• Title/Summary/Keyword: CSMA

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An Efficient Collision Resolution Method in Wireless Sensor Networks Based on IEEE 802.15.4 Slotted CSMA/CA (IEEE 802.15.4 Slotted CSMA/CA 기반 무선 센서 네트워크의 효율적인 충돌 해결 기법)

  • Jung, Kyoung-Hak;Suh, Young-Joo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37B no.9
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    • pp.750-759
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    • 2012
  • This paper addresses the collision resolution issue to enhance the performance of wireless sensor networks based on IEEE 802.15.4 slotted CSMA/CA. Some solutions in existing work try to solve this issue by adjusting Backoff Exponent (BE) value or Backoff Period (BP). In contrast to the existing solutions, the proposed scheme in this paper aims at providing high system throughput, but also achieving efficient energy consumption of sensor nodes by using Preamble Address (PA). For this, in the proposed scheme, only one sensor node begins data packet transmission by performing PA contention phase with other nodes before sending each data packet. Our simulation results show that the proposed scheme outperforms existing algorithms in terms of energy consumption and throughput.

Improvement of MAC Protocol to Reduce the Delay Latency in Real-Time Wireless Sensor Networks (실시간 무선 센서 네트워크에서 전송 지연 감소를 위한 MAC 개선 방안)

  • Jang, Ho;Jeong, Won-Suk;Lee, Ki-Dong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.8A
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    • pp.600-609
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    • 2009
  • The traditional carrier sense multiple access (CSMA) protocol like IEEE 802.11 Distributed Coordination Function (DCF) does not handle the constraints adequately, leading to degraded delay latency and throughput as the network scales are enlarged. We present more efficient method of a medium access for real-time wireless sensor networks. Proposed MAC protocol is like the randomized CSMA protocol, but unlike previous legacy protocols, it does not use a time-varying contention window from which a node randomly picks a transmission slot. To reduce the latency for the delivery of event reports, we carefully decide to select a fixed-size contention window with non-uniform probability distribution of transmitting in each slot. We show that the proposed method can offer up to severaansimes latency reduction compared to legacy of IEEE 802.11 as the size of the sensor network scales up to 256 nodes using widely using network simulation package,caS-2. We finally show that proposed MAC scheme comes close to meet bounds on the best latency being achieved by a decentralized CSMA-based MAC protocol for real-time wireless sensor networks which is sensitive to delay latency.

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.

Design and Performance Analysis of an Enhanced MAC Algorithm for the IEEE 802.11 DCF (IEEE 802.11 DCF 성능 개선을 위한 매체접근제어 알고리즘의 설계 및 성능 분석)

  • Hwang, An-Kyu;Lee, Jae-Yong;Kim, Byung-Chul
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.42 no.10 s.340
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    • pp.39-50
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    • 2005
  • In this paper, we propose a performance improving MAC algerian for the IEEE 802.11 DCF. WLAN based IEEE 802.11 uses two control methods called 'Distributed Coordination Function(UF)' and 'Point Coordination Function(PCF)'. The nF controls the Urnsmission based on carrier sense multiple access with collision detection(CSMA/CA), that decides a random backoff time with the range of contention window for each terminal. Normally, each terminal the CW double after collision, and reduces the CW to the minimum after successful transmission. This paper proposes an enhanced DCF algorithm that decreases the CW smoothly after successful transmission in order to reduce the collision Probability by utilizing the current status information of WLAN. We also analyze the throughput and delay performance for the unsaturated case mathematically. Simulation results show that our algorithm enhances the saturation throughput of WLAN. They also coincide well with the analytical results.

Design of an Effecient Local Area Computer Communication Network Controller for Office Automation (Contention Resolution Algorithm Based on CSMA/CD) (사무자동화를 위한 근거리 컴퓨터 통신망 콘트롤러 개발에 관한 연구)

  • 이명수;강창언
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.11 no.2
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    • pp.137-145
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    • 1986
  • The contention resolution algorithm with the limited packet delay time as well stable distribution as the packet delay time is proposed and implementes for improving the mean packet delay time in the network employing CSMA/CD as the access method. The implementation of node controller is based on IEEE 802.2 standard logical link control(LLC) and IEEE 802.3 standard medium access control(MAC). Some portion of IEEE 802.3 Standard MAC, and the Binary Exponential Back-off(BEB) algorithm is replaced by the proposed algorithm. From the view of normalized mean packet transmission delay time, the controller implemented here can be applicable to the office-automation system, and the factory-and laboratory-automation environment where the limited time criterion is very significant.

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Priority Based Multi-Channel MAC Protocol for Real-Time Monitoring of Weapon Flight Test Using WSNs

  • Min, Joonki;Kim, Joo-Kyoung;Kwon, Youngmi;Lee, Yong-Jae
    • Journal of Sensor Science and Technology
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    • v.22 no.1
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    • pp.18-27
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    • 2013
  • Real-time monitoring is one of the prime necessities in a weapon flight test that is required for the efficient and timely collection of large amounts of high-rate sampled data acquired by an event-trigger. The wireless sensor network is a good candidate to resolve this requirement, especially considering the inhospitable environment of a weapon flight test. In this paper, we propose a priority based multi-channel MAC protocol with CSMA/CA over a single radio for a real-time monitoring of a weapon flight test. Multi-channel transmissions of nodes can improve the network performance in wireless sensor networks. Our proposed MAC protocol has two operation modes: Normal mode and Priority Mode. In the normal mode, the node exploits the normal CSMA/CA mechanism. In the priority mode, the node has one of three grades - Class A, B, and C. The node uses a different CSMA/CA mechanism according to its grade that is determined by a signal level. High grade nodes can exploit more channels and lower backoff exponents than low ones, which allow high grade nodes to obtain more transmission opportunities. In addition, it can guarantee successful transmission of important data generated by high grade nodes. Simulation results show that the proposed MAC exhibits excellent performance in an event-triggered real-time application.

A Study on the MAC(Media Access Control) protocol for Unmanned Aerial Vehicle(UAV) (무인항공기의 매체접속제어 프로토콜 적용에 관한 연구)

  • Jo, Yun-Hyun;Yoon, In-Seop;Kim, Sang-Uk;Park, Hyo-Dal
    • The Journal of the Korea institute of electronic communication sciences
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    • v.11 no.1
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    • pp.119-124
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    • 2016
  • In this paper, we studied on MAC(Media Access Control) protocol for UAVs application. According to the number of UAVs, ground control station should control properly increased UAVs. So, we applied CSMA/CA that used in current civil aircraft to UAV communications and verified the applicability through comparison of throughput and delays of data with various message sizes, In the results, we confirmed applicability for UAVs MAC protocol.

A new MAC protocol to improve a performance in IEEE 802.11 wireless LANs (IEEE 802.11 무선 랜의 성능 향상을 위한 새로운 MAC프로토콜)

  • Hwang, Gyung-Ho
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.13 no.4
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    • pp.759-764
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    • 2009
  • A new backoff scheme for infrastructure mode in IEEE 802.11 wireless LANs is proposed to improve a performance. Each station generates a unique backoff number using total number of stations, fairness parameter included in beacon frame and an user's ID that is assigned by AP. The station sends a packet after its own backoff number of idle slots, which makes a collision free access among stations within AP's coverage. The proposed method shows better performance in the view of channel utilization and packet delay than an original IEEE 802.11 CSMA/CA backoff scheme.

A Frame Collision Reduction Method for Safety Message Broadcasting in IEEE1609.4/IEEE802.11p based VANETs

  • Wang, Lei;Jing, Weiping
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.12 no.3
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    • pp.1031-1046
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    • 2018
  • Vehicular ad hoc network (VANET) is a dedicated network to connect vehicles without any centralized administration or infrastructure. The wireless access in vehicular environments (WAVE) protocol leveraging IEEE 1609/802.11p is widely implemented for VANETs. However, in congested traffic situation, the performance of the WAVE system degrades significantly due to serious collision, especially for safety related broadcast services on the control channel (CCH) interval due to the inherent drawback of its collision avoidance mechanisms called carrier sense multiple access with collision avoidance (CSMA/CA). In this paper, we propose a method that can decrease the number of frame collisions in CCH with a few modifications to the IEEE 802.11p protocol. In the paper, vehicles still employ CSMA/CA to compete for the channel access opportunity. However, by taking advantage of periodicity of synchronization interval, a two-state switching scheme introducing two new inter frame space (IFS) is proposed to reduce the number of competing vehicles substantially and as a result, the collision probability is significantly decreased. The simulation results demonstrate the superiority of the proposed method in packet collision rate.

A Study on CSMA/CA for IEEE 802.11 WLAN Environment

  • Moon Il-Young;Cho Sung-Joon
    • Journal of information and communication convergence engineering
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    • v.4 no.2
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    • pp.71-74
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    • 2006
  • A basic access method about IEEE 802.11 MAC layer protocol using IEEE 802.11 wireless LANs is the DCF thatis based on the CSMA/CA. But, cause of IEEE 802.11 MAC layer uses original backoff algorithm (exponential backoff method), when collision occurred, the size of contention windows increases the double size Also, a time of packet transmission delay increases and efficienty is decreased by original backoff scheme. In this paper, we have analyzed TCP packet transmission time of IEEE 802.11 MAC DCF protocol for wireless LANs a proposed enhanced backoff algorithm. It is considered the transmission time of transmission control protocol (TCP) packet on the orthogonal frequency division multiplexing (OFDM) in additive white gaussian noise (A WGN) and Rician fading channel. From the results, a proposed enhanced backoff algorithm produces a better performance improvement than an original backoff in wireless LAN environment. Also, in OFDM/quadrature phase shift keying channel (QPSK), we can achieve that the transmission time in wireless channel decreases as the TCP packet size increases and based on the data collected, we can infer the correlation between packet size and the transmission time, allowing for an inference of the optimal packet size in the TCP layer.