基于免疫计算的TD-SCDMA网络基站选址优化

为了降低TD-SCDMA网络基站建设代价,给出了一种基于免疫计算的基站选址优化方案。介绍了TD-SCDMA基站建设的困难及基站选址原则,设计了基于实数编码的克隆增殖算子、克隆变异算子及克隆选择算子,给出了求解基站选址优化问题的免疫记忆克隆算法框架,并与文献中的算法进行了对比实验。实验结果表明,该算法获得的基站部署方案能以相对较低的基站建设总代价获得较高的网络覆盖率,具有较好的应用价值。     

基于多点协作联合传输的超密集组网性能分析

超密集组网的基站高密度特性会带来严重的小区间干扰,多点协作联合传输应用于超密集组网进行干扰管理是目前的研究热点,该文对多点协作联合传输时基站密度对网络性能的影响进行了分析。首先采用随机几何方法推导了3维空间基站与用户距离的概率密度函数,为选取距离用户最近的多个基站联合传输的协作机制提供了基础;然后结合有界双斜率路径损耗模型,进行用户下行链路的干扰建模,进一步推导出用户下行链路覆盖率和网络区域频谱效率的表达式,并分析了协作基站数、基站密度等参数对网络性能的影响。数值仿真表明:协作基站数为2时就可使下行链路覆盖率增加10%,且实现2到3倍的频谱效率的增益,当协作基站数为3时,费效比更优,同时可得到多点协作下的基站密度极限使区域频谱效率最高。该文工作可为下一代移动通信网络的基站部署提供理论支持。     

基于免疫算法的 TD-SCDMA 网络基站选址优化

针对已有3G基站选址优化算法的不足和TD-SCDMA网络的特点,提出了一种基于免疫算法的TD-SCDMA网络基站选址优化方案。建立了基站选址问题的数学模型,设计了基于反学习的种群初始化方案和精英交叉策略,给出了免疫优化算法框架。实验结果表明,该算法不仅能够以较小的建站代价获得较高的网络覆盖率,而且算法具有较好的收敛性。     

联合传输机制下的三维超密集网络性能分析

超密集网络（Ultra-dense Networks,UDN）作为一项新兴技术，通过密集部署微基站大幅提升了网络容量，近年来受到了广泛关注。但随着二维平面基站数量逐渐饱和，基站部署逐渐向三维（3D）立体化发展。因此，针对中央商务区（Central Business District,CBD）等未来移动通信典型应用场景，基于随机几何理论对写字楼中基站与用户的分布进行建模与分析。该场景下，考虑到实际部署情况，用户只会接收到其上方基站的信号，而忽略低楼层基站的影响。针对这一特点，基于联合传输（Joint Transmission,JT）方案的覆盖性能，推导出用户的覆盖率和遍历容量解析表达式。结果表明，覆盖率和遍历容量都随协作簇的变大而增加，收益呈递减状态。     

莱斯信道下分布式大规模MIMO系统基站选择算法的研究

该文考虑一种分布式大规模MIMO系统,假设基站端与用户之间的信道为莱斯信道,研究了该系统中基站选择的算法。首先给出了系统采用匹配滤波和迫零预编码时,用户下行可达速率的闭式表达式,并分析了系统的功率效率性能。然后基于此闭式表达式,以最大化系统的频谱效率为目标,提出了基于增量选择和基于用户优先级的基站选择算法。这两种算法只需要系统获取基站端与用户之间的信道统计特征信息,从而有效降低了系统开销。仿真结果表明,所提出的两种基站选择算法性能仍能逼近最优算法。特别地,当采用匹配滤波预编码且基站端天线数趋于无穷时,基于用户优先级的基站选择算法优于基于增量选择的算法。     

高密度小基站网络中混频自部署技术与网络容量分析

基于在密集小基站层叠网络中小基站网络混频自部署方案及关键技术,通过理论分析和数学推导相结合,研究了影响密集小基站层叠网络下行容量的关键因素,并探讨了混频部署方式对网络容量增益的影响。仿真结果和数据分析验证了所提出高密度小基站混频自部署技术对网络容量提升的有效性。     

WCDMA系统基站导频功率的联合优化

优化基站导频功率对提高WCDMA系统的网络服务性能具有重要意义,为了解决WCDMA网络基站导频功率联合分配问题,给出了一个基于免疫优化算法的基站导频功率优化方案。设计了基站导频功率分配问题的数学模型,并利用免疫优化算法进行求解,最后与文献算法进行了对比实验。实验结果表明:本文算法方案能在可接受的运行时间内找到大型通信网络中导频功率分配问题的近似最优解,具有较好的应用价值。      

5G超密集网络环境下功率控制方案研究

超密集网络(Ultra Dense Network,UDN)是一种通过密集化地部署各种低功率小基站来提升系统容量的技术,因可以解决小区覆盖盲区、实现用户无缝连接、缓解宏基站压力以及配置灵活等优点被列为未来5G通信系统的关键技术之一。在密集基站的网络部署下,基站与终端的路径损耗有所降低,在增大有益信号的同时也提升了干扰信号,影响通信系统的性能和用户终端的服务质量。为提升用户的服务质量和降低系统损耗,提出了一种跨层功率最大化方案,选取发射功率最强的小基站作为服务基站。提出一种协作功率最大化控制方案,选取2个小基站为用户提供协作式数据传输服务。仿真结果表明,2种方案均能提升用户的服务质量,后者在能效等指标上要优于前者。     

基于量子遗传算法的无线视频传感网络优化覆盖算法

针对智慧城市无线视频传感网络建设需要,提出一种基于量子遗传算法的网络优化覆盖算法。算法面向复杂的监视区场景,监视区中存在形状各异的障碍物,各区域的重要程度不同。以二维离散网格模型描述监视区场景,用编码描述矩阵表示监视区域,用七元组描述有向无线视频传感器。通过严格的数学推导得出了问题的数学规划模型。优化覆盖算法由IntialDeployment算法和OptimizedDeployment算法2部分组成,以获得最大有效覆盖率的网络部署方案为求解目标。采用量子遗传算法搜索解空间,通过合理编码染色体,优化量子旋转门参数,使算法的运算速度快,收敛性好。引入理想覆盖率和理想加权覆盖率2个极限值,采用相对比较法评判算法优劣。仿真实验和数据分析表明,算法获得的方案能很好地逼近理想极限值。在传感器节点数给定的情况下,算法能获得最大的覆盖率。     

多波束小基站协作通信的资源分配和位置规划

针对小基站加载多波束阵列天线后协作提供通信覆盖的资源分配与位置规划问题,建立了以最小化基站总功耗以及基站间负载均衡为目标函数的多目标混合整数非凸优化模型;给出了一种迭代优化算法,将问题分为用户关联、功率分配和位置部署3个子问题,在固定基站位置和波束功率下通过改进的鲸鱼算法求解出用户与波束的关联关系,在此基础上利用连续凸逼近法和改进差分进化算法交替优化功率分配和基站位置部署。数值仿真表明,多波束小基站与所提迭代算法可灵活适应复杂业务需求分布,降低网络功耗和均衡基站间负载。可为小基站加载阵列天线增强通信覆盖提供参考。     

Compound event barrier coverage in wireless sensor network

In wireless sensor networks (WSN),more and more people utilize barrier coverage to monitor compound events.The data of compound event barrier coverage (CEBC) comes from different types of sensors.It will be subject to multi-constraints under complex conditions in real-world application.Aiming at the merging problem of compound event confidence,a computational model based on joint probability density was proposed.In order to solve the optimization problem of compound event barrier coverage under multiple complex constraints,an active set multiplier policy (ASMP) was proposed.The algorithm can calculate the coverage ratio efficiently and allocate the sensor resources reasonably in compound event barrier coverage.The algorithm can simplify complex problems to reduce the computational load of the network and improve the efficiency of the network.The simulation results demonstrate that the ASMP algorithm is more efficient in the allocation of sensor resources and network optimization.     

Joint admission control algorithm based on load transfer in heterogeneous networks

A load-transfer-based joint admission control (LJAC) algorithm in heterogeneous networks was proposed.The access requirements of users were admitted based on load balancing,the dynamic load transfer of traffics in the overlapping coverage areas of heterogeneous networks were introduced,and the influence of such factors as the layout of heterogeneous networks and the vertical handoff was considered in the algorithm.The integrated system of heterogeneous networks was modeled as a multidimensional Markov chain,the steady-state probabilities were obtained and the quality of service (QoS) performance metrics were derived.Based on the Poisson point process theory,the upper bound of capacity of the heterogeneous networks satisfying QoS limitations was obtained.The admission control parameters of the integrated system of heterogeneous networks were optimized in order to maximize the resource utilization rate as well as guaranteeing the QoS of users.The simulation results demonstrate lower traffic blocking probability,lower failure probability of vertical handoff requirements,and larger system capacity gain can be achieved by using the proposed LJAC algorithm.     

Analysis of coverage probability in NOMA-HetNet based on Matern cluster process

Considering the correlation between the users and base stations and the network irregularity,the non-orthogonal multiple access heterogeneous networks (NOMA-HetNet) based on Matern cluster process (MCP) was modeled.The coverage probability of UEs was analyzed.Firstly,the signal-to-interference-plus-noise ratios (SINR) of UEs were theoretically derived.Secondly,an updating law for the upper limit of SINR was presented for the imperfect serial interference elimination (SIC) scheme,which was more consistent with the reality.Then,using the mathematical tools such as spatial coordinate system,probability theory,stochastic geometry theory and order statistics,the correlation probability and service distances of the different types of UEs were analyzed.Finally,the theoretical expression of the coverage probability of UEs was derived.The effects of cluster radius,base station density,interference residual factors on service distances,and coverage probability are verified by numerical simulations.The simulation results are consistent with the theoretical analysis,which testifies the correctness of the theoretical analysis.     

A general framework for developing adaptive fault-tolerant routingalgorithms

It is shown that Cartesian product (CP) graph-based network methods provide a useful framework for the design of reliable parallel computer systems. Given component networks with prespecified connectivity, more complex networks with known connectivity and terminal reliability can be developed. CP networks provide systematic techniques for developing reliable fault-tolerant routing schemes, even for very complex topological structures. The authors establish the theoretical foundations that relate the connectivity of a CP network, the connectivity of the component networks, and the number of faulty components: present an adaptive generic algorithm that can perform successful point-to-point routing in the presence of faults: synthesize, using the theoretical results, this adaptive fault-tolerant algorithm from algorithms written for the component networks: prove the correctness of the algorithm: and show that the algorithm ensures following an optimal path, in the presence of many faults, with high probability     

Ant Colony Optimization Based Sub-channel Allocation Algorithm for Small Cell HetNets

Two-tier heterogeneous networks (HetNets) composed of a conventional macrocellular network and small cell networks (SCNs) have been proposed in the literature with the aim to extend indoor coverage and realize efficient radio resource usage. As SCN shares the same frequency band with the underlying macrocell, the cross tier interference needs to be mitigated since the inter-SCN and cross tier interference at the SCN boundary may result in undesirable network performance degradation. In this paper, we propose an intelligent physical resource block (PRB) allocation as a solution to mitigate the downlink intra-SCN interference as well as the inter-tier interference in OFDM-based systems. The allocation of the PRBs to the network users is formulated as a graph coloring problem, and solved using an ant colony optimization (ACO)-based approach. Simulation results are provided, showing that our ACO-based algorithm outperforms the Received Power-based Allocation (RPA) and Received SINR-based Allocation (RSA) algorithms in terms of average SINR experienced by network users, outage probability, and number of required PRBs.     

异构无线传感器网络覆盖优化算法

针对异构传感网络节点在初始随机部署时产生覆盖盲区的问题,受简单随机抽样理论和最优化算法的启发,该文提出一种适用于感知半径异构的无线传感网覆盖优化算法。该算法以提高网络覆盖率和节点移动距离最小为优化目标,根据采样直线与平面感知圆的交点坐标之间的关系,建立了二次优化的数学模型。当平面中的多条采样直线段达到最优覆盖时,该文算法可以使平面的覆盖得到优化。实验证明,该算法能够有效提高异构网的覆盖率。     

基于粒子群算法的预编码设计

针对多用户多输入多输出系统的下行链路传输,提出了一种基于粒子群算法的预编码设计方案。该方案首先通过理论分析,推导出错误符号概率的函数,该函数是将平均符号错误概率构造为预编码矩阵和各用户信道信息的函数,并以最小符号错误概率为判断准则。然后利用模拟鸟群觅食的粒子群方法对其进行优化搜索,得到最佳效果。理论分析与仿真结果表明,该方案性能比传统的预编码性能更优。     

Energy efficiency optimization for HCNs based on small base station transmission power allocation

In the research of green communication, considering the base station (BS) power allocation from the perspective of energy efficiency (EE) is meaningful for heterogeneous cellular networks (HCNs) optimization. The EE of two-tier HCNs was analyzed and a new method for the network EE optimization was proposed by adjusting the small BS transmitting power. First, the HCNs ware modeled by homogeneous Poisson point processes (PPPs), and the coverage probability of BSs in each tier was derived. Second, according to the definition of EE, and the closed-form of EE was given by deriving the total power consumption and total throughput of HCNs respectively. At last, the analytical performance of the EE of HCNs on the small BS transmission power was analyzed, and a small BS power optimization algorithm was proposed to maximize the EE. Simulation results show that, the transmission power of small BS has a significant impact on the EE of HCNs. Furthermore, by optimizing the transmission power of small BS, the EE of HCNs can be improved effectively.     

Analysis of downlink power control and cooperation scheme for two‐tier heterogeneous cellular network

The traditional cellular network cannot keep pace with the dramatic growth in data traffic due to exponentially increasing number of multimedia applications and mobile subscribers. Recently, femto base stations (FBSs) are deployed with the macro base station (MBS) tier for off‐loading the data traffic and to improve the indoor coverage of the heterogeneous cellular network. However, FBS deployment also increases the cross‐tier interference of the heterogeneous cellular network resulting in outage performance degradation of MBS tier. This work develops an analytical framework to limit the cross‐tier interference of MBS tier using power control scheme (PCS). The proposed PCS works on path loss inversion and location‐based power level rule for FBS. Moreover, a cooperation scheme and an association policy with MBS (CSAPM) are introduced to improve the outage performance of the FBS tier. Tools from the stochastic geometry are used for deriving the signal to interference and noise ratio outage probability, total outage probability, and area spectral efficiency (ASE) of MBS tier and FBS tier. Additionally, ASE maximization problem is formulated to evaluate the optimal density of FBSs. The effectiveness of the proposed PCS and CSAPM on outage performance and ASE are numerically demonstrated. It is noted from the results that the proposed CSAPM can compensate the loss in outage performance of FBS tier due to PCS. Finally, simulation results validate the analytical results.     

Optimal joint utility based load balancing algorithm for heterogeneous wireless networks

The rapid development of mobile broadband services with continuously increasing traffic volumes has resulted in a number of challenges, including ubiquitous network coverage, high bandwidth, and reliable services for reasonable price, etc. To address these challenges, evolved packet system (EPS) is proposed as the evolution of the packet core network. While resource management and load balancing issues in EPS are discussed in 3GPP standardization, relatively few research works consider mechanism design for load information monitoring and evaluation. Furthermore, even though some load balancing algorithms have been proposed for integrated networks, the load balancing scheme design which achieves the optimization of joint system performance has not been extensively studied. In this paper, an inter-access system anchor based load balancing mechanism is introduced which performs load monitoring and evaluation for access gateways and networks, and an optimal load balancing algorithm is proposed for heterogeneous integrated networks. To characterize the performance of integrated networks, the concept of utility function is introduced and the comprehensive performance of integrated networks which support both single type service and multimedia service is modeled mathematically. Applying vertical handoff as an efficient mechanism for achieving load balancing, the optimal number of handoff users is obtained through solving the optimization problem. Numerical results demonstrate that load balancing between access networks can be achieved, and the optimal number of handoff users corresponding to the maximal joint network utility can be obtained.