Abstract
In wireless multi-hop networks, instead of using the traditional store-and-forward method, the relay nodes can exploit the network coding idea to encode and transmit the packets in the distributed coding-aware routing (DCAR) mechanisms, which can decrease the transmission number and achieve higher throughput. However, depending on the primary coding conditions of DCAR, the DCAR-type schemes may not only detect more coding opportunities, but also lead to an imbalanced distribution of the network load. Especially, they are not energy efficient in more complex scenarios, such as wireless ad-hoc networks. In this paper, to solve these shortcomings, we propose a constrained coding-aware routing (CCAR) mechanism with the following benefits: (1) by the constrained coding conditions, the proposed mechanism can detect good coding opportunities and assure a higher decoding probability; (2) we propose a tailored “routing + coding” discovery process, which is more lightweight and suitable for the CCAR scheme; and (3) by evaluating the length of the output queue, we can estimate the states of coding nodes to improve the efficient coding benefit. To those ends, we implement the CCAR scheme in different topologies with the ns-2 simulation tool. The simulation results show that a higher effective coding benefit ratio can be achieved by the constrained coding conditions and new coding benefit function. Moreover, the CCAR scheme has significant advantages regarding throughput, average end-to-end delay, and energy consumption.
Highlights
Over the past few years, given the increased requirements of the network throughput and delay in wireless networks, network coding (NC), proposed by Ahlswede et al, has received much attention [1].NC can achieve the upper limit of the maximum transmission flow
We compared the performance of constrained coding-aware routing (CCAR), distributed coding-aware routing (DCAR), and ad-hoc on-demand distance vector (AODV) + COPE under the random topology and evaluated the total throughput, average end-to-end delay, and energy consumption under different numbers of flows from 4–16
We reviewed the shortcomings of coding-aware routing in multi-flows and multi-rate networks and proposed a constrained coding-aware opportunistic routing (CCAR) to increase the performance of the multi-flow and multi-rate networks
Summary
Over the past few years, given the increased requirements of the network throughput and delay in wireless networks, network coding (NC), proposed by Ahlswede et al, has received much attention [1]. Compared with the traditional store-and-forward transmission method, NC allows for the intermediate nodes to mix some packets from different flows and broadcast the encoded packets to the receivers. NC-based routing scheme, called COPE, was proposed by Katti et al [5] They combined the routing protocol and network coding in a real network test-bed that can detect the coding opportunities and increase the network performance obviously [6]. Based on CAR, J.Le et al proposed a distributed coding-aware routing (DCAR) scheme [10]. The DCAR-type schemes have more coding opportunities and larger network throughput by PCC, they will cause imbalanced loads, for which the encoded and decoding nodes will coincide or be closed. To overcome the shortcomings of the DCAR-type schemes, we propose a constrained coding-aware routing (CCAR) mechanism, which is more energy-efficient and suitable for wireless ad-hoc networks.
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