suggested and       the possible destinations within the network and
tested for mobile ad-hoc networks. Research          the number of hops to each destination are
shows performance metrics like throughput,           recorded. Each entry is marked with a sequence
delay and protocol overhead in relation to           number assigned by the destination node. The
successfully transmitted data still need better      sequence numbers enable the mobile nodes to
optimization.                                        distinguish stale routes from new ones, thereby
                                                     avoiding the formation of routing loops. Routing
These all problems make efficient dynamic            tables updates are periodically transmitted
routing an important research challenge in ad hoc    throughout the network in order to maintain table
networks. Here new protocols especially reactive     consistency.
types could be considered as very useful because
they often generate much lower routing               New route broadcasts contain the address of the
overheads in comparison with proactive routing       destination, the number of hops to reach the
protocols[17].                                       destination, the sequence number of the
                                                     destination as well as a new sequence number
Thus from the above discussion we concluded a        unique to broadcast. The route labelled with the
                                                     most recent sequence number is always used. In
clear need of developing more efficient strategies
                                                     the event that two updates have the same
for routing in mobile ad-hoc network. Based on
                                                     sequence number, the route with the smaller
carried research the proposed scheme should be
                                                     metric is used in order to optimise the path.
capable of delivering an effective routing
solution while addressing other routing related      Routing is achieved by using routing tables
issues along with routing. In this context the       maintained by each node.
some of the desirable characteristics of the
proposed algorithm are bandwidth efficient,          3.2) DSDV Route Advertisement
consume less battery power and be able or can be
extended to support both uni-cast and multicast      DSDV requires nodes to periodically transmit
routing.                                             routing table update packets, regardless of
                                                     network traffic. These update packets are
                                                     broadcast throughout the network. Therefore,
3. Destination sequence        distance    vector    every node in the network knows how to reach
routing protocol                                     every other node. However due to the
                                                     dynamically varying topology, the entries in this
Based on conventional routing protocol, RIP          list may change quite frequently over time, thus
adapted for use in ad-hoc network, the               requires, route advertisement to be made quite
destination sequenced distance vector routing        often . This is to ensure that every mobile node
protocol[18] is an extension of classical bellman    can almost locate every other node in the
ford routing mechanism. In DSDV[19] routing is       network. In addition each mobile node agrees to
achieved by using routing tables maintained by       relay data packets to other nodes upon requests.
each node. The main complexity in DSDV is in         In this way even though a node does not have a
generating and maintaining these routing tables.     direct link with a particular node in the network,
DSDV requires nodes to periodically transmit         it will still be able to exchange data with that
routing table updates packets, regardless of         node.
network traffic. These update packets are
broadcast throughout the network so every node       Whenever a node broadcast data, a sequence
in the network knows how to reach every other        number is generated. In addition to data the
broadcast contains other useful information such     Any mobile node receiving new broadcast can
as destination ID, number of hops to the             find the fresh route by comparing receiving
destination and destination sequence number.         information with those that are previously
Receiver on receiving this data make sure that       recorded in its routing table. Route with recent
the received sequence number is less the             sequence number is considered as fresh route
previously recorded sequence number in receiver      while the older sequence number one‟s are
routing table. Example of a route advertised table   discarded.
is shown is figure 1.                                If the sequence number found to be same, then
                                                     the route with better metric will be selected.
Destination   Sequence    Metric
                                                     4. Mobile ad hoc on demand data delivery
F             0           F-670                      protocol
G             1           G-780
                                                     4.1) Introduction
H             3           H-890
                                                     MAODDP stands for mobile on-demand data
Figure 2 Route advertisement in DSDV                 delivery protocol. It was first proposed
                                                     pproceedings of the 3rd Annual Post-Graduate
The receiver also advertises route received in       Symposium        on  the    Convergence      of
broadcast its routing information. The receivers     Telecommunications,       Networking        and
also add an increment to the metric before           Broadcasting[20]. Since then the protocols has
advertising the route since further incoming         gone through a series of modifications[2, 5].
packets will require one more hop to reach the       Several functions to support both multicasting
destination.                                         and unicasting routing and to secure data
The settling time is calculated by maintaining a     transmission have been added in the initial
running over the most recent updates of the          specification of MAODDP.
routes for each destination. The most recent          On demand routing
measurement of the settling time is calculated by     Loop free routing with the use of sequence
maintaining weighted average over the most                numbers
recent updates of the route for each destination.     Saving battery power of the participating
A parameter also selected to indicate how long a          nodes
route has to remain stable before it is counted as    Faster network converge
truly stable. Any route more stable then this         Guaranteed data delivery to the destination.
parameter will cause a triggered update if it is
ever replaced by another route with different        In general, whenever a source node requires a
next hop or metric.                                  route to deliver data packets to the destination
                                                     for which it does not have any recorded route in
3.3) Sequence Number                                 its routing tables. It initiates route discovery and
                                                     data delivery process by broadcasting ROUTE
Broken link, which is mainly due to topology         DISCOVERY AND DATA DELIVERY
changes is described by ∞ metric which could be      PACKET (RREQD). There are three possibilities
any value greater then the maximum allowed           when this packet reaches to the intermediate
metric. Whenever a link to next hop is broken,       node. The first one if the node has a suitable path
any route through the next hop is assigned ∞         for the destination, as enclosed in the header of
metric and an updated sequence number.               RREQD packet then its forward the packet to the
Therefore the only situation when mobile node        intended destination. The second possibility
other then destination node generates sequence       when node does not have any direct path for the
number is when there is a broken link.               destination node but have idea about the closest
In summary there are two conditions when the         neighbours, in this case, node forward this
sequence number could be generated.                  packet to that node. The final possibility nodes
      Whenever a new broadcast is issued.           have no information whatsoever about the
      When a broken link is found                   destination node as specified in the RREQD, in
                                                     this case the node forward this packet to its next
 3.4) Route selection                                hop neighbours. This process is repeated until
                                                     the packet reach to the destination. Once the
packet has reached to the destination node It
broadcasts an acknowledge packet (ACK) back                       Immediately before a node broadcast a
to the source node. This acknowledge packet                        RREQD, it increments its own
confirm the source node that the previous                          sequence number.        This prevents
transmission was successful. It also help the                      problems with deleted reverse routes to
intermediate node and the source nodes to                          the source of a RREQD.
updates their routing information about all the
nodes in the path from source to the destination..
However if the nodes do not hear any thing back                   Immediately before a destination node
from the destination node before the expiry time                   broadcast an acknowledged (ACK)
of RREQD packet. It will consider the previous                     message in response to a route request
attempt as unsuccessful.                                           and data delivery packet (RRQED), it
                                                                   updates its own sequence number to
4.1) Generating Route Request and data                             the maximum of its current sequence
delivery packet (RREQD)                                            number and the destination sequence
                                                                   number in the acknowledged packet
A node floods a RREQD when it determines that                      (ACK).
it needs a route to deliver data to a destination
and does not have one available in its routing         Every route table entry at every node MUST
table. This can happen if the destination is           include the latest information available about the
previously unknown to the node, or if a                sequence number for the IP address of the
previously valid route to the destination expires      destination node for which the route table entry
or is broken. The destination sequence number          is maintained. This sequence number is called
field in the RREQD is considered as the last           the "destination sequence number". It is updated
known destination sequence number for this             whenever a node receives new information about
destination and is copied from the destination         the sequence number from RREQD packet, ACK
sequence number field in the routing table. If no      packet, or RERR messages that may be received
sequence number is known, a sequence number            related to that destination.
of zero is used. The source sequence number in
the RREQD is the node's own sequence number.           In summary, a node may change the sequence
The Flooding ID field is incremented by one            number for a particular destination only if:
from the last Flooding ID used by the current
node. Each node maintains only one Flooding                        It is itself the destination node, and
ID. The Hop Count field is set to zero.                             offers a new route to itself

A source node often expects to have bidirectional                 It receives an MAODDP messages i.e.
communications with a destination node. In                         RREQD OR ACK, with new
such cases, it is not sufficient for the source node               information about the sequence number
to have a route to the destination node; the                       for some other destination node
destination must also have a route back to the
source node. In order for this to happen as                       The path towards the destination node
efficiently as possible, any generation of an                      expires or breaks.
acknowledge packet by the destination node for
delivery to the source node, should be                 4.3) Generating acknowledge message (ACK)
accompanied by some action which notifies the          If a RREQD is successfully deliver to the
destination about a route back to the source node.     destined destination. It is the responsibility of the
                                                       destination node to issue acknowledge packet
4.5) Maintaining Sequence number                       (ACK) back to the source node. Destination node
MAODDP depends on each node in the network             MUST update its own sequence number to the
to own and maintain a sequence number to               maximum of its current sequence number and the
guarantee the loop-freedom of all the routes           destination sequence number in the RREQD
towards that node. MAODDP uses combination             packet. The destination node places the value
of sequence number and broadcast ID as a               zero in the Hop Count field of the ACK message.
precaution to avoid message looping. The
sequence number is incremented in one of two
5. Analysis and discussion

Mobile ad hoc networks suffer with high               node mobility causes continuously changing
mobility, frequent topology changes, bandwidth        topology in which routes break unpredictably
constraints, limited power and hidden terminal        and new routes form dynamically.
problem. Our research concluded[21] that almost
all of these issues are interrelated with the over    In mobile ad-hoc network, an efficient group
all routing mechanism. Therefore for a routing        communication model can ease effective
mechanism to be good enough for such an               communication among various groups in the
environment, it should be able to address some        network. At present, multicasting routing in
or all of these issues at a certain level.            mobile ad-hoc networks is gained by adopting
                                                      one of two approaches: flooding and tree-based
Most of the tables driven protocols address           routing. Flooding offers the lowest control
routing without addressing the side effects on the    overheads with very high data traffic, while tree-
other related issues such as limited bandwidth        based routing reduces data traffic in the network
and battery power of ad-hoc networks. Like            but requires many control data exchanges.
other tables driven protocols, DSDV maintain a        Studies show less efficient performance of these
consistent overview of the network by forcing         techniques on mobile ad-hoc network. Like most
each mobile nodes to broadcast continuous             of the other tables driven protocols DSDV in its
updates after a regular interval of time. This        present form does not address multicast routing.
approach clearly not very feasible for ad hoc
networking environment. Apart from bandwidth
                                                      Security is one of the important aspects of this
and battery power it could also create
                                                      technology and it needs some serious
unnecessary network head and could also a mean
                                                      attention[24, 25]. Users within the network want
of slowing down the over all routing operation.       their communication to be secure. As current
In [22] DSDV perform well for fairly static
                                                      mobile ad-hoc networks do not have any stick
topologies but become unreliable as node
                                                      security policy, this could possibly lead active
mobility and the number of traffic sources
                                                      attackers to easily exploit or possibly disable the
increase. Besides number of disadvantages, loop
                                                      mobile ad-hoc network. Security goals in mobile
free routing is considered to be one of the main      ad-hoc     networks are         reached    through
benefits of DSDV. In DSDV Optimal values for          cryptographic mechanisms such as public key
parameters like settling time is not easy to
                                                      encryption or digital signature. These
determine. This might result in unnecessary
                                                      mechanisms are backed by centralized key
bandwidth consumption. Moreover, use of
                                                      management where a trusted Certificate
continuous updates could trigger network
                                                      Authority (CA) provides public key certificate to
overhead. Further more the protocol is not            mobile nodes in order to develop mutual trust
capable of supporting multicast routing. The size     between nodes. Any disturbance with the
of the routing table is also a problem as all nodes
                                                      Certificate Authority can easily affect the
are required to maintain location information of
                                                      security of the entire network.
the other nodes in the network, regardless
weather or not this information is required.
                                                      Security therefore, is one of the important aspect
                                                      in ad-hoc networking environment[26]. A
Effective support of multicast or group               routing protocol which offers a secure routing
communication is essential for most ad-hoc
                                                      mechanism could be considered as one of the
network applications. There are many
                                                      efficient solution. DSDV however does not
applications[23] where group communication is         address security along with routing. However,
a crucial task. Group communication, both one-        besides number of disadvantages, loop free
to-many and many-to-many, has become
                                                      routing is considered to be one of the main
increasingly important in mobile ad-hoc
                                                      benefits of DSDV
networks. In mobile ad-hoc network group
communications, issues differ from those in
                                                      MAODDP is one of the reactive or on-demand
wired networks because of the variable and            protocol which offers better route utilization,
unpredictable nature of the wireless medium,          faster network coverage by establishing route
where the signal strength and propagation varies
                                                      and delivering data simultaneously same time
with the time and the environment. Moreover,
                                                      one after the other. This approach is very feasible
specially to maximize the battery life of the        would prefer not to cooperate. When nodes do
participating nodes. Unlike other on-demand          cooperate they established the necessary ad-hoc
routing protocols MAODDP reduces the number          structure    that    can     makes      multi-hop
of broadcasted packet by integrating the route       communication possible by allowing traffic flow
discovery and data packets together in a single      from a node to reach those destinations that
packet format i.e. route request and data delivery   would either require a significant amount of
packet (RREQD). Some of the unique features of       transmission energy using single              hop
MAODDP are as follows.                               communication or simply not be possible
      Centralized approached                        without routing the traffic through other nodes.
MAODDP addresses address issues security,            This further means that nodes must be willing to
bandwidth constraints and battery power along        forward traffic for other nodes, and in this way
with the routing mechanism..                         spend energy without receiving any direct
      Security                                      benefit. Thus the concept of introducing measure
MAODDP offer secure routing by introducing its       which can force participation nodes for
own security mechanism.                              collaboration into the architecture of mobile ad-
      Multicasting                                  hoc networks becomes one of the important
MAODDP support both types of routing i.e.            issues.
unicast and multicast routing figure 3.              Unlike most of the existing routing solution
                                                     MAODDP address this issue by introducing its
                                                     own unique mechanism to identify „selfish‟
                                                     nodes and thus could be used to make network
                                                     more reliable and secure.

                                                     6. Conclusion and future work

                                                     In this paper, we have presented a study based
                                                     comparison of destination sequence distance
                                                     vector routing and mobile ad hoc on demand
  Figure3 Multicasting in mobile ad-hoc              data delivery protocol. We highlighted different
                network                              aspects of these two techniques and presented a
                                                     brief description of their applicability,
      Battery power                                 operational details, suitability under different
MAODDP does not require mobile nodes to be           environments and their effects on the over all
awake all the time. A node can go into sleep         network performance. Our future work extends
mode if it is not involved in an active              this study based comparison into a simulation
transmission. Thus save considerable battery         based comparison which will be contributed to
power of the mobile nodes.                           research community as a part of ongoing effort
                                                     in this area.
        Automatic mechanism to find out if the
         transmission being failed                   7. References
MAODDP introduces a status time in the packet
header of RREQD to find out the status of the
previous transmission i.e. if the node does not      [1].    Humayun       Bakht,     Bluetooth    a
receive an acknowledge message before the                    commercial application of mobile ad
expiry of status time (st) it will regard the                hoc     networks,     in     Computing
previous transmission as unsuccessful.                       Unplugged. November 2004. p. 2.
                                                     [2].    Humayun Bakht, et al. Multicasting in
        Systematic procedure for corroboration              mobile ad hoc networks. in 9th CDMA
         of mobile devices                                   International    Conference.      25-28
In mobile ad-hoc networks each nodes relies on               October 2004. Seoul , Korea.
others to forward data packets to the other nodes    [3].    Humayun Bakht, Internet Mobile Ad
in the network. There are good numbers of                    hoc     networks,     in     Computing
reasons why mobile nodes in ad-hoc networks                  Unplugged. April 2005. p. 2.
[4].    Humayun Bakht, Understanding mobile               Symposium      on    Computers       and
        ad hoc network, in Computing                      Communications (ISCC'2004),. June
        Unplugged. June 2004. p. 2.                       29--July 1, 2004. Alexandria, Egypt.
[5].    Humayun Bakht, Madjid Merabti, and        [16].   H. Rangarajan and J.J. Garcia-Luna-
        Robert Askwith. A routing protocol for            Aceves. Using Labeled Paths for Loop-
        mobile ad hoc networks. in 1st                    free On-Demand Routing in Ad Hoc
        International Computer Engineering                Networks. in ACM MobiHoc 2004. May
        Conference. 27-30 December. Cairo ,               24--26, 2004. Tokyo, Japan.
        Egypt.                                    [17].   Samir R. Das, Charles E. Perkins, and
[6].    Humayun Bakht, Some applications of               Elizabeth M. Royer, On demand
        mobile      ad-hoc      network,     in           multipath routing for mobile ad hoc
        ComputingUnplugged. September 2004.               networks. Proceedings of the IEEE
        p. 1.                                             International Conference on Computer
[7].    Humayun Bakht, Sensor networks and                Communication and Networks, 1999.
        ad hoc networking, in Computing           [18].   S.Kannan, John E Mellor, and
        Unplugged. Oct 2004. p. 1.                        D.D.Kouvatsos, Investigation of routing
[8].    Humayun Bakht, Future of mobile ad                in DSDV. 4th Annual Post-Graduate
        hoc     networks,     in     Computing            Symposium on the Convergence of
        Unplugged. October 2004. p. 1.                    Telecommunications, Networking and
[9].    Humayun Bakht, Madjid Merabti, and                Broadcasting, Liverpool UK, 2003.
        Robert Askwith. Centralized frame for     [19].   C. E. Perkins and P. Bhagwat, Highly
        routing in mobile ad-hoc networks. in             dynamic           destination-sequenced
        International Conference on Computer              distance-vector routing (DSDV) for
        Communication              (ICCC2004).            mobile       computers.        Computer
        September, 2004. Beijing, China.                  Communications Review, 94. 24(4): p.
[10].   David B. Jhonson, Routing in Ad-Hoc               234- 244.
        Networks of Mobile Hosts. Proceedings     [20].   Humayun Bakht, Madjid Merabti, and
        of the IEEE Workshop on Mobile                    Robert Askwith. Mobile Adhoc On-
        Computing Systems and Applications,               Demand Data Delivery Protocol. in
        Dec. 1994.                                        Proceedings of the 3rd Annual Post-
[11].   Humayun Bakht, Data Communication                 Graduate      Symposium        on     the
        in mobile ad-hoc networks, in                     Convergence of Telecommunications,
        Computing Unplugged. September                    Networking and Broadcasting,. 2002.
        2004. p. 2.                               [21].   Humayun Bakht, Madjid Merabti, and
[12].   G. Pei, M. Gerla, and T.-W. Chen,                 Robert Askwith. Centralized frame for
        Fisheye State Routing in Mobile Ad Hoc            routing in mobile ad-hoc networks. in
        Networks. Proceedings of Workshop on              International Conference on Computer
        Wireless Networks        and     Mobile           Communication              (ICCC2004).
        Computing, 2000.                                  September, 2004. Beijing, China.
[13].   Charles E. Perkins and Elizabeth M.       [22].   Josh Broch, et al., A performance
        Royer, Ad-hoc On-Demand Distance                  Comparsion of Multi-Hop Wireless Ad
        Vector Routing. Proceedings of the 2nd            Hoc Network Routing Protocols. Fourth
        IEEE Workshop on Mobile Computing                 Annual      ACM/IEEE        International
        Systems and Applications, February                Conference on Mobile Computing and
        1999: p. pp. 90-100.                              Networking (MobiCom '98), 1998.
[14].   M. Mosko and J.J. Garcia-Luna-            [23].   Humayun            Bakht,         Group
        Aceves. Performance of Group                      communications in mobile ad hoc
        Communications        over      Ad-Hoc            networks, in Computing Unplugged.
        Networks. in The Seventh IEEE                     November 2004. p. 1.
        Symposium      on    Computers     and    [24].   Humayun Bakht, Importance of secure
        Communications (ISCC 02),. July 1 - 4,            routing in mobile ad hoc networks, in
        2002. Taormina/Giardini Naxos, Italy,.            Computing Unplugged. August 2004. p.
[15].   H. Rangarajan and J.J. Garcia-Luna-               2.
        Aceves.       Achieving      Loop-Free    [25].   Humayun Bakht Bakht, Technical
        Incremental Routing in Ad Hoc                     aspects of mobile ad-hoc networks, in
        Networks. in Proc. 9th IEEE                       Computing Unplugged. June 2004. p. 2.
[26].   Humayun Bakht, A focus on the
        challenges of mobile ad hoc network, in
        Computing Unplugged. August 2004. p.