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Dynamic power control for relay-aided transmission based on deep reinforcement learning

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The Journal of China Universities of Posts and Telecommunications 2019年第3期26卷 35-43,80页

作者： Qin Cai Wang Chaowei Wang Weidong zhang yinghai School of Electronic Engineering Beijing University of Posts and Telecommunications Beijing 100876 China Key Laboratory of Universal Wireless Communications Beijing University of Posts and Telecommunication Beijing 100876 China

Using relay in the wireless communication network is an efficient way to ensure the data transmission to the distant receiver. In this paper, a dynamic power control(DPC) approach is proposed for the amplify-and-forward(AF) relay-aided downlink transmission scenario based on deep reinforcement learning(DRL) to reduce the co-channel interference caused by spectrum sharing among different nodes. The relay works in a two-way half-duplex(HD) mode. Specifically, the power control of the relay is modeled as a Markov decision process(MDP) and the sum rate maximization of the network is formulated as a DRL problem. Simulation results indicate that the proposed method can significantly improve the system sum rate.

关键词： power control deep reinforcement learning relay downlink

Frequency Offset Compensation for Satellite Communication System with CE-OFDM

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China Communications 2017年第8期14卷 93-104页

作者： Gaofeng Cui Cheng Wang Weidong Wang yinghai zhang Key Laboratory of Universal Wireless Communications Ministry of Education Information&Electronics Technology Lab School of Electronic EngineeringBeijing University of Posts and Telecommunications

Constant envelope orthogonal frequency division multiplexing(CE-OFDM) is a waveform that can achieve 0d B peak-to-average power ratio and avoid the signal distortion caused by the nonlinear power amplifi er. However, the carrier frequency offset(CFO) in CE-OFDM systems can cause errors at phase unwrapper module. In this paper, a CFO estimation scheme is proposed for CEOFDM in satellite communication system. As the null subcarrier is inherent in the conjugate symmetric symbol structure at the transmitter, the proposed scheme uses the null subcarrier as prior information to estimate the CFO at the receiver. The ideal estimation range of normalized CFO is obtained by mathematical analysis. Simulation results show that the proposed scheme can estimate the CFO accurately under additive white Gaussian noise(AWGN) channel and multipath fading channel, especially for moderate and high signal-to-noise ratio(SNR).

关键词： CE-OFDM carrier frequency offset null subcarrier satellite communication

Joint Estimation of Carrier Frequency and Phase Offset Based on Pilot Symbols in Quasi-Constant Envelope OFDM Satellite Systems

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China Communications 2017年第7期14卷 184-194页

作者： Cheng Wang Gaofeng Cui Weidong Wang yinghai zhang Key Laboratory of Universal Wireless Communications Ministry of Education Beijing University of Posts and Telecommunications

Spectral efficiency and energy efficiency are two important performance indicators of satellite systems. The Quasi-Constant Envelope Orthogonal Frequency Division Multiplexing(QCE-OFDM) technique can achieve both high spectral efficiency and low peak-to-average power ratio(PAPR). Therefore, the QCE-OFDM technique is considered as a promising candidate multi-carrier technique for satellite systems. However, the Doppler effect will cause the carrier frequency offset(CFO), and the non-ideal oscillator will cause the carrier phase offset(CPO) in satellite systems. The CFO and CPO will further result in the bit-error-rate(BER) performance degradation. Hence, it is important to estimate and compensate the CFO and CPO. This paper analyzes the effects of both CFO and CPO in QCE-OFDM satellite systems. Furthermore, we propose a joint CFO and CPO estimation method based on the pilot symbols in the frequency domain. In addition, the optimal pilot symbol structure with different pilot overheads is designed according to the minimum Cramer-Rao bound(CRB) criterion. Simulation results show that the estimation accuracy of the proposed method is close to the CRB.

关键词： carrier frequency offset carrier phase offset pilot symbol structure quasi-constant envelope OFDM satellite systems.

Receiver Detection Employing Semaphore in Cognitive Radio

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China Communications 2010年第1期7卷 41-49页

作者： Wang Weidong Li Fan zhang yinghai Wang Shoufeng Wang Yongtao Beijing Jiaotong Univ Natl Engn Lab Next Generat Internet Interconnect Beijing 100044 Peoples R China

Interference from secondary users to primary users should be avoided in cognitive radio. However, it is difficult to solve the interference problem if the secondary users cannot get the information of the primary receivers. Insufficient information of primary users would result in inaccurate spectrum detecting result. To deliver the information of primary users, Receiver Detection Employing Semaphore (ReDES) is proposed in this paper. Primary receiver informs secondary users of its licensed receive frequency according to semaphore architecture directly in ReDES. The semaphore is used to determine the spectrum holes by secondary users. Frequency mapping method is come up with as a realization of ReDES. The procedure and the detailed techniques are illustrated to make ReDES scheme reasonable and feasible. Simulation results show that the proposed scheme can effectively detect the frequencies of primary receivers, and improve the accuracy of spectrum detection.

关键词： cognitive radio receiver detection hidden terminal problem.

A SDN-Based Energy Saving Strategy in Wireless Access Networks

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China Communications 2015年第8期12卷 132-145页

作者： PENG Hongyu WANG Weidong WANG Chaowei CHEN Gang zhang yinghai College of Electronic Engineering Beijing University of Posts and Telecommunications Ministry of Education Key Laboratory of Universal Wireless Communications Beijing University of Posts and Telecommunications Ministry of Education

This paper investigates on the base stations(BSs) sleeping control and energy saving in wireless network. The objective is to find the sleeping control and energy saving configuration between total power consumption and average video's quality. On the Software Defined Network(SDN) access network architecture, a type of sleeping control and active BSs' optimal transmitting time strategy is considered, the BS sleeps when there is no active users, and wakes up after a period of vacation time. In this paper, we study the active users grouping strategy, In order to spare more BSs into sleeping mode. Then this paper proposes an active BS transmitting time optimal strategy according to the users' Qo S. In the proposed strategy, the active BSs' transmitting time is minimized in order to save energy. This paper employs the mixed integer-programming model to present this optimization problem. Then we utilized a novel algorithm to save the energy in access networks and also meet the Qo S requirements. Both the analytical and simulation results show that the algorithm can effectively save energy in the access network BSs.

关键词： SDN wireless access network energy efficiency mobility

QoS-guaranteed energy saving routing strategy using SDN central control for backbone networks

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The Journal of China Universities of Posts and Telecommunications 2015年第5期22卷 92-100页

作者： Peng Hongyu Wang Weidong Wang Chaowei Chen Gang zhang yinghai College of Electronic Engineering Beijing University of Posts and Telecommunications Key Laboratory of Universal Wireless Communications Beijing University of Posts and Telecommunications

This paper targets on energy saving and considers network responding time for backbone networks. The objective is to find idle links as many as possible which can be put into sleep mode under the situation of quality of service(QoS)-guaranteed. This paper proposes a software defined network(SDN) based routing strategy which is especially aimed at QoS-guaranteed energy saving for backbone networks. Under SDN structure, the topology change of network can be detected directly by network controller. And network can be managed more easily and effectively. Based on the open shortest path first(OSPF) protocol, network topology can be changed as little as possible in our strategy. So, the network reconfiguring time caused by the energy saving strategy will be decreased dramatically. This makes the strategy more feasible. Then the backbone network energy optimizing problem is transformed to the maximum clique problem(MCP). And, this paper designed a routing strategy called backbone networks energy saving strategy(BNESS) for energy saving in backbone networks. Simulation result shows that our proposed strategy can save energy and QoS can be guaranteed.

关键词： Energy efficient networks Backbone Software define

A k-Coverage Scheduling Scheme in Wireless Sensor Network Based on Hard-Core Process in Rayleigh Fading Channel

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China Communications 2015年第11期12卷 92-103页

作者： KANG Lin LI Xiuhua zhang yinghai WANG Weidong LI Jinlan Beijing University of Posts and Telecommunications Taiyuan University of Science and Technology

Sensing coverage is a fundamental design issue in wireless sensor networks(WSNs),while sensor scheduling ensures coverage degree to the monitored event and extends the network *** this paper,we address k-coverage scheduling problem in dense WSNs,we maintain a connected k-coverage energy efficiently through a novel Hard-Core based Coordinated Scheduling(HCCS),in which hardcore is a thinning process in stochastic geometry that inhibits more than one active sensor covering any area redundantly in a minimum distance. As compared with existing coordinated scheduling,HCCS allows coordination between sensors with little communication ***,due to the traditional sensing models in k-coverage analysis is unsuitable to describe the characteristic of transmit channel in dense WSNs,we propose a novel sensing model integrating Rayleigh Fading and Distribution of Active sensors(RFDA),and derive the coverage measure and k-coverage probability for the monitored event under RFDA. In addition,we analyze the influence factors,i.e. the transmit condition and monitoring degree to the k-coverage probability. Finally,through Monte Carlo simulations,it is shown that the k-coverage probability of HCCS outperforms that of its random scheduling counterpart.

关键词： sleep scheduling rayleigh fading channel poisson point process hard-core process

A Novel System Model based on Cost-prediction for Spectrum Leasing in Cognitive Radio

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China Communications 2010年第2期7卷 32-41页

作者： Wang Weidong Wang Ben zhang yinghai Zhao Xinlei Wang Shoufeng Information ＆ Electronics Technology Lab Beijing University of Posts and Telecommunications Beijing 100876 China

In current researches on spectrum leasing, Common model and Property-right model are two main approaches to dynamic spectrum sharing. However, Common model does not consider the obligation of Primary System (PS) and is unfair to Secondary System (SS), while the cooperation based on Property-rights model has problems on its feasibility. This paper proposes a novel system model, in which a Cost-Prediction scheme for Spectrum Leasing (CPSL scheme) is designed to forecast the cost that PS would pay for leasing spectrum. Cost Function is introduced as a criterion to evaluate the potential cost of spectrum leasing for PS. The simulation results show that compared with Common model based scheme, CPSL scheme substantially improves the QoS of the delay-sensitive traffic in SS at the cost of a small degradation of PS performance.

关键词： cognitive radio spectrum leasing cost prediction dynamic spectrum sharing CPSL

Service-Oriented Middleware for Heterogeneous Environment in Intemet of Things

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China Communications 2012年第9期9卷 41-51页

作者： Wu Yuexin zhang yinghai Fan Chunxiao Zou Junwei School of Electronic Engineer Beijing University of Posts and TelecommunicationsBeijing 100876P.R.China

A great number of sensor technologies are applied in the Intemet of Things （loT） currently and more are emerging, which rmkes the loT a heterogeneous network. This paper discusses the convergence and integration problem in IoT. A Service-Oriented Middleware for Heterogeneous Environment （SOMHE） in IoT is proposed. The purpose of the middleware is to shield the differ- ence between protocols in the sensor layers such as Radio Frequency Identification （RFID） and Zig-Bee by defining the data conversion and mapping model. A Web service interface is supplied by this middleware, thus the complexity of high level appli-cation development can be reduced greatly. The feasibility and reliability of this middleware is veri-fied by a demonstration systelTL

关键词： IoT sensor layer multi-protocol mid-dleware heterogeneous