A Mobile Ad Hoc Network (MANET) is a self-governing network of mobile nodes without the inclusion of any wired links. Each node can move in an ad hoc manner and therefore, such a network should consist of routing protocols which can adapt to dynamically changing topologies. Numerous protocols have been proposed for the same. However, the trajectories followed by the individual nodes have not been distinctly dealt with. This paper presents a meticulous study on QoS parameters of proactive (OLSR) and reactive (DSR) protocols of MANETs for uniform as well as dissimilar trajectories of individual nodes in a small network of about 20 nodes. Also an examination of partial node failures for both the above mentioned protocols has been done. The performance metrics utilized in this study are average throughput and average delay. OPNET modeler has been utilized for this study. This assessment shows that for uniform trajectories, OLSR has almost same average delay but a higher average throughput as compared to DSR. Also it is seen that, as compared to uniform trajectories, non-uniform trajectories deliver a much higher average throughput. Node failures only reduce average throughputs whereas average delays remain unchanged.
MOBILE ad hoc networks (MANETs) consist of moving nodes that use wireless transmission for communication. They can be set up as and when needed due to the absence of a centralized setup. Similar to wired networks, data transfers in a MANET have varied characteristics (e.g. category and amount of data exchanged, duration of interplay, etc.) and also different Quality of Service (QoS) [1] requirements (e.g. delay, throughput). Hence, a uniform packet processing is not adequate and a QoS inspection consisting of various parameters is required.
The primary challenge in building a MANET is equipping each device (node) to continuously maintain the information required to route traffic. MANET routing protocols [2] [3] are traditionally divided into three categories as shown in Figure 1, which are Proactive Routing Protocols, Reactive Routing Protocols and also Hybrid Routing Protocols. Proactive Routing Protocols [4] [5] are also called table driven routing protocols and they constantly maintain the updated topology of the network. Each node in these protocols maintains individual routing table which consists of routing information of all the nodes present in the network. Reactive Routing Protocol is also called as on-demand routing protocol. Reactive protocols do not initiate path discovery on their own, unless they are requested. Hybrid Routing Protocols [6] is a confluence of both the above protocols and contains the advantages of both of them. The routing is initially set up with a few proactively prospected routes and thereby serves the demand from additionally activated mobile nodes through reactive flooding.
2. Related Work
In the papers referenced up till now, a good amount of analysis is done about the performance and the effectiveness of the MANET routing protocols such as OLSR [7] [8] and DSR [9] [10] . An important aspect of the research work and studies carried out by these papers is the dealing of the QoS parameters. These parameters have been analyzed by varying the number of nodes as well as the number of effective operating nodes, changing the environment of the mobile nodes, changing the distance between them, difference in the type of application and network layer protocols chosen, etc.
Also changes in physical characteristics, data rates of transfer, RTS and fragmentation threshold, packet inter-arrival time distribution, packet size distribution are some of the other factors utilized in these studies.
In the above references of both the protocols, however only a cursory attention has been given to the performance of QoS parameters in conjunction with a
variety of trajectories of the mobile nodes. Also performance of QoS parameters during events of mobile node failures are neither exclusively nor thoroughly dealt with in these studies for both these protocols. Hence a proper relationship in order to understand the interplay is needed. This paper attempts to establish this relation in order to develop a better understanding of the same.
3. Research Methodology
In order to achieve a better understanding of the QoS parameters of various trajectories, twelve simulation scenarios with 20 nodes in each of them, have been analyzed using OPNET (Optimized Network Engineering Tool) modeler version 17.5, a discrete event simulator. All nodes selected are mobile. The nodes are placed in a campus environment of 10km by 10km spread. The nodes can be any devices or machinery or even vehicles which are mobile and capable of wireless communication. File Transfer Protocol has been used in the study with load parameter set at high level. All nodes are assigned with a specific path trajectory which defines the mobility within the given time frame. The trajectories incorporated here are namely linear, curvilinear and mixed.
4. Simulation Framework
For all the above scenarios, the wireless parameters set, are shown in Table 1, as follows.
The MANET traffic generation parameters for each of the nodes are shown in Table 2 as follows.
The different results obtained have been analyzed along with their respective illustrations in the following section.
5. Simulation and Observation
Initially for the setup showed in Figure 2, the nodes are assigned a uniform
Wireless parameters
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