• 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.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06d
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• pp.311-314
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• 2011

Wi-Fi 메쉬 네트워크는 IEEE 802.11 표준을 기반으로 노트북, 스마트폰 등의 무선 단말에 인터넷 연결을 제공하기 위한 무선 다중 홉 네트워크이다. Wi-Fi 메쉬 네트워크에서는 무선 채널의 방송 특징으로 인해 발생하는 간섭(Interference) 때문에 프레임 충돌 문제가 발생한다. 본 논문에서는 이러한 프레임 간섭을 미연에 방지하는 스케줄링 MAC 프로토콜을 제안한다. 제안하는 방법은 각각의 무선 채널에서 간섭 조건을 만족하는 링크 조합을 결정하고, 이를 통하여 Wi-Fi 메쉬 네트워크의 프레임 전달 수율(Throughput)을 극대화함을 목표로 한다. 시뮬레이션 결과를 통해 본 논문에서 제시하는 스케줄링 MAC 프로토콜이 기존에 알려진 CSMA/CA 기반의 MAC 프로토콜에 비해 수율을 50 % 이상 향상함을 보인다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1C
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• pp.54-62
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• 2012

A Wi-Fi mesh network providing multi-hop wireless connections based on IEEE 802.11 PHY/MAC technology has recently received a significant attention as a network infrastructure that interconnects RFID systems and wireless sensor networks (WSNs). However, the current IEEE 802.11 contention-based MAC protocol cannot fully utilize the network capacity due to eithor frame collisions or unused network resources. In this paper, we propose a novel multi-channel scheduling MAC (MCS-MAC) protocol for Wi-Fi mesh networks. Under the secondary interference model of Wi-Fi mesh networks, the MCS-MAC protocol can maximize the network throughput via activation of collision-free links that has a maximal link weight. Through the simulations, we show that the throughput of the MCS-MAC protocol is at least three times higher than that of existing MAC protocols in Wi-Fi mesh networks.

• Journal of KIISE:Information Networking
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• v.30 no.1
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• pp.38-47
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• 2003

Communication between Bluetooth devices is based on TDD by a master unit. In this discipline, the transmission of slave packets can be made only when the master transmits a packet to the slave. Thus, some slots may be wasted when there is no user data in the master's or slave's queue due to the transmission of a POLL or NULL packet. Therefore a scheduling scheme which can minimize the slot waste is required in Bluetooth intra-piconet communication. However, since the master is responsible for the intra-piconet scheduling, it must be provided with an information on each slave's queue length to apply traditional scheduling schemes. which is impossible in Bluetooth. This paper presents a new Bluetooth intra-piconet scheduling scheme that is efficient and does not require the information on each slave's queue length. The scheduling is done based on the information about the existence of data in the master and slave queues which is derived by the master identifying the type of packets transmitted. The master schedules to communicate with the slaves according to the priorities determined based on this information. We Presents simulation results which indicate a significant improvement in the performance when our proposed scheme is used.

• Journal of the Korea Society of Computer and Information
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• v.14 no.3
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• pp.113-119
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• 2009

In this paper, we proposed an efficient TDMA scheduling algorithm for a clustered Wireless Sensor Network. Since some previous algorithms used unnecessary idle period and schedule period in each frame. It became an overhead that might consume unexpected energy and delay data transmission. To solve this problem, a dynamic scheduling algorithm according to the number of member nodes and node traffic load within a cluster was suggested. Our proposed DS-MAC(Dynamic Scheduling MAC) could save energy and reduce transmission delay Then DS-MAC was analyzed mathematically to compare with the previous algorithms.

• Journal of the Korea Society of Computer and Information
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• v.13 no.7
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• pp.157-164
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• 2008

In this paper we suggest a scheduling algorithm that transmits periodic traffics efficiently in tree-structured wireless sensor networks (WSNs). The related research[l] showed the problems such as increasing the energy consumption and decreasing the data throughput as the depth of tree increases. To solve these problems. we use idle time slots and avoid the redundancy at data transmission. Also we suggest the algorithm that transmits the control packet when it is similar to a previously measured data. And if emergency data is occurred, our proposed algorithm transits that data in EDP(Emergency Data Period) for reducing the wait time. The proposed algorithm shows more data throughput and less energy consumption than that of the related research.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.8-18
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• 2009

CableLAB published DOCSIS 3.0 Specifications to supply broadband access to homes and small businesses. The primary technique of DOCSIS 3.0 Specification is channel bonding which provides cable operators with a flexible way to significantly increase up/downstream speeds. In this paper, we propose the upstream scheduler that serves channel bonding. Proposed scheduler consists of two sub-scheduler: bonding group scheduler and channel scheduler. Also, we propose three scheduling algorithms to allocate request bandwidth of CM to each bonding channel: equivalent scheduling algorithm, current request-based scheduling algorithm, and last grant-based scheduling algorithm. In order to evaluate the performance of these algorithms and DOCSIS 3.0 MAC protocol, we develop the DOCSIS 3.0 simulator with the network simulator, OPNET, to model DOCSIS network, CMTS, and CM. Our results show that equivalent scheduling algorithm is superior to others in the view of transmission delay and throughput and DOCSIS 3.0 protocol provides higher throughput than pre-DOCSIS 3.0 protocol.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10d
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• pp.602-607
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• 2007

최근 4G 이동통신 시스템의 진화를 위한 단계로 기존의 이동통신 시스템을 유지하면서 효율 극대화를 통한 비용 절약 측면과 고 주파수 대역을 이용한 셀 간격의 협소화로 인해 나타나는 문제점에 대한 대안으로 커버리지 확대와 데이터 처리율 향상을 위한 IEEE 802.16j 표준화 작업이 진행 중에 있다. 향후 VoIP 서비스를 위한 업링크 스케줄링 기법으로 몇 가지가 IEEE 802.16j에 제시되어 있으나, 본 논문에서는 보이스 트래픽 특성 및 수학적 모델링을 통하여 기존 방법들보다 더 효율적인 대역 이용을 통해 같은 대역폭 대비 성능과 용량 면에서 개선된 스케줄링 기법인 eertPS를 제시하여 IEEE 802.16j Multi-Hop 환경하에서도 대역 효율적인 VoIP 서비스를 이용할 수 있도록 한다.

• Information and Communications Magazine
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• v.22 no.9
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• pp.51-62
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• 2005

3세대 이후의 이동통신시스템에서는 고속 및 대용량 전송을 통해 동영상, 영화, 방송 등 은 종류의 멀티미디어 서비스들이 제공될 것으로 전망된다. 본 논문에서는 이러한 서비스들의 제공이 가능한 3세대 이후 시스템으로 개발되고 있는 High-Speed Mobile Multimedia (HMm) 시스템을 매체접근제어 (MAC) 프로토콜을 중심으로 소개한다. HMm MAC 프로토콜은 광대역 무선 환경 하에서 고속의 그리고 효과적인 멀티미디어 전송을 목표로 설계되었다. 이러한 HMm MAC 프로토콜은 기지국 MAC과 단말 MAC의 두 서브시스템으로 나뉘며, 각 서브시스템은 상태관리, 전송제어, 버퍼관리, 임의 접근제어, 패킷 스케줄링 등의 기능을 수행한다.

• Journal of KIISE:Information Networking
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• v.41 no.4
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• pp.192-201
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• 2014

User scheduling boosts the Multi-User Multi-Input Multi-Output (MU-MIMO) gain by selecting an optimal set of users to increase the 802.11 Wi-Fi system capacities. Many kinds of user scheduling algorithms, however, fail to realize the advantages of MU-MIMO due to formidable Channel State Information (CSI) overhead. In this paper, we propose a user scheduling method considering such CSI exchange overhead and its MAC protocol, called ACE (Active CSI Exchange based User Scheduling for MU-MIMO Transmission). Unlike most proposals, where user scheduling is performed after an Access Point (AP) receives CSI from all users, ACE determines the best user set during the CSI exchange phase. In particular, the AP broadcasts a channel hint about previously scheduled users, and the remaining users actively send CSI reports according to their Effective Channel Gains (ECGs) calculated from the hint. Through trace-driven MATLAB simulations, we prove that the proposed scheme improves the throughput gain significantly.