• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1276-1285
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• 2015

Full-duplex communications have emerged as a key technology for next-generation wireless local area networks (WLANs). Although the key enabling technology for full-duplex communications is the self-interference cancellation (SIC) technique in the physical layer, the employment of full-duplex communications has huge potentials to substantially increase the throughput at the medium access control (MAC) layer. At the same time, full-duplex communications pose non-trivial challenges to the MAC protocol design. In this article, we first identify salient problems in supporting full-duplex communications in WLAN MAC protocols. After that, we survey the state-of-the art to address those problems and analyze their pros and cons. Finally, we present open research challenges to improve the effectiveness of full-duplex communications in WLANs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.2
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• pp.241-249
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• 1997

In this paper, a new technique is proposed for generating a minimum-length synchronizable test sequence that can be applied in the distributed test architecture where both external synchtonization and input/output operation costs are taken into consideration. the method defines a set of transformation rules that constructs a duplex digraph from a given finite state machine representation of a protocol specification rules that constructs a duplex digraph from a given finite state machine representation of a protocol specificatio such that a rural chinese postman tour of the duplex digraph can be used to generate a minimum-length synchronizable test sequence using synchronizable distinguishing sequences as the state identification sequence for each state of the given finite state machine. The method provides an elegant solution to the synchronization problem that arises during the application of a predetermined test sequence in some protocol test architectures that utilize remote testers.

• Convergence Security Journal
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• v.16 no.7
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• pp.61-68
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• 2016

As many high-tech researches are shown in various field by sharing data via computer network, a necessity for stable data-sharing environment has suggested steadily. This research covers one-way communication protocol which is newly developed through the necessity. In this protocol, data is transmitted only in one way. One-way transmission has strong possibility to protect system from uncertain and potential risk, but it is impossible to receive ACK(Acknowledge Character) packet about data. Therefore, we need to find a way which duplex protocol such as TCP, ICMP works properly and practical communication falls under one-way transmission environment. To conclude, we analysed possible scenario in each protocol from three layers - interface layer, internet layer and transmission layer and approached how to resolve the problem in each way.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.5
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• pp.426-435
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• 2013

The diversity-multiplexing tradeoff (DMT) functions of three special half-duplex (HD) dynamic decode-and-forward (DDF) protocols with multiple antennas only at the source node, only at the destination node, and only at the relay node are analytically derived. The DMT functions of these three relay protocols are compared with one another and with those of the nonorthogonal amplify and forward (NAF) protocols.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.680-682
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• 1999

This paper presents a design of central monitoring and control system using duplex redundancy modular. Communication protocol used fieldbus and application program for monitoring and control have been developed by CIMON. The performance and convenience of developed system is demonstrated cremation furnace.

• Journal of Internet Computing and Services
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• v.10 no.1
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• pp.83-91
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• 2009

The advertisement system on TV is categorized into full duplex TV and Internet Protocol Television (IPTV). For the full duplex TV or the IPTV, channel providers need a number of advertisements and pay enormous expenses for them. Therefore, this study proposes how to reduce unnecessary expenses based on users' preferences. The advertisement system based on users' preferences is designed to decrease unnecessary advertisements with less expense. To identify preferences in usual advertisements and animation advertisements is to reduce expenses due to the necessity of a number of advertisements. The proposed system was designed to provide full duplex advertisements for profits of advertisement industry and considered users' disposition based on preferences of broadcasting advertisements, through which users can have advertisement desired and providers can expect less advertisement expenses and more profits.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.7
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• pp.1244-1255
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• 1994

The wireless-LAN(Local Area Network), which is emerged as a solution to cable problem and increasing requirement for communication network, has a several problem when it transmit information MAN protocol by used wired-LAN`s MAC protocol. Media Access protocol in Wireless-LAN has great effect on system performance and much studies are processing now. The PRMA(Packet Reservation Multiple Aeecss) of reservation method has a disadvantage that the system performance was degraded become of delay time in the reservation step as a resulting of collision. In this paper, using the TDD(Time Division Duplex) method amd modified PRMA method wireless-LAN modelled to overcome disadvantage, that id delay time due to collision in reservation step. The performance evaluation fo the model was done using M/M/1//M process model and this was simulation using SLAM.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.2
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• pp.562-576
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• 2020

The power allocation optimization problem is investigated for improving the physical-layer security in two-way relaying networks, where a full-duplex relay based half-jamming protocol (HJP-FDR) is considered. Specially, by introducing a power splitter factor, HJP-FDR divides the relay's power into two parts: one for forwarding the sources' signals, the other for jamming. An optimization problem for power split factor is first developed, which is proved to be concave and closed-form solution is achieved. Moreover, we formulate a power allocation problem to determine the sources' power subject to the total power constraint. Applying the achieved closed-form solutions to the above-mentioned problems, a two-stage strategy is proposed to implement the overall power allocation. Simulation results highlight the effectiveness of our proposed algorithm and indicate the necessity of optimal power allocation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.11a
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• pp.450-455
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• 1998

This paper proposes an enhanced transport protocol for multipeer communications. It is assumed that there exists a transport connection owner that takes the roles of the establishment, management and termination of a transport connection. The proposed protocol classifies the data transfer type into simplex, duplex and N-plex multicasts and provides several transport services to support various requirements in group communications. The general operations and reliability controls of each transfer type are different from one another and carried out by a shared control tree. The QoS negotiation is performed during the creation phase. The notification of negotiated values is followed by an acknowledgment procedure for confirmation. The four-way handshake is introduced. After negotiation, such a resource reservation protocol as RSVP can reserve system and network resources according to the arbitrated values. This paper suggests a conceptual model of the transport layer and its protocol behaviors over the IP multicast and RSVP network.

• Journal of Korea Multimedia Society
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• v.2 no.3
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• pp.329-338
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• 1999

In this paper we propose a WATM MAC protocol called DTDD/PS (Dynamic Time Division Duplex using Poll/Select scheme). The idea of the DTDD/PS protocol is based that a radio cell is considered as queueing system. The MAC controller in base station is charged in coordinating terminals for the QoS requirement from each terminal. For that reason, terminals send it's own dynamic parameter represented its status, and controller controls the access of terminals and assigns time slots dynamically using received parameters. Therefore this system can satisfy the QoS of real-time service in wireless environments. To evaluate DTDD/PS protocol simulations are executed. In 25Mbps channel capacity, the voice and data coexist traffic situation, as the total number of terminal is increased, the delay of data terminals is increased rapidly. But the case of only increasing data terminals, the number of supported voice terminals is not varying. Therefore we can expect that DTDD/PS protocol can applied to multimedia traffic effectively.