Code pruning in opportunistic routing through bidirectional coding traffic comparison

Abstract

Opportunistic routing (OR) significantly improves transmission reliability and network throughput in wireless mesh networks (WMNs) by utilizing the broadcast nature of the wireless medium. Through the integration of network coding (NC), the complicated coordination to select the best forwarding node in OR can be bypassed. However, the introduction of NC exacerbates the redundant-packet-transmission problem. To mitigate this issue, existing coded OR protocols either adopt the loss-rate-based approach, employ orthogonal vectors as coded feedback, or pursue the stream-based coded OR model. However, these three solutions suffer inaccuracy and obsolescence of the loss-rate measurement, false-positive/false-negative problem, and unavailability of hop-by-hop stream-based OR, respectively. To address the above problems, we propose a simple but practical coded feedback scheme, Cumulative Coding Coefficient ACKnowledgement (C 3 ACK), based on the relevance between forward (coded packets received from upstream nodes) and backward coding traffic (coded packets overheard from downstream nodes), and apply C 3 ACK to both batch-based and stream-based coded OR models in order to prune redundant forward and backward coding traffic. Both testbed evaluation and simulation study show that our codepruning schemes can outperform existing approaches in terms of expected throughput and transmission count.

Fair coding for inter‐session network coding in wireless mesh networks

“…Coding Opportunistically (COPE) is the pioneer work that applied inter‐session network coding to wireless networks. Hereafter, numerous works have been proposed to explore the potential benefits of network coding. Some of them focused on the design and performance analysis of coding mechanism.…”

“…Besides, some works study the coding mechanism to improve the performance, other works are mainly aimed at developing the coding‐aware routing protocols, which took the coding opportunity as one of the route metric, achieving high throughput by choosing the path with a higher coding opportunity. Unlike the protocols proposed in in which the coding structure is limited within a two‐hop region, Distributed Coding‐Aware Routing Protocol (DCAR) was proposed as the first distributed coding‐aware routing mechanism, which has the capability to discover high throughput paths with coding opportunities, and in DCAR, a routing metric called coding‐aware routing metric was defined to facilitate the performance comparison between coding‐possible and coding‐impossible paths.…”

“…Most existing inter‐session coding‐based protocols focused on designing various coding‐aware routing protocols or coding mechanisms in different scenarios. Zhao et al first studied the impact of the 802.11 medium access control (MAC) protocol on the coding opportunity and identified the negative impact of existing MAC protocols on the fairness between coding flows and non‐coding flows.…”