• 한국컴퓨터정보학회논문지
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• 제26권1호
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• pp.103-110
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• 2021

본 논문에서는 5G 무선 네트워크 D2D 시스템에서 수행될 수 있는 두 가지 액세스 제어 메커니즘들을 비교해 보고 효과적인 액세스 제어 기법을 제안한다. 현재 5G D2D 시스템에서는 액세스 제어 기법이 표준 규격에 제정 되어 있지 않고 있으나, 두 가지 액세스 제어 기법들이 가능하다. 하나의 방식으로는 UE-to-Network Relay 기반의 액세스 제어 기법이고, 다른 하나의 방식으로는 Remote UE 기반의 액세스 제어 기법이다. 전자의 경우는 UE-to-Network Relay가 액세스 제어 검사를 수행하는 것이며, 후자의 경우는 Remote UE가 액세스 제어 검사를 직접 수행하는 방식이다. 실험 평가 결과, 본 논문에서는 5G 무선 네트워크 D2D 시스템에서 효율적인 액세스 제어 방안으로써 Remote UE 기반의 액세스 제어 기법을 최종 제안한다. Remote UE 기반의 액세스 제어 기법은 UE-to-Network Relay 기반의 액세스 제어 기법이 비하여, 신호 오버헤드를 최소화하고, 서로 액세스 제어 기능들이 다른 경우 보다 효율적인 액세스 제어 검사를 수행할 수 있다.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2003년도 하계학술대회
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• pp.307-309
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• 2003

In the initial deployment stage of optical access networks, optical network systems and optical fiber cables have been provided mainly for commercial buildings or users in KT. According to the demand of residential users who expect to subscribe broadband multimedia services as high bit rate services, the optical access networks get closer to the residential users as FTTCab or FTTH So, it is very important to install optical access networks economically and effectively because that the total cost and usability of optical fiber cables depends on that. Especially, one of characteristics in access networks is the possibility of variation on services demands and technology evolution. Also access networks must be prepared for the final deployment, FTTH. Therefore, the designing and planning of optical access networks are coming to be very important activity for most of telecommunications service providers.

• Journal of Communications and Networks
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• 제13권1호
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• pp.43-49
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• 2011

In this paper, a new medium access control (MAC) protocol entitled three-phase multiple access with continual contention resolution (TPMA-CCR) is proposed for wireless multi-hop ad hoc networks. This work is motivated by the previously known three-phase multiple access (TPMA) scheme of Hou and Tsai [2] which is the suitable MAC protocol for clustering multi-hop ad hoc networks owing to its beneficial attributes such as easy collision detectible, anonymous acknowledgment (ACK), and simple signaling format for the broadcast-natured networks. The new TPMA-CCR is designed to let all contending nodes participate in contentions for a medium access more aggressively than the original TPMA and with continual resolving procedures as well. Through the systematical performance analysis of the suggested protocol, it is also shown that the maximum throughput of the new protocol is not only superior to the original TPMA, but also improves on the conventional slotted carrier sense multiple access (CSMA) under certain circumstances. Thus, in terms of performance, TPMA-CCR can provide an attractive alternative to other contention-based MAC protocols for multi-hop ad hoc networks.

• 한국멀티미디어학회논문지
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• 제10권12호
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• pp.1612-1621
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• 2007

In this paper, we introduced our designed TDMA (Time Division Multiple Access) based MAC (Medium Access Control) protocol for Home Networks called HomeTDMA. We have implemented and tested it in a test bed using crossbow motes and TinyOS. We also have compared HomeTDMA and CSMA (Carrier Sense Multiple Access) in terms of space and time complexity, channel access time, delivery success ratio, and throughput. Based on our results, HomeTDMA has an advantage over CSMA on channel access time, throughput and delivery success ratioIn the case of complexity, HomeTDMA is more complex compared to CSMA. Thus, CSMA is more appropriate in wireless sensor networks (WSNs) where memory, energy, and throughput are important parameters to be considered. However, HomeTDMA has a natural advantage of collision free medium access and is very promising for home networks where a reliable transmission or data transfer and congestion control is highly preferred.

• 한국시뮬레이션학회논문지
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• 제14권2호
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• pp.83-92
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• 2005

Access networks connected in B3G networks provide its property network service. Hence, though mobile users may utilize only a network service from an access network, they can also use variety of network services from several access networks for their service satisfaction. To support heterogeneous changeable network service in access networks, the mobile terminal must implement heterogeneous system techniques so that it is able to change the network service by ISHO (Inter-System Handover) In this paper, we present the ISHO condition by the policy-based framework in B3G networks. Also, we propose an ISHO scheme to control network resources for the QoS management of a mobile session between UMTS and WLAN access networks. To support the QoS management, the proposed scheme is that it will be implemented before the resource exhaustion occurs to effect network performances.

• 한국통신학회논문지
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• 제41권8호
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• pp.928-941
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• 2016

유선 데이터 네트워크(wired data network) 영역에서 가장 많은 에너지를 요구하는 영역은 액세스 네트워크(access network) 영역이다. 오늘날 그린 네트워킹(Green networking)은 유선 데이터 네트워크에서도 통합적인 에너지 관리를 통해 에너지 낭비와 $CO_2$ 배출 감소를 유도하기 위해 주요 관심분야가 되었다. 그러나 유선 액세스 네트워크의 에너지 소모량과 $CO_2$ 배출에 의한 환경적 영향에 대해서는 널리 알려져 있지 않으며, 그에 따른 범용적이고 정량적인 평가 기준도 매우 부족하다. 본 논문에서는 유선 액세스 네트워크의 에너지 소모량을 추정하는 기존의 모델링 기법들의 문제점을 비교 분석하고 하향식(top-down) 접근법을 이용하여 대규모 유선 액세스 네트워크의 에너지 소모량을 추정하는 모델링 기법을 제안한다. 또한 제안 모델로부터 도출된 추정치를 이용하여 액세스 네트워크들이 환경에 미치는 영향도를 산출하는 모델을 제안한다. 그리고 실제 사례를 적용하여 기존 모델과 제안 모델로부터 산출한 추정치와 해당 사례에 대한 기존의 조사와 실측 데이터와 비교 평가 한다.

• Journal of Communications and Networks
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• 제2권1호
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• pp.46-57
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• 2000

Ongoing standardization effort on 3G cellular system in 3GPP (UNTS) is based on GPRS core network and promises a global standard for systems capable of offering ubiquitous access to internet for mobile users. Considered radio access systems(FDD CDMA, TDD CDMA, and EDGE) are optimized for robust mobile use. However, there are alternative relatively high-rate radio interfaces being standardized for WLAN (IEEE802.11 and HIPER-LAN/2) which are capable of delivering significantly higher data rates to static or semi-static terminals with much less overhead. Also WPANs(BLUETOOTH, IEEE802.15), which will be present in virtually every mobile handset in the near future, are offering low cast and considerable access data rate and thus are very attractive for interworking scenarios. The prospect of using these interfaces as alternative RANs inthe modular UMTS architecture is very promising. Additionally, the recent inclusion of M-IP in the UMTS R99 standard opens the way for IP-level interfacing to the core network. This article offers an overview into WLAN-Cellular interworking. A brief overview of GPRS, UMTS cellular architectures and relevant WLAN standards is given. Possible interworking architectures are presented.

• Journal of Communications and Networks
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• 제18권2호
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• pp.135-149
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• 2016

Cloud radio access network (C-RAN) refers to the virtualization of base station functionalities by means of cloud computing. This results in a novel cellular architecture in which low-cost wireless access points, known as radio units or remote radio heads, are centrally managed by a reconfigurable centralized "cloud", or central, unit. C-RAN allows operators to reduce the capital and operating expenses needed to deploy and maintain dense heterogeneous networks. This critical advantage, along with spectral efficiency, statistical multiplexing and load balancing gains, make C-RAN well positioned to be one of the key technologies in the development of 5G systems. In this paper, a succinct overview is presented regarding the state of the art on the research on C-RAN with emphasis on fronthaul compression, baseband processing, medium access control, resource allocation, system-level considerations and standardization efforts.

• Journal of Communications and Networks
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• 제13권6호
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• pp.639-654
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• 2011

In this paper, we present a channel access mechanism, referred to as the enhanced mesh coordinated channel access (eMCCA) mechanism, for IEEE 802.11s-based wireless mesh networks. The current draft of IEEE 802.11s includes an optional medium access control (MAC), denoted as MCCA, which is designed to provide collision-free and guaranteed channel access during reserved periods. However, the MCCA mechanism fails to achieve the desired goal in the presence of contending non-MCCA nodes; this is because non-MCCA nodes are not aware of MCCA reservations and have equal access opportunities during reserved periods. We first present a probabilistic analysis that reveals the extent to which the performance of MCCA may be affected by contending non-MCCA nodes. We then propose eMCCA, which allows MCCA-enabled nodes to enjoy collision-free and guaranteed channel access during reserved periods by means of prioritized and preemptive access mechanisms. Finally, we evaluate the performance of eMCCA through extensive simulations under different network scenarios. The simulation results indicate that eMCCA outperforms other mechanisms in terms of success rate, network throughput, end-to-end delay, packet-loss rate, and mesh coordinated channel access opportunity-utilization.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권3호
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• pp.911-923
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• 2014

Ad hoc cognitive radio wireless sensor networks allow secondary wireless sensor nodes to recognize spectrum opportunities and transmit data. Most existing protocols proposed for ad hoc cognitive radio wireless sensor networks require a dedicated common control channel. Allocating one channel just for control packet exchange is a waste of resources for channel-constrained networks. There are very few protocols that do not rely on a common control channel and that exchange channel-negotiation control packets during a pre-allocated time on the data channels. This, however, can require a substantial amount of time to access the channel when an incumbent is present on the channel, where the nodes are intended to negotiate for the data channel. This study examined channel access delay on cognitive radio wireless sensor networks that have no dedicated common control channel.