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( Jaeshin Jang ),( Sang Wu Kim ),( Sunghong Wie ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.6
Cooperative communications and network coding schemes have been proposed to increase system throughput for ad hoc networks. In this paper, we present throughput and delay analysis of the new network coding-enabled cooperative MAC protocol called NC-MAC, which has been proposed by us in order to significantly enhance system performance. This protocol introduces an approach that can accommodate both cooperative communication and network coding for wireless ad hoc networks by slightly increasing overhead and modifying standards. The protocol`s performance is evaluated using mathematical analysis and computer simulation and two performance measures, system throughput and average channel access delay, are used for a performance comparison with previous schemes. It is assumed that all the frames exchanged over a wireless channel are susceptible to transmission errors, which is a new but more reasonable assumption differentiating this research from previous research. Numerical results show this protocol provides significantly enhanced system performance compared with conventional cooperative MAC protocols used in previous research. For instance, system performance is 47% higher using the NC-MAC protocol than when using the rDCF protocol.
Throughput and Delay Analysis of a Reliable Cooperative MAC Protocol in Ad Hoc Networks
Jang, Jaeshin,Kim, Sang Wu,Wie, Sunghong The Korea Institute of Information and Commucation 2012 Journal of communications and networks Vol.14 No.5
In this paper, we present the performance evaluation of the reliable cooperative media access control (RCO-MAC) protocol, which has been proposed in [1] by us in order to enhance system throughput in bad wireless channel environments. The performance of this protocol is evaluated with computer simulation as well as mathematical analysis in this paper. The system throughput, two types of average delays, average channel access delay, and average system delay, which includes the queuing delay in the buffer, are used as performance metrics. In addition, two different traffic models are used for performance evaluation: The saturated traffic model for computing system throughput and average channel access delay, and the exponential data generation model for calculating average system delay. The numerical results show that the RCO-MAC protocol proposed by us provides over 20% more system throughput than the relay distributed coordination function (rDCF) scheme. The numerical results show that the RCO-MAC protocol provides a slightly higher average channel access delay over a greater number of source nodes than the rDCF. This is because a greater number of source nodes provide more opportunities for cooperative request to send (CRTS) frame collisions and because the value of the related retransmission timer is greater in the RCO-MAC protocol than in the rDCF protocol. The numerical results also confirm that the RCO-MAC protocol provides better average system delay over the whole gamut of the number of source nodes than the rDCF protocol.
Jang, Jaeshin The Korea Institute of Information and Commucation 2014 Journal of information and communication convergen Vol.12 No.4
A new cooperative MAC protocol called the busy tone cooperative medium access control (BT-COMAC) protocol is proposed to overcome the drawbacks and maximize the advantages of existing schemes. This scheme uses a new metric called decibel power to decide an appropriate helper node. Using received power strength is more efficient in selecting an appropriate helper node, especially in a densely populated network, than the effective transmission rates used in conventional schemes. All communication nodes in a communication service area are assumed to move independently. Two performance metrics are used: System throughput and channel access delay. A performance evaluation of the BT-COMAC protocol is conducted using a computer simulation over a slow fading wireless channel, and its performance results are compared with those of four existing schemes. The numerical results show that the BT-COMAC protocol improves the system throughput by approximately 15% as compared to the best existing scheme.
모바일 WiMAX 시스템을 위한 VoIP용 QoS 패킷 스케줄러 성능평가
장재신(Jaeshin Jang) 제어로봇시스템학회 2009 제어로봇시스템학회 합동학술대회 논문집 Vol.2009 No.12
본 논문에서는 모바일 WiMAX 시스템에서 VOIP 서비스를 효율적으로 수용하기 위한 역방향 링크 QoS 패킷 스케줄링 기법을 제안하고 NS-2 시뮬레이터를 사용하여 성능평가를 수행하였다. 본 성능평가 결과에 따르면 본 연구에서 제안한 알고리즘이 UGS 서비스 기법에 비해 시스템 용량이 120%, ertPS 서비스 기법에 비해 시스템 용량이 25% 정도 증가함을 확인할 수 있었다.
오류채널 환경에서 IEEE 802.11b DCF 무선 랜 프로토콜 성능평가
장재신 인제대학교 2010 仁濟論叢 Vol.25 No.1
In this paper, the IEEE 802.11b DCF wireless LAN protocol under error-prone wireless channels is simplified to a simple model for performance analysis and its performance is evaluated by mathematical approaches. In this case, it is assumed that frame transmission errors happen only when transmitting RTS control frames. The system throughput is considered as a performance measure and various numerical results based on it are obtained in cases of various number of terminals and various length of data frames. Numerical results show that the system throughput tends to decrease when the number of terminals increases and that it tends to increase when the length of data frames increases. That is because the ratio of data frames to control frames increases in the latter case and thus it causes the increase of system throughput, which coincides with our intuition.
장재신,Jang, Jaeshin 한국정보통신학회 2013 한국정보통신학회논문지 Vol.17 No.8
본 논문에서는 무선통신에서의 시스템 성능을 향상시키기 위해 협력통신에서 매우 중요한 도움노드를 선정하는 방법에 대하여 연구를 수행하였다. 본 논문에서 제안한 BT-COMAC (busy tone cooperative MAC) 프로토콜은 사후(reactive) 도움노드 선정기법을 채용하였으며, 기존 기법의 장점을 극대화하면서 단점을 보완한 새로운 협력통신용 MAC 프로토콜이다. 컴퓨터 모의실험을 통해 성능평가를 수행하였으며, 시스템 처리량과 채널 액세스 지연시간을 성능평가 척도로 사용하였다. 모든 통신노드들이 통신영역 내에서 독자적으로 움직이는 이동성 모델을 사용하였으며, 슬로우 페이딩 채널 환경에서 수신 전력을 기반으로 전송속도를 결정하는 방법을 사용하였다. 성능평가 결과 본 논문에서 제안한 기법이 기존 방식에 비해 시스템 처리량 측면에서 최대 15% 정도 성능개선을 달성한 것을 확인할 수 있었다. In this paper, we carried out a study on how to find an appropriate helper node for cooperative communications, the role of which is very import to enhance system throughput of wireless communication system. The busy tone cooperative MAC (BT-COMAC) protocol proposed in this paper is a new cooperative MAC protocol with a reactive helper node scheme and maximizes the benefits of existing schemes while making up for their shortcomings. We conducted performance evaluation of this new protocol using computer simulation experiment. System throughput in bps and channel access delay are utilized as performance measures. We used a random way point mobility model where every communication node moves independently one another, and slow fading channel where every communication node decided its transmission rate with received power basis. Numerical results show that the new MAC protocol enhances system throughput as much as 15% of the existing scheme.
이재신(Jaeshin Yi),최병대(Byungdae Choi),장재덕(Jaeduk Jang),김현수(Hyunsoo Kim) 한국자동차공학회 2002 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2002 No.5_2
In this paper, hydraulic control system was developed for an electronically controlled CVT. The hydraulic control system consists of line pressure control valve, ratio control valve, damper clutch control valve, and pressure valve. In addition, control algorithms are developed. It is found from the test results that the hydraulic control system shows satisfactory performance. It is expected that the hydraulic control system developed in this study can be used for thc development of CVT