Optimized Multicasting System to Evade Packet Loss in Mobile Adhoc Networks M.Murali and S.Vijayalakshmi Keywords : MANET’s, EGMP

7/31/2019 Optimized Multicasting System to Evade Packet Loss in Mobile Adhoc Networks M.Murali and S.Vijayalakshmi Key

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Journal of Computer Applications (JCA)

ISSN: 0974-1925, Volume V, Issue 3, 2012

78

Abstract - Group communication takes up an imperative

role in MANETs. Multicasting provides this technique

in small scale networks Group Membership

management is a tough task in dynamic topology. To

conquer the problem we suggest a protocol Efficient

Geographic Multicasting Protocol (EGMP). EGMP uses

virtual two-tier zone based structure for making the

membership management and packet delivery ratio an

efficient one. It uses bi-directional tree structure for

multicast packet delivery. The position information is

used to guide the zone structure edifice, multicast tree

construction, and multicast packet forwarding, which

resourcefully reduces the overhead for route searchingand tree structure maintenance. Finally, we design a

scheme to handle empty zone problem faced by most

routing protocols using a zone structure. The projected

architecture reduces the packet loss and gives the higher

delivery ratio. EGMP has widely lower header size and

it increases the data transmission rate over a large scale

network.

Index Terms MANETs, EGMP.

I. INTRODUCTIONEfficient support of group communication is critical for

most ad hoc network applications. However, MANET group

communications issues differ from those in wired

environments for the following reasons: The wireless

communication medium has variable and unpredictable

characteristics and the signal strength and propagation

fluctuate with respect to time and environment. Further,

node mobility creates a continuously changing

communication topology in which routing paths break and

new ones form dynamically.

A high share of applications running on the current Internet

is based on the client-server paradigm, the World Wide Web

being the most popular example. Group-CommunicationApplications (GCA) such as Instant Messaging and

Distributed Games are increasingly diffused, and take a

completely different communication pattern. In GCA, a

group of users want to communicate with each other, instead

of issuing requests to a central server.

Manuscript received 20/July/2012.

Manuscript selected 14/Aug/2012.

M.Murali, Assistant Professor, Department of Information Technology,

Sona College of Technology, Salem, India,

E-mail: [email protected].

S.Vijayalakshmi, Department of Electronics and CommunicationEngineering, Sona College of Technology, Salem, India,

E-mail: [email protected].

Even though some GCA implementations on the legacy

Internet use client/server transactions (e.g., Instant

Messaging typically uses central servers to detect user

presence and availability), the eventual communication

pattern among GCA users is more similar to P2P than to

client/server systems. MANETs can be established without

any pre-existing infrastructure. This makes plausible to run

GCA completely on-demand, as soon as a group of users

decide that they want to communicate. Based on these

remarks, we believe that Group Communication

Applications is an exciting field to be explored to identify

valuable applications for MANET users.

II.EGMP OVERVIEWA. Related Work

Conventional topology-based multicast protocol comprises

tree-based protocols (Eg.., [1]-[3]) and mesh-based

protocols (Eg.., [4], [6]).In tree-based protocol a tree is

constructed for the entire group to forward the packets.

Mesh- based protocols in turn enlarges the multicast tree

with additional paths to make it more efficient. Even

supposing we built multicast tree it is not competent for

large scale of network. EGMP instead uses location aware

approach for efficient packet forwarding and scalable forboth large size and small size network. In SPBM [5], the

network terrain is divided into quad tree with L levels. The

top level is the whole network and the bottom level is

constructed by basic squares. In [7], we proposed efficient

and robust geographic multicast protocol for MANET. We

introduce zone-supported geographic forwarding to reduce

a routing failure and provide mechanism to handle zone

partitioning. We further introduce a path optimization

process to handle multiple paths packet delivery.

B. Proposed System

We propose an efficient geographic multicast protocol(EGMP).It uses a hierarchical structure to implement

scalable and efficient group membership management. We

design a scheme to build and maintain the intrazone and

interzone topology for supporting scalable and efficient

multicast forwarding. We make use of the position

information to implement hierarchical group membership

management, and combine location service with the

hierarchical membership management to avoid

network-range location searches for the group members,

which is scalable and efficiently. With nodes self-organizing

into zones, a zone-based bi-directional tree is built in

MANET environment. We introduce an important concept

zone depth, which reflects the relationship between amember zone and the zone where the root of the tree exists.

We also design a scheme to handle the empty zone problem,

a challenging problem in designing a zone-based protocol.

Optimized Multicasting System to Evade

Packet Loss in Mobile Adhoc Networks

M.Murali a,*, S.Vijayalakshmi b, 1


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Optimized Multicasting System to Evade Packet Loss in Mobile Adhoc Networks

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Our analysis results indicate that the cost of the protocol

defined as the per-node control overhead remains constant

regardless of the network size and the group size. Our

simulation studies confirm the scalability and efficiency of

the proposed protocol.

C. EGMP Overview

EGMP Overview EGMP provides consistent and scalable

membership management and packet forwarding through avirtual two-tier zone based architecture. At the lower level

with reference to a virtual origin nodes are self-organized

themselves into a set of zones and a leader is nominated to

manage a local group membership. At the upper level a

leader is responsible for a node to join or leave a multicast

group. A local information will be integrated in a design to

built a efficient zone based multicast tree. EGMP supports

bi-directional multicast packet forwarding along the tree

structure. At the upper layer, the multicast packets will

forward both upstream to the root zone and downstream to

the leaf zones of the tree. At the lower layer, when a zone

leader receives the packets, it will send them to the group

members in its local zone. There are many issues that need

to be concentrate on EGMP to make it more efficient and

scalable. The issues related to zone management are zone

construction, maintenance, zone leader selection with

minimum overhead and potential packet loss when a group

members move across a zones. The issues related to packet

forwarding are efficient multicast path selection, handling of

empty zone problem and tree maintenance during mobility

[8].

D. Terms in EGMP

Zone: The network terrain is divided into square zones.

r: Zone size, the length of a side of the zone square. Thezone size is set to r. rt=p2, where rtis the transmission range

of the mobile nodes. To reduce intra-zone management

overhead, the intra-zone nodes can communicate directly

with each other without the need of any intermediate relays.

Zone ID: The identification of a zone. A node can calculate

its zone ID (a, b) from its position coordinates (x, y) as: a =[

xx0r], b = [ yy0r], where (x0; y0) is the position of the

virtual origin, which can be a known reference location or

determined at network setup time. A zone IDs are always

positive.

Zone center: For a zone with ID (a,b), the position of its

center (xc; yc) can be calculated as:xc =x0 + (a+ 0:5) r,yc

= y0 + (b + 0:5) r. A packet destined to a zone will beforwarded towards the center of the zone.

zLdr: Zone leader. A zLdr is elected in each zone for

managing the local zone group membership and taking part

in the upper tier multicast routing.

Tree zone: The zones on the multicast tree. The tree zones

are responsible for the multicast packet forwarding. A tree

zone may have group members or just help forward the

multicast packets for zones with members.

Root zone: The zone where the root of the multicast tree is

located.

Zone depth: The depth of a zone is used to reflect its

distance to the root zone. For a zone with ID (a; b), its depth

is:

depth = max(ja0 aj; jb0 bj);

where (a0; b0) is the root-zone ID. the root zone has depth

zero, the eight zones immediatelysurrounding the root zone

have depth one, and the outer sevenzones have depth two.

Figure 1. Zone structure and multicast session example

With the introduction of virtual zone, EGMP does not need

to track individual node movement but only needs to track

the membership change of zones, which significantly

reduces the management overhead and increases the

robustness of the proposed multicast protocol.

E. Neighbor Table Generation and Zone Leader

Election

Each node periodically sends a BEACON message to

distribute its position to aid leader election and reduce

overhead. EGMP simply insert a flag in a BEACON

message to identify a zone leader. To reduce BEACONoverhead, instead of broadcasting message in a fixed

interval, EGMP follows adaptive time interval. A

non-leader node will send a BEACON message for every

period of intvalmax and when a node moves to other zone. A

leader node has to send a message for every period of

intvalmin to broadcast its leadership role. When a node

receives a BEACON message, it records a nodeID, position

and flag to its neighbor table. When a node enters a zone it

broadcast a BEACON message to announce its existence. It

wait for Intvalmax to receive a BEACON message from other

nodes. For every period of Intvalmin it checks its neighbor

table and determine its leader in four different cases:1)Theneighbor table contains no other nodes in the same zone, it

will announce itself as the leader.2) If the node is closer to

the zone center than other nodes, it will announce its

leadership role through a beacon message with the leader

flag set.3)More than one node in the same zone have theirleader flags set, the one with the highest node ID is

elected.4) Only one of the nodes in the zone has its flag set,

then the node with the flag set is the leader.

F. Multicast Tree Construction

EGMP, instead of connecting each group member directly

to the tree, the tree is formed in the granularity of zone withthe guidance of location information, which significantly

reduces the tree management overhead. With a destination

location, a control message can be transmitted immediately

without incurring a high overhead and delay to find the path


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Journal of Computer Applications (JCA)

ISSN: 0974-1925, Volume V, Issue 3, 2012

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first, which enables quick group joining and leaving. Using

Zone depth concept the multicast tree has been built

efficiently. The optimized path is selected to deliver a

packet efficiently.

When a node M wants to join the multicast group G, if it is

not a leader node, it sends a JOIN REQ (M; PosM; G;

fMoldg) message to its zLdr, carrying its address, position,

and group to join. The address of the old group leaderMold

is an option used when there is a leader handoff and a new

leader sends an updated JOIN REQ message to its upstream

zone. If M did not receive the NEW SESSION message or it

just joined the network, it can search for the available groups

by queryin its neighbors. If a zLdr receives a JOIN REQ

message or wants to join G itself, it begins the leader joining

procedure. If the JOIN REQ message is received from a

member M of the same zone, the zLdr adds M to the

downstream node list of its multicast table.

nodeID position flag zoneID

1 (x1,y1) 1 (1,2)

10 (x10,y10) 0 (1,1)

3 (x3,y3) 1 (2,1)

13 (x13,y13) 1 (2,2)

Figure 2. The Neighbour table of Node 16 in Fig.1

When a member M wants to leave G, it sends a LEAVE (M;

G) message to its zone leader. On receiving a LEAVE

message, the leader removes the source of the LEAVE

message from its downstream node list or zone list

depending on whether the message is sent from an intra-zone

node or a downstream zone.

Figure 3. Node Leader Sending BEACON Message

G. Empty Zone Problem

A zone may become empty when all the nodes move away.

The probability that a zone is empty is approximately P

=er2 when the node density is and the zone size is r.

Assume r= 150m, which is the zone size that allows all the

nodes in the same zone to be within the transmission range,

the probability of the zone being empty is: P = 0:207 ifd=

70nodes=km2, and P = 0:509 ifd= 30nodes=km2. We can

see that the probability of a zone becoming empty is notnegligible and it is critical to address the empty zone

problem. In EGMP, if a tree zone becomes empty, the

multicast tree will be adjusted correspondingly to keep the

multicast tree connected. When a leader is moving away

from a non-root tree-zone and the zone is becoming empty,

it will send its multicast table to its upstream zone. The

upstream zone leaders will then take over all its downstream

zones, and delete this requesting zone from its downstream

zonelist. The new upstream zone needs to send JOIN

REPLY messages to all the newly added downstream zones

to notify them the change. When receiving the JOIN REPLYmessages, these downstream zones will change their

upstream zone ID accordingly

III. PERFORMANCEEVALUATIONThe simulations were run with 400 nodes randomly

distributed in an area of 2400m 2400m. The nodes moved

following the modified random waypoint mobility model.

The moving speed of nodes are uniformly set between the

minimum and maximum speed values which are set as as 1

m/s (with pause time as 100 seconds) and 20 m/s

respectively except when studying the effect of mobility.

IEEE 802.11b was used as the MAC layer protocol. Each

simulation lasted 500 simulation seconds. Each source sends

CBR data packets at 8 Kbps with packet length 512 bytes.

The CBR flows start at around 30 second so that the group

membership management has time to initialize and stop at

480 second. By default, there is one source, and one

multicast group with 100 members. A simulation result was

gained by averaging over six runs with different seeds.

Figure 4. Time Delay Vs Packet Size

Figure 5. Packet Delivery Ratio Vs Node Density


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IV. CONCLUSIONThere is an increasing demand and a big challenge to design

more scalable and reliable multicast protocol over a

dynamic Ad hoc network (MANET). In this paper, we

propose an efficient and scalable geographic multicast

protocol, EGMP, for MANET. The scalability of EGMP is

achieved through a two-tier virtual-zone-based structure,

which takes advantage of the geometric information togreatly simplify the zone management and packet

forwarding. Compared to conventional topology based

multicast protocols; the use of location information in

EGMP significantly reduces the tree construction and

maintenance overhead, and enables quicker tree structure

adaptation to the network topology change. We also develop

a scheme to handle the empty zone problem, which is

challenging for the zone-based protocols. Our results

indicate that geometric information can be used to more

efficiently construct and maintain multicast structure, and to

achieve more scalable and reliable multicast transmissions

in the presence of constant topology change of MANET.

Our simulation results demonstrate that EGMP has high

packet delivery ratio, and low control overhead and

multicast group joining delay under all cases studied, and is

scalable to both the group size and the network.

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[4] C.-C. Chiang, M. Gerla, and L. Zhang. Forwarding group multicastprotocol (FGMP) for multihop mobile wireless

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Ad-hoc Networks

[6] M. Gerla, S. J. Lee, and W. Su. On-demand multicast routingprotocol (ODMRP) for ad hoc networks.

[7] X. Xiang and X. Wang. An Efficient Geographic Multicast Protocolfor Mobile Ad Hoc Networks, Buffalo,Newyork,2006

[8] M.Saravanakarthikeyan, M.Murali and Dr.S.sujatha IdentifyingPerformance Metrics To Maximize Manets Throughput, ACE, 2010,

IEEE, pp. 357-359

BIOGRAPHY

M.Murali is working as Assistant Professor inDepartment of Information Technology at Sona

College of Technology, Salem, Tamilnadu, India for

the past two years. He received M.E degree in

Pervasive Computing Technologies from Anna

University, Trichy, Tamilnadu, India and B.E degree

in Computer science and Engineering from Kongu

Engg College, Erode affiliated to Anna University,

Chennai, Tamilnadu, India. He is a member of IAENG, IACSIT and IAOE.

S.Vijayalakshmi Research Scholar, Anna

University, Coimbatore, Tamilnadu, India working

as Assistant Professor in Department of Electronics

and Communication Engineering at Sona College of

Technology, Salem, Tamilnadu, India for the past

five years. She received M.E degree in

Communication Systems from Anna University,

Chennai, Tamilnadu, India and B.E degree in Electronics and

Communication Engineering from Sona College of Technology affiliated

to Anna University, Chennai, Tamilnadu, India.

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Optimized Multicasting System to Evade Packet Loss in Mobile Adhoc Networks M.Murali and S.Vijayalakshmi Keywords : MANET’s, EGMP