密集异构网络中基于多目标优化的资源分配策略

密集异构网络(Dense Heterogeneous Network, DHN)通过部署小基站可以提升网络容量和用户速率,但小基站的密集部署会产生巨大的能耗和严重的干扰,进而影响系统的能量效率(Energy Efficiency, EE)和频谱效率(Spectral Efficiency, SE)。在保证用户服务质量(Quality of Service, QoS)需求的前提下,为了联合优化系统的能量效率和频谱效率,研究了密集异构网络中下行链路的资源分配(Resource Allocation, RA)问题。首先,将频谱和小基站发射功率分配问题建模为联合优化系统能量效率和频谱效率的多目标优化问题;其次,提出了基于单策略多目标强化学习(Single-strategy Multi-objective Reinforcement Learning, SMRL)的资源分配算法求解所建立的多目标优化问题。仿真结果表明,与基于单目标强化学习的资源分配算法相比,所提算法可以实现系统能量效率和频谱效率的联合优化,与基于群体智能算法的资源分配算法相比,所提算法的系统能量效率提高了1%～1.5%,频谱效率...     

认知异构网络中基于克隆选择算法的动态频谱分配

建立了认知异构无线网络的系统模型。基于该模型,以网络效益最大化为目标,考虑接入网的频谱需求,接入网之间的干扰和对应异构网络不同接入技术的多粒度重叠信道之间的干扰约束条件,将频谱资源分配建模为非线性约束0-1整数规划问题,进而提出基于克隆选择的认知异构网络中动态频谱分配算法,并在该算法中设计了一种新的能够同时考虑接入网频谱需求和多粒度信道频谱资源的抗体整数编码方式。仿真结果表明,所提算法相比于贪婪分配算法,增加了网络效益,提高了频谱使用效率。     

基于集中式接入网架构的异构无线网络资源管理技术研究

未来无线通信网络将是一个多种无线接入方式共存的异构网络,如何实现异构网络在频谱、软硬件资源等方面的融合是一个亟需解决的问题.现有方案受限于不同网络独立部署的架构,无法真正实现异构网络资源的融合.针对该问题,提出了一种新型的基于集中式接入网架构的异构网络融合平台,可以在集中式资源池基础上进行异构网络间处理资源及无线资源的共享与统一管理.基于该平台,进一步阐述了异构网络资源管理的关键技术,包括基站资源虚拟化、处理资源按需分配、动态频谱共享、网络覆盖优化及性能分析验证方法等,为未来异构网络融合研究提供了一种可行的方案.     

一种基于能量感知的弹性光网络RSA算法

弹性光网络具有高频谱效率和灵活性等优点,是光网络发展的主要方向。路由和频谱分配是弹性光网络的核心技术之一。文章提出了一种改进的基于能量感知的弹性光网络RSA(路由和频谱分配)算法,在进行选路和频谱分配时,同时考虑了网络中的能耗和可用频谱资源情况。理论分析和仿真结果表明,与传统RSA算法相比,改进算法可以提高能量效率,降低业务阻塞率。     

深度学习支持下的无线异构网络中继决策分析

在无线异构网络中,中继节点的智能化决策直接影响网络的频谱效率、能量效率以及服务质量。针对无线异构网络的中继决策问题,文章提出一种基于深度Q网络的强化学习方法,概述了无线异构网络的组成及中继节点的作用,介绍了深度Q网络算法的优势及网络结构,定义了无线网络环境的状态空间、动作空间和奖励函数,构建了端到端的深度Q网络决策模型,最后通过仿真实验验证了文章所提方法的有效性。     

新一代超密集异构蜂窝无线网络研究

近年来,随着移动互联网的蓬勃发展和智能终端的快速普及,对无缝网络覆盖和高速数据传输要求日趋增强,超密集异构蜂窝无线网络通过减小小区半径,增加低功率节点数量进行超密集组网,提高无线资源利用率和频谱效率,因而引起了国内外研究学者的广泛关注。然而,超密集异构蜂窝无线网络中愈发密集的网络部署也带来了各种严峻的问题,包括超密集异构蜂窝无线网络中的系统干扰问题、无线信息的安全传输问题、以及网络运营的能量供给问题等。为此,本文首先简单介绍了超密集异构蜂窝无线网络架构,接着从干扰管理、物理层安全和能量效率等方面,深入分析了超密集异构蜂窝无线网络中的关键技术和当前挑战,最后,进一步展望了超密集异构蜂窝无线网络的未来发展。      

Massive MIMO异构网的高能效资源分配

为满足第五代移动通信系统高频谱效率和高能量效率的需求,提出一种工作在不同频段下行两层异构网中的高能量效率资源分配方法,考虑用户数据率需求和基站最大发射功率。天线和传输带宽是影响系统能量效率的关键因素。通过研究宏基站和小基站的天线资源和带宽分配发现:当系统天线数很大时,发射功耗的影响可以忽略不计;给定带宽分配因子时,达到宏基站或微基站最大发射功率的天线分配因子几乎可以达到最高能效;给定天线分配因子时,系统平均总功耗是关于带宽分配因子的下凸函数,存在全局最优带宽分配因子使能效最高。仿真结果表明,与给定带宽和天线资源的异构网和小小区网络相比,所提出的异构网可以显著提高系统能量效率,而且在大量用户、高数据率需求时能效提升更明显。      

LTE—A中协同多点传输的联合处理预编码方法

协同多点传输（CoMP）是围绕LTE—A的目标而提出的通过基站内不同远程射频单元（RRU）协作、基站和其所属中继协作和基站间协作等多种多点协作方式,减小小区边缘干扰、提高小区边缘频谱效率、增加有效覆盖的技术措施。CoMP中的联合处理技术（JP）对系统性能的提升最大,JP对性能提升的主要途径是基于信道信息的预编码技术。在不同的CoMP场景下,各种预编码方式各有优劣。越来越多的研究更集中于从压缩反馈量和优化码本设计两个角度来实现预编码的优化。     

非理想因素下的CoMP性能分析与仿真

多点协作（CoMP）能够有效改善小区边缘频谱效率,因而成为3G长期演进中高级演进（LTE-A）研究中的热点课题。为了研究存在信道状态指示参考信号（CSI-RS）估计误差和反馈时延情况下的CoMP的性能,对CSI-RS信道估计误差和时延特性进行了相应的分析,并在这些非理想因素下通过仿真对CoMP进行了性能评估,其结论是：即使考虑非理想因素的影响,CoMP技术仍然能够在很多实际场景中提高系统性能,因此,该技术在未来移动通信的研究中具有重要意义。     

LTE-Advanced中协作多点传输技术研究

为了提高小区边缘用户的性能,满足小区边缘频谱效率的要求,LTE-Advanced系统中引入了协作多点传输技术CoMP（Coordinated Multi-Point）。CoMP技术是一种干扰消除技术,通过小区间的联合调度和协作传输,使小区边缘的CoMP用户的干扰信号变为有用信号,或降低来自邻小区的干扰水平,从而提高小区边缘吞吐量,并且增强系统性能。文章主要介绍了协作多点传输技术及其原理,对CoMP技术中的协作簇选择、CoMP用户划分、用户传输方案及预编码做出了介绍,通过仿真对比得到采用CoMP技术的系统性能增益,最后对协作多点传输技术作出了展望。     

HetNet中基于上行CoMP的动态多小区接入算法

提出了HetNet中基于上行CoMP的动态多小区接入算法(UCDS),动态选择协作基站,利用CoMP机制,改善小区边缘用户的上行传输性能。进一步地,提出了基于二次判决的协作小区选择算法(DJCS),以减少参与协作的基站数,降低协作复杂度并节省基站端资源。仿真结果表明,UCDS算法能显著提高边缘用户的平均吞吐率和传输能效,而DJCS算法在保证用户性能的情况下,降低了基站端的能耗。     

协作多点蜂窝系统中的干扰协调方案研究

在协作多点(CoMP)蜂窝系统中,为了有效利用无线频谱资源,需要设计相应的分布式干扰协调机制.首先,利用相邻小区间接口交换信息的能力,设计了一种分布式的无线资源分配冲突检测与仲裁算法.接下来,针对协作多点蜂窝系统具体场景,应用所提出冲突仲裁算法,设计了包括三个步骤的分布式干扰协调方案.仿真结果表明,设计方案能够分布式地...     

A green scheduling with adaptive spatial division multiple access grouping for multi‐user coordinated multi‐point networks

Multi‐User Coordinated Multi‐Point (MU‐CoMP), which couples CoMP with Multi User‐Multiple Input Multiple Output (MU‐MIMO), appears as a promising solution to enhance the Long Term Evolution‐Advanced (LTE‐A) system performance. However, some challenging issues in MU‐CoMP networks require more investigation. First, the set of users transmitting under CoMP mode should be properly identified. Secondly, time‐frequency resource should be efficiently partitioned between CoMP and non‐CoMP users in order to improve the system radio capacity. Thirdly, a fair and green scheduler is much needed for a more energy efficient system. This paper deals with these three issues. We propose an adaptive transmission mode selection according to the total load in the cluster and to users' quality of service. The adequate size of the Spatial Division Multiple Access users' groups is also analyzed. We finally propose a new scheduling algorithm to further enhance the radio capacity and the energy consumption in the cluster. Simulations results showed that significant improvements are obtained in terms of total system throughput and outage probability in the cluster with our proposed scheme. Moreover, energy efficiency has increased by four times with our proposed scheduling algorithm as compared to commonly used schedulers. Copyright © 2015 John Wiley & Sons, Ltd.     

Cognitive radio network with coordinated multipoint joint transmission

Cognitive radio (CR) is considered to be a promising technology for future wireless networks to make opportunistic utilization of the unused or underused licensed spectrum. Meanwhile, coordinated multipoint joint transmission (CoMP JT) is another promising technique to improve the performance of cellular networks. In this paper, we propose a CR system with CoMP JT technique. We develop an analytical model of the received signal‐to‐noise ratio at a CR to determine the energy detection threshold and the minimum number of required samples for energy detection–based spectrum sensing in a CR network (CRN) with CoMP JT technique. The performance of energy detection–based spectrum sensing under the developed analytical model is evaluated by simulation and found to be reliable. We formulate an optimization problem for a CRN with CoMP JT technique to configure the channel allocation and user scheduling for maximizing the minimum throughput of the users. The problem is found to be a complex mixed integer linear programming. We solve the problem using an optimization tool for several CRN instances by limiting the number of slots in frames. Further, we propose a heuristic‐based simple channel allocation and user scheduling algorithm to maximize the minimum throughput of the users in CRNs with CoMP JT technique. The proposed algorithm is evaluated via simulation and found to be very efficient.     

Energy‐efficient cluster division for multi‐cell joint transmission technology

Coordinated Multi‐Point (CoMP) is an effective way to improve user performance in next‐generation wireless cellular networks, such as 3GPP LTE‐Advanced(LTE‐A). The base station cooperation can reduce interference, and increase the signal to interference and noise ratio (SINR) of cell‐edge users and improve the system capacity. However, the base station cooperation also adds additional power consumption for signal processing and sharing information through back‐haul links between cooperative base stations. As such, CoMP may potentially consume more energy. This paper studies such energy consumption issue in CoMP, presents a semi‐dynamic CoMP cluster division algorithm based on energy efficiency (SCCD‐EE) that can effectively adapt to users' real‐time interference, and employs the idea of Maximal Independent Set (MIS) to solve the problem of cluster overlapping. To verify the feasibility of the proposed algorithm, this paper performs comprehensive evaluations in terms of energy efficiency and system capacity. The simulation results show that the proposed semi‐dynamic cluster division algorithm can not only improve the system capacity and the quality of service (QoS) of cell‐edge users, but also achieve higher network energy efficiency compared with static cluster methods and Non‐CoMP approaches. Copyright © 2016 John Wiley & Sons, Ltd.     

无线网络呼叫接纳控制算法的研究

呼叫接纳控制（CAC,Call Admission Control）是无线网络中无线资源管理（RRM,Radio Resource Man．agement）的重要组成部分,是保证用户服务质量（QoS,Quality of Server）和提高系统资源利用效率的重要手段。简要介绍了无线网络资源管理基本模型及CAC目标,重点分析了无线网络中典型CAC算法,最后对CAC算法进一步研究方向进行了展望,这对于无线网络的实际部署与应用具有重要的实际意义。     

Spectrum efficiency sub-carrier and energy efficiency power allocation for downlink multi-user CoMP in multi-cell system

Coordinated multi-point transmission/reception （CoMP） was proposed currently as an effective technology to improve cell-edge throughput in next-generation wireless systems. Most of the existing work discussed clustering methods mostly to maximize the edge user throughput while neglecting the problem of energy efficiency, such as those algorithm clustering base stations （BSs） of better channel condition and BSs of worse channel condition together. In addition, BSs usually increase the transmit power to achieve higher throughput without any considering of interference caused to other users, that may result in energy waste. The authors focus on the throughput maximizing problem while fully considering energy saving problem in CoMP systems. A coefficient is defined to describe the fitness of clusters. Then a sub-carrier allocation algorithm with clustering method is put forward for CoMP downlink, which can save the transmit power of BS and increase the throughput. Furthermore a power allocation scheme is proposed based on non-cooperation game; in which the transmit power is decreased by BSs generally to reach the Nash equation （NE）. Simulation shows that the proposed sub-carrier allocation scheme and power allocation algorithm are better than the existing ones on users＇ throughput while consumes much less energy.     

Downlink energy efficiency modeling and optimization with backhaul awareness and interference price in ultra cellular HetNet

The cellular heterogeneous network(HetNet) with ultra dense small cells is called ultra cellular HetNet.The energy efficiency for this network is very important for future green wireless communications.The data rates and power consumptions for three parts(i.e.,macro cells,small cells,and mixed backhaul links) in ultra cellular HetNet are jointly formulated to model downlink energy efficiency considering the active base stations(BSs) and inactive BSs.Then,in order to decrease the downlink co-channel interference,the interference price functions are also jointly set up for the three parts in ultra cellular HetNet.Next,energy efficiency optimization iterative algorithm scheme using the fractional programming and Lagrangian multiplier with constraints for density of ultra dense small cells and fraction of mixed backhaul links is presented with interference pricing.The convergence and computation complexity are also proved in this scheme.The numerical simulations finally demonstrate convergence behavior of the proposed algorithm.By comparison,some conclusion can be drawn.Maximizing energy efficiency of system is lower as the density of small cell is high.The effect on maximizing energy efficiency with interference price outperforms that without interference price.And the energy efficiency increases as the fraction of mixed backhaul links is higher because of more power consumption in the microwave backhaul links.     

Energy-efficient multiple cooperative moving relay selection for heterogeneous nonorthogonal-multiple access systems

In a high-speed vehicular scenario, due to vehicle penetration loss (VPL) and fast signal fluctuations, frequent handovers occur, which results in more battery consumption. So power saving is a critical concern in high-speed wireless networks. In the past, moving relay (MR)-based heterogeneous network (HetNet) models were proposed and studied to overcome the effect of VPL, but the issue of power saving has not been studied till now for vehicular HetNet. In this paper, we propose an energy-efficient algorithm that selects the best number of cooperative MRs among multiple MRs installed on the top of the train for efficient utilization of transmission power in a NOMA-based wireless network. A half-duplex amplify-and-forward relaying protocol is used for the investigation. We define the optimization problem of energy efficiency for cooperative MR. The problem of energy maximization is stated as an optimization problem, and an energy-efficient MR selection algorithm is proposed as the solution to the optimization problem. The simulation results show that the proposed algorithm enhances the energy efficiency of vehicular and nonvehicular users and it also decreases the outage probability at fixed spectral efficiency in comparison with the fixed MR-based selection combining and maximum ratio combining diversity techniques. This result will be beneficial in vehicular communication to achieve maximum energy efficiency.     

C-RAN网络中CoMP性能分析与优化

针对无线通信中的能耗巨大和移动用户潮汐现象带来的基站利用率低下问题,C-RAN作为一种基于集中化处理、协作式无线电和实时云计算架构的无线接入网架构,是一种低成本、高性能的解决方案。针对C-RAN网络中的CoMP性能,通过计算无线链路损耗分析了JT下的CoMP的理论增益。针对C-RAN网络规划设计问题,定性分析了CoMP增益与C-RAN网络Cell数的比例关系,最后结合仿真结果给出了合理的网络规划设计建议,且理论证明其能够很好地解决移动运营商所面临的上述挑战。