• Journal of Korean Institute of Industrial Engineers
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• v.32 no.1
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• pp.1-8
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• 2006

A modified PCF(Point Coordination Function) protocol with the optimal polling sequence is defined in detail and shown to improve the efficiency of the conventional PCF protocol in IEEE 802.11 wireless LAN standard. The problem for the optimal polling sequence is formulated as TSP(Travelling Salesman Problem) with the distance values of 1's or 0's. Numerical examples show that the optimal polling sequence increases the capacity of the real-time service such as VoIP(Voice over Internet Protocol).

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.31-34
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• 2005

In this paper, we proposed a MAC protocol which can be used in power line communications(PLC). In the power line communication network, the data signal cannot travel long distance because of a serious attenuation. Consequently, we need to have a number of repeaters (amplifiers) in order to recover the signal power, which causes flooding problem in the network The proposed MAC protocol uses polling concept and solves the flooding problem in the power line communication network. The proposed protocol can be applied to power line communication networks for automatic power distribution control system. A mathematical analysis has been carried out to estimate the performance of the proposed protocol.

• Smart Structures and Systems
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• v.21 no.2
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• pp.225-234
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• 2018

E-Health allows you to supersede the central patient wireless healthcare system. Wireless Body Sensor Network (WBSN) is the first phase of the e-Health system. In this paper, we aim to understand e-Health architecture and configuration, and attempt to minimize energy consumption and latency in transmission routing protocols during restrictive latency in data delivery of WBSN phase. The goal is to concentrate on polling protocol to improve and optimize the routing time interval and schedule communication to reduce energy utilization. In this research, two types of network models routing protocols are proposed - elemental and clustering. The elemental model improves efficiency by using a polling protocol, and the clustering model is the extension of the elemental model that Destruct Supervised Decision Tree (DSDT) algorithm has been proposed to solve the time interval conflict transmission. The simulation study verifies that the proposed models deliver better performance than the existing BSN protocol for WBSN.

• Journal of the Korea Society of Computer and Information
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• v.20 no.8
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• pp.23-28
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• 2015

TPSN(Timing-sync Protocol for Sensor Networks), the representative of time synchronization protocol for WSN(wireless sensor networks), was developed to provide higher synchronization accuracy and energy efficiency. So, TPSN's approach has been referenced by so many other WSN synchronization schemes till now. However, TPSN has a collision problem due to simultaneous transmission among competing nodes, which causes more network convergence delay for a network-wide synchronization. A Polling-based scheme for TPSN is proposed in this paper. The proposed scheme not only shortens network-wide synchronization time of TPSN, but also reduce collision traffic which lead to needless power consumption. The proposed scheme's performance has been evaluated and compared with an original scheme by simulation. The results are shown to be better than the original algorithm used in TPSN.

• Journal of IKEEE
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• v.11 no.4
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• pp.171-177
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• 2007

Although the Distributed Coordination Function is the fundamental access protocol of IEEE 802.11, it cannot meet the Quality of Service (QoS) requirements in general. So, the Point Coordinate Function is provided to support QoS related services. However, it has inherent problems. Access point (AP) has no knowledge of the queue status and instantaneous channel condition of stations in the system. In this paper we propose an efficient and versatile polling scheduler that shows excellent throughput and fairness performance. Comparison with well known polling schemes is provided through computer simulation under various channel situations including error prone environments.

• 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.

• Journal of the Korea Society of Computer and Information
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• v.5 no.4
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• pp.120-125
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• 2000

SNMP(Simple Network Management Protocol) could have the overhead of network, if the number of the agent system which is managed by the management system is increased by the polling for the collection of network management information and the reply traffic for it. In this Paper, the polling method used in SNMP is improved, and Group Polling method is proposed. This can reduce the overhead of network, on case that the agent system is to be increased. The proposed method collects information by grouping agent systems, and have smaller reply latency time and communication overhead than the previous method. So if the number of agent system or the Polling count is numerous, the proposed method is more efficient. As the result of the prototype test, the increasement of agent system can have small variation of traffic and transmission delay time.

• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2544-2552
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• 1997

This paper presents three multiprocess models for parallel protocol implementation, that is, (1)channel communication model, (2)fork-join model, and (3)event polling model. For the specification of parallelism for each model, a parallel programming language, Par. C System, is used. to measure the performance of multiprocess models, we implemented the Internet Protocol Suite(IPS) Internet Protocol (IP) for each model by writing the parallel language on the Transputer. After decomposing the IP functions into two parts, that is, the sending side and the receiving side, the parallelism in both sides is exploited in the form of Multiple Instruction Single Data (MISD). Three models are evaluated and compared on the basis of various run-time overheads, such as an event sending via channels in the parallel channel communication model, process creating in the fork-join model and context switching in the event polling model, at the sending side and the receiving side. The event polling model has lower processing delays as about 77% and 9% in comparison with the channel communication model and the fork-join model at the sending side, respectively. At the receiving side, the fork-join model has lower processing delays as about 55% and 107% in comparison with the channel communication model and the event polling model, respectively.

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.2
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• pp.140-150
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• 2008

Point Coordination Function (PCF) of the IEEE 802.11 protocol providing a centrally-controlled polling-based multiple access to a wireless channel is very efficient in high load conditions. However, its performance degrades with increasing the number of terminals and decreasing the load, because of wastes related to unsuccessful polling attempts. To solve the problem, we propose and study analytically the generic dynamic polling policy using backoff concept. For this aim, we develop Markov models describing the network queues changes, what allows us to estimate such performance measures as the average MAC service time and the average MAC sojourn time, to show the dynamic polling efficiency and to tune optimally the backoff rule.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.2A
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• pp.80-89
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• 2005

In IEEE 802.11 and 802.11e for ad hoc networks, DCF and EDCA use a contention-based protocol called CSMA/CA, which is simple to implement efficient when the system is light loaded. But the performance of CSMA/CA decreases dramatically when the system load is heavy because of increasing collisions. In PCF and HCF modes, stations are controlled by a base station by polling, no collision ever occurs. However, when the system load is light, the performance is poor because few stations have data to transfer. More important, PCF and HCF can not be used in the ad hoc networks. In this paper, we address a priority-based distributed polling mechanism (PDPM) that implements polling scheme into DCF or EDCA modes for ad hoc networks by adding a polling approach before every contention-based procedure. PDPM takes the advantages of polling mechanism that avoids most of collisions in a high load condition. At the same time, it also keeps the contention-based mechanism for a light loaded condition. PDPM provides quality of service (QoS) with fewer collisions and higher throughput compared with IEEE 802.11e.