Performance Analysis of Social-Aware Routing Protocols in Delay Tolerant Networks Md. Khalid Mahbub Khan and Muhammad Sajjadur Rahim Department of Information and Communication Engineering University of Rajshahi Rajshahi-6205, Bangladesh khalidmahbub.khan@yahoo.com, sajid_ice@ru.ac.bd Abstract—In opportunistic environments data forwarding is challenging where connectivity is intermittent because of network partitioning, dynamic topologies and long delays. Traditional routing protocols of Delay Tolerant Network (DTN) exploit “Store-Carry-and-Forward” strategy in these cases. But the pitfall of this approach is the selection of perfect relay node and the determination of best data transmission moment in dense and urban areas. To route data in such dynamic, heterogeneous networks social-based routing is an emerging technique that concerns social behaviors and interactions of nodes. Here, we look into the performances of customary routing protocols of DTN, such as Epidemic, Spray-and-Wait (SNW), PRoPHET with two social-aware routing protocols: SCORP and dLife by conducting simulations in Opportunistic Network Environment (ONE) simulator through three criteria, that are: delivery ratio, average latency and transmission cost with necessary simulation settings. The performances are evaluated by varying node density and message Time-To-Live (TTL). From the outcomes of this experiment, it can be said that dLife acts best for delivery ratio but worst for average latency. On the other hand, SNW has best performance for average latency, Epidemic shows lowest performance for both delivery ratio and transmission cost, where SCORP as well as SNW show best performances for transmission cost. Keywords—delay tolerant network; social-aware routing; spray- and-wait; prophet; scorp; dlife; simulation I. INTRODUCTION Delay Tolerant Network (DTN) represents a variant structure about traditional network. DTN architectures are generally used for challenging environments where routing protocols concerned to traditional ad hoc networks cannot be utilized since such scenarios endure from lack of connectivity, sparse network densities, long and variable delays, limited device capabilities and higher bit error rate of communication channel. Conventional routing algorithms like Ad hoc On-Demand Distance Vector (AODV) or Dynamic Source Routing (DSR) require continuous connectivity between source and destination end. So, in such challenging environments, they cannot be implemented to route data accurately. This situation can be overcome by exploiting intermittent connectivity through DTN [1] [2]. In DTN, intermittent connectivity is provided by node mobility. DTN represents a class of network where the existence of well-defined path is not considered. However, at the same time source and destination node may have temporal or no connection through the network. This type of network has scattering node density. The communication capabilities are for short time of each node. Due to node mobility, one hop energy conservation connection is disrupted [3]. DTN routing techniques mostly utilize “Store- Carry-and-Forward” approach for forwarding where data is transmitted to the next node from source node while connectivity is available; if connectivity is not available data is stored by source and not be neglected. Source node carries the data until it has the connectivity with the next available node and finally delivers to that node. So, source node should choose relay node among the encountered nodes of it to take forwarding decisions in accordance with a specific routing protocol. Several routing protocols are designed for DTN environment depending on what kind of information is gathered by nodes and how they take routing decisions [4] [5]. Today, a large number of energy-constraint portable gadgets are carried, used through persons. So, to keep pace with the requirement of high speed data transmission of users, connectivity is required while on the go. Mobility is characterized by unpredictability, and as such, the networking scenario has turned into heterogeneous in nature and the change of topology is rapid. In this case, several attributes of the network can be considered that are more stable as compared to mobility. People form the network and their societal interrelationships can differ much slower than the topology. This idea may be utilized to take improved forwarding choices. Social-aware routing protocols try to detect these social mobility patterns and are best suited for this situation [6] [7] [8]. Moreover, in a social-aware network, nodes are interacted in a diverse manner where certain nodes encounter each other more usually. User’s social affiliations and attitudes are generally long-term properties. Compared with the mobility of nodes, they are less volatile. So, social-based routing protocols use various social characteristics to improve routing performance in DTN environment [4] [6] [9]. Here, performances between conventional routing approaches for DTN and social-aware routing approaches are inspected in opportunistic environment. Epidemic, PRoPHET, Spray-and- Wait (SNW), SCORP and dLife are focused in this scenario. Organization of the remaining of this paper is as follows: Investigation of DTN and social-aware routing techniques are explained in Section II. The next section describes about necessary modeling tool and environment. A comparative discussion of results is provided by Section IV and finally Section V provides the conclusions and future directions about this research.