• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제12권4호
• /
• pp.1527-1552
• /
• 2018

The rapidly-evolving demand of applications using wireless sensor networks in several areas such as building and industrial automation or smart cities, among other, makes it necessary to determine and provide QoS support mechanisms which can satisfy the requirements of applications. In this paper we propose a mechanism that establishes different QoS levels, based on Publish/Subscribe model for wireless networks to meet application requirements, to provide reliable delivery of packet and timeliness. The first level delivers packets in a best effort way. The second one intends to provide reliable packet delivery with a novel approach for Retransmission Timeout (RTO) calculation, which adjusts the RTO depending on the subscriber Packet Delivery Ratio (PDR). The third one provides the same reliable packet delivery as the second one, but in addition, it provides data aggregation trying to be efficient in terms of energy consumption and the use of network bandwidth. The last one provides timeliness in the packet delivery. We evaluate each QoS Level with several performance metrics such as PDR, Message Delivery Ratio, Duplicated and Retransmitted Packet Ratio and Packet Timeliness Ratio to demonstrate that our proposal provides significant improvements based on the increase of the PDR obtained.

• 항공우주기술
• /
• 제13권2호
• /
• pp.38-46
• /
• 2014

CRC (Cyclic Redundancy Codes)는 데이터 전송 시 오류 발생 유무를 검출하기 위한 하나의 방법으로, 정지궤도복합위성(GEO-KOMPSAT 2B) 개발에서는 정지궤도환경탑재체와 위성 간의 GRDDP (GOES-R Reliable Data Delivery Protocol)에 사용되고 있다. 본 논문에서는 CRC를 구현할 때 널리 사용하는 테이블 기반 CRC의 원리를 소개하고, 이를 기반으로 환경탑재체 개발에서 사용 중인 CRC8을 소프트웨어로 구현한 결과를 설명한다.

• Journal of Communications and Networks
• /
• 제16권2호
• /
• pp.155-161
• /
• 2014

Mobility can lead to continual loss of data and service interruptions during communications in multi-hop cognitive radio networks. Mobility of primary users (PUs) or cognitive users (CUs) requires adjustment of multi-hop communications among CUs to avoid any interference to PUs. To provide durable and reliable data routing that ensures continuous network service, we propose mobility-aware cognitive routing (MCR) for multi-hop cognitive radio networks. MCR examines the risk level of each node against interference regions and selects the most reliable path for data delivery using a Markov predictor. Through simulation, we verify that the proposed scheme can avoid route destruction preemptively and achieve reliable data delivery.

• 한국군사과학기술학회지
• /
• 제11권1호
• /
• pp.15-24
• /
• 2008

The data delivery confirmation method of MIL-STD-188-220C, which is a tactical wireless mobile Ad-Hoc communication protocol, is that a source node requires the end-to-end ack from all destination nodes and the data-link ack from 1-hop neighboring destination nodes and relaying nodes, regardless of the hop distance from a source node to destination nodes. This method has the problem to degrade the whole communication network performance because of excessive data traffic due to the duplicate use of end-to-end ack and data-link ack, and the collision among end-to-end acks on the wireless network in the case of confirming a data delivery within an 1-hop distance. In order to solve this problem, this paper has proposed the method to perform the data delivery confirmation with the improvement of communication network performance through the data traffic reduction by achieving the reliable data delivery confirmation requiring the only data-link ack within an 1-hop distance. The effects of the proposed method are analyzed in the two aspects of the data delivery confirmation delay time and the data delivery confirmation success ratio.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제8권9호
• /
• pp.3094-3109
• /
• 2014

This paper proposes a load balanced reliable routing protocol called LBR (Load Balanced Reliable routing) in wireless networks. The LBR protocol transmits messages through a reliable path considering the balancing of the traffic load. Recently, the authors have proposed a multipath-based reliable routing protocol called MRFR, which is an appealing protocol for fault tolerant reliable data transmission. However, However, MRFR has no concern with the problem of load balancing, which results in increasing congestion and consuming high energy at some network nodes. As a result, the problem affects negatively the performance of the network. Taking account of load balancing as a route selection criteria can avoid routing through the congested nodes and allows to find better routes. In this paper, we extend MRFR by considering load balancing in the route discovery process of reliable communication. The simulation results showed that the proposed protocol outperforms AODV in terms of end-to-end delay, packet delivery radio, and average jitter. Compared to MRFR, the LBR protocol has the same packet delivery ratio, and obtains a better efficiency of load balancing.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제11권3호
• /
• pp.1406-1424
• /
• 2017

Recent advancements in network infrastructures provide increased opportunities to support data delivery over multiple paths. Compared with multi-homing scenario, overlay network is regarded as an effective way to construct multiple paths between end devices without any change on the underlying network. Exploiting multipath characteristics has been explored for TCP with multi-homing device, but the corresponding exploration with overlay network has not been studied in detail yet. Motivated by improving quality of experience (QoE) for reliable data delivery, we propose a multipath message transport protocol based on application level relay (MPMTP-AR). MPMTP-AR proposes mechanisms and algorithms to support basic operations of multipath transmission. Dynamic feedback provides a foundation to distribute reasonable load to each path. Common source decrease (CSD) takes the load weight of the path with congestion into consideration to adjust congestion window. MPMTP-AR uses two-level sending buffer to ensure independence between paths and utilizes two-level receiving buffer to improve queuing performance. Finally, the MPMTP-AR is implemented on the Linux platform and evaluated by comprehensive experiments.

• 전자공학회논문지CI
• /
• 제45권6호
• /
• pp.45-51
• /
• 2008

유시티를 비롯하여 여러 시범사업에서 나타나듯이 유비쿼터스 네트워크상에서 제공되는 서비스가 다양해질수록 안정적인 데이터 전송은 필수적인 요건이 되었다. 이렇듯 신뢰성은 서비스에서 요구하는 그 외의 서비스 품질상의 요구사항들에 앞서서 해결되어야 하는 가장 기본적인 사항이 되었다. 또한 유비쿼터스 센서 네트워크에서 가장 중요시 생각하는 저전력 통신의 근간을 지키기 위해서도 효율적이며 안정적인 데이터 전송은 기본적으로 필요한 사안이 되었는데 근본적으로 효율적이고 안정적인 데이터의 전달이 에너지 절감에도 도움이 되기 때문이다. 이에 본 논문에서는 유비궈터스 센서 네트워크에서의 데이터 전송 방법에 따른 효율성과 안정성을 성능 분석을 통해서 비교해 보고자 한다.

• 한국통신학회논문지
• /
• 제42권1호
• /
• pp.128-139
• /
• 2017

VANET은 안전 운전 및 효율적인 교통 환경을 제공하는 다양한 ITS 서비스 실현을 위한 기술 중 하나이다. VANET에서의 데이터 전송은 노드들의 높은 이동성으로 인하여 복잡성을 야기한다. 본 논문에서는 VANET에서 패킷을 안정적이고 적시에 전달하는 새로운 포워딩 기법을 제안한다. 제안된 기법은 차량 만남을 예측하기 위해 트래픽 통계를 이용하고, 만남 장소에서의 성공적인 무선 전송 확률을 고려함으로써 포워딩 결정을 최적화 한다. 시뮬레이션을 통하여 제안된 포워딩 기법이 VANET 환경에서 신뢰성있는 데이터 전송을 달성함을 확인하였다.

• 국제학술발표논문집
• /
• The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
• /
• pp.187-194
• /
• 2011

Optimizing truck dispatching-intervals is imperative in ready mixed concrete (RMC) delivery process. Intervals shorter than optimal may induce queuing of idle trucks at a construction site, resulting in a long delivery cycle time. On the other hand, intervals longer than optimal can trigger work discontinuity due to a lack of available trucks where required. Therefore, the RMC delivery process should be systematically scheduled in order to minimize the occurrence of waiting trucks as well as guarantee work continuity. However, it is challenging to find optimal intervals, particularly in urban areas, due to variations in both traffic conditions and concrete placement rates at the site. Truck dispatching intervals are usually determined based on the concrete plant managers' intuitive judgments, without sufficient and reliable information regarding traffic and site conditions. Accordingly, the RMC delivery process often experiences inefficiency and/or work discontinuity. Automatic data collection (ADC) techniques (e.g., RFID or GPS) can be effective tools to assist plant managers in finding optimal dispatching intervals, thereby enhancing delivery performance. However, quantitative evidence of the extent of performance improvement has rarely been reported to data, and this is a central reason for a general reluctance within the industry to embrace these techniques, despite their potential benefits. To address this issue, this research reports on the development of a discrete event simulation model and its application to a large-scale building project in Abu Dhabi. The simulation results indicate that ADC techniques can reduce the truck idle time at site by 57% and also enhance the pouring continuity in the RMC delivery process.

• 한국농공학회:학술대회논문집
• /
• 한국농공학회 2005년도 학술발표논문집
• /
• pp.534-539
• /
• 2005

The purpose of this study is the introduction of pollutant loads's estimation into Saemangeum watershed area with M.E.'s guidebook for TMDL and GIS tool. To estimate reliable pollutants loads, it is necessary to think about characteristic of removal, discharge and runoff as time series. In this study, it was calculated for generation loads which be came from pollutant source, discharge loads which be reduced in the treatment facilities and delivery loads which be considered the self purification parameter and delivery distance. To assess the delivery distance handily, it was particularly estimated using Arc-GIS. It was met with good results that delivery loads of BOD, T-N and T-P was reflected to seasonal precipitation. Lastly to verify the estimated pollutant loads, HSPF developed by USEPA was applied to it. It was showed a relativity of observed to simulated data for flow, Temperature, DO, BOD, $NO_3^--N$ TN and TP. Consequantly, this delivery loads can make full use of model input data for prediction of pollutant loads.