• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.2
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• pp.687-708
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• 2017

The machine-to-machine (M2M) communication is featured by tremendous number of devices, small data transmission, and large uplink to downlink traffic ratio. The massive access requests generated by M2M devices would result in the current medium access control (MAC) protocol in LTE/LTE-A networks suffering from physical random access channel (PRACH) overload, high signaling overhead, and resource underutilization. As such, fairness should be carefully considered when M2M traffic coexists with human-to-human (H2H) traffic. To tackle these problems, we propose an adaptive Slotted ALOHA (S-ALOHA) and time division multiple access (TDMA) hybrid protocol. In particular, the proposed hybrid protocol divides the reserved uplink resource blocks (RBs) in a transmission cycle into the S-ALOHA part for M2M traffic with small-size packets and the TDMA part for H2H traffic with large-size packets. Adaptive resource allocation and access class barring (ACB) are exploited and optimized to maximize the channel utility with fairness constraint. Moreover, an upper performance bound for the proposed hybrid protocol is provided by performing the system equilibrium analysis. Simulation results demonstrate that, compared with pure S-ALOHA and pure TDMA protocol under a target fairness constraint of 0.9, our proposed hybrid protocol can improve the capacity by at least 9.44% when ${\lambda}_1:{\lambda}_2=1:1$and by at least 20.53% when ${\lambda}_1:{\lambda}_2=10:1$, where ${\lambda}_1,{\lambda}_2$ are traffic arrival rates of M2M and H2H traffic, respectively.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.48-48
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• 2000

We developed a wireless communication system for multiple instrumentation system. The developed system has a function of remote instrumentation and PLC(Programmable Logic Controller) control. The system consists of CC(Control and Communication) protocol, wireless media access and physical media system. For multiple wireless communication, we propose a hub polling protocol based on master-slave control concept. To show the validity of the developed system, several experiments are illustrated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.2
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• pp.250-260
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• 1993

Packet Reservation Multiple Access(PRMA) protocol provides a very efficient mechanism for many number of voice and data terminals with bursty traffic characteristics to share efficiently a common transmission channel. This protocol, however, cannot operate in high load conditions. That is, there occurs a instability problem, since the reservation channel is allowed to shrink to zero. In this paper, a more stable PRMA protocol which can avoid such problems and integrates voice and data traffic efficiently is proposed. Also, the performance of the proposed protocol is analyzed by a computer simulation. According to the simulation results, it can be shown that the proposed protocol provides a more efficient mechanism for voice/data integration and ensures a more stable operation than conventional PRMA protocol in high load conditions.

• Journal of Korean Institute of Industrial Engineers
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• v.33 no.2
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• pp.237-245
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• 2007

In this paper, a modified PCF (Point Coordination Function) MAC (Medium Access Control) Protocol is proposed to support the multiple direct link communication between STAs (STAtions) in infrastructure mode IEEE 802.11 wireless LANs. By the proposed MAC protocol, the direct link communication between STAs, which are located within the communication range of each other, is allowed without the use of AP (Access Point) as a relay. Moreover, when multiple direct data communication between STAs can be simultaneously performed with a sufficiently small interference, multiple simultaneous direct link communication is allowed for the efficient use of radio bandwidth. AP polls STAs to grant the transmission opportunities using the direct link communication by transmitting the polling frames to STAs. An efficient polling method for granting the transmission opportunities to STAs is proposed to reduce the number of the polling frame transmissions and enhance the PCF MAC performance.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.2
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• pp.70-80
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• 2008

CSMA(Carrier Sense Multiple Access) is a media access control protocol when nodes use a shared channel. To reduce the probability of collision and increase the performance, the station lust checks the state of the channel. In this paper, we study the performance improvement method based on p-persistent strategy. The p-persistent method reduces the chance of collision and improves the efficiency. However, a probability p and the number of station affect the performance. This paper proposes a dynamic CSMA multiple access based on the network status. If the possibility of collision is low, the station increases the probability p to improve the performance. In the opposite case, the station decreases the probability p. Our simulation results show that the proposed scheme outperforms any methods of CSMA multiple access according to the current persistent strategy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2A
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• pp.187-194
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• 2004

We propose priority-based reservation code multiple access (P-RCMA) which can enhance voice traffic quality of the previous RCMA. The proposed protocol maintains two power levels and consider traffic characteristics in contending shared available codes to transmit packets. P-RCMA gives priority to the voice request packets rather than data packets by capture effect at the receiver part of base station. We show numerical results from EPA (equilibrium point analysis) analysis and simulation study in terms of voice packet dropping probability and average data packet transmission delay.

• Journal of Internet Technology
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• v.20 no.1
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• pp.301-313
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• 2019

In this paper, we propose a new MAC protocol for Cognitive Radio (CR)-based IoT networks, called MSMA/CA. We extend the standard CSMA/CA, adopted in IEEE 802.11 WLANs, to the CR networks with the minimal modification since it works well in the real world. We resolve the classical hidden/exposed terminal problems by a variant of RTS/CTS mechanism and further, the hidden primary terminal problem by the mutual spectrum sensing at the transmitter and the receiver. We also modify the backoff process of CSMA/CA to incorporate the blocking of secondary transmitters, with the aim of protecting ongoing primary transmissions from aggressive secondary users. We analyze the throughput and delay of our proposed scheme using the Markov chain model on the backoff procedure, and verify its accuracy by simulations. Simulation results demonstrate that our protocol is suitable for IoT networks since the performance is insensitive to the number of users or devices.

• The Journal of the Acoustical Society of Korea
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• v.27 no.6
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• pp.279-285
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• 2008

This study includes the efficiency assessment of a multiple access protocol for UUV (Underwater unmanned vehicle) control. Most of UUVs are controled by wire now; however, wireless control is demanded because of the demerit of the wire control that limits the place and activity. This study simulates efficiency of a standardization multiple access protocol (Pure ALOHA, Slotted ALOHA, Nonpersistent CSMA, Slotted Nonpersistent ISMA) formed for the purpose of performing wireless communication controlled by the ship or communication buoy at the sea surface and by the under water communication node at the bottom in order to efficiently control the UUV's. Results show that no significant changes occur related to changing type of the mother ship and the communication node; In addition, the Non-persistent CSMA and the Slotted Non-persistent ISMA show relatively high efficiency for underwater acoustic communication.

• Journal of the Institute of Convergence Signal Processing
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• v.13 no.3
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• pp.156-161
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• 2012

Random access protocol takes advantage of constructing a decentralized wireless network due to its intrinsic spectrum sensing capability. Such technical feature goes well with cognitive radio networks consisting of heterogeneous wireless systems, in which a centralized control between heterogeneous wireless systems is hard to be implemented. Motivated by the decentralized feature of the random access, we adopt the random access protocol in cognitive radio networks, and evaluate the performance of a CSMA-based cognitive radio network.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.603-606
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• 2019

In this paper, we propose a slotted-ALOHA-based random access protocol and derive the optimal number of random slots that maximize channel throughput when multiple energy harvesting sensor devices perform random access in wireless-powered sensor networks (WPSN). Throughput numerical analysis, we prove that the throughput has a concavity with respect to the number of random slots and obtain the optimal number of slots. Simulation results show that the throughput of the proposed slotted ALOHA-based random access protocol is maximize when the derived optimal number of slots is employed in the considered WPSN.