ABSTRACT
The wireless communication revolution bought drastic changes to data networking,
telecommunication. Before wireless networks Ethernet cable was used to physically connect the
computer to a network. In this project we are create four networks and analyse the
communication between the networks. Wireless networks are used all around us. With the advent
of cellular phones in the last two decades this field grew exponentially.
To design these networks and sub networks Qualnet software is used. This reduces the effective
cost of the system and increases reliability. By using Qualnet we are able to simulate the system
to reduce and eliminate this interference as downside of wireless networks is that it may interfere
with other wireless systems and this might cause loss of data. In this project, we are designing
and simulating two scenarios followed by some brief discussion and there results.
INTRODUCTION
Firstly we need to create four wireless sub networks with 5 nodes each. All the nodes located in the each
sub network should be able to hear their neighbors or each others transmissions as they were connected to
a Hop. Routers are used to communicate two networks and three routers are placed in between the Sub
networks. Each and every node is assigned with an IP address. So it is possible to have both
connectionless and connection oriented services through the networks.
In this project we mainly discuss two scenarios in which one is mentioned above and the other is
creating multiple UDP connections and comparing the results with fading and without fading
effect.
SCENARIO A
In this scenario we need to generate two connections in the network, one UDP and the other is
TCP, and have to choose the source and destination nodes for each connection in different sub
networks.
Wireless sub network
IP Address of the sub
network
Sub network 1
190.0.1.0
Sub network 2
190.0.2.0
Sub network 3
190.0.3.0
Sub network 4
190.0.4.0
Table1: Sub networks and their IP addresses
Total number of
nodes
5
5
5
6
Nodes assigned to
sub network
1,2,3,4,5
7,8,9,10,11
13,14,15,16,17
19,20,21,22,23,24
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Router node number
6
12
18
Sub network
Sub networks A and B
Sub networks B and C
Sub networks C and D
Table2: Routers and their interfaces
Figure: interconnection among networks, routers and hops.
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So with the help of the above configuration designed, establish two types of connections in
different networks. The following are the connections
UDP
----
Source node:24
----
destination node : 17
TCP
----
Source node:1
----
destination node : 7
Properties of UDP connection:
Parameters selected for the UDP connection
Property
Start Time Distribution
Mean start time
Duration Distribution
Mean Duration
Packet size distribution
Packet size in bytes
Packet interval distribution
Mean Packet Interval
Packet generation probability
Details
Exponential
0.5 seconds
Deterministic
30 sec
Exponential
2048 bytes
Exponential
0.5
1
Table3: Configuration of UDP
Properties of TCP connection:
Parameters selected for the TCP connection
Property
Details
No. of data items
100
Start time
1second
Table4: Configurations of TCP connection
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Figure: communication with in the network and data transfer in TCP and UDP
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Figures: Traffic generation client and server Bar charts--UDP
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From the above bar charts it is very clear that that the data units sent by the source in the UDP
connection protocol is 84units and the received data units at the destination node is 84 units as
well in which there is no loss of data during the communication process. So scenario we
configured and the efficiency of the designed wireless system is good as there is no loss during
the data transmission.
Figures: File Transfer Protocol server and client Bar charts--TCP
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From the above graph of TCP communication protocol it can be observed that total number of
bytes generated are not equal to total bytes received at the destination, So there is a loss of bytes.
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Figures: UDP—Packets from and to Application layer
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Figures: TCP—Data packets sent, received and retransmitted
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Figures of MAC layer: RTS packet sent, CTS packet sent, ACK packet sent
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Figures: MAC layer: Packet drops due to retransmission, Unicast packet sent and received
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MAC Layer
Node 5
Node 6
Node 15
Node 17
RTS packets sent
25
0
44
0
CTS packets sent
23
22
ACK packets sent
0
22
0
17
Packets drop due to
retransmission limit
Unicast Packet sent to
channel
Unicast Packet received
0
0
1
0
21
0
13
0
0
21
0
13
Table5: Data Transmission and receiving of packets in MAC Layer
SCENARIO B
In this scenario we arrange multiple UDP connections in the network with source and destination
nodes in different sub networks, assuming that time interval between packet generation is
exponential and packet lengths are also exponential and Keeping average value of the packet
lengths constant during the simulation as each connection should generate at least 500packets.
In this scenario we vary the intervals for each and every simulation run. The result of variations
in time interval results in following graphs. This scenario is comparison of with fading and
without fading effect.
Figures: comparison of with and without fading effect with varied intervals.
Server
Chart Title
60000
50000
40000
30000
20000
10000
0
0.5
1
1.5
2
2.5
without fading
3
3.5
4
4.5
5
with fading
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Client
45000
Chart Title
40000
35000
30000
25000
20000
15000
10000
5000
0
0.5
1
1.5
2
2.5
without fading
3
3.5
4
with fading
4.5
5
with fading
Average End to End
Chart Title
0.016
0.014
0.012
0.01
0.008
0.006
0.004
0.002
0
0.5
1
1.5
2
without fading
2.5
3
3.5
with fading
4
4.5
5
with fading
The time interval between the generation of packets increases the traffic load of a node
decreases. As a result there is decrease in average packet delay with increasing value of packet
interval. However different factors affect the average packet delay; one of them is the actual
queue size in the router buffer. So with increasing packet interval, the average packet delay
sometimes increases sharply and sometimes decreases sharply. Overall the Average packet delay
decreases with increasing value of packet interval. The curves of UDP avg. packet delay are
depicting the same thing. As we look at various values in the graph we see that as the packet
interval goes on increasing UDP client throughput and UDP server throughput goes on
decreasing as the packet interval goes on increasing, because as packet interval is increased
packet generation becomes less thus decreasing the throughput.
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CONCLUSION
From our simulation results, we conclude that, , the best performance can be obtained using
small packet intervals at a rather high transmission rate, when the real-time applications use UDP
as a transport protocol.
In case of TCP as the packet interval is increased client Throughput and server throughput the
values increase, because as the time interval between the generation of packets increases the
traffic load of a node decrease thus decreasing the congestion.
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