• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.7A
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• pp.639-645
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• 2010

In the paper, a selection relaying scheme is proposed and analyzed in which relays retransmit the erroneous packet without checking the correctness of their received packets. The proposal not only achieves the full diversity gain in a limited number of retransmissions but it also gets better performance than other schemes. Additionally, a threshold in the number of retransmissions and the closed form expression for packet error rate (PER) are derived. Simulation results are given to confirm the accuracy of analysis and to significantly prove advantages of the proposal.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.157-163
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• 2003

IEEE 802.11a Distributed Coordination Function(DCF) Protocol을 사용하여 Real-Time MultiMedia Data의 전송을 수행할 경우, DCF Protocol의 적합하지 못한 Mechanism에 의하여, Data 전송의 극대화를 이루지 못한다. Retransmission이 반복되는 경우, Binary Slotted Exponential Backoff Mechanism은 거대한 Packet Delay와 Jitter의 원인이 되며 Automatic Repeat Request(ARQ) 방식의 Ack Mechanism은 MultiMedia Data를 전송하기에 적합하지 못하다. 본 논문은 위와 같은 문제점을 해결하기 위하여 Real-Time MultiMedia Data을 주로 전송하는 STA에 따른 Real-Time/Non-Real-Time(RT/NRT) Station(STA)의 구분과 보내고자 하는 Real-Time MultiMedia Data의 Network Traffic Load(The Required Bandwidth)를 고려하여, Modified DCF(mDCF) Protocol의 Modified Backoff(mBackOff), Modified BlockAck(mBlockAck) Mechanism을 제시함으로서, Data 전송의 극대화를 제공하며, 또한 IEEE 802.11a와의 호환성을 제공한다.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.302-305
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• 2003

3GPP RLC protocol specification adopted an error control scheme based on selective repeat ARQ. In the 3GPP ARQ, distinctive windows are provided at transmitting and receiving stations so that those stations are prohibited to send or receive data PDU's out of window. An increase in window size enhances delay performance. Such an increase, however, raises the occupancy at re-ordering buffer, which results in a long re-ordering time. Aiming at suppressing the occupancy at re-ordering buffer, we propose partial go back N scheme in this paper In the partial go back N scheme, the receiving station regards all data PDU's between the first (lowest sequence numbered) error-detected PDU and last (highest sequence numbered) error-detected PDU. By the employment of the partial go back N scheme, the occupancy at the re-ordering buffer is apparently reduced, while the delay and throughput performance may be degraded due to the remaining properties of go back N. We thus consider peak occupancy of re-ordering buffer, mean sojourn time at re-ordering buffer, mean delay time, and maximum throughput as measures to evaluate tile proposed scheme and investigate such performance by using a simulation method. From numerical examples, we observe a trade-off among performance measures and conclude that the partial go back N scheme is able to effectively reduce the occupancy of re-ordering buffer.

• 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.

• Journal of information and communication convergence engineering
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• v.2 no.1
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• pp.9-14
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• 2004

In this paper the modeling of the RLP layer in CDMA2000 is presented, which uses the NAK based ARQ scheme for Random Error Channels. The RLP performs a partial link recovery through limited number of RLP frame transmission in case of frame error. In case when the RLP fails due to excessive frame error, the control is passed on to the higher (TCP) layer. The TCP layer provides the complete end-to-end recovery. Thus the reliable performance at the TCP/RLP is essential to maintain the required Quality of Service in the DS-CDMA wireless links. The modeling is done for the performance analysis of the system in terms of the throughput and the mean extra delays, which are calculated analytically and are compared with the results generated by the simulations. This paper studies the effect of the random errors over different types of RLP frame formats and also the performance of the NAK based ARQ mechanism used under these conditions. The simulation provides with the over all characteristics of the throughput and the mean extra delay in terms of realistic environment parameters like Eb/No and probability of packet error (PE), based on the channel conditions.

• 전자공학회논문지 IE
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• v.47 no.2
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• pp.54-59
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• 2010

This paper suggests a new data link protocol with an adaptive frame length control scheme for wireless data networks which is subject to errors that occur with time variance. We analyze the proposed scheme under a two-state markov block interference(BI) model. Numerical results show that the proposed scheme can achieve high throughput performance for both dense and diffuse burst noise channels.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.183-189
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• 2003

In this paper a simulation was done to verify performance of a message transmission protocol which interfaces LDTS(Local Data Transmission System) with EIS(Electronic Interlocking System), After a stage of analyzing link specifications between LDTS and EIS, transmission messages and messaging formats, simulation parameters were extracted, applied to the error control schemes such as ARQ, FEC, HARQ, and therefrom throughputs and various performance indices were analyzed Simulation program was constructed with Matlab and Matlab GUI and then converted into a stand-alone c++ program to be used on any non-Matlab environments.

• Journal of Communications and Networks
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• v.14 no.5
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• pp.510-517
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• 2012

This paper analyzes the performance of voice-over-Internet protocol (VoIP) services in terms of the system throughput, the packet delay, and the signaling overhead in a mobile WiMAX system with a hybrid automatic repeat request (HARQ) mechanism. Furthermore, a queueing analytical model is developed with due consideration of adaptive modulation and coding, the signaling overhead, and the retransmissions of erroneous packets. The arrival process is modeled as the sum of the arrival rate at the initial transmission queue and the retransmission queue, respectively. The service rate is calculated by taking the HARQ retransmissions into consideration. This paper also evaluates the performance of VoIP services in a mobile WiMAX system with and without persistent allocation; persistent allocation is a technique used to reduce the signaling overhead for connections with a periodic traffic pattern and a relatively fixed payload. As shown in the simulation results, the HARQ mechanism increases the system throughput as well as the signaling overhead and the packet delay.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.11a
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• pp.409-411
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• 2014

WAVE 기술은 차량이 고속 이동환경에서 차량간 또는 차량과 인프라간 패킷을 짧은 시간 내에 주고 받을 수 있는 무선통신 기술이다. 본 논문의 목적은 차량이 WAVE 시스템에 통신 할 때 상대방의 인증서가 폐기 되었는지 확인하기 위한 CRL(Certificate Revocation List) 다운로드 프로토콜을 설계하는 것이다. CRL 다운로드 프로토콜은 WAVE 시스템 환경에 맞추기 위해 TCP(Transmission Control Protocol)가 아닌 UDP(User Datagram Protocol) 상에서 동작한다. 그리고 보안기능을 지원하기 위해 ECDSA 를 사용하여 상호 인증을 하고 ECIES 를 사용하여 인증서의 기밀성을 보장한다. 또한 이 프로토콜은 MAC 을 CRL 데이터에 붙여 데이터의 무결성을 보장하고, UDP 상에서 동작할 때 발생할 수 있는 데이터의 손실을 줄이기 위해 에러 및 흐름제어 방식으로 Selective repeat ARQ 를 사용한다.

• Journal of KIISE:Information Networking
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• v.36 no.5
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• pp.383-388
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• 2009

In this paper, we focus on the retransmission following transmission failure in impulse radio ultra wideband (IR-UWB). The reasons of transmission failure are classified and a new 'selfish' retransmission protocol is proposed because time hopping can support multiple transmissions at the same time. Selfish retransmission protocol retransmits packets immediately without any kind of timeout or channel observation. Simulation results show that the proposed protocol improves throughput up to 50% and decreases retransmission delay also up to 70%, compared to a conventional retransmission system in IR-UWB.