1. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 4, May – June (2013), © IAEME
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INVESTIGATING EFFECTS OF CHANNEL FADING ON ROUTING
PROTOCOLS IN WIRELESS SENSOR NETWORKS
Namrata Atre1
, Anshul Shrotriya2
, Dr. Dhiiraj Nitnawwre3
M.E. Student1
, Asst. Professor2, 3
IET, DAVV University, Khandwa Road, Indore- 452017, (M.P.) India1, 3
Medicaps Institute of Technology and Management, Rau, Indore2
ABSTRACT
Wireless Sensor Networks has emerged as an efficient concept in terms of Ad-hoc
networking, signal processing, embedded systems and many more such applications. The
main reason behind the idea is supposed to be the advancement in VLSI technology, need in
electro-mechanical systems, nano technology and wide spread of wireless communication.
But it is well known that sensors deployed within the WSNs are restricted in terms of battery
lifetime, computational capability and bandwidth. One of the major parameters that play an
important role is routing; thus routing protocols. So, in this paper we have concentrated
mainly on different protocols - DSR, AODV, DYMO, ZRP that may be used in WSN
topologies so as to find that ZRP is better in all the fading environment- Rayleigh, Ricean and
fast Rayleigh on basis of few application layer parameters.
Keywords: WSN, Fading environments, routing protocols, DSR, AODV, DYMO, ZRP.
1. INTRODUCTION
Although sensor networks are widely used, secure and reliable wireless network
according to today’s need, but they are application dependent. These networks are an
intelligent set of spatially distributed miniature nodes, each employed with a sensor that
simply examines physical quantities like temperature, pressure, humidity, etc and
communicate them throughout the entire network. Their applications lies in very extreme and
complicated environmental conditions, where keeping a constant check over nodes may not
be possible manually. In such scenarios, their restrictive parameters like energy consumption
of nodes, speed- algorithms, buffering capacity, etc. also gets affected. These parameters are
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routing dependent and routing depends on type of application being carried out. So, routing
protocols play an important role. Thus we can sum up the need of studying different routing
protocols as:
• As the WSN are application dependent, so they use different routing strategy each time.
Thus different routing protocols are used by a single network for different application.
• Since WSN are non-infrastructure based networks and are deployed in extreme
environmental conditions, where human approach becomes impossible. So, selecting
connecting links between two nodes becomes highly random. Therefore, routing becomes
crucial here and hence routing protocols need to be analyzed so as to reduce routing
delay, cost and other QoS parameters.
• WSN applications need to support critical infrastructures, security becomes an essential
issue. The need for security in sensitive WSN application has lead to design secure
multipath routing protocols.
• Nowadays, WSNs are being used as multimedia networks also which would handle heavy
traffic and data processing where cost of service has to be optimize.
The route is decided depending upon various parameters like traffic, reliability, congestion,
etc.
Routing Challenges
Depending on the application, different WSN architecture design would follow different
routing scheme. Following are few challenges that have to be met for routing decision [2]:
(i) Network Type: Either some or all nodes of networks may be stationary or mobile. Now
routing packets to/from mobile nodes is much more challenging than that for static nodes.
(ii) Network Deployment: Some networks may be self-organizing (nodes can form any
topology, hence can create any routes) or deterministic (such networks are pre-organized
manually and even the routes are fixed). Thus managing routing paths in self-organizing
WSN is more difficult than in deterministic networks.
(iii)Energy Consideration: Since each node in a WSN is battery operated therefore energy is
limited. Now, if the routing paths are long, multi hop routes must be created so as to
reduce energy consumption. But as number of hops in any routing path increases, so does
the overhead of extra header information increase.
(iv)Node Capabilities: Each node in a network has dedicated tasks to perform like relaying
information, summing information or simply sensing the data. Now depending on these
tasks each node would consume energy. Also here their buffering capacity is included.
(v) Other Factors: Cost, fault tolerance, scalability, operating environment.
Thus, a number of routing protocols have been introduced in WSN, but it is extremely
necessary to draw a comparison among them, which would guide us on designing an efficient
network.
2. ROUTING PROTOCOLS
Routing is a process that is initiated when a request to transmit/receive a data, occurs.
Then an appropriate routing path has to be decided from which the data would transmit or be
received. This is mainly done by routing protocol depending upon the topology, architecture
design, and application and a few challenges mentioned below. This is a network layer
function. The transmitter node transmits packet that contains header information (destination
address and routing path) to its nearest neighbors, which then forward it to entire network.

3. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
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With this, a response is generated by the receiver nodes to indicate the receiving of the packet
each time. This is how network topology is understood. Network topology of sensor network
can be a simple star or a multi hop mesh network. Routing is done as per the selected
protocol and the target is to communicate the packet from source to destination with
minimum resources and minimum time, i.e. shortest path has to be identified. Once the
topology of the network is resolved, shortest path is identified with the help of information
stored within the intermediate nodes. The route is decided depending upon various
parameters like traffic, reliability, congestion, etc.
In generic sense, routing protocols can be classified as follows:
Routing Protocols
Mode of
Operation
Node
Participation
Sinking
capability
Network
Structure
Proactive,
Reactive,
Hybrid
Direct,
Flat,
Clustering
Unicast,
Multicast
Hierarchical,
Data Centric,
Location Based
Table 1: Routing Protocol Classification
Proactive/Static Routing Protocol: Routing takes place on the basis of predefined path, where
the network designer manually decides which of the next nearest node will be taken by each
node.
Reactive/Dynamic Routing Protocol: Predefine routes need not be defined; rather this
decision is taken dynamically depending upon other network issues.
Hybrid Routing Protocol: This is a mixed technique where depending upon the need and
application, either static route or dynamic route is taken.
Direct Routing Protocol: Any node can transmit data to any other node directly.
Flat Routing Protocol: A node can transmit data to any other only when it finds the link free.
Clustering-Routing Protocol: Entire network is divided into small clusters. Each cluster has a
cluster head and any transmitting node sends data to the cluster head. Now, these cluster
heads communicate with each other.
Unicast Routing Protocol: Here any node can transmit data to only one of any other node
within the network.
Multicast Routing Protocol: Any node that wishes to transmit data can transmit data to a
group of nodes instead of to a single node.
Hierarchical Routing Protocol: High energy nodes will perform high energy consuming
tasks- data forwarding and processing, while low energy nodes will perform only monitoring
work.
Data Centric Routing Protocol: These are query based protocols, where any node can
transmit data only when it is required by any other node, as request. It is similar to on-
demand routing.
Location Based Routing Protocol: Such protocols requires some kind of location sensing of
the transmitting and receiving nodes so as to make shortest path decision (GPS system).
Protocols used in WSN
In this study, we have included comparison for following types of protocols that are available
in QualNet: [3]

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DSR (Dynamic Static Routing Protocol)
Dynamic Source Routing (DSR) is an on-demand routing protocol that is specifically
designed for use in multi-hop wireless ad hoc mobile networks. DSR builds routes only on-
demand by flooding Route Request packets, if a sender wishes to send data to a destination
with no known route.
AODV (Ad-hoc On-demand Distance Vector Routing Protocol)
AODV protocol is specially used for mobile ad hoc networks. It provides a quick adaptation
to dynamic link condition, link fault, low processing and memory usage overhead. It enables
dynamic, self-starting, multi hop routing between participating mobile nodes wishing to
establish and maintain an ad hoc network. AODV allows mobile nodes to obtain routes
quickly for new destinations, and does not require nodes to maintain routes to destinations
that are not in active communication. AODV allows mobile nodes to respond to link
breakages and changes in network topology in a timely manner. It uses sequence numbers to
prevent routing loops.
DYMO (Dynamic MANET On-demand Routing Protocol)
The Dynamic MANET On-demand (DYMO) routing protocol is a unicast reactive routing
protocol which is intended for use by mobile nodes in wireless multi hop networks. Here, a
Routing Message (Control Packet) is generated only when the node receives a data packet
and it does not have any routing information. The basic operation of DYMO protocol is route
discovery and route management.
ZRP (Zone Routing Protocol)
Zone Routing Protocol (ZRP) is a hybrid protocol that divides the network into overlapping
zones/virtual clusters and runs independent protocols within and between the zones. For intra
zone routing, ZRP uses IARP. For inter zone routing, ZRP uses IERP. A third protocol,
Border cast Resolution Protocol (BRP), is used to optimize the routing process between
perimeter nodes.
IARP (Intra zone Routing Protocol)- It is a proactive routing protocol used inside a zone;
IERP (Inter zone Routing Protocol)- It is an on-demand routing protocol and is used to
discover a route to remote nodes outside of the zone of the node; BRP (Border cast
Resolution Protocol)- It is used to efficiently flood broadcast packets throughout the network.
Actually, it is not a full-featured routing protocol.
These four routing protocols are analyzed on basis of different application layer parameters
for different fading models and comparison is done with the help of line graphs in the
following section.
3. SIMULATION ENVIRONMENT
This section gives the details of the simulation environment used to simulate the
results and description of parameters set. Simulation environment used here is QualNet®
Developer 5.0.2. Here, initially a scenario is created that consists of 5 nodes, out of which
one is the PAN coordinator (Full Function Device) while the other four are transmitters
(Reduced Function Devices). Now, we have applied different fading models and different
routing protocols simultaneously in this scenario. These conditions are applied repeatedly for
the same network but gradually increasing the number of nodes from 5-10-25-50-100.
Following results are drawn on the basis of the above simulation of the scenario.

5. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
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226
0
0.2
0.4
0.6
0.8
1
1.2
1.4
5 15 25 50 100
Jitter
Number of Nodes
Fast Rayleigh
DSR
AODV
DYMO
ZRP
4. RESULTS AND DISCUSSION
This section studies the results in form for few parameters like: Jitter, Average end to end
delay and Throughput to find out which protocol is efficient for different fading models.
Jitter
Jitter is a performance measure in a network. It is defined as the variability in the latency
for a network. Jitter causes packets to arrive at their destination with different timing and possibly
in a different order than they were sent, with some arriving faster and some slower than they
should. Ideally value of jitter should be as small as possible. Jitter is different for networks having
different number of nodes and for both the Rayleigh/ Ricean and Fast Rayleigh Fading model.
For both the fading models, ZRP protocol is best suited in case of jitter.
Figure 2: Jitter for different protocols in Rayleigh/ Ricean fading
Figure 3: Jitter for different protocols in Fast Rayleigh fading
Total Packets Received
DSR protocol shows a maximum value of packets received at the FFD in Rayleigh/
Ricean fading followed by ZRP with 24 packets transmitted from each node for the entire range
of the increasing number of nodes.
Fig.17. Total Packets Received for different protocols in Rayleigh/ Ricean fading
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
5 15 25 50 100
Jitter
Number of Nodes
Rayleigh/Ricean
DSR
AODV
DYMO
ZRP
0
10
20
30
40
50
60
5 15 25 50 100
TotalPacketsReceived
Number of Nodes
Rayleigh/Ricean
DSR
AODV
DYMO
ZRP

6. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
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Fig.18. Total Packets Received for different protocols in Fast Rayleigh fading
Also for fast Rayleigh fading, DSR shows highest number of packets received but
here ZRP has minimum value with AODV slightly less than DSR.
Average End to End Delay
End-to-end delay refers to the time taken for a packet to be transmitted across a network from
source to destination. It should be least for any network.
Figure 4: Delay for different protocols in Rayleigh/ Ricean fading
Figure 5: Delay for different protocols in Fast Rayleigh fading
0
10
20
30
40
50
60
70
80
5 15 25 50 100
TotalPacketsReceived
Number of Nodes
Fast Rayleigh
DSR
AODV
DYMO
ZRP
0
10
20
30
40
50
60
70
80
90
5 15 25 50 100
EndtoEndDelay(sec)
Number of Nodes
Rayleigh/Ricean
DSR
AODV
DYMO
ZRP
0
2
4
6
8
10
12
14
5 15 25 50 100
EndtoEndDelay(sec)
Number of Nodes
Fast Rayleigh
DSR
AODV
DYMO
ZRP

7. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
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In case of Rayleigh fading, all the three protocols- AODV, DYMO and ZRP has less
end to end delay, whereas in fast Rayleigh fading, ZRP is least. But in all, ZRP shows least
delay in both the cases.
Throughput (bit per sec or data packet per sec)
Throughput or network throughput is the average rate of successful message delivery
over a communication channel. The system throughput is the sum of the data rates that are
delivered to all terminals in a network. It should be as high as possible. In Rayleigh fading
environment, although DSR and AODV has increasing throughput, but then it gradually
reduces as number of nodes increase above 50 nodes. Again, ZRP has very low throughput
whereas DYMO is initially constant with minimum values and gradually increases as number
of nodes increases.
Thus, DYMO is better in Rayleigh fading. Again, in fast Rayleigh fading
environment, only ZRP has a fixed change rate and it increases on increasing number of
nodes.
Figure 6: Throughput for different protocols in Rayleigh/ Ricean fading
Figure 7: Throughput for different protocols in Fast Rayleigh fading
0
50000
100000
150000
200000
250000
5 15 25 50 100
Throughput(bits/sec)
Number of Nodes
Rayleigh/Ricean
DSR
AODV
DYMO
ZRP
0
200
400
600
800
1000
1200
1400
1600
1800
5 15 25 50 100
Throughput(bits/sec)
Number of Nodes
Fast Rayleigh
DSR
AODV
DYMO
ZRP

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5. CONCLUSION
Based upon the simulation, above results can be summed up as follows:
• ZRP protocol shows least jitter in case of Rayleigh/ Ricean as well as fast Rayleigh
fading environments.
• In Rayleigh fading AODV, DYMO and ZRP are all optimum but ZRP with hold
minimum end to end delay. Again, for fast Rayleigh ZRP is best suited.
• For maximum throughput in Rayleigh faded networks, DYMO protocol should be
preferred, whereas in fast Rayleigh, ZRP shows better results.
Thus, it is concluded that one cannot accurately say any protocol to be the best for any
environment because each scenario is designed for some specific purpose and they have to
operate under different conditions. Each protocol will give different result in different
environments for the same network as number of as WSNs are application specific.
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