The existing inter-session network coding mechanisms almost unanimously adopt "τ-interval-notification", which is used to determine the coding opportunities, and its overhead has not been analyzed.In the current study, its communication overhead and its impacts on coding opportunity and throughput were analyzed, and an adaptive reception report sending mechanism called AR2SM (Adaptive Reception Reports Sending Mechanism) was proposed.In AR2SM, the interval of broadcasting reception reports is determined adaptively according to the traffic of local network, and the reception reports carry the packets overheard in the last 2 intervals.As a result, the size of reception report and the frequency of sending reception report were both reduced on the condition of guaranteeing the coding opportunity.According to the simulator results in network simulator, the proposed mechanism reduces the overhead of transmitting the reception reports, and achieves higher throughput than the "τ-interval-notification" mechanism.

Because of the broadcast and overhearing capability of wireless networks, network coding can greatly improve throughput in wireless networks. However, our investigation of existing inter-session network coding protocols found that the short-term unfairness that existed in 802.11-based medium access control MAC protocols actually decreases the coding opportunity, which in turn compromises the throughput gain of network coding. To alleviate the negative impact of this unfairness, we propose a coding-aware cross-layer heuristic approach to optimize the coordination of network coding and MAC layer protocol, named FairCoding, which can significantly increase coding opportunities for inter-session network coding through a fair short-term traffic allocation for different coding flows. Experiment evaluation shows that the proposed mechanism can bring more coding opportunities and improve the total throughput of wireless mesh networks by up to 20%, compared with the coding mechanism, without considering the negative impact of the short-term unfairness. Copyright © 2015 John Wiley & Sons, Ltd.

Network coding is an efficient technique to improve the throughput of wireless network. It is observed that there exists short period unfairness when nodes are competing for the wireless channels, which will decrease the opportunity of inter-session network coding in WMN(Wireless Mesh Network). A coding-aware cross-layer optimization mechanism is proposed in this paper. In the proposed mechanism, the priorities of coding flows were calculated in relay nodes according to the packet number of these flows in the forward queue, and the values of the priorities were sent to the corresponding upstream nodes to adjust their MAC parameters. Experiments and simulation results show that the proposed mechanism can balance the traffic of coding flows in the relay nodes in a short period and create more coding opportunities. As a result, it will improve the total throughput of wireless mesh network.

Localized network coding can greatly improve the throughput of wireless mesh networks. In a typical practical wireless transmission mechanism using localized network coding, such as COPE, to make decision which forwarding packets should be coded together, each node needs to broadcast a notification message every interval time to inform their neighbors which packets they have buffered currently. However, the τ-interval-notification mechanism will incur non-negligible overhead, especially when τ is small, and it is difficult to determine the value of τ due to the unbalanced network payload. In this paper, we analyzed the overhead of the τ-interval-notification mechanism, and proposed a novel lightweight reception-report-notification mechanism, named ARSM, for localized network coding, in which a node will be triggered to send notification of reception reports when it has buffered k new packets, and each notification will include information of 2k latest buffered packets to decrease the message size of the notification and guarantee the coding efficiency meanwhile. Simulation results show that ARSM can achieve higher coding efficiency with less overhead, and a coding aware transmission mechanism based on ARSM will achieve a higher throughput than the one based on the τ-interval-notification mechanism.