Earticle

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.

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.

Network coding is a new method for forwarding network throughput in digital communication systems. In this paper, we introduce an efficient scheme for protecting the source data against wiretapper in linear network coding. The proposed scheme is implemented on the generated data packets in source node. We employ a well-known permutation function called Mobius transformation to transfer the existing data packet to an appropriate interchanged data packet. Then the new data packet can be sent to the intermediate nodes via output links of the source node in network securely. Indeed, the security of the proposed scheme against wiretapper is provided by employing Mobius transformation and interleaver operation on the generated data packet in source node. In the absence of cryptography systems, the proposed method is a light weight security scheme for network coding that can provide a security level easily.

네트워크 코딩위에서의 TCP 성능문제를 해결하기 위해 제안된 가장 잘 알려진 방식에서는 네트워크 코딩 계층이 혁신적인(innovative) 선형 결합을 수신하면 새로 디코드 된 패킷이 없다 하더라도 승인을 보낸다. 이 방식은 매우 효과적이지만 실제로 구현될 때에는 패킷 헤더 크기의 제한으로 인해 코딩 윈도우 크기를 제한해야 하므로 패킷 순서 바뀜 현상이 많이 발생할 때 성능이 저하될 수 있다. 본 연구에서는 네트워크 코딩 환경에서도 패킷 순서 바뀜 현상과 관련된 문제를 다루기 위해서는 중복승인을 사용하지 않고 타이머에 의존하는 TCP가 필요함을 주장한다. 또한 이러한 TCP를 위한 새로운 네트워크 코딩계층을 제안한다. 모의실험 결과는 두 개의 경로를 사용하는 라우팅 환경에서 패킷 순서가 바뀌어 수신되는 패턴에 따라 최대 19%까지 성능이 개선됨을 보여준다.

In one of the most impacting schemes proposed to address the TCP throughput problem over network coding, the network coding layer sends an acknowledgement if an innovative linear combination is received, even when a new packet is not decoded. Although this scheme is very effective, its implementation requires a limit on the coding window size. This limitation causes low TCP throughput in the presence of packet reordering. We argue that a TCP variant detecting a packet loss relying only on timers is effective in dealing with the packet reordering problem in network coding environments as well. Also we propose a new network coding layer to support such a TCP variant. Simulation results for a 2-path environment show that our proposed scheme improves TCP throughput by 19%.

본 논문에서는 다수의 릴레이(Relay)가 존재하는 환경에서 네트워크 부호화 기반 양방향 중계기 통신의 릴레이 선택 기법을 제안한다. 양방향 중계기 통신은 두 사용자가 릴레이의 도움을 받아 서로의 데이터를 교환하는 통신 방법이다. 네트워크 부호화 기반 양방향 중계기 통신은 기존의 양방향 통신에 비해 데이터 전송에 필요한 시간을 줄임으로써 더 높은 전송량을 얻을 수 있다. 본 논문에서는 다수의 릴레이가 존재하는 환경을 고려하며, 순시 신호 대 잡음비를 기준으로 최대의 성능을 가지는 릴레이를 선택하는 방법을 제안한다. 모의실험을 통하여 제안한 릴레이 선택 기법이 릴레이 개수에 따른 다이버시티 이득을 얻을 수 있음을 보인다.

In This Paper, we propose relay schemes for network-coding based two-way relay communication in multi relay channel. Two-way relay channel communication is a bi-directional communication that two users exchange their data with the help of a relay. Network-coding based Two-way relay communication can achieve more throughput compared to conventional two-way relay communication. In this paper, we propose relay selection schemes to provide maximum performance considering instantaneous signal-to-noise in multi-relay channel. Simulation results show that the proposed relay selection schemes can provide diversity order according to the number of relays.

본 논문에서는 두 사용자가 서로의 정보만을 주고받는 기존의 다중 홉 양방향 중계 통신과는 다른 두 사용자가 두 목적지 노드로 신호를 전송하는 새로운 양방향 중계통신 기법을 제안한다. 또한 기존의 다중 홉 양방향 중계 통신에서는 각 노드가 수신신호에서 자신의 신호 성분을 제거하는 back-propagating self-interference 기법을 수행해야하며, 이로 인해 각 노드에서 신호처리 복잡도가 크게 증가하는 문제점이 있다. 이러한 문제점을 해결하기 위해 본 논문에서는 back-propagating self-interference 과정을 줄일 수 있는 Pre-cancellation 기법을 적용한다. 제안하는 기법이 기존의 다중 홉 양방향 중계 통신보다 우수한 성능을 보임을 시뮬레이션 결과로 보여주며, Pre-cancellation 기법의 사용 유무에 따른 시스템 복잡도와 성능간의 trade-off관계를 분석한다.

In this paper, we propose novel two-way relaying scheme in which number of two users transmit the signal to number of two destination. The scheme is difference with conventional multi-hop two-way relay scheme in which number of two users exchange the each signal. In the conventional scheme, each user have to perform back-propagating self-interference method to remove the own signal from received signal. It occurred to increase the complexity for signal processing at the user. To overcome the problem, we apply the Pre-cancellation which can reduce the process of back-propagating self-interference to our proposal network Simulation result show that proposal scheme outperform the convention multi-hop two-way relay scheme. Also we analysis the trad-off between performance and complexity accordance with using Pre-cancellation method.

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.

Network coding is an emerging approach which is currently applied to wireless networks to improve network throughput and other performance. However, in mobile ad-hoc wireless networks, because of dynamic network topology, network coding may not improve network throughput if destination nodes fail to retrieve original packets due to lack of necessary information to decode coded packets. In this paper, we propose a Network Coding based Reliable Multicast Routing Protocol, called CRMP, in mobile ad-hoc wireless networks. Our proposed CRMP has the following novel features: i) it builds a stable mesh structure to improve coding and decoding opportunities, ii) it uses random linear network coding to simplify coding algorithm, iii) it has a local route repairing mechanism to prevent decoding failures caused by local route breaks. CRMP is especially well-suited for reliable, high speed multimedia applications. The performance of our proposed CRMP is evaluated via different scenarios. The results show that CRMP outperforms previously proposed multicast routing.

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 IP-based 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.

Network coding in Mobile Ad hoc Network (MANET) is well-known in reducing delay, increasing throughput, and improving transmission reliability. While the data throughput capacity of MANETs is unknown, the scaling of capacity with the number of nodes has recently received increasing attention. This paper proposes a Complex Field Network Coding-based Multipath Routing in MANETs (CFNC-MRM). The performance of this routing method is studied using NS2 and evaluated in terms of the packet overhead, packet delivery ratio, and packet loss ratio when a packet is transmitted. Simulation shows that the CFNC-MRM is efficient, providing reliable multipath, promising and applicable in MANETs.

Network coding is a new paradigm in data transport and promises to change many aspects of wireless sensor network (WSN). Thanks to the recently developed network coding techniques, a high-throughput low-complexity hierarchical protocol can be facilitated due to the multiple-source relay-based data transmissions built on the network coding schemes, especially for the data communications between the source node and destination node. In this paper, we propose an Energy efficient that carefully couples Network coding and Multipath routing algorithm in Wireless Sensor Networks (ENM-WSN). Through an analytical study, we provide guidance on how to choose parameters in our scheme and demonstrate that the scheme is efficient in both multipath and energy consumption. We also present an algorithm for deciding the network coding scheme for a node to further reduce energy consumption by minimizing redundant packet transmissions. Simulation results show that, with the proposed energy efficient with network coding in WSN multipath routing protocol (ENM-WSN), energy consumption, packet delivery ratio, and network lifetime can be improved in most of cases. It is an available approach to multipath routing decision.

Network coding signature schemes can be employed to pre- vent malicious modification of data in network transition. But existing network coding signature schemes are only suitable for linear network coding. To adapt to nonlinear network coding, in this paper we introduce the concept of nonlinear network coding signature scheme and its un- forgeability, and propose a unforgeable nonlinear network coding scheme based on the hardness of the small integer solution (SIS) problem in lattice-based cryptography. We first present an improvement on the theorem which presented the unforgeability of a signature scheme without identifiers proposed by David Cash et.al. in EURO- CRYPT 2010. Then a nonlinear network coding signature scheme is designed, and its unforgeability is proved by employing the Chinese remainder theorem. Thus the scheme can be used to provide cryptographic protection in nonlinear network coding.