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Optimal power allocation for homogeneous and heterogeneous CA-MIMO systems

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Science China(Information Sciences) 2013年第2期56卷 177-190页

作者： CUI QiMei KANG PeiChuan HUANG XueQing valkama mikko NIEMELA Jarno Key Laboratory of Universal Wireless Communications Beijing University of Posts and Telecommunications Department of Communications Engineering Tampere University of Technology

Carrier aggregation (CA) technique has been adopted by 3GPP LTE-Advanced due to its ability of enhancing the spectrum efficiency and peak data rates through aggregating multiple component carriers (CCs). Two main factors make power control optimization very essential for CA-MIMO radio link: the different channel characteristics in multiple CCs, and multiple power constraint conditions (per-CC, per-antenna and pertransmitter power constraints) in the actual CA system deployment. This paper firstly derives the degenerate conditions of optimal power allocation for a single-transmitter CA-MIMO system. Stemming from the derived degenerate conditions, we propose a modified hybrid gradient optimal power allocation(MHGOPA) algorithm to maximize the system performance. Simulation results verify the validity of the proposed resource allocation approach by comparing with baseline average power allocation algorithm. Finally, we extend the MHGOPA algorithm into a heterogeneous CA network with multiple transmitters working simultaneously.

关键词： LTE-advanced carrier aggregation CA-MIMO heterogenous network modified hybrid gradient optimal power allocation

Optimal energy-efficient scheme for two-way relay channel using physical layer network coding

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The Journal of China Universities of Posts and Telecommunications 2011年第6期18卷 51-58页

作者： ZHOU Min CUI Qi-mei WANG Hui TAO Xiao-feng TIAN Hui mikko valkama Key Laboratory of Universal Wireless Communications Beijing University of Posts and Telecommunications Beijing 100876 China Department of Communications Engineering Tampere University of Technology Tampere PF1-33101 Finland

Systems are always designed and optimized based on full traffic load in the current literatures. However, practical systems are seldom operating at full load, even at peak traffic hours. Instead of maximizing system rate to achieve the full load, an optimal energy-efficient scheme to minimize the transmit power with required rates is investigated in this article. The considered scenario is a two-way relay channel using amplify-and-forward protocol of physical layer network coding, where two end nodes exchange messages via multiple relay nodes within two timeslots. A joint power allocation and relay selection scheme is designed to achieve the minimum transmit power. Through convex optimization theory, we firstly prove that single relay selection scheme is the most energy-efficient way for physical layer network coding. The closed-form expressions of power allocation are also given. Numerical simulations demonstrate the performance of the designed scheme as well as the comparison among different schemes.

关键词： energy-efficient two-way relay channel physical layer network coding power allocation relay selection rate constraints

A New Fairness-Oriented Packet Scheduling Scheme with Reduced Channel Feedback for OFDMA Packet Radio Systems

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International Journal of Communications, Network and System Sciences 2009年第7期2卷 608-618页

作者： Stanislav NONCHEV mikko valkama 不详

In this paper, we propose a flexible and fairness-oriented packet scheduling approach for 3GPP UTRAN long term evolution (LTE) type packet radio systems, building on the ordinary proportional fair (PF) scheduling principle and channel quality indicator (CQI) feedback. Special emphasis is also put on practical feedback reporting mechanisms, including the effects of mobile measurement and estimation errors, reporting delays, and CQI quantization and compression. The performance of the overall scheduling and feedback re-porting process is investigated in details, in terms of cell throughput, coverage and resource allocation fairness, by using extensive quasistatic cellular system simulations in practical OFDMA system environment with frequency reuse of 1. The performance simulations show that by using the proposed modified PF ap-proach, significant coverage improvements in the order of 50% can be obtained at the expense of only 10-15% throughput loss, for all reduced feedback reporting schemes. This reflects highly improved fairness in the radio resource management (RRM) compared to other existing schedulers, without essentially com-promising the cell capacity. Furthermore, we demonstrate the improved functionality increase in radio re-source management for UE’s utilizing multi-antenna diversity receivers.

关键词： Radio Resource Management Packet Scheduling Proportional-Fair Channel Quality Feedback Throughput Fairness

Advances in Digital Front-End and Software RF Processing:Part I

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ZTE Communications 2011年第3期9卷 1-2页

作者： mikko valkama Serioja Ovidiu TatuTomohisa Wada

One of the biggest technology trends in wireless broadband, radar, sonar, and broadcasting systems is software radio frequency processing and digital front-end. This trend encompasses a broad range of topics, from circuit design and signal processing to system integration. It includes digital up-conversion （DUC） and down-conversion （DDC）, digital predistortion （DPD）,

关键词： RF Advances in Digital Front-End and Software RF Processing SDR

The Linearized Calderón Problem on Complex Manifolds

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Acta Mathematica Sinica,English Series 2019年第6期35卷 1043-1056页

作者： Colin GUILLARMOU mikko SALO Leo TZOU Laboratoire de Mathématiques d'Orsay Université Paris-Sud CNRS Université Paris-Saclay Department of Mathematics and Statistics University of Jyv?skyl? School of Mathematics and Statistics University of Sydney

In this note we show that on any compact subdomain of a K?hler manifold that admits sufficiently many global holomorphic functions, the products of harmonic functions form a complete set. This gives a positive answer to the linearized anisotropic Calderón problem on a class of complex manifolds that includes compact subdomains of Stein manifolds and sufficiently small subdomains of K?hler manifolds. Some of these manifolds do not admit limiting Carleman weights, and thus cannot be treated by standard methods for the Calderón problem in higher dimensions. The argument is based on constructing Morse holomorphic functions with approximately prescribed critical points. This extends earlier results from the case of Riemann surfaces to higher dimensional complex manifolds.

关键词： Inverse problem Calderón problem complex manifold

Control of exterior ballistic properties of spin-stabilized bullet by optimizing internal mass distribution

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Defence Technology（防务技术） 2019年第1期15卷 38-50页

作者： Janne Lahti Timo Sailaranta mikko Harju Kai Virtanen Systems Analysis Laboratory Department of Mathematics and Systems AnalysisAalto University Aero RD Ltd Systems Analysis Laboratory Department of Mathematics and Systems AnalysisAalto Universit Department of Military Technology National Defence University of Finland

This paper introduces a novel approach for controlling the exterior ballistic properties of spin-stabilized bullets by optimizing their internal mass distributions. Specifically, the properties of interest are the bullets’ stability characteristics that are examined through dynamic and gyroscopic stability *** analytical expressions for aerodynamic quantities are also derived to address the compressibility of air. These expressions are utilized in a bullet model that enables efficient computation of the stability parameters for a given mass distribution. The bullet model is used in the formulation of nonlinear optimization problems that provide optimal mass distributions with respect to given goals, i.e., desired stability characteristics. The bullet types investigated in this paper are a long range bullet and a limited range training bullet. In the optimization of the mass distribution of the long range bullet, the goal is that the bullet stays stable for as long as possible. The mass distribution of the training bullet is optimized such that the bullet is stable at launch but becomes unstable shortly afterwards. The global optimal solutions obtained with the new approach fulfill the desired stability characteristics better than currently used uniformly filled bullets. Overall, the optimization approach reveals a new goal focused philosophy for bullet design compared to current trial and error design practices.

关键词： Aerodynamics Bullet Exterior ballistics Mass properties Optimization Stability

Dynamic ModeⅡfracture behavior of rocks under hydrostatic pressure using the short core in compression(SCC)method

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International Journal of Mining Science and Technology 2021年第5期31卷 927-937页

作者： Wei Yao Ying XuChonglang Wang Kaiwen Xia mikko Hokka State Key Laboratory of Hydraulic Engineering Simulation and Safety School of Civil EngineeringTianjin UniversityTianjin 300072China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China Engineering Materials Science Faculty of Engineering and Natural SciencesTampere University(TAU)POB 589FI-33014 TampereFinland Department of Civil&Mineral Engineering University of TorontoTorontoON M5S 1A4Canada

The shear failure of rocks under both a static triaxial stress and a dynamic disturbance is common in deep underground engineering and it is therefore essential for the design of underground engineering to quantitively estimate the dynamic ModeⅡfracture toughness KⅡCof rocks under a triaxial stress ***,the method for determining the dynamic KⅡCof rocks under a triaxial stress has not been developed *** an optimal sample preparation,the short core in compression(SCC)method was designed and verified in this study to measure the dynamic KⅡCof Fangshan marble(FM)subjected to different hydrostatic pressures through a triaxial dynamic testing *** formula for calculating the dynamic KⅡCof the rock SCC specimen under hydrostatic pressures was obtained by using the finite element method in combination with secondary *** experimental results indicate that the failure mode of the rock SCC specimen under a hydrostatic pressure is the shear fracture and the KⅡCof FM increases as the loading *** addition,at a given loading rate the dynamic rock KⅡCis barely affected by hydrostatic *** important observation is that the dynamic fracture energy of FM enhances with loading rates and hydrostatic pressures.

关键词： Loading rate Finite element method ModeⅡfracture toughness Fangshan marble Hydrostatic pressure Short core in compression

Long-term outcomes and quality of life in patients with Hirschsprung disease

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World Journal of Pediatric Surgery 2024年第3期7卷 181-186页

作者： mikko P Pakarinen Annika Mutanen Department of Pediatric Surgery University of Helsinki Children's HospitalHelsinkiFinland

Although patients with Hirschsprung disease are mostly affected by imperfect bowel function and fecal control in the long term,they are also predisposed to lower urinary tract symptoms,impaired sexual functions,infertility,psychosocial issues,and decreased quality of ***,but notable comorbidities,which may manifest after childhood,include inflammatory bowel disease and familial medullary thyroid *** frequent occurrence of fecal incontinence and constipation,the overall long-term outlook is quite optimistic as social continence with a good quality of life can be achieved by efficient bowel management also in those affected patients,whose self-coping strategies and medical treatment remain *** dysfunction and other potential long-term complications are best managed by an interdisciplinary specialized approach not overlooking psychosocial issues,which also helps to correctly identify areas requiring continuing input by adult healthcare for young adult patients after *** research is needed to unravel the pathophysiological mechanisms of the long-term bowel dysfunction to identify novel therapeutic targets for development of more efficient innovative management strategies and thereby improvement of quality of life.

关键词： patients impaired life

A CFD study on the hydrodynamic response of a small-scale ice floe induced by a passing ship

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Journal of Hydrodynamics 2024年第2期36卷 290-299页

作者： Zongyu Jiang Spyros Hirdaris Sasan Tavakoli mikko Suominen Pentti Kujala Marine and Arctic Technology Department of Mechanical EngineeringAalto UniversityEspooFinland Global Ship Systems Centre ABS Hellenic SM LLC.AthensGreece Department of Infrastructure Engineering The University of MelbourneMelbourneAustralia

A Reynolds averaged Navier-Stokes(RANS)computational fluid dynamics(CFD)model is built to investigate the hydrodynamic response of a circular ice floe under the influence of a passing ship in calm *** ship,mirroring the KRISO Container Ship’s hull design,progresses near an ice floe whose diameter is 30%of the ship’s length and its thickness is 3 *** ship advances at a constant speed,which is handled by using the overset mesh *** study focuses on the ice floe’s motions and the hydrodynamic forces induced by three speeds and three transverse distances of the passing *** reveal that ship-generated wakes notably influence the ice floe’s motions,with a greater influence on sway than ***,the ship’s speed and proximity distinctly affect the ice floe’s motions.

关键词： Hydrodynamics ship-ice interactions ice floe Reynolds averaged Navier-Stokes(RANS)computational fluid dynamics(CFD)