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The multi-hop wireless sensor network (WSN) suffers from energy limitation and eavesdropping attacks. We propose a simple and energy-efficient convergecast mechanism using inter-flow random linear network coding that can provide confidentiality to the multi-hop WSN. Our scheme consists of two steps, constructing a logical tree of sensor nodes rooted at the sink node, with using the Bloom filter, and transmitting sensory data encoded by sensor nodes along the logical tree upward to the sink where the encoded data are decoded according to our proposed multi-hop network coding (MHNC) mechanism. We conducted simulations using OMNET++ CASTALIA-3.3 framework and validated that MHNC outperforms the conventional mechanism in terms of packet delivery ratio, data delivery time and energy efficiency.

The network coding mechanism has attracted much attention because of its advantage of enhanced network throughput which is a desirable characteristic especially in a multi-hop wireless network with limited link capacity such as the device-to-device (D2D) communication network of 5G. COPE proposes to use the XOR-based network coding in the two-hop wireless network topology. For multi-hop wireless networks, the Distributed Coding-Aware Routing (DCAR) mechanism was proposed, in which the coding conditions for two flows intersecting at an intermediate node are defined and the routing metric to improve the coding opportunity by preferring those routes with longer queues is designed. Because the routes with longer queues may increase the delay, DCAR is inefficient in delivering real-time multimedia traffic flows. In this paper, we propose a network coding-aware routing protocol for multi-hop wireless networks that enhances DCAR by considering traffic load distribution and link quality. From this, we can achieve higher network throughput and lower end-to-end delay at the same time for the proper delivery of time-sensitive data flow. The Qualnet-based simulation results show that our proposed scheme outperforms DCAR in terms of throughput and delay.

A simple relay selection scheme is proposed for analog network coding using differential modulation (ANC-DM). We propose a relay selection scheme based solely on the received signal power in which their own information is canceled out at each source node. The proposed power-based relay selection scheme is further applied to analog network coding using double-differential modulation (ANC-DDM), which is suitable for channels with carrier offset. Simulation results show that our proposed simple power-based criterion for relay selection in ANC-DM system has little loss compared to the optimal relay selection scheme using ideal BER.

In this paper, we mathematically analyze bit-error rate (BER) and diversity order of physical-layer network coding (PNC) scheme in the two-way relay channel (TWRC) under the assumption of multiple antennas at relay node. We assume the quadrature phase shift keying (QPSK) modulation for simple data transmission in IoT applications, and max?min transmit antenna selection (TAS) scheme in the broadcast (BC) phase for achieving full diversity gain. In particular, we obtain the upper bound of BER at the multiple access (MA) phase, while deriving the exact BER performance at the BC phase. To the best our knowledge, the mathematical analysis in this paper is the first analytical results in the literature. Through computer simulations, the analytical results are validated.

Versatile Video Coding (VVC) promised to provide the same video quality as HEVC with 50 % bitrate reduction, which was introduced in 2020. Our suggested method for VVC Intra-coding is residue super-resolution convolutional neural network (RSR-CNN) utilizing downsampling and upsampling procedures. We present an effective complexity reduced VVC intra-coding scheme based on residue SR-CNN. Reducing an original video's resolution in both the vertical and horizontal directions is all that is required to execute down sampling. Increasing the video dimensions for improved visual quality, convolutional neural networks are utilized in the upsampling process to create residue super-resolution. Specifically, for every block, we train a CNN model to perform residue SR after downsampling and compressing the residue at low resolution, and then we carry out motion estimation (ME) and motion compensation (MC) to extract the residue. Using the MC prediction signal, a new residue SR-CNN is designed. Additionally, this work comprehensively examines the complexity and performance of VVC intra-coding tools and integrates them with the residue SR-CNN method. The experiments demonstrate a substantial time savings of 40 % in encoding with BDBR coding gains of 4.2 %, and 2.9 % in AI and RA configurations respectively.

네트워크의 성능 향상을 위해 제안된 네트워크 코딩은 P2P 시스템과 같은 멀티캐스팅 네트워크의 성능을 향상 시킨다고 알려져 있다. 네트워크 코딩 기법은 발신지와 목적지 사이의 중간 노드들에서 부호화 작업이 이루어지고, 목적지 노드에서는 여러 단계를 거쳐 부호화된 데이터를 전달 받기 때문에 발신 노드가 보낸 실제 정보를 얻기 위해서 복호화 과정을 거쳐야 하므로 복호화 연산의 성능은 전체 네트워크의 성능에 영향을 미치게 된다. 본 연구에서 복호화 과정에 필요한 갈로아 유한체에서의 가우스 소거법 연산을 FPGA(Field Programmable Gate Array)를 이용한 HW기반 가속화 시스템을 구현하였다. 논문에서는 하드웨어 구현에 있어 병렬처리, 파이프라인 데이터 처리 등의 이슈에 대해 논하고, 그 성능을 범용 시스템 상에서 SW로 수행하는 경우와 비교하였다. FPGA를 활용하여 복호화 전용 가속기능을 구현할 경우, Pentium 4 기반의 범용 시스템과 비교해서 20배, ARM기반 임베디드 시스템에 비해서는 140배 이상의 성능향상을 보였으며, 이를 활용할 경우 소규모의 연산 자원을 이용해서 효율적인 네트워크 코딩 시스템을 구현할 수 있을 것으로 기대된다.

Network Coding enhances performance of multi-cast network system, e.g., P2P(Peer-to-Peer) system. The Receivers in the network that use network coding technique have to decode the received messages which are encoded by intermediate nodes as well as sender node. Hence, decoding operations of network coding system are more complex than those of normal network system; therefore, performance of decoding operations have a significant influence on performance of the entire network system. In this paper, we address the issues regarding implementation of FPGA-based acceleration engines of Gaussian eliminations on finite Galois field. We compare the decoding performance on FPGAs with SW based implementations on P-4 processor and ARM embedded processor. The result shows that FPGA implementation outperforms contemporary widespread P-4 processor and ARM processors by 20 and 140 times, respectively. Utilizing the technique introduced in this paper, an efficient network coding system could be realized with a low level of computing resources.

현재 실시간 스트리밍 서비스와 P2P 파일 공유와 같은 대용량 데이터 전송에 대한 지역 가 입자들의 요구는 날이 갈 수록 증가하고 있는 추세이다. E-PON 시스템은 기본적으로 IEEE 802.1D 브리지 기능을 사 용하여 지역가입자간 데이터를 주고받는 방법을 제공한다. 그러나 증가된 지역 가입자간 전송 요구는 동일한 링 크 대역폭을 공유하는 외 부 인터넷 트래픽의 품질에 심각한 영향을 미칠 수 있다. 지역 가입자간 데이터 교환을 위해 단순히 발신지의 패킷 을 목적지에 전달하는 기존의 통신 방법으로는 이에 대한 효과적인 대처를 할 수 없다. 본 연구에서는 지역 통신의 방법으로 패킷 burst 개념의 네트워크 코딩을 적용한 E-PON 시스템을 제안한다. 제안된 시 스템은 하향으로 전달 되는 지역 패킷 량을 줄여서 외부 인터넷 트래픽을 수용할 수 있도록 상대적으로 확장된 대 역폭을 제공한다. 기존의 전송 방법에 비해 제안된 시스템은 PON 내부 트래픽에 대하여 throughput, delay 성능을 향 상시킬 뿐 아니라, 외부 인터넷 서비스의 품질 저하를 줄일 수 있는 효과가 있음을 실험 결과는 보여주고 있다.

Recently, the demand for the local traffic such as real-time streaming and P2P file- sharing requiring large amounts of data is rapidly rising. The E-PON in itself supports a communication mechanism for local subscribers using the IEEE 802.1D bridge function. However, the increased request for local communication whose traffic is jointed into external Internet seriously deteriorates the quality of Internet service. Depending on the existing bridge function for local data exchange that simply relays a packet to the destination can not handle this problem effectively. In this study, for local communication, we proposes a novel E-PON system employing network coding with a packet burst concept. The proposed E-PON system provides relatively extended bandwidth for Internet traffic by reducing the number of local packets for downstream. Compared to existing system, simulation results show that the proposed achieves considerable improvement in performance regarding throughput and delay for intra-PON traffic as well as the quality of service for external Internet traffic.

In this paper, we propose a joint distributed rate control algorithm and distributed resource allocation algorithm in multiradio multichannel multihop wireless networks with network coding. Our formulation provides a method of finding active links from the source to the destination and utilizing the resources from the available ones in order to maximize the network utility. Distributed schemes are used to approximate the upper bound within the feasible solution region of the optimization problem. The performance evaluation results show that the proposed scheme can effectively exploits multiple radios and channels.

최근 이동통신 뿐 만 아니라 TV방송 등에서도 릴레이를 이용한 양방향 무선채널의 전송효율을 높이기 위한 네트워크 코딩에 관한 연구가 활발히 진행되고 있다. 본 논문에서는 동시에 여러 개의 릴레이가 전송하는 대신 최선 의 릴레이를 이용하여 양방향 데이터를 전송하는 네트워크 코딩 시스템의 평균 전송용량 및 오수신율을 유도하였다. 일반적으로 양방향 통신 시스템의 경우 순방향 및 역방향 링크의 데이터 비대칭성이 존재하므로, 데이터 대칭 링크와 비대칭 링크도 포함하여 성능을 유도하였다. 유도한 결과 병렬 릴레이의 수가 증가할수록 공간 다이버시티에 의한 신 호 대 잡음비(SNR) 이득이 증가함을 알 수 있었고, 대칭 링크의 경우 주어진 조건하에서 단일 릴레이를 사용하였을 때보다 9개의 릴레이가 존재하는 경우 11.4 dB의 SNR 이득을 얻을 수 있었다. 또한 비대칭 링크의 경우, 오수신율은 데이터 비대칭성보다는 릴레이의 수에 민감하다는 결과를 얻었다.

Recently, network coding has been actively studied to increase the spectral efficiency of two-way relay wireless channels such as cellular systems as well as broadcasting systems. In this paper, we derive the average transmission capacity and the outage probability of a network coding system, which utilizes two-way data transmission via the best relay rather than multiple relays. Since the data unbalance between the forward and the reverse link in two-way communication systems exists, we include the asymmetric link as well as the symmetric link in the analysis. It is noticed that the space diversity gain increases as the increase of the number of relays. Also we obtain 11.4 dB signal-to-noise ratio (SNR) gain with 9 relays compared to that with single relay in symmetrical link at the given conditions. In asymmetrical links, we denotes that the outage probability is more sensitive to the number of relays rather than data unbalance between the links.

본 논문에서는 네트워크 코딩 및 파운 테인 코드를 사용한 간단한 양방향 전송 프로토콜을 제안한다. 특히, 제안된 기법의 경우, 두 소스는 중계기의 도움으로 서로에게 메시지를 전송하기위해 디지털 파운틴 코드를 사용한다. 또한, 중계기는 파운틴 코드와 네트워크 코딩을 사용하여 수신 받은 소스의 메시지를 서로의 소스에게 전송한다. 제 안된 프로토콜의 성능을 평가하기위해 레일리 페이딩 채널에서 다양한 몬테-카를로 시뮬레이션을 통하여 전체 평균 처리량을 확인한다. 그 결과 제안된 프로토콜은 높은 SNR 영역에서 네트워크 코딩 기술을 사용하지 않는 두 방향 릴 레이 전송 프로토콜보다 우수함을 확인하였다.

In this paper, we propose a simple bidirectional transmission protocol using network coding and digital Fountain codes. In particular, in the proposed scheme, two sources use digital Fountain codes to transmit their message to each other with the help of relays. Then, relays use Fountain codes and network coding to forward the source messages to both sources. To evaluate performance of the proposed protocols, we present the average total throughput over Rayleigh fading channels via Various Monte-Carlo simulations. Results show that the proposed protocol outperforms the two-way relaying transmission protocol without using network coding technique at high SNR region.

실제 네트워크에서 압도적인 비중을 차지하는 TCP 트래픽의 성능은 네트워크 코딩 기법에서도 고려해야 할 중요한 요소이다. 그러나 무선 메쉬 네트워크에서의 네트워크 코딩 기법이 새로이 제안될 때 이를 위한 성능 평가는 대개의 경우 전송 계층에서의 프로토콜로서 TCP가 아닌 다른 프로토콜을 사용하여 이루어져 왔다. 이는 네트워크 코딩의 패킷 전송 형태에 대한 영향이 TCP 성능에 부정적인 요소로 작용하기 때문이다. 네트워크 코딩을 기반으로 하는 대부분의 무선 메쉬 네트워크 패킷 전송 방식에서는 패킷들을 받은 노드들 중 어느 노드가 네트워크 코딩을 하여 전달할 것인가를 정한다. 본 논문에서는 이 전달자 노드들이 TCP 성능에 미치는 영향에 대해 살펴본다.

Most traffic in the real internet is TCP traffic. Therefore newly proposed network coding schemes must consider their effects on TCP performance. However, in most studies on network coding, performance evaluation has been conducted using other types of traffic than TCP traffic because network coding has effects on the pattern of packet transmission, which again can impact TCP performance. In most packet transmission schemes based on network coding for wireless mesh networks, it is determined which node, among the ones that received a broadcasted packet, should encode and forward it. In this paper, we examine how the forwarder nodes impact TCP performance.

In this paper, we consider the transmission scheme for asymmetric decode-and-forward (DF) multi-input multi-output (MIMO) two-way relay system with channel estimation error. In order to transmit with asymmetric data rates from the relay to the receivers according to their individual link qualities, we propose a novel transmission scheme for the broadcast phase by employing a priori bit information. The proposed scheme employs multi-antenna and network coding at the relay. The idea is the weaker link receiver exploits a priori bit information in each transmit symbol, so that it only needs to decode on a subset of the transmit symbol constellation. Subject to the same bit error rate constraint, the weaker link receiver can decode at lower signal-to-noise ratio compared to the stronger link. The different signal labeling used for mapping bits to symbols at the relay cause different minimum Euclidean distance, so it is shown to be crucial for the performance at the receivers. Subsequently, we investigate the effect of the channel estimation error on the system performance. Simulations show that the proposed transmission scheme can be applied to practical scenarios with asymmetric channel qualities.

네트워크 코딩이 사용되는 무선 메쉬 망에서의 TCP 처리량 저하 문제가 잘 알려져 있는 것에 비하면 효과적인 해결방안은 아직 많이 제안되지 않은 편이다. 지금까지 제안된 대부분의 방안들은 네트워크 코딩의 부작용으로 나타나는 패킷 바뀜 현상을 완화하기 위해 하위 계층에서 패킷 순서를 맞추도록 하거나 코딩 기회의 희소성 문제를 해결하기 위해 네트워크 내부에서의 패킷 전송률을 조정하려고 한다. 본 논문에서는 기존의 표준 TCP들에 대한 모의실험을 통해, TCP 승인 패킷의 손실과 복제 또한 TCP의 처리량에 상당한 영향을 미칠 수 있음을 보여주고 코드화된 무선 메쉬 망에서의 TCP 처리량 문제의 해소를 위해서는 중복 승인에 의존하지 않는 TCP가 더 적합함을 보여준다.

While the TCP throughput degradation problem in coded wireless mesh networks is well-known, few effective solutions have been proposed. Most schemes proposed attempts to mask packet reordering by ordering packets at a lower layer or to adjust a packet transmission rate to solve the scarcity problem of coding opportunities. Through the throughput comparison of traditional standard TCP variants, we show that losses and duplication of TCP acknowledgements in coded wireless mesh networks can impact throughput. In addition, we show that a TCP variant that does not rely on duplicate acknowledgements is more suitable for coded wireless mesh networks.

양방향 중계 채널에서는 중계기가 복호 후 재전송 혹은 증폭 후 재전송 프로토콜을 기반으로 두 사용자에게 네트워크 부호화된 신호를 전송한다. 이러한 양방향 중계 채널 시스템에서 신호 대 잡음비(SNR)가 낮은 환경에서는 복호 후 재전송 프로토콜이 최대 전송량을 가지고, 신호 대 잡음비가 높은 환경에서는 증폭 후 재전송 프로토콜이 최대 전송량을 가진다. 따라서 본 논문에서는 양방향 중계 채널에서 중계기가 수신한 신호 대 잡음비에 따라 증폭 후 재전송(Amplify-and-Forward, AF) 혹은 복호 후 재전송(Decode-and-Forward, DF)프로토콜을 결정하는 능동적인 전송 기법을 제안하였다. 전송 기법이 스위칭(switching)되는 최적의 임계값을 계산하였고, 제안하는 기법이 기존의 양방향 중계 채널에서의 전송 기법보다 우수한 전송량을 보임을 수식적인 결과를 통해 확인하였다.

In the two-way relay channel, the relay employ Amplify-and-Forward (AF) or Decode-and-Forward (DF) protocol, and broadcast the network-coded signal to both user. In the system, DF protocol provides maximum throughput at low signal to noise ratio(SNR). On the other hand, at high SNR, AF protocol provides maximum throughput. The paper propose active transmission scheme which employ Amplify-and-Forward or Decode-and-Forward protocol based on received SNR at the relay over Two-way relay channel. The optimal threshold is investigated numerically for switching the protocol. Through numerical results, we confirm that the proposed scheme outperforms conventional schemes over two-way relay channel.

Network Coding (NC) is a new paradigm for network communication. In network coding, intermediate nodes create new packets by algebraically combining ingress packets and send it to its neighbor node by broadcast manner. NC has rapidly emerged as a major research area in information theory due to its wide applicability to communication through real networks. Network coding is expected to improve throughput and channel efficiency in the wireless multi-hop network. Many researches have been carried out to employ network coding to wireless ad-hoc network. In this paper, we proposed a dynamic queue management to improve coding opportunistic to enhance efficiency of NC. In our design, intermediate nodes are buffering incoming packets to encode queue. We expect that the proposed algorithm shall improve encoding rate of network coded packet and also reduce end to end latency. From the simulation, the proposed algorithm achieved better performance in terms of coding gain and packet delivery rate than static queue management scheme.

Network Coding (NC) is a new paradigm for network communication. In network coding, intermediate nodes create new packets by algebraically combining ingress packets and send it to its neighbor node by broadcast manner. NC has rapidly emerged as a major research area in information theory due to its wide applicability to communication through real networks. Network coding is expected to improve throughput and channel efficiency in the wireless multi-hop network. Many researches have been carried out to employ network coding to wireless ad-hoc network. In this paper, we proposed a dynamic queue management to improve coding opportunistic to enhance efficiency of NC. In our design, intermediate nodes are buffering incoming packets to encode queue. We expect that the proposed algorithm shall improve encoding rate of network coded packet and also reduce end to end latency. From the simulation, the proposed algorithm achieved better performance in terms of coding gain and packet delivery rate than static queue management scheme.

A Mobile Ad Hoc Network (MANET) is a dynamic wireless network that can be formed without the need for any pre-existing infrastructure in which each node can act as a router. Due to bandwidth constraint and dynamic topology of mobile ad hoc networks, multipath supported routing is a very important research issue. This paper proposes a Network Coding-based Priority-packet Scheduler Multipath routing in MANET using fuzzy controllers (NC-PSM). Specifically, differentiated packet scheme with feedback preference information (FPI) is studied in detail to illustrate the implement of the new approach. Simulation shows that the approach is efficient, promising and applicable in MANETs. The performance of the NC-PSM is studied using NS2 and evaluated in terms of the packet delivery ratio, packet overhead, and average end-to-end delay when a packet is transmitted. Simulation shows that the approach is efficient, promising and applicable in MANETs.

Since wireless sensor networks have limited energy resources, energy efficiency and reliable data transmission rate are key issues in designing the topology. In this paper, a new root protocol NCQ-DD is proposed in order to solve the issue of limited performance of DD in wireless sensor networks. NCQ-DD greatly improves traditional DD protocol by utilizing random linear network coding technology and service quality perception. Experimental results show that the new routing protocol can save network bandwidth resources and sensor node’s energy, improve data transmission rate and ensure reliable transmission, thus increasing the lifetime of sensor networks.

Privacy threat is one of crucial issues for the wide deployment of Vehicular Ad-hoc Networks. Due to the open nature of the wireless communications, many kinds of attacks such as eavesdropping and traffic analysis can be launched by various malicious adversaries. Network coding allows intermediate nodes to encode/mix incoming message, thus it can provide a feasible way to thwart effectively eavesdropping and traffic analysis attacks. Inspired by newly developed secure network coding solution, we propose a privacy preservation scheme for online service access in VANET. The proposed scheme can achieve data confidentiality and flow untraceability, and protect the identity and location privacy of vehicles. Moreover, because lightweight coding operation is performed on message content instead of computation-expensive public key encryption, the proposed scheme is much more efficient than traditional privacy preservation scheme, such as Mix-net and Onion Routing based scheme. Finally, security analysis and simulation demonstrate the validity and efficiency of the proposed scheme.