• International journal of advanced smart convergence
• /
• 제2권1호
• /
• pp.6-11
• /
• 2013

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.

• Journal of Digital Convergence
• /
• 제10권7호
• /
• pp.161-166
• /
• 2012

When a car accident happened on a highway, the accident vehicle should broadcast a safe message to its neighbors in order to prevent a chain-reaction collision. Also, there is a problem that the estimation accuracy is low because of the memory limit from increasing the sampling count. In this paper, we proposes a HVC systems using a back-off algorithm applied to a gaussian model. And we proposes a MAC protocol preventing the communication delay by separating the neighbor count collection channel, data channel, and RSU communication channel. As a result, we show the frame reception success rate of our protocol improved about 10% than the previous protocol.

• Journal of the Institute of Electronics and Information Engineers
• /
• 제51권11호
• /
• pp.11-18
• /
• 2014

Most of the energy efficient MAC protocols for wireless sensor networks (WSNs) are based on duty cycling in a single channel and show competitive performances in a small number of traffic flows; however, under concurrent multiple flows, they result in significant performance degradation due to contention and collision. We propose a multi-channel pipelining (MCP) method for convergecast WSN in order to address these problems. In MCP, a staggered dynamic phase shift (SDPS) algorithms devised to minimize end-to-end latency by dynamically staggering wake-up schedule of nodes on a multi-hop path. Also, a phase-locking identification (PLI) algorithm is proposed to optimize energy efficiency. Based on these algorithms, multiple flows can be dynamically pipelined in one of multiple channels and successively handled by sink switched to each channel. We present an analytical model to compute the duty cycle and the latency of MCP and validate the model by simulation. Simulation evaluation shows that our proposal is superior to existing protocols: X-MAC and DPS-MAC in terms of duty cycle, end-to-end latency, delivery ratio, and aggregate throughput.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• 제17권10호
• /
• pp.2281-2287
• /
• 2013

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. Network Coding 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. Prior researches have been carried out to employ network coding to wireless ad-hoc network. In our study, intermediate nodes identify one-hop bidirectional flows for network coding decision. We expect that the proposed scheme shall improve decoding success rate of network coded packet. From the simulation, the proposed network coding scheme achieved better performance in terms of coding gain and packet delivery rate than traditional network coding scheme.

• Journal of KIISE:Information Networking
• /
• 제36권6호
• /
• pp.528-535
• /
• 2009

This paper proposes a mechanism to increase performance using cooperative communications in IEEE 802.11 environment. Existing algorithms use one relay between a source and a destination, which is a 2 hop relay. The proposed algorithm utilizes more than one relay to complement inefficiency of using one relay. In the proposed mechanism, an AP manages network information (rate), which is used to select relays of a source by the AP. The AP notifies the selected relays to the source and neighbor nodes, and the source transmits data to the relays for cooperative communications. Moreover, relays are given to have an opportunity to send its own data right after relaying the source's data. So relays are compensated for the power to send the source's data and overall throughput is improved.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• 제13권5호
• /
• pp.17-26
• /
• 2013

ISO/IEC 29157 originally developed in the Republic of Korea and is based on commercially available PicoCast v1.0. ISO/IEC JTC1 SC6 was registered by the international standard on May 2010. A single platform for a variety of applications and media formats to support development objectives were. ISO/IEC 29157 based wireless networks, ie, Pico-net to master node periodically transmit sync signal is synchronized to the number of slave nodes have the communications structure. Pico-net also supports a variety of network topologies and direct communication between nodes(single-hop communication) and QoS is guaranteed. But Pico-net network structure has the following problems. Loss of communication problems due to mobile nodes, resulting in limitations of node mobility and wireless network operation range of conventional wireless networks operating range less than 1/4 was reduced to the problem. In this paper, a possible solution to the problems mentioned is proposed, using multi-hop communication technology and sync signal transmission technology between nodes.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 한국해양정보통신학회 2008년도 추계종합학술대회 B
• /
• pp.373-376
• /
• 2008

Wireless sensor networks consist of thousands of sensor nodes that have low power, low footprint and low computational capacities. So the burning issues in the design and deployment of these sensor nodes in the practical application areas include the energy conservation and network lifetime. Efficient routing schemes can help reduce the energy consumption and thus increase the network lifetime. This paper deals with the comparative analysis of popular routing protocols such as LEACH, LEACH-C, MTE, and PEGASIS. The protocols are compared by using performance me tries such as system lifetime, the time for first node death, and total system energy.

• The KIPS Transactions:PartC
• /
• 제11C권7호
• /
• pp.905-916
• /
• 2004

Self-organizing hierarchical ad hoc network (SOHAN) is a new ad-hoc network architecture designed to improve the scalability properties of conventional 'flat' ad hoc networks. This network architecture consists of three tiers of ad-hoc nodes, i.e.. access points, forwarding nodes and mobile nodes. This paper presents a topology discovery and routing protocol for the self-organization of SOHAN. We propose a cross-layer path metric based on link quality and MAC delay which plays a key role in producing an optimal cluster-based hierarchical topology with high throughput capacity. The topology discovery protocol provides the basis for routing which takes place in layer 2.5 using MAC addresses. The routing protocol is based on AODV with appropriate modifications to take advantage of the hierarchical topology and interact with the discovery protocol. Simulation results are presented which show the improved performance as well as scalability properties of SOHAN in terms of through-put capacity, end-to-end delay, packet delivery ratio and control overhead.

• Convergence Security Journal
• /
• 제8권1호
• /
• pp.9-18
• /
• 2008

This paper propose CAR-TO-CAR protocol which can prevent the cars at high-speed from a multiple clash accident at highway with exchanging information. we construct cluster be linked with distance took from GPS(Global Positioning System) because there is no connection at cars on the road. The proposed method solved the overload problem by establishing route because construct the cluster at the IEEE 802.11 MAC class. 'Multi-hop Routing protocol' based on Active Network enable stable Network to be formed by using Active Network.

• Proceedings of the Korean Information Science Society Conference
• /
• 한국정보과학회 2003년도 가을 학술발표논문집 Vol.30 No.2 (3)
• /
• pp.475-477
• /
• 2003

본 논문에서는 IEEE 802.11 을 기반으로 하는 무선 Ad Hoc 망에서 데이터의 송신자 노드와 목적지 노드의 중간 노드들의 전송을 방해하고 채널을 경쟁하는 경쟁노드들이 Shortest­path 라우팅 경로 설정에 미치는 영향을 분석한다. 데이터를 전송하는 중간 노드들이 다수의 경쟁노드를 가지고 있을 경우 MAC delay 가 큰 변수로 작용하며 multi­hop 환경이기 때문에 hidden terminal 문제가 발생한다. 또한 AODV 와 같은 on­demand 라우팅 알고리즘은 경로를 찾기 위해서 Route Request 패킷을 브로드캐스트 하는데 이때 브로드캐스트 패킷의 성공적인 전송이 보장되지 않기 때문에 경쟁노드의 방해가 심한 경우 경로를 찾는데 실패할 가능성이 높아진다. 본 논문에서는 이러한 특성들을 근거로 경쟁노드의 수와 분포가 라우팅 경로 선택에 영향을 미친다는 것을 지적한다.