• Journal of the Korean Institute of Telematics and Electronics B
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• v.28B no.5
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• pp.404-410
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• 1991

In this paper,a network interface unit of token-passing bus network and its driving software are implemented based on Mini-MAP. This network interface unit performs the function of MAC layer which is responsible for transmission and reception of frames as well as the management of logical ring. The driving software performs the management of data buffer and the report of errors, if ocoured, to the higher layer. Motorola MC68824 of is used as a TBC(Token Bus Controller) and Intel80186 as a CPU for network interface unit. The operation of network interface unit is verified by self-test which checks the functioning of TBC and CPU. In addition each module of driving software is tested to check the functions regarding transmission and reception of frames.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.4
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• pp.135-142
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• 2012

DSRC system is a communication system that consists of road side equipment and on board equipment to provide services of communication technology for intelligent transportation systems. In this paper, we carry out a short-range dedicated high-speed wireless communications via DSRC system based on board equipment that is installed in the vehicle and road side equipment through wireless channels of communication. on board equipment is system that have a memory which initialization information is stored, it loads physical layer and MAC layer, LLC layer, L7 layer in turn. In the upper, it should analyze the various commands that are sent from roadside base stations, and carry out the operation which is in accordance with the command. and also it designs the structure of protocol stack which is TRM Layer loaded that is to initialize on L7 layer and MAC layer and efficiently designs operation between on board equipment and the road side equipment.

• Journal of KIISE:Information Networking
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• v.34 no.3
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• pp.175-185
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• 2007

In IEEE 802.15.4 (Low-Rate Wireless Personal Area Network) specification, a successful reception and validation of a data or MAC command frame can be confirmed with an acknowledgment. However, the specification does not support security for acknowledgment frame; the lack of a MAC covering acknowledgments allows an adversary to forge an acknowledgment for any frame. This paper proposes an identity authentication mechanism at the link layer for acknowledgment frame in IEEE 802.15.4 network. With the proposed mechanism there is only three bits for authentication, which can greatly reduce overhead of device. The encrypted bit stream for identity authentication will be transmitted to device by coordinator within association process. Statistical method and simulation results prove that our mechanism is successful in handling MAC layer attack.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8B
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• pp.712-721
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• 2012

In this paper, we propose an Enhanced cross-layer Geographic Forwarding (EGF) protocol for wireless sensor networks (WSNs). EGF uses an optimal back-off time to make the packet forwarding decisions using only source and destination's location information and energy cost without information about neighbor nodes' location or the number of one hop neighbor nodes. EGF is also a cross-layer protocol by combining efficient asynchronous MAC and geographic routing protocol. The proposed protocol can find optimal next hop location quickly without broadcasting node's location update and with minimizing overhead. In our performance evaluation, EGF has better performance in terms of packet success ratio, energy efficiency and end-to-end delay in wireless sensor networks.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.2 s.314
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• pp.19-24
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• 2007

In this paper, we deal with suggestion of energy efficient MAC protocol. The scheme(I-MAC) makes the active duty-cycle duration based on by utilizing data frequency. Data frequency is made by checking a check bit of Link layer. By being studies on NS-2 simulation environments, the proposed scheme was proved to be improved in terms of energy efficiency of 50 % and to be similar to throughput of S-MAC on every time interval.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.1
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• pp.141-150
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• 2011

In this paper, we propose a Cross-Layer Cooperative Routing(CLCR) architecture to support transmission efficiency in mobile wireless sensor networks. The main features and contributions of the proposed architecture and method are as follows. First, the clustering which uses the location information of nodes is utilized as infrastructure. Second, a cross-layer strategy which uses the technologies of network layer, MAC layer, physical layer together to support transmission efficiency and channel efficiency for cooperative-aided routing and transmission. Third, we consider realistic approach in the view points of the mobile ad-hoc wireless sensor networks while conventional methods just consider fixed sensor network environments. The performance evaluation of the proposed method is performed via simulation using OPNET and theoretical analysis. The results of performance evaluation of the proposed CLCR show improvement of transmission efficiency by the proposed CLCR.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.253-256
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• 2001

This paper describes a high speed MAC(Media Access Control) function chip for IEEE 802.11 MAC layer protocol. The MAC chip has control registers and interrupt scheme for interface with CPU and deals with transmission/reception of data as a unit of frame. The developed MAC chip is composed of protocol control block, transmission block, and reception block which supports the BCF function in IEEE 802.11 specification. The test suite which is adopted in order to verify operation of the MAC chip includes various functions, such as RTS-CTS frame exchange procedure, correct IFS(Inter Frame Space)timing, access procedure, random backoff procedure, retransmission procedure, fragmented frame transmission/reception procedure, duplicate reception frame detection, NAV(Network Allocation Vector), reception error processing, broadcast frame transmission/reception procedure, beacon frame transmission/reception procedure, and transmission/reception FIEO operation. By using this technique, it is possible to reduce the load of CPU and firmware size in high speed wireless LAN system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3B
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• pp.456-463
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• 2000

Bidirectional cable TV networks using HFC(Hybrid Fiber Coaxial) networks need MAC (Medium access control) protocols to have efficient access in upstream channels. In this paper, we have studied and evaluated several contention resolution algorithms and mapping of higher layer traffic described in IEEE 802.14 and MCNS (Multimedial Cable Network System) MAC protocols with respect to IP, ABR and CBR traffic types. IEEE 802.14 MAC protocol demonstrates better performance for transmitting ATM cells while the MCNS MAC protocols for the IP traffic.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.451-453
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• 2003

본 논문은 블루투스 MAC 계층에서의 패킷 스케줄링 성능의 개선을 목적으로 한다 현재 대부분의 많은 블루투스 MAC 계층 스케줄링 방식은 라운드로빈(RR)을 사용하고 있는데, 많은 슬롯과 시간을 낭비하게 되고 최적화된 업링크와 다운링크에 적합하지 않다. 한편, 블루투스의 마스터 노드에서 생기는 자원 낭비 문제를 해결하기 위한 몇 가지 MAC 스케줄링 알고리즘이 있다. 본 논문에서는 Bin-packing 과 DRR 을 이용하는 MAC 계층에서의 효과적인 패킷 스케줄링 알고리즘을 제안하고 시뮬레이션을 통해서 그 성능이 기존 방식에 비해 우월함을 보인다.

• Journal of Information Technology Services
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• v.10 no.3
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• pp.237-250
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• 2011

Recently, Wireless Sensor Networks (WSN) require energy performance and guaranteed delivery delay time, contrarily with previous MAC protocols that aim to high throughput mostly. In order to satisfy the new significant requirements, many MAC protocols of WSN employ and try to enhance the duty cycle mechanism which is energy efficient technique in MAC layer. This duty cycle mechanism is oriented by toggling the transceiver conditions composed of wakeup and sleep states. The synchronous MAC protocols perform the period synchronization process. Hence, these are energy efficient in periodic monitoring environment, but are inefficient in where an event is incurred rarely and infrequently. Otherwise, the performance of asynchronous MAC protocols are contrarily with synchronous protocols. In this paper, we design two models consisting Always-busy and Always-idle ti simplify the general network congestion conditions. Through these models, moreover, we analyze two types MAC protocols in terms of energy efficiency and delay performance by analytical results. Additionally, we also evaluate two MAC protocols with two gongestion models that we designed. By the analytical and simulated results, we provide the general and efficient decision method in which protocols are more appropriate in a certain WSN environment.