• 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.

• Journal of KIISE:Information Networking
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• v.35 no.4
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• pp.326-336
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• 2008

Wireless sensor networks have been studied with two typical applications called event-driven and periodic monitoring. Although these applications have different core requirements, they have the same low latency requirement. However, main issue of the protocol in wireless sensor networks was focused on an energy efficiency, so it has not considered the latency problem. In this paper, we propose the RA-MAC, an energy efficient and low latency MAC protocol using a new channel access mechanism and the RTS Aggregation scheme for wireless sensor networks. Our simulation results show that the RA-MAC provides energy savings and latency reduction.

• Smart Media Journal
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• v.1 no.1
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• pp.17-26
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• 2012

In cognitive radio networks (CRNs), unlicensed users sense the licensed spectrum bands and opportunistically access them without interfering operations of licensed users. Especially, in ad hoc networks, the MAC layer plays an important role in coordinating unlicensed users access to the spectrum and, thus, a number of MAC protocols have been studied recently. In this paper, we comparatively examine MAC protocols in cognitive radio ad hoc networks (CRAHNs). First, we categorize the protocols on the basis of common control channel (CCC) requirements and further review major implementations for each category. Then, we make a qualitative comparison of the protocols in terms of inherent characteristics and performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.5B
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• pp.457-465
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• 2003

In this paper, we analyze the performances of variable MAC (Medium Access Control) protocols and present an efficient MAC protocol for Ethernet PON (Passive Optical Network). We consider three MAC protocols: static TDMA, dynamic TDMA, and Interleaved polling. Static TDMA assigns an equal amount of bandwidth to all ONUs regardless of the request information but Dynamic TDMA dynamically allocates the bandwidth to each ONU considering its request. Interleaved Polling operates a cycle with variable time period and a polling method for informing a uplink transmission chance to each ONU. This paper theoretically analyzes the available bandwidth for each of three protocols. We also implement the simulation models for them by using OPNET and evaluates the performances under various bursty traffic environments. The results are compared and analyzed in terms of channel utilization and queueing delay.

• 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.

• KIISE Transactions on Computing Practices
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• v.22 no.8
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• pp.381-386
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• 2016

Recently full-duplex communication in wireless networks is enabled by the advancement of self-interference cancellation technology. Full-duplex radio is a promising technology for next-generation wireless local area networks (WLAN) because it can simultaneously transmit and receive signals within the same frequency band. Since legacy medium access control (MAC) protocols are designed based on half-duplex communication, they are not suitable for full-duplex communication. In this paper, we discuss considerations of full-duplex communication and propose a novel full-duplex MAC protocol. We conducted a simulation to measure the throughput of our MAC protocol. Through the simulation results, we can verify that significant throughput gains of the proposed full-duplex MAC protocol, thus comparing the basic full-duplex MAC protocol.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.91-94
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• 2012

철도 차량의 상태를 측정하고 모니터링하기 위하여 센서를 이용한 다양한 장비들이 이용되고 있다. 하지만 현재 사용되고 있는 장치들은 대부분 유선 네트워크를 기반으로 하고 있기 때문에 공간적, 비용적인 제약을 받는다. 이러한 제약을 극복하기 위하여 무선 통신을 이용하는 방법이 있으며, 다양한 MAC 프로토콜을 통해 데이터를 송수신할 수 있다. 하지만 무선 센서네트워크에 사용되는 MAC 프로토콜은 매우 다양한 종류가 있으며, 각각의 MAC 프로토콜은 데이터 송수신 속도, 배터리 소모량 등에 있어서 다양한 특성을 지닌다. 본 논문에서는 센서네트워크에서 사용되는 다양한 MAC 프로토콜의 특성을 분석하여, 공간과 사용시간에 있어서 제약적인 철도 센서 기기에 적합한 프로토콜을 선별할 수 있도록 한다.

• Proceedings of the KAIS Fall Conference
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• 2010.05a
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• pp.41-44
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• 2010

무선 센서 네트워크 MAC 프로토콜에서 에너지 효율성은 중요한 이슈들 중 하나이다. 기존 MAC Protocol에서는 overhearing, idle listening 등 각종 문제들로 인해 불필요한 에너지 소모가 일어나게 된다. 본 논문에서는 이러한 문제점을 해결하기 위해 프리엠블 신호의 길이를 데이터의 발생 유무에 따라 동적으로 조절 가능한 DPL(Dynamic Preamble Length)-MAC 프로토콜을 제안하였다. 그리고 기존의 비동기 방식의 무선 센서 네트워크 MAC 프로토콜들과 본 논문에서 제안한 DPL-MAC 프로토콜을 시뮬레이션 하여 에너지 소모 관점에서 비교 분석 평가 하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.5A
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• pp.526-535
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• 2008

Recently, several MAC protocols using the directional antennas have been proposed for wireless mobile ad hoc networks. In the theory, it can improve spatial reuse and communication throughput in the Mobile Ad-hoc networks. But, or However even though direction transmissions using the Directional MAC protocol(D-MAC) are expected to provide significant improvements, they causes other problems such as deafness problem and fairness problem. In this paper, we analyze the D-MAC protocol in Mobile Ad-hoc network for Vehicle to vehicle(V2V) communication. Through the results of the analysis, We the fundamental problem of D-MAC protocol and finally we suggest new D-MAC protocol for V2V networks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.2
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• pp.471-476
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• 2015

In this paper, we propose an energy efficient hybrid MAC protocol for multi-hop wireless sensor networks. The proposed MAC protocol used a hybrid mechanism, in which contention-based MAC protocol and contention free MAC protocol are combined. The sensor nodes located far from the sink node usually send few data packet since they try to send measured data by themselves. So contention-based MAC protocol is useful among them. But other nodes located near sink node usually have lots of data packets since they plays as a relay node. Contention-based MAC protocol among them is not suitable. Using contention-based MAC protocol in heavy data traffic environment, packet collisions and transmission delay may increase. In this paper, slot assignment between sender nodes by sink node is used. The proposed mechanism is efficient in energy and latency. Results showed that our MAC protocol outperformed other protocol in terms of data packet delivery delay and energy consumption.