The selection of routes is an important issue in wireless networks when network coding is used. Existing research formulate network-coding-aware routing as a linear optimization program. However, deploying such method in real wireless networks is impractical. To solve this issue, in this paper, a practical network-coding aware routing protocol is proposed for unicast sessions in wireless networks. The protocol is based on a novel routing metric design that captures the characteristics of network coding and unicast sessions. To ensure the novel routing metric can operate with practical and widely available path calculation mechanisms, a unique mapping process is used to map a real wireless network to a virtual network. The mapping process ensures that the paths with the biggest coding opportunities will be selected by commonly used path calculation mechanisms. Simulation results show that the proposed routing protocol is effective.

Different geographic routing protocols have different requirements on routing metric designs to ensure proper operation. Combining a wrong type of routing metrics with a geographic routing protocol may produce unexpected results, such as geographic routing loops and unreachable nodes. In this paper, we propose a novel routing algebra system to investigate the compatibilities between routing metrics and three geographic routing protocols including greedy, face, and combined greedy-face routing. Five important algebraic properties, respectively, named odd symmetry, transitivity, strict order, source independence, and local minimum freeness, are defined in this algebra system. Based on these algebraic properties, the necessary and sufficient conditions for loop-free, delivery-guaranteed, and consistent routing are derived when greedy, face, and combined greedy-face routing serve as packet forwarding schemes or as path discovery algorithms, respectively. Our work provides essential criteria for evaluating and designing geographic routing protocols.

Different geographic routing protocols have different requirements on routing metric designs to ensure proper operation. Combining a wrong type of routing metric with a geographic routing protocol may produce unexpected results, such as geographic routing loops and unreachable nodes. In this paper, we propose a novel routing algebra system to investigate the compatibilities between routing metrics and three geographic routing protocols including greedy, face and combined-greedy- face routing. Four important algebraic properties, respectively named odd symmetry, transitivity, source independence and local minimum freeness, are defined in this algebra system. Based on these algebraic properties, the necessary and sufficient conditions for loop-free and delivery guaranteed routing are derived when greedy, face and combined-greedy-face routing serve as packet forwarding schemes or as path discovery algorithms respectively. Our work provides essential criterions for evaluating and designing geographic routing protocols.

Free-riding restricts the development of P2P systems. Existing incentive mechanisms take no consideration for the individual and social payoff. To address these problems, this paper presents a novel P2P incentive mechanism. Simulations show that the proposed mechanism can increase the social payoff of the whole P2P systems rapidly, and accelerate the cooperation between nodes.