Mobile Ad Hoc Network Manet Routing Protocol Base Computer Science Essay

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Abstract - This paper appraises and compares the routing protocols of mobile ad hoc networks (MANET) for wireless sensor networks (WSNs). It focuses and compares the performance analysis based on QoS factors which are the throughput and delay between DSR and OLSR protocols for mesh network with a single source. In this research, Dynamic Source Routing (DSR) is a simple and efficient routing protocol and Optimized Link State Routing (OLSR) is a proactive routing protocol for mobile ad hoc networks. In wireless ad hoc network, the nodes must be able to interconnect each other to establish the link or connection from source to the destination.

Keywords: DSR, OLSR, MANET, WSN, OPNET.

INTRODUCTION

A Wireless Sensor Networks (WSNs) is a network of wireless sensor nodes. Each node is a computer with attached sensors that can process, exchange sensed-data, as well as, communicate wirelessly among themselves to perform various tasks. Wireless Sensor Networks (WSNs) have gained attention in both industry and research community because they are expected to bring the interaction between human, environment and machine to a new level. Typically in WSN, it rely on large number of cheap devices, able to collaborate in distributed network data fusion and processing tasks, with the final results that are equivalent to those obtained with centralized processing. All the sensor nodes will coordinate locally and send the message to a common sink.

Fig 1: Mobile Ad Hoc Networks-MANETs. [1]

To deliver crucial information from the environment in real time, it is impossible with wired sensor networks whereas wireless sensor networks are used for data collection and processing in real time from inaccessible environment. In this case, wireless sensor networks will play important roles to deliver the message or data from outbound area to the centralized destination. Due to these characteristics, wireless sensor networks can be deployed in many environments for different purposes [2]. The primary constituent components for a WSN are one or more base station and many sensor nodes. Such small device normally low-cost and battery operated or powered by solar. Due to the small design, they are tightly constraint in terms of energy, storage capacity and data processing. Sensor nodes typically relayed the information directly to the destination depending on the scale of the networks. The ambient conditions in the environment are measured by sensors and then measurements are processed in order to assess the situation accurately in area around the sensors. Over a large geographical area, large numbers of sensor nodes are deployed for accurate monitoring. Due to the limited radio range of the sensor nodes and in need of increasing the network size for large network coverage, therefore data transmission i.e. communication to the base station (BS) is made possible with the help of intermediate nodes.

Many ad hoc routing protocols such as AODV, DSR, DSDR, TORA and OLSR which have been developed particularly for mobile wireless ad hoc network performed satisfactorily in MANET [3][4]. Since wireless sensor network is also an unstructured network and embodiment of MANET, the implementation of MANET routing protocols in WSN should be considered and it is a first step of pervasive computing towards the application of wireless ad hoc networks. However, we have seen limited researches of how good the performance of MANET routing protocols perform on wireless sensor networks [5] [6].

Many researchers have been conducted to solve the multi hop routing problem in wireless sensor networks with multiple source nodes and mobility, each based on different assumptions and intuitions. However, little is known about the actual performance of these MANET protocols and no attempt has previously been made to directly compare them for small scale network. This paper is meant to provide quantitative analysis and comparing the performance of two types of MANET routing protocols which are DSR and OLSR for different type of different number of sensor nodes in small scale networks.

ROUTING PROTOCOLS

Dynamic Source Routing (DSR)

The DSR is a reactive [7, 8] protocol that explores the concept of source routing, in which the sequence of nodes composing a route is informed in the header of each packet. Hence, the source node ought to know the complete route to destination nodes. All nodes maintain a route cache that contains previously identified routes. When a node has a packet to send to a particular destination, if it does not know a valid route, it broadcasts a route request packet, indicating the destination address and a route record that contains the source address only. Each neighbor without a valid route to the destination includes its own address in the route record and then also broadcasts the packet. After reaching the destination or an intermediate node with a valid route to the destination in its cache, a route reply packet is generated containing the route record identified in the route request. If the node generating the route reply is an intermediate node, it appends its cached route [9] to the route record before answering the route request. DSR can be adopted in networks that support symmetric and asymmetric links. When the ad hoc network support symmetric links, route reply packets are always propagated through reverse paths, which are the inverse of the routes indicated in request packets. As a consequence, route request and reply packets establish routes in both directions. DSR can also maintain multiple routes to each destination.

Optimized Link State Routing (OLSR)

It is a proactive routing protocol and is also called as table driven protocol because it permanently stores and updates its routing table. OLSR keeps track of routing table in order to provide a route if needed. OLSR can be implemented in any ad hoc network. Due to its nature OLSR is called as proactive routing protocol. Multipoint relay (MPR) nodes are shown in the given Fig. 2. All the nodes in the network do not broadcast the route packets. Just Multipoint Relay (MPR) nodes broadcast route packets. These MPR nodes can be selected in the neighbor of source node. Each node in the network keeps a list of MPR nodes.

Fig.2: MPR node sends the TC message

SIMULATION SETUP

All the simulations are extensively conducted using OPNET MODELER 14.0 simulator for two routing protocols: DSR and OLSR. OPNET MODELER is a Microsoft Windows based platform and one of the powerful network simulation tools and claims to have an intensive analyzing feature to provide the best environment for comparing and coordinating output obtained [10] [11].In this research, sensor nodes are randomly distributed in mesh and constructed in 1000m x 1000m area with different number of nodes: 15, 25 and 35. In the simulation scenarios, all the sensors are motionless. The aim of analyzing the behavior by maintaining the position of sensor nodes is to determine the improvements of each routing protocol for particular number of nodes. The simulations run for 300 seconds and uses Karn's algorithm to accurately estimate the round trip message. The simulation parameters configured in this research are influenced from previous works by different researchers [12] [13] [14] [15]. However, those papers were focus on the network simulation which consists of 30 nodes or more and implementation of node mobility.

The traffic configured from source to destination throughout this research is low resolution video. The wireless LAN buffer size was set to 1024000 bits to improve the heavier flow of video application that was generated in the network. The transmission distances are limited to 150 meters to make sure that the packets will be transmitted hop-by-hop to reach the destination. The channel setting was set to auto-assign to avoid the manual error during the transmission.

Figure 1: Simulation Scenario for 25 Nodes

TABLE 1

WIRELESS SIMULATION PARAMETERS

Parameters

Value

WLAN MAC address

Auto Assigned

Physical Characteristics

802.1g

Data Rate

24 Mbps

Tx Power

0.05

Reception-Power Threshold

-90

Short Retry Limit

7

Long Rety Limit

4

Max Receive Lifetime (secs)

0.5

AP Beacon Interval (secs)

0.02

Buffer Size (bits)

1024000

Large Packet Processing

Fragment

HCF Status

Promoted

Rx Group Configuration

Distance & Path Loss

Receiver Selection

Strict Match or Partial Overlap

Transmission distance

150 m

Mobility

No

TABLE 2

CONSTANT DSR PARAMETERS

Parameters

Value

Time Between Retransmitted Request

500ms

Size of Source Route Header Carrying n Addresses

4n + 4 bytes

Timeout For Non-propagating Search

30ms

Time to Hold Packets Awaiting Routes

30s

Maximum Rate for Request Sending Replies for a Route

1/sec

TABLE 3

CONSTANT OLSR PARAMETERS

Parameters

Value

Willingness

Willingness Always

Hello Interval (seconds)

2

TC Interval (seconds)

5

Neighbour Hold Time (seconds)

6

Topology Hold Time (seconds)

15

Duplicate Message Hold Time (seconds)

30

Addressing Mode

IPV4

The parameters for OLSR shown in table 3 and it is similar to those in [15].

SIMULATION RESULTS

The simulation criterion was configured as similar to previous studies except the simulation seed was set to 256 and the duration was set to 300 seconds. The Update Interval was set to 500000 events means it specifies how often simulation calculates events/second data. The Simulations run based on "kernel-type" reference was chosen for more accurate, real-time simulation and consistent results, but the time taken to run the simulations will be longer than the other two references.

Throughput

Fig. 3: Throughput of DSR vs OLSR for 15 Nodes

Fig. 4: Throughput of DSR vs OLSR for 20 Nodes

Fig. 5: Throughput of DSR vs OLSR for 25 Nodes

Delay

Fig. 6: Average delay for 15 Nodes

Fig. 7: Average delay for 20 Nodes

Fig. 8: Average delay for 25 Nodes

CONCLUSION

Fig. 9: Average routing traffic of DSR vs OLSR for 25 Nodes

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