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Energy-efficient resource allocation for hybrid bursty services in multi-relay OFDM networks

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Science China(Information Sciences) 2017年第10期60卷 169-186页

作者： Yuhao ZHANG qimei cui Ning WANG Yanzhao HOU Weiliang XIE School of Information and Communication Engineering Beijing University of Posts and Telecommunications China Telecom Corporation Limited

In this paper, we propose mapped two-way water filling(MTWF) scheme to maximize energy efficiency(EE) for hybrid bursty services with quality of services(Qo S) requirements in two-way multirelay(TWMR) OFDM networks. The bursty traffic is first analyzed by strictly proved equivalent homogeneous Poisson process, based on which the Qo S requirements are converted into sum-rate constraints. The formulated non-convex EE maximization problem, including subcarrier assignment, relay selection(RS) and rate allocation, is NP-hard involving combinatorial optimization. To conduct optimal RS on each subcarrier without priori bursty traffic knowledge, we utilize some approximate relationships under high data rate demands to remove its dependence on two-way data rates, and simplify the whole optimization problem as well. After the optimal channel configuration is obtained, which only depends on channel conditions, subcarrier assignment is attained through elitist selection genetic algorithm(ESGA), and rate allocation of each service is fulfilled by deducing two-way water filling principle. A new equivalent optimization objective function is proposed next as the simple evaluating index in ESGA to reduce complexity. Finally, simulations are carried out to verify the superiority and convergence of our scheme, as well as the applicability for different scenarios.

关键词： energy efficiency resource allocation hybrid bursty services two-way multi-relay genetic algorithm

Energy-aware deployment of dense heterogeneous cellular networks with QoS constraints

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Science China(Information Sciences) 2017年第4期60卷 148-165页

作者： qimei cui Zhiyan cui Wei ZHENG Riku JNTTI Weiliang XIE National Engineering Laboratory for Mobile Network Security Beijing University of Posts and Telecommunications Department of Communications and Networking Aalto University China Telecom Corporation Limited

The base station(BS) configuration is a key factor to improve energy efficiency(EE). In this paper,we focus on designing the network deployment parameters(i.e., BS densities) for biased K-tier heterogeneous cellular network(HCN) with quality of service(Qo S) provisioning. Using appropriate approximations, we derive the closed-form expressions of optimal BS density across all tiers to minimize the area power consumption(APC) by applying the stochastic geometry theory, while satisfying the users’ Qo S requirements. These results are used to obtain some new insights into the EE performance of biased HCN deployment. With the aid of this approach, the best type of BSs to be deployed or switched off for energy saving purposes can be identified from the perspectives of BS transmission power. More precisely, if the BS transmission power ratio between an arbitrary pair of tiers of K-tier HCN, e.g., the small cell BS and macro BS tiers, is higher than a threshold which is a function of path loss exponent, bias factor and power consumption, the small cell BSs are *** opposite situation takes place otherwise. Furthermore, it is also shown that, compared to the unbiased HCN scenario, significant energy savings are possible by appropriately biasing the HCN and optimizing the BS density, subject to the Qo S constraints among all tiers.

关键词： heterogeneous cellular networks stochastic geometry energy efficiency BS density energy saving

Multi-pair massive MIMO amplify-and-forward relaying system with low-resolution ADCs:performance analysis and power control

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Science China(Information Sciences) 2018年第2期61卷 164-181页

作者： qimei cui Yinjun LIU Yinsheng LIU Weiliang XIE Yong ZHAO National Engineering Laboratory for Mobile Network Security Beijing University of Posts and Telecommunications State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong University China Telecom Corporation Limited

In this paper, we focus on a general multi-pair massive MIMO amplify-and-forward(AF) relaying system where the relay antennas employ low-resolution analog-to-digital converters(ADCs) to reduce the hardware cost. First, considering the effect of low quantization on channel estimation, a tight closed form approximation of the system ergodic achievable rate is derived. Second, some asymptotic analysis is presented to reveal the impacts of the system parameters on the achievable rate. Particularly, the generalized power scaling schemes are characterized. The results indicate that in some cases, when the number of relay antennas grows without bound, the impact of the finite resolution ADCs on data transmission can be eliminated. To enhance the achievable rate of the quantized systems, the optimal user and relay power control schemes are proposed. Furthermore, to reap all the benefits of low-resolution ADCs, another power control scheme is also designed to minimize the total power consumption while guaranteeing the quality-of-service(Qo S)requirement of each user, which can help draw some useful insights into the optimal ADC resolution from power saving perspectives. The simulation results confirm the accuracy of our theoretical analysis and the effectiveness of the proposed power control schemes.

关键词： massive MIMO relaying system imperfect CSI low quantization power control

Stochastic geometry based analysis for heterogeneous networks: a perspective on meta distribution

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Science China(Information Sciences) 2020年第12期63卷 230-250页

作者： Xinlei YU qimei cui Yuanjie WANG Na LI Xiaofeng TAO Mikko VALKAMA National Engineering Laboratory for Mobile Network Technologies Beijing University of Posts and Telecommunications National Computer Network Emergency Response Technical Team/Coordination Center of China (CNCERT/CC) Department of Electrical Engineering Tampere University

The meta distribution as a new performance metric can provide much more fine-grained information about the individual link reliability, and is of great value for the analysis and design of the future cellular networks. In this paper, we investigate the stochastic geometry based analysis for heterogeneous networks from the perspective on the meta distribution. The comprehensive overview for the fundamental framework of the meta distribution is provided, which involves the concepts of the meta distribution and its related performance metric(e.g., mean local delay and spatial outage capacity) and the efficient calculation methods of the meta distribution. The insights of the meta distribution are also stated by the comparison with standard success probability. The various applications of the meta distribution to heterogeneous networks are summarized and categorized by different types of technologies. Furthermore, some open issues and future work are discussed to promote the development and application of the meta distribution.

关键词： meta distribution stochastic geometry heterogeneous network success probability per-link reliability

Two-Timescale Online Learning of Joint User Association and Resource Scheduling in Dynamic Mobile Edge Computing

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China Communications 2021年第8期18卷 316-331页

作者： Jian Zhang qimei cui Xuefei Zhang Xueqing Huang Xiaofeng Tao National Engineering Laboratory for Mobile Network Technologies Beijing University of Posts and TelecommunicationsBeijing 100876China Department of Computer Science New York Institute of TechnologyOld WestburyNY11568USA

For the mobile edge computing network consisting of multiple base stations and resourceconstrained user devices,network cost in terms of energy and delay will incur during task offloading from the user to the edge *** the limitations imposed on transmission capacity,computing resource,and connection capacity,the per-slot online learning algorithm is first proposed to minimize the time-averaged network *** particular,by leveraging the theories of stochastic gradient descent and minimum cost maximum flow,the user association is jointly optimized with resource scheduling in each time *** theoretical analysis proves that the proposed approach can achieve asymptotic optimality without any prior knowledge of the network ***,to alleviate the high network overhead incurred during user handover and task migration,a two-timescale optimization approach is proposed to avoid frequent changes in user *** user association executed on a large timescale and the resource scheduling decided on the single time slot,the asymptotic optimality is *** results verify the effectiveness of the proposed online learning algorithms.

关键词： user association resource scheduling stochastic gradient descent two-timescale optimization mobile edge computing

Cross-Layer Framework for Capacity Analysis in Multiuser Ultra-Dense Networks with Cell DTx

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China Communications 2019年第9期16卷 106-121页

作者： Qing Li Yu Chen qimei cui Yu Gu Guoqiang Mao National Engineering Laboratory for Mobile Network Technologies Beijing University of Posts and TelecommunicationsBeijing 100876China School of Computing and Communications University of Technology SydneyNSW 2007Australia

Cell discontinuous transmission(Cell DTx)is a key technology to mitigate inter-cell interference(ICI)in ultra-dense networks(UDNs).The aim of this work is to understand the impact of Cell DTx on physical-layer sum rates of SBSs and link-layer quality-of-service(QoS)performance in multiuser *** this work,we develop a cross-layer framework for capacity analysis in multiuser UDNs with Cell *** particular,we first extend the traditional one-dimensional effective capacity model to a new multidimensional effective capacity model to derive the sum rate and the effective ***,we propose a new iterative bisection search algorithm that is capable of approximating QoS *** convergence of this new algorithm to a unique QoS exponent vector is later ***,we apply this framework to the round-robin and the max-C/I scheduling *** results show that our framework is accurate in approximating 1)queue length distribution,2)delay distribution and 3)sum rates under the above two scheduling policies,and further show that with the Cell DTx,systems have approximately 30% higher sum rate and 35% smaller average delay than those in full-buffer scenarios.

关键词： effective capacity QoS performance sum rates multiuser scheduling ultra-dense network (UDN)

Modeling and Performance Analysis of UAV-Aided Millimeter Wave Cellular Networks with Stochastic Geometry

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China Communications 2024年第6期21卷 146-162页

作者： Li Junruo Wang Yuanjie cui qimei Hou Yanzhao Tao Xiaofeng National Engineering Laboratory for Mobile Network Technologies Beijing University of Posts and TelecommunicationsBeijing 100876China National Computer Network Emergency Response Technical Team/Coordination Center of China(CNCERT/CC) Beijing 100029China Department of Broadband Communication Peng Cheng LaboratoryShenzhen 518055China

UAV-aided cellular networks,millimeter wave(mm-wave) communications and multi-antenna techniques are viewed as promising components of the solution for beyond-5G(B5G) and even 6G *** leveraging the power of stochastic geometry,this paper aims at providing an effective framework for modeling and analyzing a UAV-aided heterogeneous cellular network,where the terrestrial base stations(TBSs) and the UAV base stations(UBSs) coexist,and the UBSs are provided with mm-wave and multi-antenna *** modeling the TBSs as a PPP and the UBSs as a Matern hard-core point process of type Ⅱ(MPH-Ⅱ),approximated but accurate analytical results for the average rate of the typical user of both tiers are derived through an approximation method based on the mean interference-to-signal ratio(MISR) *** influence of some relevant parameters is discussed in detail,and some insights into the network deployment and optimization are *** results show that some trade-offs are worthy of being considered,such as the antenna array size,the altitude of the UAVs and the power control factor of the UBSs.

关键词： average rate downlink millimeter wave point process theory SIR stochastic geometry UAVaided cellular networks

Vehicle-oriented ridesharing package delivery in blockchain system

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Digital Communications and Networks 2024年第4期10卷 1014-1023页

作者： Xuefei Zhang Junjie Liu Yijing Li qimei cui Xiaofeng Tao Ren Ping Liu Wenzheng Li Department of Information and Communication Engineering Beijing University of Posts and TelecommunicationsBeijing100876China Department of Electrical and Data Engineering University of Technology SydneySydneyAustralia Department of Information Technology Beijing University of TechnologyBeijing100876China

Package delivery via ridesharing provides appealing benefits of lower delivery cost and efficient vehicle *** existing ridesharing systems operate the matching of ridesharing in a centralized manner,which may result in the single point of failure once the controller breaks down or is under *** tackle such problems,our goal in this paper is to develop a blockchain-based package delivery ridesharing system,where decentralization is adopted to remove intermediaries and direct transactions between the providers and the requestors are *** complete the matching process under decentralized structure,an Event-Triggered Distributed Deep Reinforcement Learning(ETDDRL)algorithm is proposed to generate/update the real-time ridesharing orders for the new coming ridesharing requests from a local *** results reveal the vast potential of the ETDDRL matching algorithm under the blockchain framework for the promotion of the ridesharing ***,we develop an application for Android-based terminals to verify the ETDDRL matching algorithm.

关键词： Blockchain Dynamic matching Ridesharing package delivery

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