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Resource Allocation with QoS Supporting in Macro-Femtocell Networks
Jongchan Lee,Moonho Lee 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.1
The macro-femto overlaid LTE-Advanced networks have been drawing many attentions from mobile operators with their capability of extending coverages and supporting higher data rates. Effective and efficient resource allocation schemes must be preceded in order to deploy this overlaid cellular network successfully. This paper proposes the adaptive resource management scheme which categorizes the entire time-frequency resource blocks of the overlaid cellular network into the dedicated and the shared one, and allocates these resources stage by stage on the basis of user location and user-required data rate in order to expand the user accommodation capacity. Moreover, it enables to share loads evenly in the overlaid cellular network by performing cross-tier handovers from the macrocell to the femtocell so as to maximize the total packet throughput to a certain degree. We used a simulation to evaluate the effectiveness of our scheme with the performance measure of the outage probability and total packet throughput.
The Complex Reverse Jacket Transform
MoonHo Lee 에스케이텔레콤 (주) 2001 Telecommunications Review Vol.11 No.3
A novel discrete unitary orthogonal transform is introduced in this paper, namely the Complex Reverse Jacket Transform (CRJT). This transform has 4 elements such as {1, -1, +j, -j}, which are generated based on the Center Weighted Hadamard Matrix (CWHM). The CRJT belongs to the family of discrete orthogonal transformations and it is analogous to Discrete Fourier Transform (DFT) to deal with complex inputs. To deal with complex signals, the CRJT has some inherent computational advantages, and can be used to analyze and synthesize complex input functions. The CRJT can be applied in several areas of information processing, sequence filtering and optimally flat spectrum for cryptography and useful for finite fields of constructing error control codes.
Resource Reservation to Support Service Continuity in OFDMA Systems
( Jongchan Lee ),( Moonho Lee ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.12
When the load in a multi-cell orthogonal frequency division multiple access (OFDMA) system is allowed to excessively increase in face of frequent handover, the cell area becomes smaller than the designed size, and thus continuity of quality of service (QoS) for handover requests cannot be guaranteed. To efficiently support the mobility of a mobile terminal (MT), we should adaptively cope with the resource demand of handover calls. This paper proposes a twofold resource-reservation scheme for OFDMA systems to guarantee continuity of QoS for various mobile multimedia services during MT handover from lightly to heavily loaded cells. Our twofold scheme attempts to guarantee service continuity for handover and to maximize resource allocation efficiency. We performed a simulation to evaluate our scheme in terms of outage probability, handover failure rate, total throughput, and blocking rate.
Sub-channel Allocation Based on Multi-level Priority in OFDMA Systems
( Jongchan Lee ),( Moonho Lee ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.8
Packet-based mobile multimedia services for the Internet differ with respect to their resource requirements, performance objectives, and resource usage efficiencies. Nonetheless, each mobile terminal should support a variety of multimedia services, sometimes even simultaneously. This paper proposes a sub-channel allocation scheme based on multi-level priority for supporting mobile multimedia services in an Orthogonal Frequency Division Multiple Access (OFDMA) system. We attempt to optimize the system for satisfying the Quality of Service (QoS) requirements of users and maximize the capacity of the system at the same time. In order to achieve this goal, the proposed scheme considers the Signal-to-Interference-plus-Noise Ratio (SINR) of co-sub-channels in adjacent cells, the Signal-to-Noise Ratio (SNR) grade of each sub-channel in the local cell on a per-user basis, and the characteristics of the individual services before allocating sub-channels. We used a simulation to evaluate our scheme with the performance measure of the outage probabilities, delays, and throughput.
퍼지 집합 이론을 활용한 무선인지 주파수 할당 알고리즘
이문호(Moonho Lee),이종찬(Jongchan Lee) 한국통신학회 2008 韓國通信學會論文誌 Vol.33 No.9B
무선 인지 기반의 시스템에서, 주 사용자를 위한 주파수 할당을 보장하면서도 부가 사용자에게도 끊김없는 서비스를 제공해야 한다. 부가 사용자의 멀티미디어 데이터의 전송 시 무선 링크의 빈번한 변경 때문으로 인한 데이터 전송 지연과 손실이 발생할 경우 QoS 저하를 피할 수 없게 된다. 부가 사용자에게도 끊김없는 서비스를 유지하기 위해서는 효율적인 주파수 자원 관리가 필요하다. 본 논문에서는 퍼지 다기준 의사 결정 방법에 근거한 주파수 선정 방법을 제안한다. 제안되는 주파수선정 방법은 퍼지 집합 이론을 활용하며 주파수 선택을 위한 결정 프로세스에 기존의 전파 수신 감도 이외에 셀 부하, 데이터 전송률, 가용 대역 등을 고려한다. 시뮬레이션을 통하여, 제안된 방법이 수신 신호 세기만을 사용하는 기존의 방법보다 우수함을 보인다. In a cognitive radio based system, quality of service (QoS) for the secondary user must be maintained as much as possible even while that of the primary user is protected all the time. In particular, switching wireless links for the secondary user during the transmission of multimedia data causes delay and information loss, and QoS degradations occur inevitably. The efficient resource management scheme is necessary to support the seamless multimedia service to the secondary user. This paper proposes a novel frequency selection method based on Multi-Criteria Decision Making (MCDM), in which uncertain parameters such as received signal strength, cell load, data rate, and available bandwidth are considered during the decision process for the frequency selection with the fuzzy set theory. Through simulation, we show that our proposed frequency selection method provides a better performance than the conventional methods which consider the received signal strength only.
Mobile Location Estimation for WCDMA System
Jongchan Lee(이종찬),Moonho Lee(이문호) 한국데이타베이스학회 2007 Journal of information technology applications & m Vol.14 No.4
In the microcell- or picocell-based system the frequent movements of the mobile bring about excessive traffics into the networks. A mobile location estimation mechanism can facilitate both efficient resource allocation and better QoS provisioning through handoff optimization. Existing location estimation schemes consider only LOS model and have poor performance in presence of multi-path and shadowing. In this paper we study a novel scheme which can increase estimation accuracy by considering NLOS environment and other multiple decision parameters than the received signal strength.