Robust resource allocation algorithm for heterogeneous wireless networkwith SWIPT

To improve energy efficiency and robustness of heterogeneous wireless networks with wireless information and power transfer,the robust joint transmit power and power splitting resource allocation problem was studied.Based on mini-max probability machine and Dinkelbach method,the original NP-hard problem was transformed into a solvable convex optimization form,meanwhile a distributed dual resource allocation algorithm was proposed.Additionally,both computational complexity and robust sensitivity were analyzed.Simulation results show that the proposed algorithm can guarantee the quality of service requirements of macro cellular users and femtocell users under channel uncertainties.     

大规模MIMO OFDMA下行系统能效资源分配算法

针对大规模多输入多输出（MIMO）正交频分多址(OFDMA)下行移动通信系统,提出了一种基于能效最优的资源分配算法。所提算法在采用迫零(ZF)预编码的情况下,以最大化系统能效的下界为准则,同时考虑每个用户的最低速率要求,通过调整带宽分配、功率分配和基站天线数分配来优化能效函数。首先根据优化条件提出了一种迭代算法确定每个用户的带宽分配,然后利用分数规划的性质并采用凸优化方法,通过联合调整基站端的发射天线数和用户的发射功率来优化能效函数。仿真结果表明,所提算法在较少迭代次数的同时能够取得较好的系统能效性能和吞吐量性能。     

Terminal battery status information based fairness-aware SWIPT strategy

To solve the battery depletion problem,the terminals’ battery status information (BSI) was proposed to be taken into consideration in simultaneous wireless information and power transfer (SWIPT) strategies,and a SWIPT strategy to guarantee the rate fairness was provided.BSI determined the terminals’ sufferable received rate and harvested energy.The proposed scheme was formulated as an optimization problem to max-min user rate,with rate/energy requirement constraints and the sufferable rate/energy constraints.To solve optimization problem,the receivers were firstly classified with their battery level,then the optimal solutions were obtained by the proposed iteration optimization-based algorithm.With the proposed scheme,the transmit power and the power splitting factor would be controlled and the data rate at receivers,especially the receivers that with lower battery level would be restricted,avoiding the required battery consumption to exceed battery level.Simulation results reveal that the proposed scheme can prolong battery lifetime and avoid the battery depletion problem,and its fairness performance is strengthened with the difference decreasing among the receivers’ battery level.     

双智能反射平面辅助无线携能通信系统的安全通信优化

研究采用两个智能反射平面保障无线携能通信系统信息传输的物理层安全。通过联合优化两个智能反射平面的反射波束成形和基站的发射波束成形以最大化系统的总信息传输速率,同时满足基站的发射功率约束、能量收集用户的最小能量收集约束与最大窃听速率约束,以及智能反射平面反射系数的模一约束。由于存在两个智能反射平面之间的反射链路,所构建优化问题的优化变量高度耦合,难以直接求解。提出一种基于交替优化、半正定松弛和连续凸逼近的算法求问题的次优解。仿真结果表明,与现有的基准方案相比,所提算法能在保证信息传输安全和满足能量传输要求的情况下大幅提高系统的总数据速率。     

单小区多用户下行OFDM系统资源分配算法研究

多用户正交频分复用(OFDM)系统中,充分利用多载波系统的多用户分集进行合理无线资源分配,能够显著提高系统容量和最大限度提高频谱利用率。经过广泛的研究,很多有效资源分配算法已经被提出来。重点讨论了单小区多用户OFDM系统关于子载波、比特及功率等无线资源的分配问题,介绍现有的研究成果,包括常见的模型及求解方法,并介绍近期的研究热点,包括多小区系统、多入多出(MIMO)系统等。     

Joint subcarrier and power allocation for uplink relay‐enhanced OFDM systems

There has been a lot of research works considering the resource allocation of the downlink multihop orthogonal frequency division multiplexing systems. However, due to the distributed nature of the uplink power constraints, the resource allocation in the uplink multihop systems, where multiple mobile stations transmit to one base station with the aid of one or many relay stations, has much difference and has not been well investigated so far. In this paper, we originally study the joint subcarrier and power allocation problem for the uplink dual‐hop transmission with the aim to maximize the system transmit rate. The resource allocation problem is approximated to be a concave maximization problem. By using mathematical decomposition techniques, the problem is first decoupled and solved by the proposed near‐optimal method, which has low‐computation complexity. Then, our algorithm is extended to the case with subcarrier matching on the dual hops. Numerical results show that our proposed algorithm improves the system transmission rate. Compared with the equal power allocation schemes, our algorithm can achieve significant gain in system transmit rate. Copyright © 2010 John Wiley & Sons, Ltd.     

Energy efficiency maximization resource allocation algorithm in wireless-powered backscatter communication network

In order to alleviate the energy consumption problem caused by the increasing number of Internet of things (IoT) nodes,an energy-efficient (EE) maximization based resource allocation algorithm was proposed for multi-carrier wireless-powered backscatter communication network.Firstly,a multivariable and nonlinear resource allocation model was formulated to jointly optimize transmit power,transmission time,reflection coefficient,and energy-harvesting allocation coefficient,where the maximum transmit power constraint of the power station and the minimum harvested energy constraint at the backscatter device were considered.Then,the original non-convex optimization problem was transformed into a convex one which was solved by using Dinkelbach’s method and the variable substitution approach.Furthermore,the analytical solution of the resource allocation problem was obtained based on Lagrange dual theory.Simulation results verify that the proposed algorithm has better EE by comparing it with the existing algorithm under pure backscatter mode and algorithm under the harvested-then-transmit mode.     

Rate adaptive resource allocation for OFDM downlink transmission

In this paper, we present a multiuser rate adaptive resource allocation for OFDM downlink transmission. This new algorithm assign one bit at a time to user that has the minimum total power in the subcarrier that requires the least additional power. Simulation results show that the proposed algorithm achieves a higher capacity than previous existing algorithms and distributed the overall capacity more fairly among users.     

全双工信息与能量同传系统的鲁棒性预编码及高能效时隙分配方案

最近全双工信息与能量同传系统（FD-SWIPT）受到高度重视,区别于现有研究,本文在最大化多天线FD-SWIPT系统的和速率的同时,考虑了其鲁棒性和能量效率,并提出了一种FD-SWIPT系统的鲁棒性预编码及高能效时隙分配方案.由于优化涉及的因素很多,这是一个多个变量的非凸优化问题,在数学上很难求解.首先,为减少全双工系统中自干扰对和速率造成的影响,基于奇异值分解及最小均方误差算法对系统自干扰进行消除;然后,固定时隙分配因子,在自干扰信道存在估计误差的情况下,基于一阶泰勒凸逼近对原优化问题进行鲁棒预编码设计,并给出相应的迭代算法;进一步,提出了不同约束条件下的时隙分配方案,并推导了不同方案下的时隙分配因子的最优解.最后,通过仿真实验与现有结果比较,验证了本文方案的性能优势.     

Fairness based resource allocation for uplink OFDMA systems

This article investigates two fairness criteria with regard to adaptive resource allocation for uplink orthogonal frequency division multiple access （OFDMA） systems. Nash bargaining solution （NBS） fairness and proportional fairness （PF） are two suitable candidates for fairness consideration, and both can provide attractive trade-offs between total throughput and each user＇s capacity. Utilizing Karush-Kuhn- Tucker （KKT） condition and iterative method, two effective algorithms are designed, to achieve NBS fairness and proportional fairness, respectively. Simulation results show that the proposed resource allocation algorithms achieve good tradeoff between the overall rate and fairness, with little performance loss from the total capacity.     

Secure resource allocation in hybrid energy-harvesting relay and full-duplex receiver

Taking into account the wireless physical layer security in energy-constrained relaying systems,a secure resource allocation scheme was proposed under simultaneous wireless information and power transfer (SWIPT) protocol.The utility optimization problem was considered aiming to maximize the secrecy rate by jointly optimizing the power splitting (PS) ratio and the transmit powers under the constraint of the transmit powers of the nodes and the harvested energy of the relay.The objective problem,which is non-convex,was decoupled into two subproblems.One was to optimize the PS ratio,another was to optimize the transmit powers.The optimal solution of the subproblems can be obtained in the closed-form.Then,the suboptimal solution is obtained with the proposed convergent iterative algorithm.Simulation results show the effects of artificial noise signal,residual self-interference signal,transmit power of nodes,amplification factor of relay and other factors on the security performance.Compared with the traditional gradient descent algorithm,the proposed algorithm can reduce more than 80% of the computational load,while the algorithm has the slightly better performance.     

AF中继下行链路系统的能效资源分配方案

为最大化放大转发中继系统的下行链路总能效,结合系统的电路功率,提出了一种基于能效的中继选择和功率分配联合方案.为降低复杂度,采用分步式次优化方案,利用虚拟直传信道增益得到中继选择方法,并将中继系统转换为单跳系统;然后利用凸规划得到最优功率分配.此外,为适应不同的用户分布,提出联合小区呼吸机制的分配方案.仿真结果表明,所提次优联合方案逼近最优值,联合小区呼吸的方案可适应不同的用户分布并进一步提升能效.     

System utility based resource allocation for multi-cell OFDM system

Utility based resource allocation strategy in multi-cell orthogonal frequency-division multiplexing (OFDM) system plays a critical role in next generation mobile communication systems. Based on the analysis of risk aversion utility functions, this article proposed the system utility based utility, which is named the customer satisfaction (CS) utility. Compared with the proportional fairness (PF) utility, the CS utility reflects the user demands better, and enables the system to adjust its resource allocation according to both the traffic requirements and the resource situation.     

认知无线携能通信的关键技术及其研究进展

认知无线电（CR）与无线携能通信（SWIPT）的结合已经成为当今高能效认知无线通信的研究热点之一。首先阐述了SWIPT与认知SWIPT网络,而后介绍了SWIPT网络中两种接收机结构并给出相应的能量收集公式。然后,给出了认知SWIPT系统模型及其与协作中继技术、MIMO技术相结合进行系统建模的研究进展,并对认知SWIPT网络关键技术的未来研究方向进行了展望。最后,总结了近年来对认知SWIPT网络关键技术的研究成果,为高能效的安全认知SWIPT通信理论研究与未来应用提供了一定的借鉴意义。     

Coalition-based downlink resource allocation for LTE system with divide-and-conquer approach

To take advantage of the multiuser diversity resulted from the variation in channel conditions among the users,it has become an interesting and challenging problem to efficiently allocate the resources such as subcarriers,bits,and power.Most of current research concentrates on solving the resource-allocation problem for all users together in a centralized way,which brings about high computational complexity and makes it impractical for real system.Therefore,a coalitional game framework for downlink multi-user resource allocation in long term evolution(LTE) system is proposed,based on the divide-and-conquer idea.The goal is to maximize the overall system data rate under the constraints of each user’s minimal rate requirement and maximal transmit power of base station while considering the fairness among users.In this framework,a coalitional formation algorithm is proposed to achieve optimal coalition formation and a two-user bargaining algorithm is designed to bargain channel assignment between two users.The total computational complexity is greatly reduced in comparison with conventional methods.The simulation results show that the proposed algorithms acquire a good tradeoff between the overall system throughout and fairness,compared to maximal rate and max-min schemes.     

多载波多用户下行NOMA系统的资源分配算法

非正交多址接入技术作为5G的候选技术之一受到了广泛关注。研究了以系统吞吐量优化为目标的多载波多用户NOMA系统下行链路的资源分配问题。在该问题的求解中,为了提高系统的吞吐量,子载波间采用线性注水算法,叠加用户间采用分数阶功率分配算法。同时,考虑了远近用户数目不等场景下能够调度更多的用户,在NOMA传输方案设计中引入时分的概念,将整个时间段t分为两个时隙,在不同时隙内实现不同远近用户分组的动态配对方案,从而在保证用户公平性的基础上,充分利用子信道资源,实现系统吞吐量的优化。仿真结果表明,对比于传统NOMA和OFDMA,提出的方法可以在相同的发射功率情况下传输更多的比特数。     

基于QoS保证的多用户OFDM系统跨层资源分配

针对正交频分复用(OFDM)系统资源分配和调度问题,提出一种基于第三代移动通信长期演进(LTE)系统的分块跨层资源分配算法。此算法考虑物理层的信道状态信息、媒体接入层(MAC)的有限用户缓存队列长度、用户的丢失率和时延等QoS要求,以提高系统频谱效率为总体目标。通过从实时视频业务和混合业务两种业务类型下进行大量对比分析,得出提出的算法能有效提高系统的频谱效率和降低系统时延。     

Energy-efficient resource allocation scheme for device-to-device communication underlaying LTE-A uplink

To cope with the co-channel interference between cellular links and device-to-device (D2D) links concurrently transmitting with the long term evolution-advanced (LTE-A) uplink spectrum,a joint resource allocation scheme was pro-posed to maximize the global energy efficiency of D2D links.The above problem can be decomposed into the power control subproblem and the channel assignment subproblem.Specifically,the power control subproblem can be optimally solved with the help of Dinkelbach method and Lagrange duality.Based on the above results,the channel assignment subproblem turns out to be the set packing problem which was generally NP-hard problem,Therefore,a heuristic algo-rithm was further devised to achieve a tradeoff between performance and complexity.Simulations show that the proposed joint resource allocation scheme outperforms the ones where only single resource variable is optimized,and it achieves the polynomial-time complexity at only minor performance loss when compared to the global optimum.     

基于IRS辅助的SWIPT物联网系统安全波束成形设计

为满足绿色万物互联的智能信号处理部署和物理层安全的新要求,针对基于智能反射面辅助的无线携能通信物联网系统中可持续能量供应紧缺问题,提出了一种安全波束成形设计方法.考虑保密速率、发射功率和IRS反射相移约束,以最大化能量采集器采集功率为目标,联合优化基站发射波束成形矩阵和干扰机协方差矩阵以及IRS相移,将优化问题建模为具...     

IRS辅助的SWIPT系统中基于能效优先的波束成形设计与优化

以智能反射面(intelligent reflecting surface,IRS)辅助的无线携能通信(simultaneous wireless information and power transfer,SWIPT)系统为背景,研究了该系统中基于能效优先的多天线发送端有源波束成形与IRS无源波束成形联合设计与优化方法。以最大化接收端的最小能效为优化目标,构造在发送端功率、接收端能量阈值、IRS相移等多约束下的非线性优化问题,用交替方向乘子法(alternating direction method of multipliers,ADMM)求解。采用Dinkelbach算法转化目标函数,通过奇异值分解(singular value decomposition,SVD)和半定松弛(semi-definite relaxation,SDR)得到发送端有源波束成形向量。采用SDR得到IRS相移矩阵与反射波束成形向量。结果表明,该系统显著降低了系统能量收集(energy harvesting,EH)接收端的能量阈值。当系统总电路功耗为−15 dBm时,所提方案的用户能效为300 KB/J。当IRS反射阵源数与发送天线数均为最大值时,系统可达最大能效。