Performance analysis in wireless network coding: An approach based on service curve model

This paper studies the interplay between network coding and spatial reuse in wireless mesh networks. We present a method that attempts to maximize the system performance by exploiting effectively (and not greedily) coding opportunities through appropriate routing and achieving efficient spectrum reuse through opportunistic link scheduling. We show that judiciously selecting coding structures requires proper transmission power allocation to better manage cumulative interference in the network, and thus yield better spectrum spatial reuse and effective multi-hop system throughput. We present an optimization model for this complex design problem, which relies on the enumeration of all possible schedules and decompose it into subproblems which we can solve more efficiently. Our numerical results indicate that optimal joint coding and scheduling with proper power allocation yields a performance enhancement of more than 10% over that with maximal power transmission and more than 45% enhancement over a coding oblivious design model. Our results also revealed that network coding has only marginal benefits (~6%) in a dense network and that in such networks managing interference through proper power allocation yields very good performance.

Practical wireless network coding (e.g., COPE) is a promising technique that can enhance the throughput of wireless networks. However, such a technique also bears a serious security drawback: it breaks the current privacy-preserving protocols (e.g., Onion Routing), since their operations conflict each other. As user privacy in wireless networks is highly valued nowadays, a new privacy-preserving scheme that can function with wireless network coding becomes indispensable. To address such a challenge, we apply the idea of cooperative networking and design a novel anonymity scheme named ANOC, which can function in network-coding-based wireless mesh networks. ANOC is built upon the classic Onion Routing protocol, and resolves its conflict with network coding by introducing efficient cooperation among relay nodes. Using ANOC, we can perform network coding to achieve a higher throughput, while still preserving user privacy in wireless mesh networks. We formally show how ANOC achieves the property of relationship anonymity, and conduct extensive experiments via nsclick to demonstrates its feasibility and efficiency when integrated with network coding.

This paper studies joint scheduling and network coding in wireless multicast networks with independent sources. Designing a network coding solution for wireless networks involves scheduling interference-free transmissions and optimizing a performance measure for the predetermined scheduling sets, followed by constructing network codes for the specific solution. In such a design process, the results of prior steps need to provide enough information to the subsequent steps. In this paper, we formulate a linear optimization problem whose results can be used to design a coding solution. We build our work on previous works and present statistics that show the importance of incorporating unequal timeshares in designing network codes. In particular, our statistics show a throughput improvement of about 35% in maximum flow problems and energy savings between 13% and 30%, depending on the network size, in minimum energy problems. We also present the requirements of code construction algorithms for wireless networks that capture the broadcast property of these networks and can design proper codes when timeshares are unequal. In particular, the adaptation of a centralized network coding scheme for wireless networks is discussed. Overall, the work reported here provides a three-step solution to derive network codes that optimize a performance criterion of interest while also solving the scheduling problem in multihop wireless networks.

In this paper, we investigate the problem of network coding and media scheduling in wireless multihop networks. Unique characteristics of the wireless media, such as omnidirectional transmissions and destructive interference, as well as having one transceiver per wireless node, imply new code design constraints for wireless networks. Here, we formulate a linear program to solve the joint scheduling and network coding problem. Using our formulation, we demonstrate that for a large percentage of randomly generated wireless networks, the optimal scheduling time shares are unequal. All the existing network code design algorithms are based on equal scheduling time shares or the considered joint optimization problems do not have sufficient information for scheduling flows during unequal time shares. Therefore, we provide these statistics to emphasize the importance of enabling the code design algorithms to include unequal time shares. Our simulations further show that the network throughput can be significantly improved if the network code is properly designed to incorporate unequal time shares.

In this paper, a joint network and channel coding (JNCC) strategy with retransmissions is proposed for two canonical network elements, broadcast channel with receiver side information (BC-SI) and orthogonal multiple access channel with correlated sources (MAC-CS). By extending the derived results for BC-SI and orthogonal MAC-CS to a multi-hop wireless network with multiple sources and multiple destinations (MS-MD), we propose a complete JNCC strategy. We also quantify the network throughput by applying the renewal-reward theorem. The results show that our proposed JNCC strategy outperforms conventional separate network and channel coding (SNCC) strategy with random linear network coding (RLNC), thus proving an instance where joint coding is better than separate coding in wireless networks.

In this paper, we propose an advanced transmission protocol for the next generation wireless access network using wireless network coding (WNC). As an alternative to conventional cooperative multipoint (CoMP) as described in LTE-A, WNC enables access point cooperation, combining the flows using network coding functions, instead of sending multiple separate information flows across the backhaul network. WNC in principle enables this cooperation with less backhaul load than CoMP transmission, while providing superior performance compared with CoMP in terms of outage probability.

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.

Energy efficiency is a critical problem for wireless sensor networks. In past decades, network coding has been proved as a promising technology to reduce the number of transmissions, save energy, and improve network throughput, especially suitable for the wireless network that motivates the emergence of network coding aware routings. However, existing network coding aware routings have the failure decoding problem, because of defective network coding conditions. On the other hand, existing network coding aware routings usually consider the ideal traffic scheduling and neglect nodes’ energy and load which are important to wireless sensor networks. Therefore, it is not appropriate to directly apply existing network coding aware routings in wireless sensor networks. Regarding the problems above problems, this paper proposes traffic-shaped network coding aware routing (TSCAR) for wireless sensor networks. In the TSCAR, a universal network coding condition is presented to solve the false decoding problem. And traffic shaping mechanism is proposed to shape the traffic of different flows to create more coding actions when coding opportunities exist. In addition, network calculus is used to analyze the delay of the TSCAR. Besides, a coding, load, and energy aware routing metrics are proposed to evaluate the discovered paths. Extensive simulation results demonstrate that the TSCAR increases the number of coding opportunities and the proportion of coded packets, improves network throughput, and extends the network lifetime of wireless sensor networks.

Traditional approach for data transmission in wireless networks with the shared medium, e.g., 802.11 standard family, incurs significant overheads to transmit messages in multiple source - multiple destination (MSMD) schemes. Network coding is new paradigm that increases effectiveness of transmissions in a wireless network with the shared medium and MSMD. We have considered the results of the emulation with COPE-like network coding and various Transmission Control Protocol (TCP) congestion control algorithms in wireless networks. In emulated scheme two nodes stream data to each other through bottleneck relay node. BBR TCP protocol showed the best results in this relaying scheme with enabled COPE-like network coding.

Much of the prior research on wireless network coding assumed WiFi channels. In this paper, we investigate NC performance on wireless TDMA channels. We show that a practical network coding scheme over TDMA MAC can approach theoretical network capacity in lossless conditions. We also show that TDMA wireless network coding is robust to packet loss and mobility,. Finally, we show the importance of forwarding rate to ensure reliability and performance.

A Wireless Network Coding (WNC) a.k.a. a Physical Layer Network Coding in multi-source multi-node scenarios has shown its potential to increase network throughput compared to a communication based on an orthogonal separation of individual transmissions. In this paper we analyse necessary steps that have to be done to initialize the WNC communication including mainly establishing of relay operations. In our set-up a core network (we named it a cloud), that provides the WNC capabilities of reliable source – destination communication, starts its operation with no system state (connectivity) knowledge. Our goal is to design an algorithm that is capable to gain this information directly from the received constellation that is formed by the superposition of unknown number of transmitting sources with random channel realization and provide it to any cloud node. The algorithm has to be designed to work with the minimum demands on source node cooperation, the most of the functionality is laid upon the cloud.KeywordsPhysical LayerWireless Network CodingAutomatic Modulation Classification

Achieving optimal transmission throughput in data networks is known as a fundamental but hard problem. The situation is exacerbated in multi-hop wireless networks due to the interference among local wireless transmissions. In this paper, we propose a general modeling and solution framework for the throughput optimization problem in wireless networks. In our framework, data routing, wireless medium contention and network coding are jointly considered to achieve the optimal network performance. The primal-dual solution method in the framework represents a cross-layer optimization approach. It decomposes the original problem into data routing sub-problems at the network layer, and power allocation sub-problems at the physical layer. Various effective solutions are discussed for each sub-problem, verifying that our framework may handle the throughput optimization problem in an efficient and distributed fashion for a broad range of wireless network scenarios.

The Lifted MRD (Maximum Rank Distance) code was introduced by Silva et al. to correct link errors and erasures for network coding systems. It achieves the generalized asymptotic Singleton bound for network error correction codes, and was shown to be equivalent to the Koetter-Kschischang code. However, in wireless network coding, undetected link errors that occur early in the network may accumulate and propagate beyond the decoding capability of the Lifted MRD code at the destination node. In this paper, we address this problem by a few strategies: detect and track possible error packets as erasure packets as they propagate through the network, reverse the error propagation process at the destination node by exploiting knowledge of the erasure packet positions, and double the MRD decoding capability by using erasure-and-error decoding. Algorithms to implement the above strategies are designed for low network overhead and low computational complexity. Simulation results show that the proposed scheme significantly improves the reliability of network coding over unreliable wireless links.

In this paper a practical routing algorithm is proposed that increases the network throughput irrespective of the network traffic load. Its effectiveness is based on an efficient cost function which achieves a successful trade-off between the use of the minimum-hop routes and the application of the load-balancing concept. Moreover, it employs the known Trunk Reservation notion according to a probability that increases linearly with the traffic load. This results in an effective compromise of the performance of the algorithm between light and heavy traffic loads. Finally, its simplicity and its suitability for a real-time application render it as an efficient routing algorithm for ATM networks. Copyright © 1999 John Wiley & Sons, Ltd.

We formulate a new problem which bridges between source coding and enhancement in wireless acoustic sensor networks. We consider a network of wireless microphones, each of which encoding its own measurement under a covariance matrix distortion constraint and sending it to a fusion center. To process the data at the center, we use a recent spatio-temporal prediction filter. We assume that a weighted sum-rate for the network is specified. The problem is to allocate optimal distortion matrices to the nodes in order to achieve a maximum output SNR at the fusion center after processing the received data, while the weighted sum-rate for the network is no more than the specified value. We formulate this problem as an optimization problem for which we derive a set of equalities imposed on the solution by studying the KKT conditions. In particular, for the special case of scalar sources with two microphones and a sum-rate constraint, we derive the distortion allocation in closed form and will show that if the given sum-rate is higher than a critical value, the stationary points from the KKT conditions lead to distortion allocations which maximize the output SNR of the filter