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Power Allocation for Wireless Powered MIMO Transmissions with Non-Linear RF Energy Conversion Models

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China Communications 2017年第2期14卷 57-64页

作者： Liqin Shi liqiang zhao Kai Liang State Key Laboratory of Integrated Service Networks Xidian University Xi'an 710071 China

We study a radio frequency(RF) wireless energy transfer(WET) enabled multiple input multiple output(MIMO) system. A time slotted transmission pattern is considered. Each slot can be divided into two phases, downlink(DL) WET and uplink(UL) wireless information transmission(WIT). Since energy conversion efficiency of the energy harvesting circuits are ***, the conventional linear model leads to a mismatch for resource allocation. In this paper, the power allocation algorithm considering the practical *** energy harvesting circuits is studied. The optimization problem is formulated to maximize the energy efficiency of system with multiple constraints, i.e., the transmission power, the received power and the minimum harvested energy, which is a *** problem. We transform the objective function from fractional form into an equivalent objective function in subtractive form and provide an iterative power allocation algorithm to achieve the optimal solution. Numerical results show that our proposed algorithm with the *** RF energy conversion models can achieve much better performance than the algorithm with the conventional linear model.

关键词： WET MIMO non-linear energy conversion model energy efficiency power allocation

Heterogeneous Control and Data Sub-network for Millimeter-Wave Communications

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China Communications 2015年第S1期12卷 58-66页

作者： ZHANG Xiaoxiao zhao liqiang LIANG Kai Key Laboratory of Integrated Service Networks Xidian University

Millimeter-wave(mmWave) communications are highly focused as a powerful mean enabling to perform very high data transmission. However it has several inherent shortcomings like directional transmission and serious attenuation in atmosphere. So it is difficult to implement random access in mm Wave WLANs. In this paper, a heterogeneous control and data sub-network architecture is presented, which decouples the traditional WLAN into 2.4 or 5GHz control sub-network and mm Wave data sub-network in both PHY and MAC layers. In control sub-network, DCF is adopted to transmit control information and in data sub-network, PCF is adopted to ensure the Qo S. Moreover, an omnidirectional transmission is employed in the control sub-network to support users' random access. The data sub-network only covers the required serving area by using directional antennas for specific users and can be adjusted dynamically based on control information. Simulations indicate that compared with the conventional WLANs, heterogeneous mm Wave WLANs can provide both random access and high throughput.

关键词： millimeter-wave heterogeneous network WLAN IEEE802.11

Radio Access Network Slicing Based on C/U Plane Separation

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China Communications 2017年第12期14卷 134-141页

作者： Hui zhao liqiang zhao Kai Liang Chengkang Pan State Key Laboratory of Integrated Service Networks Xidian University Xi'an 710071 Shaanxi Province China China Mobile Research Institute Beijing 100053 China

Network slicing achieves many interests from industry and academics due to its flexibility and *** this paper,we present a novel slicing scheme for radio access networks(RANs) based on control/user(C/U) plane ***,we divide e NBs into two sub-e NBs called Ce NB and Ue NB,for transmitting control data and user data respectively,thereby facilitating C/U plane ***,upon Ce NBs and Ue NBs being virtualized,we develop two RAN slices for control and user plane *** results show the feasibility of the proposed scheme.

关键词： C/U plane separation RAN slic-ing virtualization air interface

Joint Resource Allocation and Coordinated Computation Offloading for Fog Radio Access Networks

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China Communications 2016年第S2期13卷 131-139页

作者： Kai Liang liqiang zhao Xiaohui zhao Yong Wang Shumao Ou State Key Laboratory of Integrated Service Networks Xidian University Department of Computing and Communication Technologies Oxford Brookes University

The cloud radio access network(C-RAN) and the fog computing have been recently proposed to tackle the dramatically increasing traffic demands and to provide better quality of service(QoS) to user equipment(UE).Considering the better computation capability of the cloud RAN(10 times larger than that of the fog RAN) and the lower transmission delay of the fog computing,we propose a joint resource allocation and coordinated computation offloading algorithm for the fog RAN(F-RAN),which takes the advantage of C-RAN and fog ***,the F-RAN splits a computation task into the fog computing part and the cloud computing *** on the constraints of maximum transmission delay tolerance,fronthaul and backhaul capacity limits,we minimize the energy cost and obtain optimal computational resource allocation for multiple UE,transmission power allocation of each UE and the event splitting *** results have been proposed with the comparison of existing methods.

关键词： fog RAN C-RAN computation offloading resource allocation

Performance Analysis of Cooperative NOMA with Energy Harvesting in Multi-Cell Networks

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China Communications 2019年第11期16卷 120-129页

作者： Cheng Guo Jie Xin liqiang zhao Xiaoli Chu State Key Laboratory of Integrated Service Networks Xidian UniversityXi’anChina Department of Electronic and Electrical Engineering University of SheffieldSheffieldUK

In this paper,an energy harvesting enabled cooperative non-orthogonal multiple access(NOMA)system for a multi-cell network is ***,during the direct transmission phase,base stations send their superposed messages to the near users and far users simultaneously according to a NOMA principle,while the near users act as energy harvesting enabled relays employing a power splitting *** the cooperative phase,the near users transmit their decoded messages to the corresponding far users using harvested *** tools from stochastic geometry,we firstly calculate the signal to interference ratios of the users in each NOMA group including one near user and one far ***,the closed-form expressions of the coverage probability,ergodic rate,and energy efficiency are derived *** results validate the derived expressions and show that the energy harvesting enabled cooperative NOMA system in a multi-cell network can improve the coverage probability,ergodic rate,and energy efficiency compared to its counterpart OMA system.

关键词： non-orthogonal multiple access energy harvesting coverage probability ergodic rate stochastic geometry energy efficiency

Beyond 5G Networks: Integration of Communication, Computing, Caching, and Control

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China Communications 2023年第7期20卷 137-174页

作者： Musbahu Mohammed Adam liqiang zhao Kezhi Wang Zhu Han State Key Laboratory of Integrated Service Networks Xidian UniversityXi’an 710071China Department of Computer and Information Sciences Northumbria UniversityNewcastle upon TyneUK Department of Electrical and Computer Engineering University of HoustonHoustonTX 77004 USAand also with the Department of Computer Science and EngineeringKyung Hee UniversitySeoul 02447 South Korea

In recent years,the exponential proliferation of smart devices with their intelligent applications poses severe challenges on conventional cellular *** challenges can be potentially overcome by integrating communication,computing,caching,and control(i4C)*** this survey,we first give a snapshot of different aspects of the i4C,comprising background,motivation,leading technological enablers,potential applications,and use ***,we describe different models of communication,computing,caching,and control(4C)to lay the foundation of the integration *** review current stateof-the-art research efforts related to the i4C,focusing on recent trends of both conventional and artificial intelligence(AI)-based integration *** also highlight the need for intelligence in resources ***,we discuss the integration of sensing and communication(ISAC)and classify the integration approaches into various ***,we propose open challenges and present future research directions for beyond 5G networks,such as 6G.

关键词： 4C 6G integration of communication,computing,caching,and control i4C multi-access edge computing(MEC)

Impact of seawater acidification on shell property of the Manila clam Ruditapes philippinarum grown within and without sediment

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Journal of Oceanology and Limnology 2020年第1期38卷 236-248页

作者： YUAN Hongmei XU Xian YANG Feng zhao liqiang YAN Xiwu Engineering Research Center of Shellfish Culture and Breeding of Liaoning Province Dalian Ocean UniversityDalian 116023China Ecological Monitoring and Evaluation Division Wuhan SINOECO Ecological Science&Technology Co.Ltd.Wuhan 430080China

Although the impact of ocean acidification on marine bivalves has been previously investigated under mainly controlled laboratory conditions,it is still unclear whether the impact of acidification on sediment-burrowing species differs between those within or without *** order to fill this gap in our knowledge,we compared shell properties of the infaunal Manila clam(Ruditapes philippinarum)exposed to three pH concentrations(7.4,7.7,and 8.0),within and without *** the first experiment(140 d),clams were exposed to seawater in an acidification system without sediment.A decrease in shell weight corresponding to the increase in dissolution rate was observed in the group ofpH 7.4,at which shell color disappeared or *** observations confirmed the changes of the external shell *** the second experiment(170 d),sediment was placed at the bottom of each exposure *** effects were found obvious in shell dissolution rate and shell color in the shell specimens exposed to overlying seawater but not found in the shell specimens exposed to *** the experimental period was longer in the second experiment,shell specimens in the first experiment were more seriously damaged than those in the second experiment under acidic seawater *** results,in relation to the defense function of the shell,show that marine bivalves in burrowing behavior are more adaptable to seawater acidification than those who do not burrow into sediment.

关键词： ocean acidification sediment Manila clam(Ruditapes philippinarum) shell properties

Enhanced PSO Based Energy-Efficient Resource Allocation and CQI Based MCS Selection in LTE-A Heterogeneous System

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China Communications 2016年第11期13卷 197-204页

作者： Jianbo Du liqiang zhao Jie Feng Jie Xin Yong Wang State Key Laboratory of Integrated Service Networks Xidian University

In order to maximize system energy efficiency(EE) under user quality of service(Qo S) restraints in Long Term Evolution-Advanced(LTE-A) networks,a constrained joint resource optimization allocation scheme is presented,which is NP-hard. Hence,we divide it into three sub-problems to reduce computation complexity,i.e.,the resource block(RB) allocation,the power distribution,and the modulation and coding scheme(MCS) assignment for user codewords. Then an enhanced heuristic approach GAPSO is proposed and is adopted in the RB and power allocation respectively to reduce computational complexity further on. Moreover,a novel MCS allocation scheme is put forward,which could make a good balance between the system reliability and availability under different channel conditions. Simulation results show that the proposed GAPSO could achieve better performance in convergence speed and global optimum searching,and that the joint resource allocation scheme could improve energy efficiency effectively under user Qo S requirements.

关键词： LTE-A radio resource allocation MCSs assignment energy efficiency particle swarm optimization

Wind regimes and associated sand dune types in the hinterland of the Badain Jaran Desert,China

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Journal of Arid Land 2022年第5期14卷 473-489页

作者： MENG Nan WANG Nai'ang zhao liqiang NIU Zhenmin SUN Jiaqi Center for Glacier and Desert Research College of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China

Wind controls the formation and development of sand ***,understanding the wind regimes is necessary in sand dune *** this study,we combined the wind data from 2017 to 2019 at four meteorological stations(Cherigele and Wuertabulage stations in the lake basins,and Yikeri and Sumujilin stations on the top of sand dunes)in the hinterland of the Badain Jaran Desert in China,with high resolution Google Earth images to analyze the correlation between the wind energy environments and dune *** results of data analysis indicated that both the wind direction and sand drift intensity exhibited notable spatial and temporal *** highest level of wind activity was observed in *** and northeasterly winds were the dominant in the Badain Jaran *** the Cherigele,Wuertabulage,and Yikeri stations,the drift potential(DP)was below 200.00 vector units(VU).The wind energy environments in most areas could be classified as low-energy *** resultant drift direction differed at different stations and in different seasons,but the overall direction was mainly the *** resultant drift potential(RDP)/DP ratio was greater than 0.30 in most parts of the study area,suggesting that the wind regimes mainly exhibited unimodal or bimodal *** between the thermodynamic properties and the unique landscape settings of lakes and sand dunes could alter the local circulation and intensify the complexity of the wind *** wind regimes were weaker in the lake basins than on the top of sand *** dunes were the most dominant types of sand dunes in the study area,and the wind regimes at most stations were consistent with sand dune *** was thus the main dynamic factor affecting the formation of sand dunes in the Badain Jaran Desert *** results of this study are important for understanding the relationship between the wind regimes and aeolian landforms of the dune field in the desert

关键词： sand-driving wind drift potential wind energy environment sand dune local circulation Badain Jaran Desert