IMPLEMENTING PACKET BROADCASTING ALGORITHM OF MIMO BASED MOBILE AD-HOC NETWORKS TO EXPLOIT DIVERSITY

International Journal of Network Security & Its Applications (IJNSA), Vol.6, No.2, March 2014
DOI : 10.5121/ijnsa.2014.6203 33
IMPLEMENTING PACKET BROADCASTING
ALGORITHM OF MIMO BASED MOBILE AD-HOC
NETWORKS TO EXPLOIT DIVERSITY
Swati Chowdhuri1
, Santanu Maiti2
, Dr. Sheli Sinha Chaudhuri3
and Dr.
P.K.Baneerjee4
1,2
Asst.Professor, ECE, Seacom Engineering College, Howrah-711302
3
Associate Professor, ETCE, Jadavpur University, kolkata-700032
4
Professor, ETCE, Jadavpur University, kolkata-700032
ABSTRACT
With the rapid growth of wireless communication infras,,tructure over the recent few years, new
challenges has been posed on the system and analysis on wireless adhoc networking. Implementation of
MIMO communication in such type of network is enhancing the packet transmission capabilities. There
are different techniques for cooperative transmission and broadcasting packet in MIMO equipped
Mobile Adhoc Network. We have employed a model network in the OPNET environment and propose a
new scheduling algorithm based on investigating the different broadcasting algorithm. The new
broadcasting algorithm improves the packet transmission rate of the network based on energy
performance of the network and minimizes the BER for different transmission mode which is illustrated
in this paper. The simulations are done in MATLAB and OPNET environment and the simulated result
for the packet transmission rate are collected and shown in the tabular form. Also simulate the network
for generating a comparative statement for each mobile node. And performance analysis is also done for
the model network. The main focus is to minimize BER and improve information efficiency of the
network.
KEYWORDS
Multi Input Multi Output (MIMO), adhoc network, cooperative transmission, opportunistic large array,
packet broadcast.
1. INTRODUCTION
The major elements for successful implementation of MIMO communication systems are
coding and signal processing. The signal transmission technique using multiple antennas at the
two sides of a communication links has a great potential to significantly improve the
transmission efficiency of the wireless communication system without the need for extra
operational frequency bandwidth [1,2,3]. To improve the spectral efficiency, MIMO antenna
elements are integrated to the transmitting and receiving links of the communication systems.
Multiple antenna elements with associated signal processing algorithm have to be implemented
at mobile nodes. A new scheduling algorithm is discussed which is related with the firing of the
network nodes. These changes the energy of the network i.e. transmission efficiency of the
network by discussing Energy-Performance Metric (EPM). Packet transmission is an important
parameter of the considering network which is depends on minimization of BER and improve
packet transmission rate. In this chapter we have implemented the packet broadcasting
algorithm of MIMO based Mobile adhoc network for exploiting diversity. In Mobile adhoc

34
network, conventional flooding broadcast mechanism has some limitation. We have
implemented a physical layer technique that is cooperative transmission which is a much more
efficient method than traditional flooding broadcast [3,4]. This new technique allows
transmission collectively i.e. not to be capable to forward the data individually from a set of
asynchronous transmitter to a remote destination. The multiple transmitter acts as an antenna
array-an Opportunistic Large Array, or OLA – to transmit the message from set of
asynchronous transmitter to remote destination. The transmission algorithm is designed in such
a manner to exploit the diversity and improve the Network Utility Function (NUF).
2. COOPERATIVE TRANSMISSION MECHANISM
Cooperative transmission (CT) mechanism is based on resource sharing method. Here two or
more node cooperates to transmit the same message as a result two or more single antenna
transmitters achieve the benefits of an array transmitter [5,6]. The key idea in user-cooperation
is that of resource-sharing among multiple nodes in a network. The main motive of exploration
of user-cooperation is that to share power and computation with neighboring nodes can lead to
save the overall network resources. Conventional flooding mechanism has some limitation due
to installation cost of multiple antennas on the terminals, additional processing time and the
coherence distance between the transmitting and receiving antennas. To minimize processing
time and coherence distance long range communication is simply impossible. A single long
range link with a chain is replace by a number of short range links by placing a series of nodes
in between the source and destination [7,8]. In the Mobile adhoc network, cooperative
transmission is about exploiting the broadcasting nature by transforming single-antenna
terminals into a virtual antenna array. Thus, the multiple signals are transmitted from source to
destination terminals through different uncorrelated channels using Relay terminal provide
benefits of spatial diversity. An example of single-relay cooperative scenarios is shown in
Figure 1. Source terminal (S) transmits a signal to the destination terminal (D) through two
paths for overhear the signal. One is direct path (S-D) and other one is via the relay terminal R.
When Relay terminal (R) is in a cooperative mode, it forwards the source message to the
destination D. As a result D receives two signals: the original one transmitted from S through
the direct path (S-D) and the relayed one forwarded by R through the relayed path (S-R-D).
These two received signals are combined at the destination terminal to achieve a better spatial
diversity compared to the receive signal achieved with a single direct path.
Figure 1: Example of Cooperative Transmission
The main cooperation is done by intermediate nodes of the network along the data transmission
route for the multi-hop networks. A single relay terminal or a set of relay terminals helps on
data relaying from a previous terminal (source terminal) to a next-hop terminal (destination
terminal)[9,10]. Spatial diversity is the main advantage provided by cooperative

35
communications. This property can be expressed in terms of increased diversity order. The
Amplify-and-Forward (AF) scheme is a cooperative transmission scheme.
3. ALGORITHMS FOR COOPERATIVE TRANSMISSION
To exploit the multiuser diversity and traffic demand for channel condition an integrated
scheduling scheme is proposed here. This scheduling algorithm takes the advantages of the
random topology of MIMO based adhoc networks. A group of nodes forming a mesh network
take the advantages of cooperative transmission; the sender node can transmit multiple data to
downstream nodes or receiving nodes, while a receiver can receive packets from upstream node
or transmitting nodes. The data scheduling schemes used here operate in cross layers and with
the consideration of physical channel condition and service requirement of the user traffic. The
scheduling requests can be categorized as centralized scheduling, hierarchical scheduling and
decentralized scheduling based on their system architecture. In centralized scheduling, central
scheduler collects the information of network resources. In Hierarchical system different
scheduling policy is used for local and global scheduling, and this does not depends on the
single scheduler. In decentralized scheduling the distributed schedulers interact with each other
and schedule jobs at remote nodes for execution. Local schedulers can submit jobs to the
receiver or receive from transmitter through direct communication or a central job pool. In the
simulation environment we use centralized scheduling algorithm.
In this algorithm the scheduling time depends on the processing time of the nodes of the
network and firing time of the node. Data to network bandwidth consists of information about
the requirement on the resource that is necessary to execute a particular job firing for the node
in the network environment. The congestion control process decides which packets to be
injected for transmission. The next packet to be transmitted is determined by the job-scheduling
algorithm. Mobile adhoc scheduling algorithms are responsible for firing of the network nodes
as well as the job scheduling process. Scheduling requests for firing node can be controlled by
Network Utility Maximization (NUM) which is defined as
( )
f
f X
U
Max∑
subject to
( )
∑ ≤ e
f C
X where e
S
f ∈
where e
C be the capacity of the server, e
S be the set of flows passing through the server and
f
X be the current injection rate into flow f. ()
.
f
U is defined as the utility function. Network
utility function represents the network efficiency by the given packet transmission rate and
Energy Performance Metric (EPM) [16]. Joint Energy Performance Metric (EPM) for mobile
adhoc networks explain the characteristics of the routing protocols for both performance and
energy consumption. A good metric will capture the average behavior of a system, as common-
case events determine the total utilization of a network. A family of energy-performance
metrics is defined in our proposed scheduling method using the following equations:
( ) ( )( )α
α ⋅
= formance
Averageper
rgy
Averageene
EPM
where α is a parameter that determines the weighting between energy and performance [11,12].
We first measure the energy and performance metric of the MIMO based Mobile adhoc
network to evaluate the algorithm. The average energy of a network is simply the total network
energy over the number of nodes. Measuring average network performance of an adhoc
network is more difficult. We choose to measure the average performance of a network based

36
on its ability to successfully deliver packets. The transmission efficiency is defined as the ratio
of Network packet received to Network packet transmitted. Now substituting these definitions
into the prior definition of EPM (α) we get,
( )=
α
EPM (Network energy per node) (Transmission efficiency)- α
( )=
α
EPM (Network energy/ node) (Network packet transmitted/network packet received)- α
The choice of α is more important and difficult to get suitable EPM metric (the unit of
energy). At ( )
0
EPM the metric reduces to a pure energy metric and for ( )
∞
EPM the metric is
a pure performance metric. The main goal is to use a metric with a value somewhere in
between these extremes. We will initially assume the value of α to be one and show empirically
that this is a reasonable metric parameter for adhoc network routing protocols.
Cooperative Transmission is summarized as follows:
• Downstream transmission: Sender node transmit
Upstream Transmission: Receiver node receive
• Considering Scheduling algorithm as centralized, based on physical channel condition
of the network and network traffic
• Node firing is related with the processing time which is determined by scheduling
algorithm for Network Utility Maximization (NUM)
• Network Utility Function (NUF) depends on Packet transmission rate and Energy
Performance Metric (EPM).
• EPM depends on parameter α,
α=0, Pure energy metric
α=1, Pure performance metric.
4. SIMULATION MODEL AND RESULTS
We have a randomly deployed adhoc network with 40 number of nodes in the area of 10,000
(100*100) sqft in the OPNET environment. The model is devised to operate the nodes in
AODV protocol based on IEEE 802.11b distribution coordination function (DCF). The
deployed network is shown in Figure 2.
Figure 2: Randomly distributed MANET (deployed network)

37
The selected network environment is shown in Table 1.
Table 1:
Node Transmission
Power
.005Watt
Operational Mode 802.11b standard
Data rate 11 Mbps
Adhoc routing protocol AODV
Technology WLAN (adhoc)
As the power consumption is a major factor of the adhoc network we have set the minimum
power for the node. The operating power of each node of the network is set to 5 mWatt. We
have seen that if the power set is less then there is more packet failure with the time, by
considering the different power we have judiciously made the choice of the 5 mWatt power.
4.1 Minimization of Bit Error Rate (BER)
The large-scale natures of the adhoc network consisting of a large number of nodes in dense
deployments naturally encourage the use of distributed arrays of nodes. OLA based broadcast
transmission minimizes Bit Error rate (BER) in different transmission mode (Half duplex, Full
duplex) after considering Maximal Ratio Combining (MRC) non cooperative broadcast. BER at
different transmission mode and BER on OLA performance of the network are shown in Figure
3a and 3b.
Figure 3a: BER vs SNR at different transmission mode

38
Figure 3b: BER on OLA performance
4.2 Packet transmission analysis of the model network
The deployed network in the OPNET environment is shown in Figure 2 is used to measure the
packet transmission rate through simulation. The simulated result shown in Figure 4a, 4b and
4c indicates the processing and transmission of packet with time. Packet transmission with time
is shown in table 2. The performance of different node in terms of their packet created, copied
and destroyed is shown in table 3. A comparative study is made for packet transmission of each
40 nodes of the network in Figure 5. The packet lost for MANET Gateway in the network is
very small or zero. During simulation the supporting devices like application config (node_0)
and profile config (node_43) don’t take direct role regarding packet transmission in the
network. After implementation of the algorithm the simulated results shows time for packet
delivery process and firing of the node. As describe in the algorithm node firing is depends on
the time which is determined the scheduling algorithm. Ethernet delay is calculated based on
processing time of the packet transmission for the node consisting of the network. Firing of
each adhoc node and Ethernet delay is shown in Figure 7 and 8.
Figure 4a: 50% Packet sent

39
Figure 4b: 75% Packet sent
Figure 4c: 100% Packet sent
Packet transmission rate is shown in Table 2.
Table 2:
Packet transmission in percentage Time in sec
50% 45
75% 66
100% 92

40
Packet transmission strategies for the model network are shown in Table 3.
Table 3:

41
Figure 5: Comparative study of packet transmission strategies
Figure 6:Firing of adhoc node
Figure 7: Ethernet Delay for each node in the model Network

42
5. CONCLUSIONS
In this chapter we have implemented a broadcasting algorithm in the MIMO based Mobile
adhoc network. We have analyzed and simulated the deployed network in the OPNET
environment. The simulated result shows that the BER is minimized after considering MRC
(Maximal Ratio Combining) in different transmission mode (Full duplex and Half duplex). The
simulated result also shows a comparative study of packet transmission strategy (Packet
created, Copied and destroyed) of each node of the network. The processing time of the
network which is related with packet delivery process and firing of the node is also evaluated.
The packet transmission rate of the network is increased after implementing the algorithm. This
type of algorithm not only uses to minimize BER but also increases the packet transmission
rate. In the hostile environment where BER is too high, this algorithm is more advantageous to
minimize the BER and increase the packet transmission rate.
6. REFERENCES
[1] Anna Scaglione,, “Opportunistic Large Arrays: Cooperative Transmission in Wireless Multihop
Adhoc Networks to Reach Far Distances,” IEEE Transaction on Signal Processing, Vol.51, No.8, Aug
2003.
[2] Vandana Rohokale, Nandkumar Kulkarni, Horia Cornean, “Cooperative Opportunistic Large Array
Approach for Cognitive Radio Networks” 978-1-4244-6363-3/10/$26.00c 2010 IEEE.
[3] Edoardo S. Biagioni “Algorithms for Communication in Wireless multi-hop adhoc Networks using
Broadcasts in Opportunistic Large Arrays (OLA)”.
[4] Lakshmi Thanayankizil and Mary Ann Ingram, “Reactive Routing For Multi-hop Dynamic Adhoc
Networks Based On Opportunistic Large Arrays,” in Proc. IEEE Military Commun. Conf. (MILCOM),
Oct. 2000, vol. 2, pp. 861-865.
[5]. L. Thanayankizil, A. Kailas, and M. A. Ingram, “A simple cooperative transmission protocol for
Energy efficient broadcasting over multi-hop wireless networks”, KICS/IEEE Journal of
Communications and Networks, vol.10, no.2, pp.213-220, June 2008.
[6]. Lakshmi V. Thanayankizil, Aravind Kailas, Mary Ann Ingram, "Energy- Efficient Strategies for
Cooperative Communications in Wireless Sensor Networks," sensor comm, pp.541-546, 2007
International Conference on Sensor Technologies and Applications (SENSORCOMM 2007), 2007.
[7] Thesis on Cooperative Communications in Adhoc Networks by Wasimon Panichpattanakul.
[8] B.Chen and M.J. Gans, “MIMO communications in adhoc networks.” IEEE transactions on signal
processing, vol 54, no 7, July 2006.
[9] Pei Liu, Zhifeng Tao, Zinan Lin, Elza Erkip, and Shivendra Panwa,” Cooperative Wireless
Communications: A Cross-Layer Approach” IEEE Wireless Communications August 2006.
[10] Edoardo S. Biagioni “Collision Free Broadcasting in Wireless AdHoc Networks using Cooperativ
Diversity”.
[11] A. Nosratinia, T. E. Hunter and A. Hedayat, “Cooperative communication in wireless networks,”
IEEE Communications Magazine, vol. 42, pp. 74-80, Oct. 2004.
[12] S.M. Alamouti. A simple transmit diversity technique for wireless communications. IEEE JSAC,
16(8):14511458, 1998.
Authors:
Swati Chowdhuri: Presently, she is an Asst.Professor of Seacom Engineering College. She
has been completed B.E. in Electronics and communication Engg from Burdwan University
with Honours in the year of 2005 and completed M.Tech in Computer Technology from
Jadavpur University in the year of 2009. Her research interests in the field of “MIMO based
Mobile Ad-hoc networks”.

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