Network Coding Scheme Research Articles

Achieving the Near-Capacity of Two-Way Relay Channels With Modulation-Coded Physical-Layer Network Coding

We propose and design a practical modulation-coded (MC) physical-layer network coding (PNC) scheme to approach the capacity limits of Gaussian and fading two-way relay channels (TWRCs). In the proposed scheme, an irregular repeat–accumulate (IRA) MC over $\textrm{GF}(q)$ with the same random coset is employed at two users, which directly maps the message sequences into coded PAM or QAM symbol sequences. The relay chooses appropriate network coding coefficients and computes the associated finite-field linear combinations of the two users' message sequences using an iterative belief propagation algorithm. For a symmetric Gaussian TWRC, we show that, by introducing the same random coset vector at the two users and a time-varying accumulator in the IRA code, the MC-PNC scheme exhibits symmetry and permutation-invariant properties for the soft information distribution of the network-coded message sequence (NCMS). We explore these properties in analyzing the convergence behavior of the scheme and optimizing the MC to approach the capacity limit of a TWRC. For a block fading TWRC, we present a new MC linear PNC scheme and an algorithm used at the relay for computing the NCMS. We demonstrate that our developed schemes achieve near-capacity performance in both Gaussian and Rayleigh fading TWRCs. For example, our designed codes over GF(7) and GF(3) with a code rate of 3/4 are within 1 and 1.2 dB of the TWRC capacity, respectively. Our method can be regarded as a practical embodiment of the notion of compute-and-forward with a good nested lattice code, and it can be applied to a wide range of network configurations.

A Low-Jitter Wireless Transmission Based on Buffer Management in Coding-Aware Routing

It is significant to reduce packet jitter for real-time applications in a wireless network. Existing coding-aware routing algorithms use the opportunistic network coding (ONC) scheme in a packet coding algorithm. The ONC scheme never delays packets to wait for the arrival of a future coding opportunity. The loss of some potential coding opportunities may degrade the contribution of network coding to jitter performance. In addition, most of the existing coding-aware routing algorithms assume that all flows participating in the network have equal rate. This is unrealistic, since multi-rate environments often appear. To overcome the above problem and expand coding-aware routing to multi-rate scenarios, from the view of data transmission, we present a low-jitter wireless transmission algorithm based on buffer management (BLJCAR), which decides packets in coding node according to the queue-length based threshold policy instead of the regular ONC policy as used in existing coding-aware routing algorithms. BLJCAR is a unified framework to merge the single rate case and multiple rate case. Simulations results show that the BLJCAR algorithm embedded in coding-aware routing outperforms the traditional ONC policy in terms of jitter, packet delivery delay, packet loss ratio and network throughput in network congestion in any traffic rates.

A User Grouping Based Opportunistic Network Coding Scheme for Multi-user Multi-relay Uplink Transmissions

In this paper, we study a User Grouping based Opportunistic Network Coding (UG-ONC) scheme for multi-user multi-relay uplink transmission scenario. In traditional opportunistic network coding (ONC) schemes, the use of network coding is often determined by the state of relays, i.e., buffer, packets waiting time, packets' successful decoding. However, whether the use of network coding is beneficial to the users is not considered. In our proposed UG-ONC scheme, whether network coding is adopted is not only determined by the state of relays, but also by the link quality between users and base station, that is, determined by the state of users. We consider two information-theoretic metrics, i.e., outage probability and throughput, to evaluate the validity and reliability of the UG-ONC scheme. And the approximate expressions of outage probability and throughput are derived. To further examine the performance of the scheme, we compare UG-ONC scheme with an existent network coding scheme. Monte Carlo simulations are presented to validate our analysis. The results show that our proposed UG-ONC scheme achieves considerable gains over the traditional network coding scheme. Our proposed UG-ONC scheme gives a new thought for designing opportunistic network coding.

Security analysis of a homomorphic signature scheme for network coding

AbstractRecently, Liu and Wang proposed a homomorphic signature scheme for network coding, which was claimed to resist against pollution attacks. However, we show that in Liu and Wang's scheme, after several generations, the adversary is able to launch a successful forgery attack with a high probability. Therefore, Liu and Wang's scheme is not secure. After analyzing the cause of the attack, an improved scheme is given, which can combat against the proposed attack in an efficient way. Copyright © 2015 John Wiley & Sons, Ltd.

Linear Vector Physical-Layer Network Coding for MIMO Two-Way Relay Channels: Design and Performance Analysis

In this paper, we propose a new linear vector physical-layer network coding (NC) scheme for spatial multiplexing multiple-input multiple-output (MIMO) two-way relay channel (TWRC) where the channel state information (CSI) is not available at the transmitters. In this scheme, each user transmits $M$ independent quadrature amplitude modulation signal streams respectively from its $M$ antennas to the relay. Based on the receiver-side CSI, the relay determines a NC generator matrix for linear vector network coding, and reconstructs the associated $M$ linear combinations of all messages. We present an explicit solution for the generator matrix that minimizes the error probability at a high SNR, as well as an efficient algorithm to find the optimized solution. We propose a novel typical error event analysis that exploits a new characterization of the deep fade events for the TWRC. We derive a new closed-form expression for the average error probability of the proposed scheme over a Rayleigh fading MIMO TWRC. Our analysis shows that the proposed scheme achieves the optimal error rate performance at a high SNR. Numerical results show that the proposed scheme significantly outperforms existing schemes, and match well with our analytical results.

Joint network and fountain codes design for relay-assisted multi-user system

In relay-assisted multi-user system, relay coding is important to enhance the robustness and reliability of cooperative transmission. For better adaptability and efficiency, two joint network and fountain coding (JNFC) schemes are proposed. When the condition of all direct channels is worse, JNFC scheme based on distributed LT(DLT) codes is used. Otherwise, JNFC scheme based on multi-dimensional LT(MD-LT) codes is suited. For both two above-mentioned schemes, the united degree distribution design method for short-length fountain codes is proposed. For the latter scheme, MD-LT codes are proposed for equal error protection (EEP) of each user. Simulation results and analysis show that the united degree distribution need less decoding overhead compared with other degree distribution for short-length fountain codes. And then, all users are protected equally in despite of asymmetric uplinks.

A Prioritized Network Coding Scheme based E-WP Algorithm for Packet Recovery in DVB-IPDC System

DVB-H is developed to broadcast digital videos to mobile handsets, but data loss is a concern due to the wireless broadcasting nature. In this paper, take WiMAX as an IPbased wireless network to recover the loss packets in DVB-H, and take E-WP based on network coding as the encoding packet selection algorithm. Furthermore, a prioritized scheme EWP-PNC based on E-WP packet selection algorithm is proposed. In this scheme, take a base station in WiMAX as encoding node to encode any two packets that meet the encoding and decoding necessary and sufficient condition into an encoding recovery packet according to the current lost packet distribution, and calculate the benefit of each encoding packet to decide the final priority of all encoding packets. The goals of this scheme are to improve the lost packet recovery ratio and reduce the discarded packet ratio. According to the simulation results, the validity of this scheme is proved.

A Prioritized Network Coding Scheme based E-WP Algorithm for Packet Recovery in DVB-IPDC System

A Prioritized Network Coding Scheme based E-WP Algorithm for Packet Recovery in DVB-IPDC System

A Network Coding Scheme to Improve Throughput for IEEE 802.11 WLAN

In IEEE 802.11 infrastructure wireless local area network (WLAN), the communication between any two nodes is relayed by an access point (AP), which becomes the bottleneck of WLAN and severely restr...

Opportunistic Network Coding Scheme for Two-Way Relay Wireless Networks: A Sum-Rate Maximization Approach

Applying network coding (NC) in the downlink of two-way relay networks can significantly increase the throughput. However, the fading nature of wireless channels usually causes great asymmetry between two downlink channels, which can degrade the performance of NC. Therefore, it is very necessary to perform an opportunistic scheme that selects between broadcast and unicast at the relay node based on channel side information. This paper focuses on the fundamental limit of the sum rate in the downlink. To solve the maximization problem of the sum rate in the downlink, we first introduce an auxiliary variable, known as marginal capacity income of transmit power, and then derive the corresponding power allocation in closed-form expression and present an opportunistic switching selection strategy between broadcast/unicast. Numerical results also show that our proposed scheme achieves a larger downlink sum throughput compared with other existing known schemes.

On the performance of network coding and forwarding schemes with different degrees of redundancy for wireless mesh networks

This work explores the throughput and delay that can be achieved by various forwarding schemes, employing multiple paths and different degrees of redundancy, focusing on linear network coding. The key contribution of the study is an analytical framework for modeling the throughput and delay for various schemes, considering wireless mesh networks where unicast traffic is forwarded and hop-by-hop retransmissions are employed for achieving reliability. The analytical framework is generalized for an arbitrary number of paths and hops per path. Another key contribution of the study is the evaluation and extension of the numerical results, drawn from the analysis, through system-level simulations. Our results show that, in scenarios with significant interference, the best throughput-delay tradeoff is achieved by single path forwarding. Moreover, when significant interference is present and network coding employs the larger packet generation size, it experiences higher delay than the other schemes. This is due to the inter-arrival times aggregating over all coded packets required to decode a packet generation.

TCPNC-DGSA: Efficient Network Coding Scheme for TCP in Multi-hop Cognitive Radio Networks

Cognitive radio (CR) has emerged as a promising solution to enhance spectrum utilization. In CR networks (CRNs), the secondary users can opportunistically exploit frequency bands when the primary users (PUs) do not occupy the bands. In this communication paradigm, transmission control protocol (TCP) performance may suffer from significant degradation due to the features of CRNs. In this paper, we investigate the limitations of TCP in multi-channel multi-radio multi-hop CRNs, and propose a novel TCP called TCP Network Coding Dynamic Generation Size Adjustment (TCPNC-DGSA) based on network coding. We dynamically adjust generation size in network coding operation according to the wireless communication environment--Generation Round Trip Time. In the meanwhile, we modify the TCP mechanism to fit into CRNs, by considering spectrum sensing state, spectrum changing state and presence of PUs. The simulation results indicate that TCPNC-DGSA can significantly improve the network performance in terms of throughput, bandwidth efficiency and delay. To the best of our knowledge, TCPNC-DGSA is the first TCP for CRNs from a network coding perspective, which can guarantee a quality of service in terms of delay.

Resource Allocation Strategies for Network-Coded Video Broadcasting Services Over LTE-Advanced

Video service delivery over 3GPP Long Term Evolution-Advanced (LTE-A) networks is gaining momentum with the adoption of the evolved Multimedia Broadcast Multicast Service (eMBMS). In this paper, we address the challenge of optimizing the radio resource allocation process so that heterogeneous groups of users, according to their propagation conditions, can receive layered video streams at predefined and progressively decreasing service levels matched to respective user groups. A key aspect of the proposed system model is that video streams are delivered as eMBMS flows that utilize the random linear network coding (NC) principle. Furthermore, the transmission rate and NC scheme of each eMBMS flow are jointly optimized. The simulation results show that the proposed strategy can exploit user heterogeneity to optimize the allocated radio resources while achieving desired service levels for different user groups.

서브 패킷 단위의 네트워크 코딩 및 채널 코딩 결합 기법

서브 패킷 단위의 네트워크 코딩 및 채널 코딩 결합 기법

Novel Section-Based Joint Network Coding and Scheduling Scheme in WMNs: JNCS

Guaranteeing quality of service over a multihop wireless network is difficult because end-to-end (ETE) delay is accumulated at each hop in a multihop flow. Recently, research has been conducted on network coding (NC) schemes as an alternative mechanism to significantly increase the utilization of valuable resources in multihop wireless networks. This paper proposes a new section-based joint NC and scheduling scheme that can reduce ETE delay and enhance resource efficiency in a multihop wireless network. Next, this paper derives the average ETE delay of the proposed scheme and simulates a TDMA network where the proposed scheme is deployed. Finally, this paper compares the performance of the proposed scheme with that of the conventional sequential scheduling scheme. From the performance analysis and simulation results, the proposed scheme gives more delay- and energy-efficient slot assignments even if the NC operation is applied, resulting in a use of fewer network resources and a reduction in ETE delay.

Security concerns and countermeasures in network coding based communication systems: A survey

This survey paper shows the state of the art in security mechanisms, where a deep review of the current research and the status of this topic is carried out. We start by introducing network coding and its variety of applications in enhancing current traditional networks. In particular, we analyze two key protocol types, namely, state-aware and stateless protocols, specifying the benefits and disadvantages of each one of them. We also present the key security assumptions of network coding (NC) systems as well as a detailed analysis of the security goals and threats, both passive and active. Current proposed security mechanisms and schemes for NC in the literature are classified too. This paper also presents a detailed taxonomy of the different NC security mechanisms and schemes reported in the literature.

Analog Network Coding for Multi-User Multi-Carrier Differential Chaos Shift Keying Communication System

This paper presents the design and performance analysis of an analog network coding (ANC) scheme for multi-user multi-carrier differential chaos shift keying (MC-DCSK) modulation. The incentives to employ the MC-DCSK system are to achieve a better spectral efficiency and more efficient energy consumption compared to that of a conventional DCSK system. The proposed scheme considers a network comprising L user nodes (L ≥ 2) and a single relay node R. In this scheme, called the ANC-based two-way relay system, all users transmit their signals to the relay in the first time slot, and the relay forwards the superposition of the received signals each of the user nodes in the second time slot. At the receiver end, each user mitigates the overall interference by subtracting its own data signal from the received combined signal and then starts the decoding process. The system design is analytically studied, and the corresponding theoretical bit error rate expression for the multipath fading channel is derived. Additionally, the conventional ANC-DCSK scheme is analyzed and compared to the proposed ANC-based MC-DCSK scheme to show the improvement in the performance of our approach. Finally, to validate the accuracy of the methodology, the simulation results are compared to the related theoretical expressions.

On the Design of Cognitive-Radio-Inspired Asymmetric Network Coding Transmissions in MIMO Systems

In this paper, a cognitive-radio-inspired asymmetric network coding (CR-AsNC) scheme is proposed for multiple-input–multiple-output (MIMO) cellular transmissions, where information exchange among users and base-station (BS) broadcasting can be accomplished simultaneously. The key idea is to apply the concept of cognitive radio (CR) in network coding transmissions, where the BS tries sending new information while helping users' transmissions as a relay. In particular, we design an asymmetric network coding method for information exchange between the BS and the users, although many existing works consider the design of network coding in symmetric scenarios. To approach the optimal performance, an iterative precoding design for CR-AsNC is first developed. Then, a channel-diagonalization-based precoding design with low complexity is proposed, to which power allocation can be optimized with a closed-form solution. The simulation results show that the proposed CR-AsNC scheme with precoding optimization can significantly improve system transmission performance.

Mixed Noisy Network Coding and Cooperative Unicasting in Wireless Networks

The problem of communicating a single message to a destination in presence of multiple relay nodes, referred to as cooperative unicast network, is considered. First, we introduce mixed noisy network coding (MNNC) scheme which generalizes noisy network coding where relays are allowed to decode-and-forward (DF) messages while all of them (without exception) transmit noisy descriptions of their observations. These descriptions are exploited at the destination and DF relays aim to decode the transmitted messages while creating full cooperation among the nodes. Moreover, the destination and DF relays can independently select the set of descriptions to be decoded or treated as interference. This concept is further extended to multihopping scenarios, referred to as layered MNNC, where DF relays are organized into disjoint groups representing one hop in the network. For cooperative unicast additive white Gaussian noise (AWGN) networks, we show that-provided DF relays are properly chosen-MNNC improves over all previously established constant gaps to the cut-set bound. Second, we consider the composite cooperative unicast network where the channel parameters are randomly drawn before communication starts and remain fixed during the transmission. Each draw is assumed to be unknown at the source and fully known at the destination but only partly known at the relays. We introduce through MNNC scheme the concept of selective coding strategy (SCS) that enables relays to decide dynamically whether, in addition to communicate noisy descriptions, is possible to decode and forward messages. It is demonstrated through slow-fading AWGN relay networks that SCS clearly outperforms conventional coding schemes.

Differential space–time network coding in MIMO two‐way relay channel network

SummaryThis paper focuses on noncoherent detection scheme for multiple‐input multiple‐output two‐way relay channel network with two two‐antennas source nodes and one single‐antenna relay node. An orthogonal differential space–time network coding (ODSTNC) scheme based on relay detection and forward protocol is proposed. The proposed scheme combines space–time coding with network coding, and the differential modulation and detection are used in both multiple access stage and broadcast stage. The multiple‐symbol differential detection is employed at the relay. The maximum likelihood decision and its low‐complexity sphere decoding decision are given. The upper and lower bounds on the average symbol error probability for this system under differential binary phase shift keying (DBPSK) are derived, and a diversity order of 2 is confirmed to be achieved. The simulation results show that the ODSTNC scheme has good performance, and it is available for the applications of far distance signal transmission between two terminals where channel state information is unknown. Copyright © 2014 John Wiley & Sons, Ltd.