Delay Control Network Coding Technique

—In this paper, we consider the problem of minimizing the delay for data exchange among a group of wireless clients, where each client initially holds a subset of the packets and needs to get all the packets held by other clients. It is assumed that clients cannot communicate with each another directly, they can only exchange packets through a wireless relay. To minimize the total transmission delay during data exchange process, we need to determine at every client, which packets to be uploaded and how to encode the packets. It is also important for the relay node to decide how to encode multiple packets from different clients and select the transmission rate in the downloading process, such that every client can decode all required packets in shortest delay. We first formulate theoretically the above problem of minimizing the total transmission delay as an integer programming, and show that its complexity is NP hard. We then propose an efficient heuristic algorithm, which consists of two processes: uploading process, i.e., how to select and encode the packets from the clients to the relay, and downloading process, i.e., how the relay encode packets and select transmission rate for broadcast to all clients. For each process, theoretical formulation has been derived to minimize their transmission delay, and efficient algorithms are proposed separately. Finally, simulation results demonstrate the effectiveness of the proposed algorithm in reducing the total data exchange delay.

In this work, we present an analytical study of the average delay and network throughput for packet dissemination using network coding in multihop wireless network scenario, where the generation of the packets is a stochastic process. The main challenge for the relay when it receives a packet is whether to wait for a coding opportunity and therefore reduce the network congestion or to send the packet directly without coding and reduce the packet delay. So, we propose a probabilistic approach for the relay when it receives a packet, and then we develop an analytical framework to address the trade-off between the throughput and the delay, we investigate the condition to maintain the stability of the system. We also provide the optimum transmission probability that achieves the minimum fair delay between the two sources and results in an optimum throughput. In the symmetric case (e.g. two flows with the same rate), we show that the optimum fair delay can be achieved with probability of transmission 0.5. We also show that despite of the flow data rate, using this probability in symmetric flows will result in an almost 33 per cent improvement in the bandwidth consumption and in an equal hop delay for both flows that is 0.5/λ where λ is the average flow data rate. Moreover, for asymmetric rate flows, we provide the optimum transmission probability and its corresponding fair delay and throughput improvement. We carry out simulation to verify our analytical model.

2013 IEEE International Conference on Communications (ICC), 2013

A characterization of systematic network coding over multi-hop wireless networks is key towards understanding the trade-off between complexity and delay performance of networks that preserve the systematic structure. This paper studies the case of a relay channel, where the source's objective is to deliver a given number of data packets to a receiver with the aid of a relay. The source broadcasts to both the receiver and the relay using one frequency, while the relay uses another frequency for transmissions to the receiver, allowing for a full-duplex operation of the relay. We analyze the decoding complexity and delay performance of two types of relays: one that preserves the systematic structure of the code from the source; another that does not. A systematic relay forwards uncoded packets upon reception, but transmits coded packets to the receiver after receiving the first coded packet from the source. On the other hand, a non-systematic relay always transmits linear combinations of previously received packets. We compare the performance of these two alternatives by analytically characterizing the expected transmission completion time as well as the number of uncoded packets forwarded by the relay. Our numerical results show that, for a poor channel between the source and the receiver, preserving the systematic structure at the relay (i) allows a significant increase in the number of uncoded packets received by the receiver, thus reducing the decoding complexity, and (ii) preserves close to optimal delay performance.

Proceedings of the 13th annual ACM international conference on Mobile computing and networking - MobiCom '07, 2007

Network coding is seen as a promising technique to improve network throughput. In this paper, we study two important problems in localized network coding in wireless networks, which only requires each node to know about and coordinate with one-hop neighbors. In particular, we first establish a condition that is both necessary and sufficient for useful coding to be possible. We show this condition is much weaker than expected, and hence allows a variety of coding schemes to suit different network conditions and application preferences. Based on the understanding we establish, we are able to design a robust coding technique called loop coding that can improve network throughput and TCP throughput simultaneously.

In this paper we have analysed the different types of Information exchange in wireless network that includes Unicast, Broadcast & Multicast &elaborate about the role of Network coding in such information exchanges. Recently it has been shown that network coding improves network reliability by reducing the number of packet retransmission. Network coding is a developing method which is currently pragmatic to wireless networks to improve network throughput and other performance. Contemplate cooperative wireless network in which there are several sources & several relays. The unreliable wireless channels, the quality of network links between nodes can vary; which result in the failure of intermediate nodes which results in to the linear combination of incoming massage in network coding scheme. At base station we have proposed the recovery performance of sources massages.

2009

Abstract We survey a representative subset of proposed protocols that use network coding in wireless environments. We provide a comparison of these with respect to the following aspects: supported communication primitives, backward compatibility, layers involved (from physical to transport layer), and implementation complexity. The report concludes with directions for future research.

2013 International Conference on Green Computing, Communication and Conservation of Energy (ICGCE), 2013

Network coding is a new technology that motivates us to rethink about networking in wireless networks. Network coding of wireless helps to improve the performance networks. The existing network infrastructure will not support to the network coding communications. This concept requires us modifying the existing network communications. In this paper we brief the principles of network coding, network coding techniques, benefits and applications. We also discuss the current research topics of interest and the issues related to network coding aware routing in wireless ad hoc networks and we also present the simulation results which describe the energy gain and number of transmissions in traditional routing versus network coding.

IEEE Journal on Selected Areas in Communications, 2009

In recent years, network coding has become one of the most interesting fields and has attracted considerable attention from both industry and academia. The idea of network coding is based on the concept of allowing intermediate nodes to encode and combine incoming packets instead of only copy and forward them. This approach, by augmenting the multicast and broadcast efficiency of multi-hop wireless networks, increases the capacity of the network and improves its throughput and robustness. While a wide variety of papers described applications of network coding in different types of networks such as delay tolerant networks, peer to peer networks and wireless sensor networks, the detailed practical implementation of network coding has not been noted in most papers. Since applying network coding in real scenarios requires an acceptable understanding of mathematics and algebra, especially linear equations, reduced row echelon matrices, field and its operations, this paper provides a comprehensive guidance for the implementation of almost all required concepts in network coding. The paper explains the implementation details of network coding in real scenarios and describes the effect of the field size on network coding.

This paper focuses on using Network Coding (NC) with TCP for multi-hop wireless networks to provide faulttolerant and timely delivery of streaming data. The paper shows that there is an inherent latency in video playback when TCP with random linear NC is employed. With the objective of reducing latency and jitter at the receiver, the paper proposes a Variable Bucket size based Network Coding (VBNC) technique that modifies the TCP congestion control to adapt to the arriving traffic and dynamic network conditions. Simulation results demonstrate that on an average the proposed algorithm reduces observed latency at playback by 80% and jitter by more than 50% over standard TCP. More importantly, a significant reduction in the initial start-up delay is observed which enhances the performance of streaming services.

Wireless networks are one of the most essential components of the communication networks. In contrast to the wired networks, the inherent broadcast nature of wireless networks provides a breeding ground for both opportunities and challenges ranging from security to reliability. Moreover, energy is a fundamental design constraint in wireless networks. The boom of wireless network is closely coupled with the schemes that can reduce energy consumption. Network coding for the wireless networks is seen as a potential candidate scheme that can help overcome the energy and security challenges while providing significant benefits. This paper presents a basic model for formulating network coding problem in wireless setting. Since the optimal solution to wireless network coding is NP (nondeterministic polynomial-time)-hard, we intend to explore the impact of different parameters with random and non-random solutions. We present extensive simulation to show the strength of random network coding scheme in general wireless network scenarios. This study provide a comprehensive insight into the limits of wireless network coding.

IEEE Transactions on Information Theory, 2012

We study the throughput-delay performance tradeoff in large-scale wireless ad hoc networks. It has been shown that the per source-destination pair throughput can be improved from Θ(1/ √ n log n) to Θ(1) if nodes are allowed to move and a 2-hop relay scheme is employed. The price paid for such an improvement on throughput is large delay. Indeed, the delay scaling of the 2-hop relay scheme is Θ(n log n) under the random walk mobility model. In this paper, we employ coding techniques to improve the throughput-delay trade-off for mobile wireless networks. For the random walk mobility model, we improve the delay from Θ(n log n) to Θ(n) by employing Reed-Solomon codes. Our approach maintains the diversity gained by mobility while decreasing the delay.

2007

Network coding is a new paradigm that is promising to change the way networking is done. In network coding intermediate nodes combine different packets to exploit more bandwidth and throughput. In addition, network coding reduces both delay and energy requirements.

2009 IEEE 9th Malaysia International Conference on Communications (MICC), 2009

Owing to its potential of enhancing the network performance and to the large number of applications it can be suited for, wireless network coding is attracting a lot of interest from both the academic and the industrial communities. A common assumption in most of the literature is the presence of a single intermediate relay node where the network coding operation takes place. However, in an actual wireless system, a multitude of relaying nodes would exist, thus potentially further improving the performance; but with this the issue of relay selection arises. In this paper we study the performance of network coding in presence of opportunistic relay selection. We conjecture that relay selection schemes should be aware of, and account for, the network coding operation in case of its presence. Based on system level simulation results, it is demonstrated that such an awareness provides considerable capacity gains as compared to its traditional opportunistic counterparts, in addition to increased fairness among the encoded sources.

2008 5th IEEE International Conference on Mobile Ad Hoc and Sensor Systems, 2008

Network coding is a highly efficient data dissemination mechanism for wireless networks. Since network coded information can only be recovered after delivering a sufficient number of coded packets, the resulting decoding delay can become problematic for delay-sensitive applications such as real-time media streaming. Motivated by this observation, we consider several algorithms that minimize the decoding delay and analyze their performance by means of simulation. The algorithms differ both in the required information about the state of the neighbors' buffers and in the way this knowledge is used to decide which packets to combine through coding operations. Our results show that a greedy algorithm, whose encodings maximize the number of nodes at which a coded packet is immediately decodable significantly outperforms existing network coding protocols.