• 인터넷정보학회논문지
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• 제23권5호
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• pp.9-15
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• 2022

본 논문은 매크로 기지국(Macro base station, MBS) 커버리지에 위치한 건물 내부의 밀집된 스몰셀 네트워크 환경에서 매크로 사용자 단말(Macro user equipment, MUE)의 성능향상을 위한 채널 선택 기반 다중점 협력통신(Coordinated multi-point, CoMP) 방법을 제안한다. 제안하는 CoMP 방법에서 건물 내에 위치한 MUE의 성능향상을 위해 스몰셀 기지국(Small-cell base station, SBS)들이 이웃한 MUE에게 간섭을 적게 미치는 방법으로 채널을 선택하고 CoMP가 필요한 MUE에게 적절한 신호를 송신한다. 시뮬레이션 결과에서 제안하는 CoMP 방법이 기존의 랜덤채널할당 기반의 스몰셀 네트워크 방법과 CoMP방법보다 MUE의 성능을 각각 최대 164%와 51%까지 향상시킨다.

• 한국전자파학회논문지
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• 제23권1호
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• pp.14-20
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• 2012

셀룰러 이동 통신 시스템에서 협력적으로 신호를 전송하는 CoMP(Coordinated Multi-Point transmission and reception) 방식은 기지국 간 간섭을 매우 효과적으로 제어하여 시스템의 전송률을 증가시킨다. 그러나 협력적 전송에 참여하는 기지국의 개수가 증가할수록 기지국 간 공유가 요구되는 채널 상태 정보 및 전송 데이터의 교환으로 인한 오버헤드가 비약적으로 증가하는 문제를 발생시킨다. 본 논문에서는 제한적 궤환량을 고려하여 전송 효율이 높은 기지국들만을 협력적 전송에 참여시키는 부분적 CoMP 전송 방식을 제안한다. 이를 위해 시스템 내 코어 망은 사용자가 선호하는 기지국 정보를 반영하여 협력 기지국 조합을 구성한다. 또한, 사용자들의 채널 환경에 따라 선호하는 협력 기지국 조합이 상이할 수 있으므로 코어 망은 구성된 협력 기지국 조합을 다이나믹하게 변형하여 적용한다. 컴퓨터 시뮬레이션을 이용하여 제한적 궤환량 사용 시 기존의 비협력적 기지국 전송 방식과 협력적 기지국 전송 방식과의 평균 전송률 성능을 비교하고, 이를 통해 제안 방식의 우수성을 입증한다.

• Journal of information and communication convergence engineering
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• 제11권3호
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• pp.167-172
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• 2013

Recently, mobile communication systems are suffering from exponentially increasing data traffic. As a promising solution to the increase in data traffic, a coordinated multi-point transmission and reception (CoMP) scheme has been proposed. Although a great deal of research has been done on this new technology, the performance of mobile communication systems with CoMP has not been evaluated properly in a typical indoor environment. To address this, we have developed a system-level simulator and evaluated the performance of mobile communication systems with CoMP. Unlike previous works, we have used an actual antenna pattern in our simulator and link-level results are properly taken into account through link-level abstraction. By using a system-level simulator, we have evaluated the performance of mobile communication systems with CoMP in an indoor environment and found that unlike an outdoor cellular environment, CoMP may not improve the performance of overall mobile communication systems in an indoor environment.

• 전자공학회논문지
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• 제50권8호
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• pp.45-52
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• 2013

다중 포인트 협력 통신 기술(CoMP; Coordinated Multi-Point)은 3GPP(3rd Generation Partnership Project)의 LTE-A(Long Term Evolution-Advanced) 시스템 기술 중 하나로 고려된다. 본 논문에서는 CoMP 기술의 세부 기법 중 하나인 CB(Coordinated Beamforming) 기법에 대하여 설계하고, 이를 바탕으로 성능 분석이 이루어졌다. LTE-A 시스템의 이종 네트워크(HetNet; Heterogeneous Network) 환경에서 몬테카를로 모의실험이 이루어졌으며, CDF(Cumulative Distribution Function) 그래프를 통하여 그 성능을 확인한다. 모의실험 결과를 통해 CoMP 기술을 사용하였을 때 성능 이득을 얻을 수 있으며, CoMP 기술에 다양한 스케줄링 및 프리코딩 기법을 적용하였을 때 더 좋은 성능을 가져오는 것을 확인할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권9호
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• pp.2982-3003
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• 2014

With the explosive deployment of the wireless communications technology, the increased QoS requirement has sparked keen interest in network planning and optimization. As the major players in wireless network optimization, the BS's resource utilization and mobile user's QoS can be improved a lot by the load-balancing technology. In this paper, we propose a load-balancing strategy that uses Coordinated Multiple Points (CoMP) technology among the Base Stations (BS) to effectively extend network coverage and increase edge users signal quality. To use universally, different patterns of load-balancing based on CoMP are modeled and discussed. We define two QoS metrics to be guaranteed during CoMP load balancing: call blocking rate and efficient throughput. The closed-form expressions for these two QoS metrics are derived. The load-balancing capacity and QoS performances with different CoMP patterns are evaluated and analyzed in low-dense and high-dense traffic system. The numerical results present the reasonable CoMP load balancing pattern choice with guaranteed QoS in each system.

• 천문학회지
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• 제54권2호
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• pp.49-60
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• 2021

Observations of line of sight (LOS) Doppler velocity and non-thermal line width in the off-limb solar corona are often used for investigating the Alfvén wave signatures in the corona. In this study, we compare LOS Doppler velocities and non-thermal line widths obtained simultaneously from two different instruments, Coronal Multichannel Polarimeter (CoMP) and Hinode/EUV Imaging Spectrometer (EIS), on various off-limb coronal regions: flaring and quiescent active regions, equatorial quiet region, and polar prominence and plume regions observed in 2012-2014. CoMP provides the polarization at the Fe xiii 10747 Å coronal forbidden lines which allows their spectral line intensity, LOS Doppler velocity, and line width to be measured with a low spectral resolution of 1.2 Å in 2-D off limb corona between 1.05 and 1.40 RSun, while Hinode/EIS gives us the EUV spectral information with a high spectral resolution (0.025 Å) in a limited field of view raster scan. In order to compare them, we make pseudo raster scan CoMP maps using information of each EIS scan slit time and position. We compare the CoMP and EIS spectroscopic maps by visual inspection, and examine their pixel to pixel correlations and percentages of pixel numbers satisfying the condition that the differences between CoMP and EIS spectroscopic quantities are within the EIS measurement accuracy: ±3 km s-1 for LOS Doppler velocity and ±9 km s-1 for non-thermal width. The main results are summarized as follows. By comparing CoMP and EIS Doppler velocity distributions, we find that they are consistent with each other overall in the active regions and equatorial quiet region (0.25 ≤ CC ≤ 0.7), while they are partially similar to each other in the overlying loops of prominences and near the bottom of the polar plume (0.02 ≤ CC ≤ 0.18). CoMP Doppler velocities are consistent with the EIS ones within the EIS measurement accuracy in most regions (≥ 87% of pixels) except for the polar region (45% of pixels). We find that CoMP and EIS non-thermal width distributions are similar overall in the active regions (0.06 ≤ CC ≤ 0.61), while they seem to be different in the others (-0.1 ≤ CC ≤ 0.00). CoMP non-thermal widths are similar to EIS ones within the EIS measurement accuracy in a quiescent active region (79% of pixels), while they do not match in the other regions (≤ 61% of pixels); the CoMP observations tend to underestimate the widths by about 20% to 40% compared to the EIS ones. Our results demonstrate that CoMP observations can provide reliable 2-D LOS Doppler velocity distributions on active regions and might provide their non-thermal width distributions.

• 인터넷정보학회논문지
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• 제22권6호
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• pp.9-15
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• 2021

고밀도 이기종 네트워크에서 스몰셀 기지국(Small-cell base station, SBS)의 수가 증가하면 매크로 단말(Macrocell user equipment, MUE)의 간섭량도 증가하여 수신 신호대 간섭 및 잡음비(Signal-to-interference and noise ratio, SINR)와 시스템 용량이 감소한다. 따라서, 본 논문에서는 SBS의 수가 증가하여도 MUE의 성능을 보장하기 위한 스몰셀 기반 다중점 협력통신(Cooperative Multi-Point, CoMP) 방법을 제안한다. 제안하는 방법은 MUE가 주어진 SINR 임계값을 만족하기 위해 주변에 위치한 SBS들을 선택하고, 선택된 SBS는 MUE에게 CoMP를 제공하여 성능을 향상시킨다. 시뮬레이션 결과를 통해 제안하는 스몰셀 기반 CoMP 방법이 다른 간섭관리 및 CoMP 방법과 비교해 스몰셀 단말의 성능은 크게 감소되지 않으면서 MUE의 평균 SINR과 시스템 용량이 향상됨을 보인다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2016년도 춘계학술발표대회
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• pp.98-100
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• 2016

Coordinated multi-point (CoMP) transmission adopt the Base Stations (BS) cooperatively process User Equipment (UE) connected to multi-points to improve UEs spectral efficiency at the cell edge and eliminate the inter-cell interference (ICI). This technology is important for UEs at the cell edge. Considering the real environment, energy consumption and cost situation, we propose in a Local C-RAN architecture deployment of CoMP and observed its spectral efficiency and Signal-to-Interference and Noise Ratio (SINR) in intra-site CoMP scenarios. Simulation results show that this approach has significantly enhanced than Non-CoMP.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권9호
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• pp.1596-1612
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• 2011

Coordinated Multi-Point (CoMP) transmission / reception is being studied in Long Term Evolution-Advanced (LTE-A) for future evolution of the $3^{rd}$ Generation Partnership Project (3GPP) LTE. Support of soft handover is essential for improving the performance of cell edge users. CoMP provides a natural framework for enabling soft handover in the LTE system. This paper evaluates the soft handover gain in LTE-A downlink. Mathematical analysis of signal to interference plus noise ratio (SINR) gain and the handover margins for soft handover and hard handover are derived. CoMP system model is developed and an inter-cell and intra-cell interference model is derived, taking into account the pathloss, shadowing, cell loading, and traffic activity. Reference signal received power (RSRP) is used to define the triggers and the measurements for soft handover. Our results indicate that parameter choices such as handover margin and the CoMP set size impact CoMP performance gain.

• Journal of Communications and Networks
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• 제18권2호
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• pp.150-161
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• 2016

Coordinated multi-point transmission (CoMP) techniques are being touted as enabling technologies for interference mitigation in next generation heterogeneous wireless networks (HetNets). In this paper, we present a comparative performance study of uplink (UL) CoMP algorithms for the 3GPP LTE HetNets. Focusing on a distributed and functionally-split architecture, we consider six distinct UL-CoMP algorithms: 1. Joint reception in the frequency-domain (JRFD) 2. Two-stage equalization (TSEQ) 3. Log-likelihood ratio exchange (LLR-E) 4. Symmetric TSEQ (S-TSEQ) 5. Transport block selection diversity (TBSD) 6. Coordinated scheduling with adaptive interference mitigation (CS-AIM) where JRFD, TSEQ, S-TSEQ, TBSD and CS-AIM are our main contributions in this paper, and quantify their relative performances via the post-processing signal-to-interference-plus-noise ratio distributions.We also compare the CoMP-specific front-haul rate requirements for all the schemes considered in this paper. Our results indicate that, with a linear minimum mean-square error receiver, the JRFD and TSEQ have identical performances, whereas S-TSEQ relaxes the front-haul latency requirements while approaching the performance of TSEQ. Furthermore, in a HetNet environment, we find that CS-AIM provides an attractive alternative to TBSD and LLR-E with a significantly reduced CoMP-specific front-haul rate requirement.