• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.2
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• pp.345-350
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• 2009

In this paper, it is reviewed vulnerability of security in S-MAC communication protocol of sensor network, and analyzed in the respect of power efficiency, which is consumed at each stage of communication procedure in according to vulnerability of denial of service. Therefore, from research results, it can be induced the need of authentication scheme, which is considered reliability, efficiency and security of normal S-MAC communication.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.598-600
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• 2003

Ad­hoc 무선 망에서 directional antenna의 사용은 interference를 감소시키고 spatial reuse의 증가, 그리고 네트워크 전체의 capacity 증가 등의 장점을 제공한다. 하지만 기존의 IEEE 802.11 MAC protocol은 omnidirectional antenna를 고려하여 디자인되었기 때문에 기존의 MAC protocol이 directional antennas에 사용될 경우 directional antennas의 장점을 효율적으로 제공하지 못한다. Directional antenna는 이러한 장점을 가지는 반면에 RTS/CTS를 방향성 있는 전송을 하기 때문에 hidden terminal과 이웃 노드의 위치를 파악하는데 있어서 많은 문제를 가지고 있다. 이 논문에서 우리가 제안하는 MAC protocol은 directional antennas 특성상의 문제점을 해결하여 directional antennas의 장점을 최대한 이용한다.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.3
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• pp.439-444
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• 2017

Wireless sensor network technology is a rapidly growing technology of ubiquitous computing environment and application and research are being carried out in various fields. The sensor nodes constituting the wireless sensor network maintain the life cycle by using the battery in the distributed network environment, so energy efficiency is more important than QoS requirement. In MAC protocol of IEEE802.15.4, MAC protocol study adaptive to traffic and standardization work emphasizing reliability and efficiency in wireless sensor network environment are underway. but, Wireless sensor networks have the problem that the response speed of the sensor node drops as the energy efficiency decreases. In this paper, we designed the MAC protocol with improved energy efficiency of the whole network by analyzing the MAC protocol of the synchronous method and the hybrid method.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.2 s.314
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• pp.25-30
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• 2007

Sensor Nodes are composed of battery which cannot be easily changed. So, it is very important to reduce energy consumption of Sensor Nodes. In this paper, we implemented Sensor Network system using changed S-MAC to save energy with Zigbee. We deceased energy consumption of node by reducing duty cycle in ACTIVE part. According to experiment, using supposed algorithm is better than using S-MAC about $25\sim30%$ in energy consumption.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.493-495
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• 2005

지금까지 무선 센서 네트워크에서 에너지를 효율적으로 사용하기 위한 많은 라우팅 및 MAC 프로토콜들이 개발되어 왔다. 특히 에너지 효율적 센서 MAC 프로토콜들 중 Sensor-MAC (S-MAC) 프로토콜은 listen 시간과 sleep 시간을 주기적으로 반복하여, 데이터 전송이 없을 경우 노드의 통신 모듈을 Sleep시킴으로써 그 만큼의 에너지를 절약한다. 노드의 sleep시간이 길수록 더 많은 에너지를 절약할 수 있으나, 대신 sleep시간에 발생된 데이터는 다시 다음 주기의 listen시간이 시작될 때까지 지연되어야 한다는 단점이 있다. 이러한 데이터 전송 지연은 센서 네트워크에서 다양한 어플리케이션을 지원하기 위해 반드시 개선되어야 할 사항이다. 본 논문에서는 S-MAC의 listen/sleep 주기를 그대로 사용하여 에너지를 절약하면서도, 큰 오버헤드를 발생시키지 않고 데이터 전송시의 지연 시간을 최소화하는 기법에 대해 논의한다. 또한 시뮬레이션을 통해 기존의 S-MAC 및 Adaptive S-MAC 프로토콜과 지연시간 및 에너지 소비량을 비교하여, 제안된 기법이 지연시간을 감소시키면서도 기존 MAC 프로토콜들과 비슷한 에너지 소비량을 갖는다는 것을 증명하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.511-513
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• 2005

S-MAC은 전송 지연을 희생하고 전체 센서 노드의 동작 수영을 연장하기 위한 무선 센서 네트워크에 특화된 MAC(Medium Access Control) 프로토콜이다. IEEE 802.11을 수정하여 만들어진 S-MAC은 주기적인 Listen and Sleep 스케줄방식을 사용하여 무선 센서 네트워크에서 발생하는 에너지 소모를 줄였다. S-MAC을 사용하는 무선 센서 네트워크에서 초기에 수행하는 것이 자신의 동작 주기를 결정하고 알리는 것이다. 이 과정에서 무작위(randomization)로 선택된 시간을 사용하여 스케줄한 결과 다원화된 스케줄이 발생된다. 결국 서로 다른 스케줄 클러스터가 만들어지고 이 클러스터 경계에 있는 노드는 어긋난 Listen시간으로 인해 서로 통신을 하지 못한다. S-MAC 에서는 서로 다른 스케줄을 수용하는 경계 노드(border node)를 두어 해결하고 있다. 하지만, 경계 노드는 다른 노드에 비해 에너지 소모가 높고 브로드캐스트 형식의 데이터 전송 효율이 떨어진다. 본 논문에서는 이러한 S-MAC의 다원화된 스케줄 방식의 문제점을 해결하는 H-SYNC(Heartbeat-SYNC) 스케줄 일원화 방안을 제안하고 시뮬레이션을 통해 성능비교 및 평가를 실시한 결과 낮은 에너지 소모를 달성하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4B
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• pp.391-398
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• 2011

In this paper, we propose a MAC protocol for visible light wireless LAN using LED light. The proposed MAC protocol has a function of automatic direction optimization for LED transceiver. There is periodical time slot for broadcasting and registration in the proposed MAC protocol. We used polling method for data transfer in the protocol since visible light is hard to detect carrier and collision by other mobile stations; thus we cannot use CSMA/CD method in visible light LAN. We also amended the MAC frame of IEEE 802.11 to propose a revised version for visible light wireless LAN using LED light. We investigate the performance of the proposed MAC protocol. When the bit rate of physical layer is 100 Mb/s, the net data throughput using the proposed MAC protocol is estimated to 94.386 Mb/s.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2638-2647
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• 2010

X-MAC reduces transmission delay and energy consumption by using a short preamble instead of the existing long preamble. To solve the problem of X-MAC, this paper proposes a new MAC protocol called Express-MAC. The wireless sensor network is mainly used for the purpose of gathering event data or situation information. Especially, the transmission pattern of the sensor network with the purpose of event detection such as intrusion detection is very intermittent as well as successively occurring when a single event takes place in most cases. By reflecting sensor network's key transmission patterns as above, EX-MAC has used multi-hub path's path reservation system and awake section's transmission time reservation method in data transmission when the first event takes place. The awake time reservation in transmission path has improved successive data transmission's end-to-end delay, and it has also increased efficiency in terms of energy consumption by reducing the preamble length of data transmission and reception node.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10B
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• pp.866-871
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• 2006

This paper presents the design of a reservation-based MAC protocol to support multimedia traffic over mobile ad-hoc networks and evaluates its performance. Our MAC protocol is based on a hierarchical approach consisting of two sub-layers. The lower sub-layer of the MAC protocol with reservation provides a fundamental access method using CSMA/CA in order to support asynchronous data traffic over mobile ad-hoc networks. The upper sub-layer supports real-time periodic data by making a slot reservation before transmitting actual data. The proposed protocol has been validated through simulations using ns-2. The results show that the proposed MAC protocol can offer higher throughput and lower delay than standard implementations of the IEEE 802.11.

• Journal of IKEEE
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• v.16 no.2
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• pp.86-94
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• 2012

Synchronization MAC Protocol such as S-MAC and T-MAC utilize duty cycling technique which peroidically operate wake-up and sleep state for reducing energy consumption. But synchronization MAC showed low energy efficiency because of additional control packets. For better energy consumption, Asychronization MAC protocols are suggested. For example, B-MAC, and X-MAC protocol adopt Low Power Listening (LPL) technique with CSMA algorithm. All nodes in these protocols joining a network with independent duty cycle schedules without additional synchronization control packets. For this reason, asynchronous MAC protocol improve energy efficiency. In this study, a low-power MAC protocol which is based on X-MAC protocol for wireless sensor network is proposed for better energy efficiency. For this protocol, we suggest preamble numbering, and virtual-synchronization technique between sender and receive node. Using TelosB mote for evaluate energy efficiency.