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Top1. Introduction
An ad-hoc network refers to a network that is generally created for a particular purpose. They are mostly created for one-time use only, that’s why they are rottenly termed as temporary networks. MANET (Mobile Ad-hoc Network) is an ad-hoc network only, which is a self-organising gathering of wireless portable nodes that forms a momentary and dynamic wireless network deprived of any infrastructure. The rudimentary notion of using MANET is that the exchange of information in between the portable nodes count on the swift arrangement of a momentary network. Also, each node in a MANET can travel spontaneously in any direction and can change its links to the other nodes repeatedly. The rudimentary defy in establishing a MANET, is the constant preservation of routing information at each node. Figure 1 shows a basic structure of nodes in MANET.
Figure 1. Example of ad-hoc network
The routing conventions of such networks are isolated in three gatherings: Proactive Routing Protocols (Table Driven), Reactive Routing Protocols (Request Driven) and Hybrid Routing Protocols (Combination of Proactive and Reactive).
The Hybrid Protocols attempt to fuse different parts of proactive and reactive routing conventions. They are habitually used to give progressive routing. They use distance vectors to establish the best possible paths and report routing information only when there is a transformation in the topology of the network.
Hybrid Routing Protocols joins the benefits of both the protocols and attempt to achieve the high performance parameters. The hybrid protocols are proficient enough to render higher scalability than its corresponding protocols. The creativity of hybrid protocols is that they make an effort to be liberate from the single point failures in the network and bottleneck problems by allowing all the nodes to route and forward data in case of unattainability of ideal path. Ex. ZRP, TORA.
After elaborating the efficient Hybrid protocol the next section of the paper contains the various literature surveyed to learn and draw conclusion on the topic.
Top2. Literature Review
The Literature Review shows up to the numerous studies carried out in the field of Hybrid Routing Protocols of MANET and also includes the contrast of the hybrid routing protocols with reactive and proactive routing protocols.
The various challenges of MANET has been discussed in (Pdmalaya & Bhavani, 2016); that includes the infrastructure less scenario, limited memory, resource constraints, the dynamic topology of MANET along with the limited computing capacity. All the above discussed issues in MANET demands for a new or modified network strategies that can be used for a better and efficient communication. Along with this, the routing serves a decisive role in enumerating the path to the destination from the source. In addition to that the other major challenge in MANET is mobility modelling & control that bids for a noticeable human focus as it makes the topology of MANET more assert.
The light has been brought to the various network simulators in (Deepshikha & Sharma, 2016); that are handy now a days in the market such as Ns2, Ns3, OMNET++, OPNET, NetSim, J-Sim, GloMoSim, REAL, QualNet, jist and SWAN. The purpose of these open source network simulators is to analyse the network performance and its metrics of measurement. The performance parameters for these simulators are generally Packet Delivery Ratio, Routing Overhead, Throughput, Average end to end delay and Path Optimality. Also, the major factors that affects the efficient routing in MANET during communication are Network Size and Ever Changing Topology. During their research it has been found that the OMNET++ and Ns3, both the simulators have been categorised as the most mature simulators. The OMNET++ provides a better GUI support whereas Ns3 performs tremendously in case of large models. Further, the researchers may carry out a comparison between various MANET routing protocols with the help of more than 2 open source network simulators.
The work presented in (Murali et al., 2017) had considered SZRP that has a major objective to achieve the efficient secure neighbour discovery, secure routing packets, identification of noxious nodes and forbidding these nodes from demolishing the network. This will certainly enhance the working of the basic ZRP.