• Title/Summary/Keyword: 매체접속제어 프로토콜

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Prioritized Packet Reservation CDMA Protocolfor Integrated Voice and Data Services (CDMA 망에서의 음성 및 데이터 통합 서비스를 위한 우선권 기반의 패킷 예약 접속 프로토콜)

  • Kim, Yong-Jin;Kang, Chung-Gu
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.37 no.1
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    • pp.32-43
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    • 2000
  • In this paper, we investigate the existing medium access control (MAC) protocols to integrate the voice and data services in packet-based CDMA networks and furthermore, propose a new approach to circumvent the operational limits inherent in them. We propose the $P^2R$-CDMA (Prioritized Packet Reservation Code Division Multiple Access) protocol for the uplink in the synchronous multi-code CDMA system, which employs the centralized frame-based slot reservation along with the dynamic slot assignment in the base station using the QoS-oriented dynamic priority of individual terminal. The simulation results show that, as compared with the existing scheme based on the adaptive permission probability control (APC), the proposed approach can significantly improve the system capacity while guaranteeing the real-time requirement of voice service.

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The Modified Aviation TDMA Protocol for an Improvement in Aeronautical RF Spectrum Utilization (항공통신에서 효율적인 RF 주파수 활용을 위한 항공용 TDMA 변형 프로토콜)

  • Park, Hyo Dal
    • Journal of Advanced Navigation Technology
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    • v.1 no.1
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    • pp.47-58
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    • 1997
  • In this paper, the modified aviation TDMA protocol that can improve the aeronautical communication spectrum utilization is studied to satisfy the increasing air traffic demands. Currently European states proposed the scheme reducing the channel spacing from current 25 kHz to 8.33 kHz and U. S. FAA proposed the system using TDMA technique that divides access into four parallel circuits. The modified aviation TDMA protocol can complement the defects of these current systems. In modified aviation TDMA protocol, message channel that is used between aircraft and ground station is divided into uplink channel and downlink channel. After receiving the acknowledgement of the reservation request, aircraft sends messages at the allocated slots. Numerical analysis and simulation results show that the modified aviation TDMA scheme has high channel efficiency in the aviation environment.

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A Study on Priority Allocation Algorithm According to Air Traffic in Aeronautical Communication Environment (항공이동통신환경에서 항공교통량에 따른 우선순위 할당 알고리즘에 관한 연구)

  • Jo, Yun-Hyun;Kim, Yong-Kyun;Kim, Sang-Uk;Park, Hyo-Dal
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.9 no.1
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    • pp.91-100
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    • 2010
  • According to the recent increase in air traffic a more efficient air traffic flow control is required. This paper proposes the algorithm for efficient air traffic flow control. Aeronautical communication environment is different from the common communication environment since it needs a direct communication between stations (or airplanes) and requires a strict priority for safety message. Moreover, the wide area for basic service causes high propagation delay. In this paper, by using existing CSMA/CA Media Access Control (MAC) protocol, we set the message priorities according to air traffic condition (congestion airport area, approach control area, En route area, and ocean area). This prioritization scheme enables the data transmission with higher access probability. Simulation results confirm that our protocol shows better performance in terms of channel efficiency and success probability compared to exisiting CSMA/CA protocol.

ETSI BRAN(Broadband Radio Access Network)의 무선 ATM 및 광대역 무선 액세스 네트워크 표준화 및 기술동향

  • 이우용;김용진;강충구
    • Information and Communications Magazine
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    • v.15 no.11
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    • pp.124-142
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    • 1998
  • ETSI BRAN (Broadband Radio Access Network)는 고속 무선 LAN 또는 고정 광대역 무선액세스 네트워크에서의 무선 접촉 계층과 ATM 및 IP(Internet Protocol) 코어 네트워크와의 연동을 위한 일부 기능을 표준화하기 위한 과제이다. 특히, BRAN의 HIPERLAN type-2(HIPERLAN/2)의 경우에는 과제의 범위는 무선 접속면, 무선 부시스템에서의 서비스 인터페이스, 서비스 구현에서 요구되는 연동 및 각종 지원 기능을 표준화하며, 무선 접속면의 경우에는 다수 벤더간의 상호 호환성을 제공할 수 있는 인터페이스를 구현하는 것이다. HIPERLAN/2의 기술 규격은 코어 네트워크와 독립적인 물리계층 및 데이터 링크 제어 (DATA Link Control: DLC) 계층과 서로 상이한 코어 네트워크와의 연동을 위한 네트워크 수렴 부계층을 다루게 될 것이며, 초기 단계에서는 ATM과 IP 코어 네트워크와의 연동 기능을 제시하게 될 것이다. 따라서 HIPERLAN/2기반의 시스템 규격을 제시하기 위해서는 네트워크 계층 및 기타 상위 계층에 대한 규격이 요규되며, 이는 ATM Forum에서의 무선 ATM 신호 방식 규격, IETF(Internet Engineering Task Force)의 IP규격, 그리고 ETSI의 SMG (Special Mobile Group) 프로젝트에서 표준화되고 있는 UMTS (Universal Mobile Telecommunication Service) 규격 등과 접목될 것이다. 결과적으로 무선 ATM 관점에서는 완전한 시스템 규격 작성은 ETSI BRAN과 ATM Forum에서 무선 접속 규격과 이동성 관리 및 신호 방식으로 각각 이원화되어 진행되고 있다. 현재 물리 계층에서의 전송 방식은 OFDM(Orthogonal Frequency Division Multiplexing)으로 확정되었으며, DLC 계층에서는 고정 길이의 TDD (Time Division Duplexing) TDMA 프레임 구조를 기반으로 AP (Access Point)에 의해 동적으로 상향 링크 자원을 예약 할당하는 매체 접근 제어 (Medium Access Control: MAC) 프로토콜이 고려되고 있다. 이와 같은 DLC 계층에서는 기본적으로 짧은 길이의 패킷을 통해 다양한 대역폭의 멀티미디어 트래픽을 효율적으로 수용하면서 ATM 네트워크뿐만 아니라 향후 IP 네트워크에서 요구하는 각 서비스별 QoS (Quality of Service)를 개별적으로 보장할 수 있는 기능을 구현하고자 한다. 향후 이 부문에 대한 표준화가 본격적으로 진행될 것으로 예상되며 HIPERLAN/2의 경우에는 1999년 중반까지 1차 기능 규격을 완료할 예정이며, BRAN 전반에 대한 완전한 규격을 2002년까지 완성하는 것을 목표로 하고 있다.

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Underwater Experiment on CSMA/CA Protocol Using Commercial Modems (상용 모뎀 제어를 통한 수중 CSMA/CA 프로토콜 시험)

  • Cho, Junho;Lee, Sang-Kug;Shin, Jungchae;Lee, Tae-Jin;Cho, Ho-Shin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39C no.6
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    • pp.457-465
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    • 2014
  • This paper introduces a test bed for communication protocol schemes of underwater acoustic sensor network, and also shows experimental results obtained from the test bed. As a testing protocol, carrier sense multiple access/collision avoidance (CSMA/CA) is evaluated on underwater acoustic channel. A sensor node is equipped with a DSP control board of ATmega2560 and a commercial underwater modem produced by Benthos. The control board not only manipulates a GPS signal to acquire the information of location and time, but also controls the underwater modem to operate according to the procedure designed for a given testing protocol. Whenever any event takes place such as exchanging control/data packets between underwater modems and acquiring location and timing information, each sensor node reports them through radio frequency (RF) air interface to a central station located on the ground. The four kinds of packets for CSMA/CA, RTS(Request To Send), CTS(Clear to Send), DATA, ACK(Acknowledgement) are designed according to the underwater communication environment and are analyzed through the lake experiment from the point of feasibility of CSMA/CA in underwater acoustic communications.

A Study on protocol analysis between KTX control system and sub-devices (고속열차(KTX)제어시스템과 하부장치간 프로토콜 분석연구)

  • Kim, Hyeong-In;Jung, Sung-Youn;Kim, Hyun-Shik;Jung, Do-Won;Kim, Chi-Tae;Kim, Dong-Hyun
    • Proceedings of the KSR Conference
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    • 2007.11a
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    • pp.179-186
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    • 2007
  • KTX control systems mutually control OBCS, ATC, MBU, TECA, MDT, ABU, HVAC, TRAE, PID and FDTR, KTX OBCS as master, and controls other sub-control devices as slave, using various serial lines. In order to analyze physical structure of various serial link lines and mutual data transmission structure, serial line analyzer is used in many ways. To use serial line analyzer, prior and professional technics about High Speed Train and experience of using device are necessary. In spite of difficult situation of space and environment where we work for maintenance of High Speed Train, in presenting basic structure about physical connection method aquired by sub-device serial line data collection and about communication data analysis, I hope that this research will be helpful for the person who work for similar area. Also, I hope that this research will help diagnostic work of High Speed Train, which is necessary for test run of independently developed High Speed Train.

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A Study of Mobile Ad-hoc Network Protocols for Ultra Narrowband Video Streaming over Tactical Combat Radio Networks (초협대역 영상전송 전투무선망을 위한 Mobile Ad-hoc Network 프로토콜 연구)

  • Seo, Myunghwan;Kim, Kihun;Ko, Yun-Soo;Kim, Kyungwoo;Kim, Donghyun;Choi, Jeung Won
    • Journal of the Korea Institute of Military Science and Technology
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    • v.23 no.4
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    • pp.371-380
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    • 2020
  • Video is principal information that facilitates commander's immediate command decision. Due to fading characteristics of radio link, however, it is difficult to stably transmit video in a multi-hop wireless environment. In this paper, we propose a MANET structure composed of a link adaptive routing protocol and a TDMA MAC protocol to stably transmit video traffic in a ultra-narrowband video streaming network. The routing protocol can adapt to link state change and select a stable route. The TDMA protocol enables collision-free video transmission to a destination using multi-hop dynamic resource allocation. As a result of simulation, the proposed MANET structure shows better video transmission performance than proposed MANET structure without link quality adaption, AODV with CSMA/CA, and OLSR with CSMA/CA structures.

ARQ-based Multicast for OFDMA Systems (OFDMA 시스템의 ARQ 기반 멀티캐스트 방법)

  • Kim, Sung-Won
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.13 no.1
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    • pp.161-169
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    • 2009
  • Multicast-based data communication is an efficient communication scheme in wireless networks where the Media Access Control (MAC) layer is based on one-hop broadcast from one source to multiple receivers. Compared with unicast, multicast over wireless channel should handle varying channel conditions of multiple users and user mobility to achieve good quality for all users. However, IEEE 802.11 does not support reliable multicast due to its inability to exchange RTS/CTS and ACK with multiple recipients. Thus, several MAC layer protocols have been proposed to provide reliable multicast. For the reliable multicast, an additional overhead is introduced and it degrades the system performance. In this paper, we propose a cross-layer design to reduce the control overhead for reliable multicast in OFDMA systems. We present an analytical formulation of the system throughput associated with the overhead.

A Multi-Dimensional Node Pairing Scheme for NOMA in Underwater Acoustic Sensor Networks (수중 음향 센서 네트워크에서 비직교 다중 접속을 위한 다차원 노드 페어링 기법)

  • Cheon, Jinyong;Cho, Ho-Shin
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.6
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    • pp.1-10
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    • 2021
  • The interest in underwater acoustic sensor networks (UWASNs), along with the rapid development of underwater industries, has increased. To operate UWASNs efficiently, it is important to adopt well-designed medium access control (MAC) protocols that prevent collisions and allow the sharing of resources between nodes efficiently. On the other hand, underwater channels suffer from a narrow bandwidth, long propagation delay, and low data rate, so existing terrestrial node pairing schemes for non orthogonal multiple access (NOMA) cannot be applied directly to underwater environments. Therefore, a multi-dimensional node pairing scheme is proposed to consider the unique underwater channel in UWASNs. Conventional NOMA schemes have considered the channel quality only in node pairing. Unlike previous schemes, the proposed scheme considers the channel gain and many other features, such as node fairness, traffic load, and the age of data packets to find the best node-pair. In addition, the sender employs a list of candidates for node-pairs rather than path loss to reduce the computational complexity. The simulation results showed that the proposed scheme outperforms the conventional scheme by considering the fairness factor with 23.8% increases in throughput, 28% decreases in latency, and 5.7% improvements in fairness at best.

Adaptive Collision Resolution Algorithm for Improving Delay of Services in B-WLL System (B-WLL 시스템에서 서비스 지연 향상을 위한 충돌 해소 알고리즘)

  • Ahn, Kye-Hyun;Park, Byoung-Joo;Baek, Seung-Kwon;Kim, Eung-Bae;Kim, Young-Chon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.27 no.1B
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    • pp.42-48
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    • 2002
  • In broadband wireless networks, the effective meeting of the QoS guarantees may strongly depend on the Contention Resolution Algorithm used in the uplink contention period. The time it takes a station to transmit a successful request to the base station, or request delay, must be kept low even during periods of high contention. If a request suffers many collisions, it cannot rely on the preemptive scheduler to receive low access delays. However, the conventional collision resolution algorithm has a problem that all collided stations are treated equally regardless of their delay from previous contention periods. Some requests may have very long request delay caused by continuous collisions. In this paper, we propose an adaptive collision resolution algorithm for fast random access in broadband wireless networks. The design goal is to provide quick access to the request with a high number of collisions. To do this, the proposed algorithm separates the whole contention region into multiple sub regions and permits access through each sub region only to the requests with equal number of collisions. The sub region is adaptively created according to the feedback information of previous random access. By simulation, the proposed algorithm can improve the performance in terms of throughput, random delay and complementary distribution of random delay by its ability to isolate higher priorities from lower ones. We can notice the algorithm provides efficiency and random access delay in random access environment.