• Journal of Information Processing Systems
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• 제11권3호
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• pp.465-482
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• 2015

IEEE 802.11p is a standard MAC protocol for wireless access in vehicular environments (WAVEs). If a packet collision happens when a safety message is sent out, IEEE 802.11p chooses a random back-off counter value in a fixed-size contention window. However, depending on the random choice of back-off counter value, it is still possible that less important messages are sent out first while more important messages are delayed longer until sent out. In this paper, we present a new scheme for safety message scheduling, called the enhanced message priority mechanism (EMPM). It consists of the following two components: the benefit-value algorithm, which calculates the priority of the messages depending on the speed, deceleration, and message lifetime; and the back-off counter selection algorithm, which chooses the non-uniform back-off counter value in order to reduce the collision probability and to enhance the throughput of the highly beneficial messages. Numerical results show that the EMPM can significantly improve the throughput and delay of messages with high benefits when compared with existing MAC protocols. Consequently, the EMPM can provide better QoS support for the more important and urgent messages.

• 한국도로학회논문집
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• 제13권3호
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• pp.83-91
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• 2011

VMS(Variable Message Sign)는 도로의 이용자에게 하류부의 교통정보를 제공하여 운전자의 경로선택을 위한 의사결정정보와 목적지까지 이동하기위하여 소요되는 통행시간정보를 제공한다. 하지만, VMS에 표출할 수 있는 정보의 개수는 표출면수에 의한 제약이 있기 때문에 신중하게 결정되어야 한다. 지금까지 기 구축된 이벤트의 메시지 표출우선순위는 발생된 이벤트의 심각도만을 고려하여 우선순위 규칙을 적용하고 있다. 하지만 VMS를 더욱 효율적으로 운영하기 위해서는 통행수요가 많은 경로에 교통정보를 우선적으로 제공할 때 그 정보의 수혜자가 가장 많을 것이다. 그러므로 실시간으로 기종점을 파악하여 더욱 많은 운전자가 경로선택이 가능한 정보를 제공받을 수 있도록 정보제공 전략을 수립할 필요가 있다. 본 연구에서는 주도로와 진출입 램프의 검지기 데이터를 이용하여 시간분할 기종점 추정방법론으로 통행수요를 추정하였으며, 추정된 기종점자료를 바탕으로 정보제공 우선순위를 결정할 수 있는 정보제공 전략을 소개하였다.

• 한국통신학회논문지
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• 제39B권10호
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• pp.629-644
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• 2014

The goal of this paper is to consider a co-design approach between time delay compensation and the message scheduling for CAN-Based Networked Control Systems (NCS). First we propose a hybrid priority scheme for the message scheduling in order to improve the Quality of Service (QoS). Second we present the way to calculate the closed-loop communication time delay and then compensate this time delay using the pole placement design method in order to improve the Quality of Control (QoC). The final objective is the implementation of a co-design which is the combination of the compensation for communication time delays and the message scheduling in order to have a more efficient NCS design.

• 한국멀티미디어학회논문지
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• 제17권10호
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• pp.1220-1228
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• 2014

Emergency Warning Service will be the most important service of VANET. Transmission delay is the most important performance criteria of the warning service. Most legacy research takes a way to minimize the packet collision. However those approach has a critical weak point on urban environment where there is a blind area of electric wave. So another issue is required in order to provide enhanced warning message propagation technique to overcome the urban environment problem. In this paper, I proposed an enhanced warning message propagation scheme in the poor electric wave environment as the intersection area. Proposed scheme forwards the warning message to the blind area by enhanced forwarding node selection technique. For efficiency of warning message propagation, I suggest forwarding priority for decision of forwarding node. And the node has a direct mode or redirect mode depending on neighbor nodes. The simulation was carried out to evaluate the performance. The simulation results show that proposed scheme has the superior performance compared to legacy warning message technique.

• 한국정밀공학회지
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• 제26권10호
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• pp.40-46
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• 2009

Recently CAN (Controller Area Network) is widely used as an in-vehicle networking protocol for intelligent vehicle. The identifier field (ID) of CAN is used not only to differentiate the messages but also to give different priorities to access the bus. This paper presents a dynamic 10 allocation algorithm in order to enhance the real-time quality-of-service (QoS) performance. When the network traffic is increased, this algorithm can allocate a network resource to lower priority message without degradation of the real-time QoS performance of higher priority message. In order to demonstrate the algorithm's feasibility, message transmission delays have been measured with and without the algorithm on an experimental network test bed.

• 스마트미디어저널
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• 제4권1호
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• pp.25-32
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• 2015

Powering wireless sensors with energy harvested from the environment is coming of age due to the increasing power densities of both storage and harvesting devices and the electronics performing energy efficient energy conversion. In order to maximize the functionality of the wireless sensor network, minimize missing packets, minimize latency and prevent the waste of energy, problems like congestion and inefficient energy usage must be addressed. Many sleep-awake protocols and efficient message priority techniques have been developed to properly manage the energy of the nodes and to minimize congestion. For a WSN that is operating in a strictly energy constrained environment, an energy-efficient transmission strategy is necessary. In this paper, we present a novel transmission priority decision scheme for a heterogeneous body sensor network composed of normal nodes and an energy harvesting node that acts as a cluster head. The energy harvesting node's decision whether or not to clear a normal node for sending is based on a set of metrics which includes the energy harvesting node's remaining energy, the total harvested energy, the type of message in a normal node's queue and finally, the implementation context of the wireless sensor network.

• 대한전기학회논문지:시스템및제어부문D
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• 제55권1호
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• pp.24-30
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• 2006

The Controller Area Network (CAN) is being widely used for real-time control application and small-scale distributed computer controller systems. When the stuff bits are generated by bit-stuffing mechanism in the CAN network, it causes jitter including variations in response time and delay In order to eliminate this jitter, stuff bits must be controlled to minimize the response time and to reduce the variation of data transmission time. This paper proposes the method to reduce the stuff bits by restriction of available identifier and bit mask using exclusive OR operation. This da manipulation method are pretty useful to the real-time control strategy with respect to performance. However, the CAN may exhibit unfair behavior under heavy traffic conditions. When there are both high and low priority messages ready for transmission, the proposed precedence priority filtering method allows one low priority message to be exchanged between any two adjacent higher priority messages. In this way, the length of each transmission delays is upper bounded. These procedures are implemented as local controllers for the ISHURO(Inha Semvung Humanoid Robot).

• 한국컴퓨터정보학회논문지
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• 제22권11호
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• pp.39-47
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• 2017

In this paper, we propose a message transmission processing structure for efficient use of radio resources. Existing tactical data links have more data and accumulate more data than the amount of tactical data planned according to the situation. This may result in delays in operations and additional problems. To prevent this, priority is assigned to the message and transmission is performed according to the priority on a single basis. And we design a processing structure that can update duplicate messages and delete old messages in order to prevent waste of radio resources. Experiments are conducted to verify that these structures can be implemented and applied to data links.

• 한국콘텐츠학회논문지
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• 제9권11호
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• pp.100-107
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• 2009

본 연구는 병원고객관리를 위한 의료용 CRM 시스템의 설계를 목적으로 한다. 본 CRM 시스템은 병원에서 제공하는 정보 및 세미나를 필요로 하는 환자들의 우선순위 검색과 이를 통해 검색 결과 내의 인원별, 지역별 등의 연관 검색이 가능하도록 하였다. 고객은 병원에서 발송한 메시지를 받고, 세미나에 참여의사를 밝히는 메시지를 병원에서 실시간으로 출력하고 이를 관리한다. 이를 통해 병원에서는 고객이 참가할 세미나의 참여도를 파악하고, 세미나에 적극적으로 참여하는 환자들을 별도로 관리하여 향후 세미나 개최 시 우선적으로 서비스를 제공할 수 있도록 설계하였다.

• 한국통신학회논문지
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• 제29권11B
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• pp.956-966
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• 2004

향후 NGN(Next Generation Network)은 패킷 기반의 QoS가 제공되는 네트웍으로 발전하고 있다. 본 논문에서는 MPLS 네트웍에서의 보다 효율적인 경로 선택에 관한 기법으로 Service interruption time을 줄이는 복구방법을 제안한다. 장애복구의 주요 성능 중의 하나인 복구자원사용의 효율성을 높이기 위해서 각 노드들 간의 state information을 fault detector 와 bandwidth broker가 서로 공유하여 장애 발생 시 복구를 위한 message transmission time을 줄였다. 또한 트래픽양의 변화에 따라 망 전체의 필요한 대역폭을 효과적으로 관리하고 변화시킴으로써 대역폭 사용의 효율성을 개선하였다. 그리고 우선순위 서비스를 제공할 수 있는 MPLS 망에서 우선순위에 따른 트래픽에 대해서도 전체 망에 도메인을 나눔으로써 우선순위가 높은 트래픽에 대한 종단간 복구방법에 대해 효율적인 자원 할당을 하며 낮은 우선순위의 트래픽에 대해서 장애가 발생한 도메인 내에서만 경로 복구를 하여 재설정을 위한 시간을 줄일 수 있고, 불필요한 메시지의 전달을 줄일 수 있다