• Title/Summary/Keyword: 타임 슬롯

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A MAC Protocol for Voice/Data Integrated Services Using R_ALOHA Scheme In Wideband Wireless Networks (광대역 무선망에서 R_ALOHA 기법을 적용한 음성/데이타 통합 서비스 UC 프로토콜)

  • 임인택
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.3 no.1
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    • pp.155-162
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    • 1999
  • In this paper, an R_ALOHA_CDMA protocol is proposed for voice and data integrated services in the hybrid TDMA/CDMA wireless networks. In the hybrid TDMA/CDMA systems, the backward logical channels are composed of time slots with multiple spreading codes per slot. In the proposed protocol, a voice terminal can reserve a spreading code to transmit voice packets during a talkspurt. On the other hand, whenever a data terminal generates a packet, it transmits the packet through one of the available spreading codes. Throughout the results, it is shown that the system capacity increases in proportion to the number of spreading codes.

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Design of Variable Timeslot for Hybrid MAC (하이브리드 MAC을 위한 가변 타임슬롯 설계)

  • Ryu, Jeong-Kyu;Lee, Seong-Real
    • Journal of Advanced Navigation Technology
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    • v.24 no.6
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    • pp.613-619
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    • 2020
  • Hybrid media access control (MAC) is used in internet of things (IoT) network, because of communication feature concern with data capacity and communication interval between gateway and sensor nodes and the cost efficiency. Hybrid MAC consists of TDMA and CSMA generally. The distance between gateway and sensor node is openly changed in marine IoT network. Therefore, it is needed to control the period of timeslot of hybrid MAC used in marine IoT network. In this paper, the design rule of TDMA timeslot with the variable period depending on communication distance was proposed. It was confirmed from the analysis that 72 times communication between gateway and sensor nodes is possible in LoRa network by using the proposed TDMA variable timeslot scheme.

A Study on the Traffic Analysis of Optical Subscriber Network (광가입자망의 트래픽 분석에 관한 연구)

  • Jung, Hae-Young;Lee, Heung-Jae;Choe, Jin-Kyu;Rhee, Woo-Seop;Yu, Jea-Hoon
    • Journal of IKEEE
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    • v.6 no.2 s.11
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    • pp.161-168
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    • 2002
  • Network of these days, A transmission medium of information is replaced from electric signal to optical signal to accept various and increased network traffic. In this paper, we develop simulation program using AweSim and simulate EPON system as a high-speed optical subscriber network with various conditions. The effects of number of ONUs, effects of network load and effects of slot assignment schemes have been evaluated. The simulation results show that slot assignment schemes and number of ONUs is major factor of network performance. The variable-number slot scheme is more efficient than fixed-length slot scheme in the traffic processing.

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MAC Protocol based on Resource Status-Sensing Scheme for Integrated Voice/Data Services (음성/데이타 통합 서비스를 위한 자원 상태 감지 기법 기반 MAC프로토콜)

  • Lim, In-Taek
    • Journal of KIISE:Information Networking
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    • v.29 no.2
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    • pp.141-155
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    • 2002
  • A medium access control protocol is proposed for integrated voice and data services in the packet CDMA network with a small coverage. Uplink channels are composed of time slots and multiple spreading codes for each slot. This protocol gives higher access priority to the delay-sensitive voice traffic than to the data traffic. During a talkspurt, voice terminals reserve a spreading code to transmit multiple voice packets. On the other hand, whenever generating a data packet, data terminals transmit a packet based on the status information of spreading codes in the current slot, which is received from base station. In this protocol, voice packet does not come into collision with data packet. Therefore, this protocol can increase the maximum number of voice terminals.

Media Access Control Protocol based on Dynamic Time Slot Assignment in Underwater Mobile Ad-hoc Network (동적 타임 슬롯 할당에 기반한 수중 모바일 Ad-hoc 네트워크에서의 매체접근제어 프로토콜)

  • Shin, Seung-Won;Kim, Yung-Pyo;Yun, Nam-Yeol;Park, Soo-Hyun
    • Journal of the Korea Society for Simulation
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    • v.20 no.4
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    • pp.81-89
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    • 2011
  • Underwater wireless network can be useful in various fields such as underwater environment observation, catastrophe prevention, ocean resources exploration, ocean organism research, and vessel sinking exploration. We need to develop an efficient design for Medium Access Control (MAC) protocol to improve multiple data communication in underwater environment. Aloha protocol is one of the basic and simple protocols, but it has disadvantage such as collision occurs oftenly in communication. If there is collision occured in RF communication, problem can be solved by re-sending the data, but using low frequency in underwater, the re-transmission has difficulties due to slow bit-rate. So, Time Division Multiple Access (TDMA) based MAC protocol is going to be used to avoid collisions, but if there is no data to send in existing TDMA, time slot should not be used. Therefore, this paper proposes dynamic TDMA protocol mechanism with reducing the time slots by sending short "I Have No Data" (IHND) message, if there is no data to transmit. Also, this paper presents mathematic analysis model in relation to data throughput, channel efficiency and verifies performance superiority by comparing the existing TDMA protocols.

Novel PD Sensor Design for Stator Winding Diagnosis of Turbine Generators (터빈발전기의 고정자권선 진단을 위한 새로운 부분방전 센서설계)

  • Yi, Sang-Hwa;Hwang, Don-Ha;Kang, Dong-Sik
    • Proceedings of the KIEE Conference
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    • 2007.07a
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    • pp.2042-2043
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    • 2007
  • 고압회전기의 운전중 부분방전을 효과적으로 측정하고 진단하기위해 고정자 권선과 슬롯사이에 취부 되는 방향성 결합기형태의 부분방전센서가 일부 사용되고 있다. 기존 결합기형 센서는 마이크로스트립 등의 전송선로 타입으로, 센서 출력 단자의 효과적인 매칭을 목표로 설계되었으나, 센싱도체의 폭이 좁아 권선으로부터 효과적인 커플링이 힘들다. 본 논문에서는 고정자 권선 및 슬롯 구조의 전계분포 계산결과를 바탕으로 부분방전 신호 측정에 효과적인 형태의 센서를 설계하였다. 제작된 센서를 실제와 동일한 고정자 권선 및 슬롯 구조에서 타 센서와 비교하여 성능을 시험한 결과, 기존 마이크로스트립타입의 센서와 상용센서에 비해 좋은 감도를 가지는 것으로 나타났다.

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Design and Validation of MAC Protocol for B-WLL System (B-WLL MAC 프로토콜의 설계 및 검증)

  • 백승권
    • Proceedings of the Korean Information Science Society Conference
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    • 1999.10c
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    • pp.646-648
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    • 1999
  • 본 논문에서는 가입자망의 고속화를 실현하는 방안으로 개발되고 있는 B-WLL 시스템의 MAC 프로토콜을 설계하고 검증하였다. MAC 프로토콜의 설계는 DAVIC에서 제시하는 MAC 메시지를 사용하여 SDL로 설계했으며, 가변적인 경쟁/예약 타임 슬롯할당 알고리즘을 적용했다. 또한 설계한 MAC 프로토콜의 유효성을 검증하기 위하여 Object(GEODE의 SDL Design Tracer를 이용하여 문법적인 오류를 검사하고, MSC를 생성하여 프로토콜의 동작절차에 대해 검증하였다. 검증의 결과, 설계한 MAC 프로토콜이 절차에 따라 정확하게 동작했으며, B-WLL 시스템이 지원하는 모든 서비스에 대해 유효함을 확인했다.

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Enhanced WMAN System based on Region and Time Partitioning D-TDD OFDM Architecture (영역/시간 세분화 D-TDD OFDM 구조에 기반한 새로운 WMAN 시스템 구조 설계)

  • Kim, Mee-Ran;Cheong, Hee-Jeong;Kim, Nak-Myeong
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.43 no.11 s.353
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    • pp.68-77
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    • 2006
  • In accommodating the asymmetric traffic for future wireless multimedia services, the dynamic time division duplexing (D-TDD) scheme is considered as one of the key solutions. With the D-TDD mode, however, the inter-BS and inter-MS interference is inevitable during the cross time slot (CTS) period, and this interference seriously degrades the system performance. To mitigate such interference, we propose a region and time partitioning D-TDD architecture for OFDM systems. Each time slot in the CTS period is split into several minislots, and then each cell is divided into as many regions as the number of minislots per time slot. We then assign the minislots only to the users in its predefined corresponding region. On top of such architecture which inherently separates the interfering entities farther from each other, we design a robust time slot allocation scheme so that the inter-cell interference can be minimized. By the computer simulation, it has been verified that the proposed scheme outperforms the conventional time slot allocation methods in both the outage probability and the bandwidth efficiency.

System Optimization, Full Data Rate and Transmission Power of Decode-and-Forward Cooperative Communication in WSN (WSN환경에서 Decode-and-Forward 협력통신의 시스템 최적화 및 최대전송률과 저전력에 관한 연구)

  • Kim, Gun-Seok;Kong, Hyung-Yun
    • The KIPS Transactions:PartC
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    • v.14C no.7
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    • pp.597-602
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    • 2007
  • In conventional cooperative communication data rate is 1/2 than non cooperative protocols. In this paper, we propose a full data rate DF (Decode and Forward) cooperative transmission scheme. Proposed scheme is based on time division multiplexing (TDM) channel access. When DF protocol has full data rate, it can not obtain diversity gain under the pairwise error probability (PEP) view point. If it increases time slot to obtain diversity gain, then data rate is reduced. The proposed algorithm uses orthogonal frequency and constellation rotation to obtain both full data rate and diversity order 2. Moreover, performance is analyzed according to distance and optimized components that affect the system performance by using computer simulation. The simulation results revealed that the cooperation can save the network power up to 7dB over direct transmission and 5dB over multi-hop transmission at BER of $10^{-2}$. Besides, it can improve date rate of system compared with the conventional DF protocol.

Pilot Hopping Scheme for Massive Antenna Systems in Cellular Networks (극다중 안테나 셀룰러 시스템을 위한 파일럿 도약 기법)

  • Kim, Seong Hwan;Ban, Tae-Won;Lee, Wongsup;Ryu, Jong Yeol
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.21 no.4
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    • pp.718-723
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    • 2017
  • We propose a pilot hopping scheme that improves the limited system capacity due to pilot contamination in multi-cell environment with large-scale antenna arrays at a base station, assuming the infinite number of antennas. In the conventional fixed pilot scheme, each user obtains the same signal-to-interference ratio (SIR) over a long period of time. Therefore, a user with strong interference has continuously low SIR which degrades its service quality. In the proposed pilot hopping scheme, different pilot signals are used for each time slot, and different amounts of interference are received every time. When such a pilot hopping technique is applied, the SIR fluctuates at every time slot. When the Hybrid Automatic Repeat & reQuest (HARQ) technique is applied in such a channel, the outage probability and transmission rate are improved. We show that there is the performance gain of the proposed scheme over the conventional scheme through computer simulations.