Background: In traditional networks, nodes drop messages in order to free up enough space for buffer optimization. However, keeping messages alive until it reaches its destination is crucial in Opportunistic Networks. Therefore, this paper proposes an Acumen Message Drop scheme (AMD) that consider the impact of the message drop decision on data dissemination performance. Methods: In order to achieve this goal, AMD drops the message based on the following considerations: the estimated time of message's arrival to its destination, message time to live, message transmission time, and the waiting time of the message in the queue. AMD scheme works as a plug-in in any routing protocol. Results: Performance evaluation shows that the integration of the proposed scheme with the PRoPHET routing protocol may increase efficiency by up to 80%, while if integrated with Epidemic routing protocol, efficiency increases by up to 35%. Moreover, the proposed system significantly increases performance in the case of networks with limited resources. Conclusion: To the best of our knowledge, most of the previous works did not address the issue of formulating the message drop decision in the non-social stateless opportunistic networks without affecting performance.

Recently, opportunistic networks (OppNets) are considered as one of the most attractive developments of mobile ad hoc networks that have emerged, thanks to the development of intelligent devices. Owing to the harsh and dynamic topology of these networks, attaining high delivery ratio is a challenging issue. Hence, it is imperative to select which node's attribute must be adjusted to achieve a higher performance in such unpredictable networks. A mutual information-based weighting scheme (MIWS) that exploits the entropy concept to assess the impact of the nodes' attributes on the network performance was proposed. The weighting procedure aims to figure out the correlative relations between different attributes and delivery ratio performance of the network. The high weight of certain attributes implies a correspondingly high impact in achieving efficient data forwarding. The proposed scheme is proofed conceptually and simulated using the Opportunistic Network Environment simulator. In contrast to previous studies conducted in the context of weight resolution, the proposed approach allows us to address this issue in real-time stateless non-social OppNets. Regardless of the deployed routing protocol, experiments show that adjusting nodes' attributes based on the proposed MIWS can improve the performance up to encouraging delivery ratios. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Recently, opportunistic networks are considered as one of the most attractive developments of ad hoc mobile networks (MANETs) that have emerged thanks to the development of intelligent devices. Due to the mobility-related instability of the paths between nodes and due to the limited buffer and energy resources, the ultimate objective of routing protocols in opportunistic networks is to enable the exchange of information between users. In such harsh environments, it is difficult to exactly pin down the services provided by these networks. To this end, we present in this paper a study on the performance analysis of six of the most popular routing protocols in opportunistic networks, namely, epidemic, PRoPHET, MaxProp, Spray and Wait, Spray and Focus, and Encounter-Based Routing (EBR). We firstly described these protocols and presented their algorithms. Thereafter, we carried out a comparative study of these protocols using exhaustive performance testing experiments with different numbers of nodes, traffic loads, message lifetime, and buffer size. The results of this investigation are with an important role in helping network designers to improve performance in such challenging networks.

Recently, Opportunistic Networks (OppNets) are considered to be one of the most attractive developments of Mobile Ad Hoc Networks that have arisen thanks to the development of intelligent devices. OppNets are characterized by a rough and dynamic topology as well as unpredictable contacts and contact times. Data is forwarded and stored in intermediate nodes until the next opportunity occurs. Therefore, achieving a high delivery ratio in OppNets is a challenging issue. It is imperative that any routing protocol use network resources, as far as they are available, in order to achieve higher network performance. In this article, we introduce the Resource-Aware Routing (ReAR) protocol which dynamically controls the buffer usage with the aim of balancing the load in resource-constrained, stateless and non-social OppNets. The ReAR protocol invokes our recently introduced mutual informationbased weighting approach to estimate the impact of the buffer size on the network performance and ultimately to regulate the buffer consumption in real time. The proposed routing protocol is proofed conceptually and simulated using the Opportunistic Network Environment simulator. Experiments show that the ReAR protocol outperforms a set of well-known routing protocols such as EBR, Epidemic MaxProp, energy-aware Spray and Wait and energy-aware PRoPHET in terms of message delivery ratio and overhead ratio.