• Journal of Communications and Networks
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• 제14권5호
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• pp.524-532
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• 2012

In this paper, we present the performance evaluation of the reliable cooperative media access control (RCO-MAC) protocol, which has been proposed in [1] by us in order to enhance system throughput in bad wireless channel environments. The performance of this protocol is evaluated with computer simulation as well as mathematical analysis in this paper. The system throughput, two types of average delays, average channel access delay, and average system delay, which includes the queuing delay in the buffer, are used as performance metrics. In addition, two different traffic models are used for performance evaluation: The saturated traffic model for computing system throughput and average channel access delay, and the exponential data generation model for calculating average system delay. The numerical results show that the RCO-MAC protocol proposed by us provides over 20% more system throughput than the relay distributed coordination function (rDCF) scheme. The numerical results show that the RCO-MAC protocol provides a slightly higher average channel access delay over a greater number of source nodes than the rDCF. This is because a greater number of source nodes provide more opportunities for cooperative request to send (CRTS) frame collisions and because the value of the related retransmission timer is greater in the RCO-MAC protocol than in the rDCF protocol. The numerical results also confirm that the RCO-MAC protocol provides better average system delay over the whole gamut of the number of source nodes than the rDCF protocol.

• 한국통신학회논문지
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• 제30권10A호
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• pp.877-885
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• 2005

Home Phoneline Networking Alliance (HomePNA) 2.0 기술은 기존의 댁내 전화 선로를 이용하여 홈 네트워크를 구축하는 기술로서, 4-32 Mbps의 고속 데이터 전송 속도를 제공한다. 이러한 HomePNA 2.0의 Medium Access Control(MAC) 프로토콜은 IEEE 802.3 Carrier Sense Multiple Access with Collision Detection (CSMA/CD) 방식을 사용하면서, Quality of Service(QoS) 알고리즘을 제공하구 충돌 해결 알고리즘은 Distributed Fair Priority Queuing(DFPQ) 알고리즘을 사용한다. 본 논문은 HomePNA 2.0 MAC 프로토콜 성능의 중요 요소인 포화 처리율(Saturation Throughput), 패킷 지연(Packet Delay) 및 패킷 지터(Packet Jitter)에 대한 수학적인 모델을 제안하고, 이에 대한 모의 실험(Simulation) 결과를 제공하며, 각각의 모의 실험 결과를 분석함으로써, HomePNA 2.0 MAC 프로토콜의 성능을 종합적으로 분석한다.

• Journal of information and communication convergence engineering
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• 제7권4호
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• pp.480-488
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• 2009

A channel-shared modified accelerative pre-allocation wavelength division multiple access (CMAP-WDMA) media access control (MAC) has been proposed for metro-WDMA networks, as an extension of modified pre-allocation wavelength division multiple access (MAP-WDMA) MAC protocol. Similarly, CAP WDMA as an extension of accelerative pre-allocation wavelength division multiple access (AP-WDMA) MAC protocol. Performance of CMAP- and CAP-WDMA was extensively investigated under several channel sharing methods (CSMs), asymmetric traffic load patterns (TLPs), and non-uniform traffic distribution patterns (TDPs). The result showed that the channel utilization of the CMAP-WDMA always outperforms that of CAP-WDMA at the expense of longer channel access delay for channel shared case while CMAP-WDMA provided higher channel utilization at specific network conditions but always shorter channel access delay than CAP-WDMA for non-channel shared case. Additionally both for CMAP- and CAP-WDMA, determining an effective CSM is a critical design issue because TDPs and TLPs can be neither managed nor expected while CSM is manageable, and the CSM supporting the best channel utilization can be recommended.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권9호
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• pp.2302-2322
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• 2012

Wireless Body Area Networks (WBANs) are introduced as an enabling technology in tele-health for patient monitoring. Designing an efficient Medium Access Control (MAC) protocol is the main challenge in WBANs because of their various applications and strict requirements such as low level of energy consumption, low transmission delay, the wide range of data rates and prioritizing emergency data. In this paper, we propose a new MAC protocol to provide different requirements of WBANs targeted for medical applications. The proposed MAC provides an efficient emergency response mechanism by considering the correlation between medical signals. It also reduces the power consumption of nodes by minimizing contention access, reducing the probability of the collision and using an efficient synchronization algorithm. In addition, the proposed MAC protocol increases the data rate of the nodes by allocating the resources according to the condition of the network. Analytical and simulation results show that the proposed MAC protocol outperforms IEEE 802.15.4 MAC protocol in terms of power consumption level as well as the average response delay. Also, the comparison results of the proposed MAC with IEEE 802.15.6 MAC protocol show a tradeoff between average response delay and medical data rate.

• 대한전자공학회논문지TC
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• 제40권7호
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• pp.261-272
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• 2003

Ethernet PON(Passive Optical Network)은 최근 활발하게 연구되고 있는 경제적이고 효율적인 가입자망이다. 차세대 가입자망인 Ethernet PON의 MAC(Media Access Control) 프로토콜은 TDMA(Time Division Multiple Access)방식을 기본으로 하며, QoS(Qualify of Service)를 보장해야 하는 전용회선(Leased Line) 가입자에 적합한 고정 할당 방식과 LAN/MAN의 최선형(Best Effort) 방식에 적합한 동적 할당 방식으로 나눌 수 있다. 본 논문에서는 이들 프로토콜의 성능을 분석하기 위하여 OPNET 시뮬레이션 도구를 이용해 Ethernet PON 모델을 설계한다. 설계된 모델에 대한 단대단 Ethernet 지연(end-to-end Ethernet delay), 큐잉 지연(queuing delay), 처리(throughput)과 사용률(utilization) 분석을 통해서 MAC 프로토콜을 검증하고, 하나의 OLT(Optical Line Terminal)가 수용할 수 있는 최적의 ONU(Optical Network Unit) 개수를 산정한다. 또한, 적정한 ONU의 버퍼 크기를 제안하여 Ethernet PON의 망 효율을 극대화하는 방안을 제시한다.

• 대한전자공학회논문지TC
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• 제39권5호
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• pp.225-231
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• 2002

본 논문에서는 무선 MAC 프로토콜상에서 실시간 응용의 QoS를 보장할 수 있는 지연 민감도를 고려한 차별적인 충돌해결 기법을 제안한다. 제안된 기법은 충돌해결을 위해 접근 요구 메시지들을 지연에 따라 서로 다르게 다루며, 이를 위해 본 논문에서는 지연 민감도가 높은 트래픽의 충돌해결을 보다 빠르게 해결하기 위해 CRP (Collision Resolution Period) 구간을 사용한다. 성능분석과 시뮬레이션 결과 제안된 프로토콜이 접근지연과 충돌의 정도를 줄임으로서 실시간 응용의 지연요구조건을 성공적으로 보장함을 보여준다

• Journal of Communications and Networks
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• 제17권3호
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• pp.247-255
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• 2015

In this paper, we propose an adaptive time division multiple access based medium access control (MAC) protocol, called bitmap-assisted shortest job first based MAC (BS-MAC), for hierarchical wireless sensor networks (WSNs). The main contribution of BS-MAC is that: (a) It uses small size time slots. (b) The number of those time slots is more than the number of member nodes. (c) Shortest job first (SJF) algorithm to schedule time slots. (d) Short node address (1 byte) to identify members nodes. First two contributions of BS-MAC handle adaptive traffic loads of all members in an efficient manner. The SJF algorithm reduces node's job completion time and to minimize the average packet delay of nodes. The short node address reduces the control overhead and makes the proposed scheme an energy efficient. The simulation results verify that the proposed BS-MAC transmits more data with less delay and energy consumption compared to the existing MAC protocols.

• East Asian mathematical journal
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• 제27권1호
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• pp.23-33
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• 2011

Due to underutilization of spectrum under current inefficient and static spectrum management policy, various kinds of opportunistic spectrum access (OSA) strategies have appeared. Myopic policy is a simple and robust OSA strategy with reduced complexity that maximizes immediate throughput. In this paper, we propose mathematical models to evaluate the throughput and the MAC delay of a myopic policy under saturation tra c conditions. Using the MAC delay distribution, we evaluate the packet delay of secondary users under nonsaturation conditions. Numerical results are given to show the performance of the myopic policy in cognitive radio networks.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.423-425
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• 2007

In this paper, Medium Access Control(MAC) protocol designed for Wireless Body area Sensor Network(Bio-MAC) is proposed, Because in WBSN, the number of node is limited and each node has different characteristics. Also, reliability in transmitting vital data sensed at each node and periodic transmission should be considered so that general MAC protocol cannot satisfy such requirements of biomedical sensors in WBSN. Bio-MAC aims at optimal MAC protocol in WBSN. For this, Bio-MAC used Pattern -SuperFrame, which modified IEE E 802.15.4-based SuperFrame structurely. Bio-MAC based on TDMA uses Medium Access-priority and Pattern eXchange -Beacon method for dynamic slot allocation by considering critical sensing data or power consumption level of sensor no de etc. Also, because of the least delay time. Bio-MAC is suitable in the periodic transmission of vital signal data. The simulation results demonstrate that a efficient performance in WBSN can be achieved through the proposed Bio-MAC.

• Journal of information and communication convergence engineering
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• 제15권1호
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• pp.28-36
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• 2017

The medium access control (MAC) protocol based on dynamic time division multiple access/time division duplex (TDMA/TDD) is responsible for random access control and radio resource allocation in dynamic traffic environments. These functions of random access and resource allocation are very important to prevent wastage of resources and improve MAC performance according to various network conditions. In this paper, we propose new random access and resource allocation schemes to guarantee quality of service (QoS) and provide priority services in a dynamic TDMA/TDD system. First, for the QoS guarantee, we propose an adaptive random access and resource allocation scheme by introducing an access probability. Second, for providing priority service, we propose a priority-based random access and resource allocation scheme by extending the first adaptive scheme in both a centralized and a distributed manner. The analysis and simulation results show that the proposed MAC protocol outperforms the legacy MAC protocol using a simple binary exponential backoff algorithm, and provides good differential performance according to priorities with respect to the throughput and delay.