• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.12
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• pp.1076-1084
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• 2012

In the CS/CB(Coordinated Scheduling/Beamforming) scheme, the cell edge user throughput is increased by selecting MIMO (Multiple Input Multiple Output) precoders which can minimize the interferences from adjacent base stations (BSs). However, in current LTE(Long Term Evolution) systems, the serving cell is selected in the initialization stage by using the synchronization signals and cell specific reference signals transmitted by adjacent BSs with a single antenna. The selected BS in the initialization stage may not be the best one since the MIMO precoding gain has not been considered in the cell selection stage. In this paper, a new cell selection technique is proposed for LTE systems with MIMO precoder by taking into account the effect of the precoder in the initialization stage. The proposed technique enables a user equipment (UE) in the cell boundary to select the serving BS by using the information (channel rank, effective channel capacity, and effective SINR(Signal to Interference plus Noise Ratio)) acquired from cell specific reference signals of candidate BSs. It is verified by computer simulation that the proposed technique can increase the channel capacity significantly in the multi-cell environments, compared with the conventional CS/CB scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6A
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• pp.555-567
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• 2010

Unlike single-hop systems, multi-hop systems that use relay nodes assign a part of the overall resources to relay communications. If efficient resource allocation schemes are not adopted, this leads to a loss of resources. Moreover, because we may not be able to guarantee high-link performance due to the adjacent-cell interference in relay-based cellular systems, resource efficiency can be severely decreased. In this paper, we propose efficient resource allocation schemes for downlink relay-based networks in 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution)-Advanced systems. Unlike conventional schemes that have static resource regions for each data link, the proposed schemes dynamically allocate the resources of each link to resource blocks, by considering the channel state and the capacity of each link. We also propose resource overlapping schemes in which two different links overlap at the same resource region, so as to improve cell or user throughput performance. The proposed resource overlapping schemes do not require additional processes such as interference cancellation in users, thank to considering additional interference from resource overlapping in advance.

• Journal of Advanced Navigation Technology
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• v.16 no.3
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• pp.471-479
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• 2012

In cellular femto systems, femto Base stations(f-BSs) can be installed unnecessarily and overcrowded in small areas. This will cause an interference problem and it can impact on the capacity, blocking probability, and coverage of femtocells in the shared channel systems. In this paper, we propose a load distribution scheme by using forced handover and probabilistic subchannel scheduling policy to resolve the problem. The proposed scheme operates in distributed manner though communication with neighboring f-BSs, and includes self-detection of overcrowded area and radio resource management based on measurements. We evaluate the performance of the proposed scheme in terms of average cell throughput and average throughput per users.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.155-155
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• 2012

기존의 플로팅 타입의 비휘발성 메모리 소자는 스케일 법칙에 따른 인접 셀 간의 간섭현상과 높은 동작 전압에 의한 누설전류가 증가하는 문제가 발생을 하게 된다. 이를 해결하고자 SONOS (Si/SiO2/Si3N4/SiO2/Si) 구조를 가지는 전하트랩 타입의 비휘발성 메모리 소자가 제안되었다. 하지만 터널링 베리어의 두께에 따라서 쓰기/지우기 특성은 향상이 되지만 전하 보존특성은 열화가 되는 trad-off 특성을 가지며, 또한 쓰기/지우기 반복 특성에 따라 누설전류가 증가하게 되는 현상을 보인다. 이러한 특성을 향상 시키고자 많은 연구가 진행이 되고 있으며, 특히 엔지니어드 터널베리어에 대한 연구가 주목을 받고 있다. 비휘발성 메모리에 대한 엔지니어드 기술은 각 베리어; 터널, 트랩 그리고 블로킹 층에 대해서 단일 층이 아닌 다층의 베리어를 적층을 하여 유전율, 밴드갭 그리고 두께를 고려하여 말 그대로 엔지니어링 하는 것을 뜻한다. 그 결과 보다 효과적으로 기판으로부터 전자와 홀이 트랩 층으로 주입이 되고, 동시에 다층을 적층하므로 물리적인 두께를 두껍게 형성할 수가 있고 그 결과 전하 보전 특성 또한 우수하게 된다. 본 연구는 터널링 베리어에 대한 엔지니어드 기술로써, Si3N4를 기반으로 하고 높은 유전율과 낮은 뉴설전류 특성을 보이는 ZrO2을 두 번째 층으로 하는 엔지니어드 터널베리어 메모리 소자를 제작 하여 메모리 특성을 확인 하였으며, 또한 Si3N4/ZrO2의 터널베리어의 터널링 특성과 전하 트랩특성을 온도에 따라서 특성 분석을 하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.11
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• pp.1256-1263
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• 2012

Assigning different frequency resources among adjacent cells, namely the frequency reuse technique can be utilized to mitigate intercell interference, which is a major cause of performance degradation in cellular systems. Since most of conventional frequency reuse patterns are limited to the two-dimensional environment, the research for the three-dimensional frequency reuse would be beneficial especially for the implementation of femto cells in downtown office buildings. We propose frequency reuse patterns in three-dimensional space and evaluate their performance of each pattern in terms of channel capacity. In particular, we show that the proposed three-dimensional frequency reuse patterns can be applied for carrier-aggregated transmission of LTE-Advanced systems. The performance of the proposed patterns is evaluated using computer simulation.

• Journal of Advanced Navigation Technology
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• v.14 no.6
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• pp.859-864
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• 2010

In the next generation system, a study on realization of Multi-Core system is in progress for applying it in multi service network. Therefore some mobile systems are expected to be appeared. These systems can support WiBro, WCDMA, CDMA, etc with single terminal. These systems have to support various FA using broadband frequency and hand over to other service network. Especially, in the telecommunication system composed of cell, the transmit power can be interference at adjacent system, has effect on system channel capacity and cell size. In this paper, we improve the unstable transmit power caused by unsettled system operation, propose the RF(Radio Frequency) Calibration method which can use the transmit power stably even during hand over between heterogeneous networks causing unstable power change. Also we used proposed method and analysed used electricity of system during hand over between heterogeneous networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6A
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• pp.642-647
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• 2007

HAP(High Altitude Platform) systems have been proposed due to their unique advantages over terrestrial and satellite systems as the alternative wireless communication system to deliver the third generation IMT-2000 wireless services. It has been required to study for the power control in W-CDMA HAP system as well as the terrestrial mobile system in order to mitigate interference and increase the capacity. In this paper, a new power control has been proposed for HAP system considering the interference profile into the DB(distributed balancing) SIR(signal to interference ratio)-based algorithm which has been considered in terrestrial system, and estimated by the outage performance of the proposed DB algorithm is better remarkably than DBPA(distance-based power allocation) which is proposed for HAP system, and it is the same regardless of the antenna maximum gain and its sidelobe characteristics.

• The Journal of the Korea institute of electronic communication sciences
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• v.1 no.2
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• pp.120-126
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• 2006

In this paper, we propose for improving QoS in hospital wireless network using Cellular-IP/PRC(Paging Route Cache) with Paging Cache and Route Cache in Cellular-IP. Although the Cellular-IP/PRC technology is devised for mobile internet communication, it has its vulnerability in frequent handoff environment. This handoff state machine using differentiated handoff improves quality of services in Cellular-IP/PRC. Suggested algorithm shows better performance than existing technology in wireless mobile internet communication environment. When speech quality is secured considering increment of interference to receive in case of suppose that proposed acceptance method grooves base radio station capacity of transfer node is plenty, and most of contiguity cell transfer node was accepted at groove base radio station with a blow, groove base radio station new trench lake acceptance method based on transmission of a message electric power estimate of transfer node be. Do it so that may apply composing PC(Paging Cache) and RC(Routing Cache) that was used to manage paging and router in radio Internet network in integral management and all nodes as one PRC(Paging Router Cache), and add hand off state machine in transfer node so that can manage hand off of transfer node and Roaming state efficiently, and studies so that achieve connection function at node. Analyze benevolent person who influence on telephone traffic in system environment and forecasts each link currency rank and imbalance degree, forecast most close and important lake interception probability and lake falling off probability, GoS(Grade of Service), efficiency of cell capacity in QoS because applies algorithm proposing based on algorithm use gun send-receive electric power that judge by looking downward link whether currency book was limited and accepts or intercept lake and handles and displays QoS performance improvement.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.6
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• pp.1302-1308
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• 2005

Propose Cellular-IP/PRC network with united paging and Cellular IP special duality that use roof information administration cache to secure lake acceptance method in wireless Internet environment and QoS in lesser extent cell environment. When speech quality is secured considering increment of interference to receive in case of suppose that proposed acceptance method grooves base radio station capacity of transfer node is plenty, and moat of contiguity cell transfer node was accepted at groove base radio station with a blow, groove base radio station new trench lake acceptance method based on transmission of a message electric power estimate of transfer node be. Do it so that may apply composing PC(Paging Cache) and RC(Routing Cache) that was used to manage paging and router in radio Internet network in integral management and all nodes as one PRC(Paging Router Cache), and add hand off state machine in transfer node so that can manage hand off of transfer node and Roaming state efficiently, and studies so that achieve connection function at node. Analyze benevolent person who influence on telephone traffic in system environment and forecasts each link currency rank and imbalance degree, forecast most close and important lake interception probability and lake falling off probability, GoS(Grade of Service), efficiency of cell capacity in QoS because applies algorithm proposing based on algorithm use gun send-receive electric power that judge by looking downward link whether currency book was limited and accepts or intercept lake and handles and displays QoS performance improvement.

• The Journal of the Korea institute of electronic communication sciences
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• v.3 no.3
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• pp.188-194
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• 2008

In this paper, we propose for improving QoS in Hospital wireless network using Cellular-IP/PRC(Paging Route Cache) with Paging Cache and Route Cache in Cellular-IP and propose for performance of realtime and non-real time handoff service using Handoff state machine Paging Route Cache. Although the Cellular-IP/PRC technology is devised for mobile internet communication, it has its vulnerability in frequent handoff environment. This handoff state machine using differentiated handoff improves quality of services in Cellular-IP/PRC Suggested algorithm shows better performance than existing technology in wireless mobile internet communication environment. When speech quality is secured considering increment of interference to receive in case of suppose that proposed acceptance method grooves base radio station capacity of transfer node is plenty, and moat of contiguity cell transfer node was accepted at groove base radio station with a blow, groove base radio station new trench lake acceptance method based on transmission of a message electric power estimate of transfer node be. Do it so that may apply composing PC(Paging Cache) and RC(Routing Cache) that was used to manage paging and router in radio Internet network in integral management and all nodes as one PRC(Paging Router Cache), and add hand off state machine in transfer node so that can manage hand off of transfer node and Roaming state efficiently, and studies so that achieve connection function at node. Analyze benevolent person who influence on telephone traffic in system environment and forecasts each link currency rank and imbalance degree, forecast most close and important lake interception probability and lake falling off probability, GoS(Grade of Service), efficiency of cell capacity in QoS because applies algorithm proposing based on algorithm use gun send-receive electric power that judge by looking downward link whether currency book was limited and accepts or intercept lake and handles and displays QoS performance improvement.