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Top1. Introduction
In mobile adhoc networks, constraints such as node’s mobility, sparse connectivity and short range radio communication can stop the communication between nodes and it can results in high latency in transmitting messages between the nodes. In that situation Opportunistic networks are favorable to deal with interruption of communication between nodes. An Opportunistic Network (OppNet) (Pelusi et al., 2006) is a set of wireless mobile devices where there is no end-to-end connectivity between nodes. The OppNet start with initial seed and develops into an extended OppNet by taking help from neighbor nodes. The connectivity in opportunistic networks is retained by the nodes only when they are in contact of each other and then nodes can communicate with each other using their in-built technology such as wi-fi or bluetooth. When a node wants to send a message but there is no connected path, it preserves the message in its buffer till it meets suitable node opportunistically, i.e. store-carry-forward mechanism is applied to deliver the message from source to destination. Therefore, Opportunistic networks are habitually termed as a subclass of Delay-Tolerant Networks (Fall, 2003).
There occurs a connected path from source to destination node in traditional networks and if a destination node is not reached in this case, a link failure occurs whereas in OppNets, the message could be transmitted from source to destination using the communication opportunities among the nodes. OppNets can be used in various fields such as smart transportation system, industrial networks, interplanetary networks, military networks, underwater networks, remote rural networks, disaster situation and tracking wildlife using sensor networks. The information technology and communication technology have an essential role in making advancement in class of living style with smart resolutions as smart cities. The smart transport management system is example of such smart solutions as shown in figure 1. Here the sensors (for example accelerometer, light sensor, proximity sensor) are fitted in vehicles for performing various functions. The sensors equipped with vehicles sense the surrounding environment and predict the upcoming environmental conditions based on that. In this way the sensors support to analyze the traffic information, report accidents, identify over speed vehicles, and also give information about available parking slots, etc. in the desired city. As, the sensors nodes in smart traffic management have limited energy, so process of smart traffic management face numerous challenges as stated below.
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The energy or battery of nodes is limited
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Message transmission and reception process is energy consuming
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Message redundancy will be required due to unsteady network topology.
Figure 1.
Example of Smart Traffic Management (Sobin CC et al., 2017)
Moreover, there are chances of regular interruptions in vehicular network due to fast speed of the vehicles. So it will need re-transmission of messages and demand additional energy. It is clear from above facts that functioning of smart traffic management system is energy-consuming and if the sensors or actuator are self-powered, there can be numerous major problems that need to be addressed for efficiency.