• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.517-520
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• 2005

Wireless sensor network combines sensing and computing technology which can sense light, temperature, vibration, magnetic field and wind etc, as each purpose of using those. Wireless nodes operate signal processing skill which has proceeded sensed information from the sensor, transmission which makes information reached to observer and limited energy managing skill which is needed on account of using battery to operate wireless. To make responsible measuring and sensing out of them, efficient energy management is so important to maintain life time of network. In this paper, after explaining CSMA/CA(Carrier Sense Multiple Access/Collision Avoidance) traditional wireless MAC protocol, and ER-MAC(Energy Rate Medium Access Control) which are not managing resource of hardware but MAN(Medium Access Control), data-link layer out of OSI 7 layer. We would like to analyze those efficiency of power saving comparing with each protocol.

• Journal of Communications and Networks
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• v.16 no.4
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• pp.385-396
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• 2014

In this paper, we present a formal method for modeling and checking an enhanced version of the carrier sense multiple access with collision avoidance protocol related to the IEEE 802.11 MAC layer, which has been proposed as the standard protocol for wireless local area networks. We deal mainly with the distributed coordination function (DCF) procedure of this protocol throughout a sequence of transformation steps. First, we use the unified modeling language state machines to thoroughly capture the behavior of wireless stations implementing a DCF, and then translate them into the input language of the UPPAAL model checking tool, which is a network of communicating timed automata. Finally, we proceed by checking of some of the safety and liveness properties, such as deadlock-freedom, using this tool.

• Journal of the Korea Society for Simulation
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• v.14 no.3
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• pp.101-108
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• 2005

IEEE 802.15.4 low-rate Wireless Personal Area Networks (WPAN) are expected to provide ubiquitous networking between small personal/home devices and sensors with low power consumption and low cost features. The technology employs special CSMA/CA (Carrier Sense Multiple Access/collision Avoidance) to save power consumption for small or portable WPAN-enabled devices. In this paper, we simulation the slotted CSMA/CA of IEEE 802.15.4 MAC and evaluate its performance limit in order to grasp the characteristics of Medium Access Control (MAC) of IEEE 802.15.4 WPAN.

• Proceedings of the Korea Society for Simulation Conference
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• 2005.05a
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• pp.10-14
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• 2005

IEEE 802.15.4 low-rate Wireless Personal Area Networks(WPAN) are expected to provide ubiquitous networking between small personal/home devices and sensors with low power consumption and low cost features. The technology employs special CSMA/CA (Carrier Sense Multiple Access/collision Avoidance) to save power consumption for small or portable WPAN-enabled devices. In this paper, we simulation the slotted CSMA/CA of IEEE 802.15.4 MAC and evaluate its performance limit in order to grasp the characteristics of Medium Access Control (MAC) of IEEE 802.15.4 WPAN.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.10 s.340
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• pp.39-50
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• 2005

In this paper, we propose a performance improving MAC algerian for the IEEE 802.11 DCF. WLAN based IEEE 802.11 uses two control methods called 'Distributed Coordination Function(UF)' and 'Point Coordination Function(PCF)'. The nF controls the Urnsmission based on carrier sense multiple access with collision detection(CSMA/CA), that decides a random backoff time with the range of contention window for each terminal. Normally, each terminal the CW double after collision, and reduces the CW to the minimum after successful transmission. This paper proposes an enhanced DCF algorithm that decreases the CW smoothly after successful transmission in order to reduce the collision Probability by utilizing the current status information of WLAN. We also analyze the throughput and delay performance for the unsaturated case mathematically. Simulation results show that our algorithm enhances the saturation throughput of WLAN. They also coincide well with the analytical results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.388-394
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• 2008

In this paper, MAC(Medium Access Control) algorithm for the IEEE 802.11 DCF(Distributed Coordination Function) improving the performance is proposed and analyzed by simulation. The MAC of IEEE 802.11 WLAN to control data transmission uses two control methods called DCF and PCF(Point Coordination function). The DCF controls the transmission based on CSMA/CA(Carrier Sense Multiple Access With Collision Avoidance). The DCF shows excellent performance relatively in situation that competition station is less but has a problem that performance is fallen from throughput and delay viewpoint in situation that competition station is increased. This paper proposes an enhanced DCF algorithm that increases the CW to maximal CW after collision and decreases the CW smoothly after successful transmission in order to reduce the collision probability by utilizing the current status information of WLAN. To prove efficiency of proposed algorithm, a lots of simulations are conducted and analyzed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.7B
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• pp.463-471
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• 2007

Because of MANET's dynamic characteristic, the hidden node problem can happen. Thus it must use with distributed channel access. In Ad hoc networks, carrier sense multiple access with collision avoidance(CSMA/CA) is one of the most widely used medium access control(MAC) schemes for asynchronous data traffics. However, CSMA/CA could not guarantee the quality of multimedia traffics. CSMA is a contention based protocol. Therefor once a node gets a channel, it can momopolze. Thus the fairness problem with channel starvation will happen. We will propose a new MAC protocol to guarantee QoS for multimedia data in ad hoc networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.8A
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• pp.827-835
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• 2007

In this paper, the extension method of data transmission range as adapting AAS(Adaptive Antenna Systems) in ECMA(European Computer Manufacturers Association) standard MB-OFDM(MultiBand-Orthogonal Frequency Division Multiplexing) UWB systems is proposed, and the complementary beamforming method which can solve hidden beam problem when we adapt AAS in CSMA/CA(Carrier Sense Multiple Access with Collision Avoidance) systems is proposed. To design the complementary beamforming, Gram-Schmidt orthogonalization is utilized, whose beam pattern exhibits perfect nulling at the main beam angles and provides uniform power for detection of channel utilization out of main beam. The proposed method can be utilized with any arbitrary beamforming when we make main beamforming. Through computer simulation, it can be shown that proposed AAS and complementary beamforming increase data transmission range from 2m to 3.95m in 480Mbps data transmission system and increase throughput about 20% as compared with general UWB AAS systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1462-1476
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• 2017

The current literature on discrete-time Markov chain (DTMC) based analysis of IEEE 802.15.6 MAC protocols for wireless body area networks (WBANs), do not consider the ACK timeout state, wherein the colliding nodes check the ill fate of their transmissions, while other contending nodes perform backoff check that slot as usual. In this paper, our DTMC model accurately captures the carrier sense multiple access with collision avoidance (CSMA/CA) mechanism of IEEE 802.15.6 medium access control (MAC) and allows the contending nodes performing backoff to utilize the ACK timeout slot during collisions. The compared rigorous results are obtained by considering a non-ideal channel in non-saturation conditions, and CSMA/CA parameters pertaining to UWB PHY of IEEE 802.15.6 MAC protocols.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.6
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• pp.457-465
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• 2014

This paper introduces a test bed for communication protocol schemes of underwater acoustic sensor network, and also shows experimental results obtained from the test bed. As a testing protocol, carrier sense multiple access/collision avoidance (CSMA/CA) is evaluated on underwater acoustic channel. A sensor node is equipped with a DSP control board of ATmega2560 and a commercial underwater modem produced by Benthos. The control board not only manipulates a GPS signal to acquire the information of location and time, but also controls the underwater modem to operate according to the procedure designed for a given testing protocol. Whenever any event takes place such as exchanging control/data packets between underwater modems and acquiring location and timing information, each sensor node reports them through radio frequency (RF) air interface to a central station located on the ground. The four kinds of packets for CSMA/CA, RTS(Request To Send), CTS(Clear to Send), DATA, ACK(Acknowledgement) are designed according to the underwater communication environment and are analyzed through the lake experiment from the point of feasibility of CSMA/CA in underwater acoustic communications.