• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.633-636
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• 2011

The paper deals with the performance of contention-based medium access control (MAC) protocols for underwater sensor networks. We extensively analyze the number of received-packets and the end-to-end delay of ALOHA, CSMA, CSMA-RTS-CTS and CSMA-RTS-CTS-ACK protocols using a Qualnet underwater network simulator which accommodates diverse underwater acoustic channel environments. Using simulation results, we support an engineering table to determine an adequate contention-based MAC protocol for underwater sensor networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.4
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• pp.605-613
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• 1994

In this paper, we evaluate performance of multiple access for distributed wireless communication network by CSMA protocol. It is envident that the existence of hidden node in an environment degrades the performance of CSMA. In order to improve performance due to the problem of hidden node, the previous paper used random multiple access protocols a as such as ISMA, BTMA, BCMA. In this paper, We propose a protocol that we can improve performance by allowing node to sense the carrier of any other transmission on the channel in the distributed wireless communication networks The probability of transmission success was obtained by steady stats analysis under given assumptions. We confirmed that hidden node problem be virtually elimated by using a new protocol.

• Journal of the Korea Institute of Military Science and Technology
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• v.2 no.2
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• pp.117-130
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• 1999

In this paper, the performance of data communication function of military radio equipment P-999K is analyzed based on the standard CSMA/CA protocol which is DFWMAC standard protocol done by IEEE802.11 work group. Basic three standard protocols, i.e. Basic CSMA/CA, Stop & Wait ARQ and 4-Way Handshake CSMA/CA protocols are analyzed and compared with each other under the hidden terminal environment. The computer simulation is also done by using SIMSCRIPT II.5 which is popular software tool for an independent processing. The results show that p-persistent(with p=0.3) CSMA scheme is superior to non-persistent CSMA scheme with non-hidden terminal condition, but the performances of both schemes are almost same with hidden terminal situation. And the results of computer simulations are also showed that Basic CSMA/CA protocol is superior to the other protocols when the ratio of hidden terminals is below 10 % of total user population, however, with the above 20% hidden terminals environment and the higher offered traffic conditions the 4-Way Handshake CSMA/CA protocol shows the most superior performance.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10c
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• pp.685-687
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• 2001

최근 인터넷의 급격한 성장의 일면에는 CSMA/CD 프로토콜에 기반을 둔 이더넷 네트워크 망의 중추적인 서비스 제공에 있다고 볼 수 있다. 사용자의 기하급수적 증가와 더불어 인터넷망의 복잡성은 이더넷 인터넷망에서의 각 호스트들간의 데이터 층들을 급속하게 야기시켜, 전체적인 서비스 지연을 초래하는 경우가 발생되고 있다. 본 논문에서는 전송예약을 통해 기존 CSMA/CD 프로토콜에서의 프레임 충돌횟수를 줄이고 전송효율 또한 높이는 방안을 제시한다.

• Information and Communications Magazine
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• v.29 no.9
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• pp.70-77
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• 2012

Carrier Sensing Multiple Access (CSMA)로 불리는 임의 접근 방식은 무선 통신 시스템에서 흔하게 사용되는 프로토콜이다. 이 CSMA 프로토콜은 데이터 전송에 앞서 자신의 링크 상황을 먼저 파악 한 후에 전송이 가능한 경우에 전송을 시도하는 방식이다. 매우 간단하며 분산적으로 동작이 진행되기 때문에 쉽게 실제 시스템에 적용되어 사용되고 있다. 이와 같은 간단하고 분산적인 CSMA 알고리즘이 최적 전송효율을 달성 할 수 있다는 사실이 최근에 밝혀졌다. 이러한 발견을 바탕으로 많은 연구들이 다양한 조건에서 전송효율을 극대화 시키는 방법에 대해 다뤘다. 본고에서는 최근의 이러한 연구 동향을 정리하고, 앞으로 해결해야 할 문제를 정리하였다.

• Journal of Advanced Navigation Technology
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• v.7 no.2
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• pp.199-205
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• 2003

In this paper, CSMA/CA protocol is modified for aeronautical VHF communication through collision alleviation and the change of retransmission slot selection method in flag used transmission. When collision occurred in the contention period of CSMA/CA process, it is generally waiting for retransmission delay and it has the double size of CW(Contention Window). To solve this problem, this paper modifies the change procedure of original contention window size and reduces the state transition in collision among the whole of it. Also, in this paper we reduces the second collision probability through the station has to enter Backoff mode with increased contention window in the first collision. In the result of simulation, it is verified that it has good property in throughput and delay, So the proposed protocol is suitable for aeronautical VHF communication.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.12
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• pp.5835-5854
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• 2017

The implementation of IEEE 802.15.6 in Wireless Body Area Network (WBAN) is contention based. Meanwhile, IEEE 802.15.4 MAC provides limited 16 channels in the Superframe structure, making it unfit for N heterogeneous nature of patient's data. Also, the Beacon-enabled Carrier-Sense Multiple Access/Collision-Avoidance (CSMA/CA) scheduling access scheme in WBAN, allocates Contention-free Period (CAP) channels to emergency and non-emergency Biomedical Sensors (BMSs) using contention mechanism, increasing repetition in rounds. This reduces performance of the MAC protocol causing higher data collisions and delay, low data reliability, BMSs packet retransmissions and increased energy consumption. Moreover, it has no traffic differentiation method. This paper proposes a Low-delay Traffic-Aware Medium Access Control (LTA-MAC) protocol to provide sufficient channels with a higher bandwidth, and allocates them individually to non-emergency and emergency data. Also, a Contention Differentiated Adaptive Slot Allocation CSMA-CA (CDASA-CSMA/CA) for scheduling access scheme is proposed to reduce repetition in rounds, and assists in channels allocation to BMSs. Furthermore, an On-demand (OD) slot in the LTA-MAC to resolve the patient's data drops in the CSMA/CA scheme due to exceeding of threshold values in contentions is introduced. Simulation results demonstrate advantages of the proposed schemes over the IEEE 802.15.4 MAC and CSMA/CA scheme in terms of success rate, packet delivery delay, and energy consumption.

• Journal of Korea Society of Industrial Information Systems
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• v.20 no.1
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• pp.27-35
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• 2015

In this paper, we suggested a RS485 based CSMA/CD protocol that is available in low speed multi-node networks such as industry control communication network and home network etc. The suggested protocol was compared to widely used Master-Slave protocol, Modbus. We modeled realistic control network and showed that the average delay and throughput performance were significantly improved in the different transmission rates.

• Journal of Korea Multimedia Society
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• v.10 no.12
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• pp.1612-1621
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• 2007

In this paper, we introduced our designed TDMA (Time Division Multiple Access) based MAC (Medium Access Control) protocol for Home Networks called HomeTDMA. We have implemented and tested it in a test bed using crossbow motes and TinyOS. We also have compared HomeTDMA and CSMA (Carrier Sense Multiple Access) in terms of space and time complexity, channel access time, delivery success ratio, and throughput. Based on our results, HomeTDMA has an advantage over CSMA on channel access time, throughput and delivery success ratioIn the case of complexity, HomeTDMA is more complex compared to CSMA. Thus, CSMA is more appropriate in wireless sensor networks (WSNs) where memory, energy, and throughput are important parameters to be considered. However, HomeTDMA has a natural advantage of collision free medium access and is very promising for home networks where a reliable transmission or data transfer and congestion control is highly preferred.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.231-234
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• 2003

In this paper, we propose the enhanced CSMA/CA MAC protocol fir mobile multi-hop wireless Ad-hoc networks. In the conventional wireless Ad-hoc network such as WLAN using CSMA/CA MAC protocol, communications between terminals that fn connected within multi-hop node may degrade the transmission efficiencies as increasing the multi-hop nodes because of RTS-CTS-DATA-ACK message exchange between terminals. In this raper, we apply the ACK/RTS control message into multi-hop transmission between terminals for wireless ad-hoc networks and improve the data traffic transmission efficiencies compared with conventional CSMA/CA MAC protocol used in WLAN.