Mobile Opportunistic Networks (OppNets) are infrastructure-less networks consisting of wireless mobile nodes and have been a focus of research for years. OppNets can be scaled up to support rapid growth of wireless devices and technologies, especially smartphones and tablets. Mobile Ad Hoc Networks (MANETs), one of OppNets technologies, have a high potential to be used for facilitating an extension for the Internet and a backup communication platform in disaster situation. However, a connection disruption due to node mobility and unreliable wireless links is possible to trigger a flooding operation of route repair process. This results in transmission delay and packet loss. The flooding of routing packets is an expensive operation cost in MANETs which affects network reliability and wastes limited resources such as network bandwidth and node energy. These are obstacles to practical implementation of MANETs in real-world environment. In this paper, we propose Low Overhead Localized Flooding (LOLF), an efficient overhead reduction routing extension based on Query Localization (QL) routing protocol. The purpose of this work is to control the propagation of routing packets in the route discovery and route repair mechanisms while incurring only a small increase in the size of control information in the packet. Simulation results from extensive experiments show that our proposed method can reduce overall routing overhead, energy consumption, and end-to-end delay without sacrificing the packet delivery ratio compared to existing protocols.

Delay-Tolerant Network (DTN) is a network technology which can provide communication in an environment where an end-to-end path may not be possible. Over the past years, Epidemic Routing has been recognized as the DTN protocol that can deliver messages quickly by spreading messages from node to node all over the network. However, many pieces of research argue against using Epidemic Routing due to the large number of message exchanges. In this paper, we propose Speed Epidemic Routing (SEd), which is the renovation of Epidemic Routing scheme. By applying broadcast transmission, we can increase the speed of messages spreading and reduce forwarding redundant messages. The simulation results show that SEd is a protocol providing high delivery rate and low packet rate at the same time.

Owing to the heterogeneity and high degree of connectivity of various networks, there likely exist multiple available paths between a source and a destination. An effective model of delay-controlled load distribution becomes essential to efficiently utilize such parallel paths for multimedia data transmission and real-time applications, which are commonly known to be sensitive to packet delay, packet delay variation, and packet reordering. Recent research on load distribution has focused on load balancing efficiency, bandwidth utilization, and packet order preservation; however, a majority of the solutions do not address delay-related issues. This paper proposes a new load distribution model aiming to minimize the difference among end-to-end delays, thereby reducing packet delay variation and risk of packet reordering without additional network overhead. In general, the lower the risk of packet reordering, the smaller the delay induced by the packet reordering recovery process, i.e., extra delay induced by the packet reordering recovery process is expected to decrease. Therefore, our model can reduce not only the end-to-end delay but also the packet reordering recovery time. Finally, our proposed model is shown to outperform other existing models, via analysis and simulations.