Inter-flow and Intra-flow Network Coding Based Opportunistic Routing in Lossy Wireless Networks
Date Issued
2012
Date
2012
Author(s)
Yeh, Shu-Hao
Abstract
Opportunistic routing (OR) and inter-flow network coding are two promising techniques to improve the system throughput by exploiting the broadcast nature of wireless medium. However, they are suitable in different scenarios. Opportunistic routing is expected to be more effective in highly lossy network, because it has more chances for a packet to make progress toward the destination. In contrast, inter-flow network coding degrades coding opportunities under poor channel quality. On the other hand, inter-flow network coding is expected to have more coding opportunities when multiple flows cross at a node, while the throughput gains of MORE, the state-of-the-art intra-flow network coding based opportunistic routing protocol, decreases with an increased number of flows.
In this work, we propose a new efficient network coding-based opportunistic routing protocol called Hierarchical Network Coding (HNC), which takes advantage of both intra-flow network coding based opportunistic routing and inter-flow network coding for lossy wireless networks. In a lossy environment, each linear combination of packets (i.e., coded packet) may not be able to arrive at each forwarder intact. The challenge of this work is to determine which packets to be XORed for transmission at each forwarder based on the partially received packets within all combinations. To tackle the problem, we propose two heuristic packet selection algorithms. We compare the performance via simulations, which show that the proposed HNC outperforms MORE in multiple-flow scenario, demonstrating that our proposed heuristic algorithms are indeed excellent solutions to combine the inter-flow network coding and intra-flow network coding.
Subjects
opportunistic routing
inter-flow network coding
intra-flow network coding
wireless network
Type
thesis
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