基站天线的发展与应用

分别从宽带化、多频化及小型化3个方面阐述了移动通信基站天线的基本发展趋势,最后通过分析对比其技术演进与发展,重点介绍未来移动通信系统MIMO天线及有源天线的使用方法及优点。     

基站天线中的馈电网络

分析同轴线、PCB带状线/微带线、空气带状线/微带线等3种基站天线设计中常用的无源馈电网络形式,并介绍DBF技术的特点及其在有源基站天线中应用的前景。     

5G基站硬件架构及演进研究

基站硬件架构决定了设备形态与性能,进而影响5G网络的服务能力。5G时代多样化的业务需求对网络能力提出了更高要求,推动5G基站向专用硬件增强与架构通用化2个方向持续演进。介绍了5G基站的硬件架构、核心器件及产业发展状况,分析了基站硬件架构的未来发展趋势。     

应急通信空中平台的基站天线选型

基站天线升空可以增大网络覆盖面积,同时不受地面灾害的影响。文章基于空天地一体化通信网络演进思路,介绍了基站天线的分类、空中平台的分类、空中通信平台在抢险救灾中的典型应用、应急通信空中通信平台的实施方式和空中平台基站天线的选型思路。     

移动通信基站天线的关键技术研究进展

基站天线作为移动通信系统中的重要部件,对通信质量起至关重要的作用,其关键技术被广泛研究。通过对基站天线的电调技术、极化技术、宽带技术、阵列天线多频技术和基站天线小型化技术等的研究发展历程介绍,分析了这些关键技术在工程上的实现方法与措施,总结了这5个关键技术今后的研究重点和发展方向。在基站天线下一步的发展中,需要将多个关键技术完美地结合在一起,阵列天线多频技术和基站天线小型化技术将成为今后的研究热点。     

多频基站天线品质保证——大功率测试方法研究

针对当前4G网络多频基站天线的品质问题,通过大功率测试方法,介绍基站天线质量稳定性、射频电路设计优化、基站天线散热性能、射频特性的稳定性等,对未来5G有源天线的品质稳定性、可靠性测试和大功率测试具有较高的参考意义,是一种测试方法指导.     

无线通信系统中的软基站技术

无线通信系统经过多年的发展,各制式出现融合的趋势。同时运营商降低采购和运营成本的需求,使得支持多种制式、平滑演进的＂软基站＂成为无线基站演进的方向。文章对无线通信系统软基站的相关技术背景进行了介绍,并对实际软基站的架构设计思想、系统模块构成及关键技术等进行了提纲挈领地分析。文章指出未来软基站将继续向集成度更高、基带资源调配更灵活、传输方式更丰富、成本更低、节能更环保几个方向发展。     

基站天线向何处去

基站天线是移动通信无线接入系统的重要组成部分,其发展受到多方面因素的影响,特别是移动通信网络不断向广度和深度的扩张,造成基站布局越来越密集。5G通信时代的到来,意味着运营商需要建设更多的基站。一方面,移动通信的不断发展,新的系统不断推出,对基站天线提出了新要求,同时,运营商为了提供更高质量的网络服务,     

基站建设及基站天线的研究

为了能够满足基站易于选址、优质快速的建站要求和易维护、低成本、高可靠的运行要求,本文时以方舱来实现一体化结构基站做出一番探讨.从系统设计的观点阐述了移动通信高性能基站天线设计的几个关健问题,介绍了智能天线技术在基站中的应用,并且用HFSS软件仿真了一种新型的对称阵于天线,该天线驻波比小于2的带宽可以达到60%,真有良好的宽频带特性.     

TD—LTE基站平滑升级方案

随着数据业务的高速增长,运营商逐渐把业务发展的重心从话音业务转移到数据业务上来。为保证用户的良好感知度,无线通信技术必须快速地向4G时代演进。介绍了TD—LTE无线网络架构,说明了TD—LTE基站的平滑升级主要是在原有TD-SCDMA基站的基础上,从BBU、RRU、天线等设备上到TDS/TDL双模基站的演进,最后通过具体的案例说明了升级方案的可行性。     

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.     

Evolutionary multiobjective optimization of cellular base station locations using modified NSGA-II

In this paper, various parameters of cellular base station (BS) placement problem such as site coordinates, transmitting power, height and tilt angle are determined using evolutionary multiobjective algorithm to obtain better compromised solutions. The maximization of service coverage and minimization of cost are considered as conflicting objectives by satisfying inequality constraints such as handover, traffic demand and overlap. For the purpose of simulation, a 15 × 15 Km² synthetic test system is discretized as hexagonal cell structure and necessary simulations are carried out to calculate receiving field strength at various points. The path loss is calculated using Hata model. To improve the diversity and uniformity of the obtained nondominated solutions, controlled elitism and dynamic crowding distance operators are introduced in non-dominated sorting genetic algorithm-II (NSGA-II) and are designated as modified NSGA-II (MNSGA-II). The optimal placement for BS is determined using MNSGA-II and NSGA-II. The effect of maximum number of function evaluations, handover and overlap on the performances of the algorithms is studied. A better distributed Pareto-front is obtained in MNSGA- II when compared with NSGA- II. The results reveal that, increasing of overlap percentage not only increases the coverage but also increases the overlap and handover error. The coverage percentage is indirectly proportional to the number of antennas involved in the handover constraint. The simulation results reveal that the proposed technique is more suitable for real-world BS placement problem.     

Optimal base station selection for anycast routing in wireless sensor networks

Energy constraints have a significant impact on the design and operation of wireless sensor networks. This paper investigates the base station (BS) selection (or anycast) problem in wireless sensor networks. A wireless sensor network having multiple BSs (data sink nodes) is considered. Each source node must send all its locally generated data to only one of the BSs. To maximize network lifetime, it is essential to optimally match each source node to a particular BS and find an optimal routing solution. A polynomial time heuristic is proposed for optimal BS selection and anycast via a sequential fixing procedure. Through extensive simulation results, it is shown that this algorithm has excellent performance behavior and provides a near-optimal solution.     

Efficient models for base station antennas for human exposure assessment

Two simple and accurate models for base-station (BS) panel antennas are proposed for human-exposure assessment. Panel antennas comprise an antenna array with low coupling between its unit cells. The proposed model is based on the superposition of shifted radiating field contributions in amplitude and phase of a unit cell of the panel antenna. In the first model, the electric field is obtained via a full wave analysis of the antenna unit cell. In the second model, a far-field approximation of the unit cell is utilized, and is valid at about two wavelengths away from the antenna. It is shown that the second model can be used as an interactive tool for the verification of compliance to exposure limits of BS panel antennas as required by standards.     

Planning UMTS base station location: optimization models with power control and algorithms

Classical coverage models, adopted for second-generation cellular systems, are not suited for planning Universal Mobile Telecommunication System (UMTS) base station (BS) location because they are only based on signal predictions and do not consider the traffic distribution, the signal quality requirements, and the power control (PC) mechanism. We propose discrete optimization models and algorithms aimed at supporting the decisions in the process of planning where to locate new BSs. These models consider the signal-to-interference ratio as quality measure and capture at different levels of detail the signal quality requirements and the specific PC mechanism of the wideband CDMA air interface. Given that these UMTS BS location models are nonpolynomial (NP)-hard, we propose two randomized greedy procedures and a tabu search algorithm for the uplink (mobile to BS) direction which is the most stringent one from the traffic point of view in the presence of balanced connections such as voice calls. The different models, which take into account installation costs, signal quality and traffic coverage, and the corresponding algorithms, are compared on families of small to large-size instances generated by using classical propagation models.     

On WCDMA base station selection criteria

This letter presents a BS selection criterion for WCDMA that allows selecting the base station requiring the minimum transmission power in both the uplink and downlink direction. The importance of minimizing transmitted power lies on the associated interference reduction and, consequently, the capacity increase. Furthermore, it is shown that, with a proper setting of the parameters, the criterion used in practical WCDMA systems based on Ec/Io measurements can be adjusted to provide results similar to the proposed method.     

On the energy efficiency of base station cooperation under limited backhaul capacity

Recently, energy-efficient (EE) communications have received increasing interest specially in cellular networks. Promising techniques, such as multiple input multiple output (MIMO) and base station (BS) cooperation schemes, have been widely studied in the past to improve the spectral efficiency and the reliability. Nowadays, the purpose is to investigate how these techniques can reduce the energy consumption of the systems. In this paper, we address for a single-user scenario, the energy efficiency of two BSs cooperation under limited backhaul capacity. In order to evaluate the EE metric, we provide first an information-theoretical analysis based on the outage probability, for a quantization model over the backhaul. Then, we extend this EE analysis to a more practical approach with data transmission over the backhaul. For both approaches, we identify by numerical/simulation results the cooperation scenarios that can save energy depending on the backhaul capacity.     

Joint packet scheduling and dynamic base station assignment for CDMA data networks

In current code division multiple access (CDMA) based wireless systems, a base station (BS) schedules packets independently of its neighbours, which may lead to resource wastage and the degradation of the system's performance. In wireless networks, in order to achieve an efficient packet scheduling, there are two conflicting performance metrics that have to be optimized: throughput and fairness. Their maximization is a key goal, particularly in next-generation wireless networks. This paper proposes joint packet scheduling and BS assignment schemes for a cluster of interdependent neighbouring BSs in CDMA-based wireless networks, in order to enhance the system performance through dynamic load balancing. The proposed schemes are based on sector subdivision in terms of average required resource per mobile station and utility function approach. The fairness is achieved by minimizing the variance of the delay for the remaining head-of-queue packets. Inter-cell and intra-cell interferences from scheduled packets are also minimized in order to increase the system capacity and performance. The simulation results show that our proposed schemes perform better than existing schemes available in the open literature. Copyright © 2007 John Wiley & Sons, Ltd.     

Adaptive terminal to base station assignment in BFWA systems

In point-multipoint systems the signal to interference plus noise ratio highly depends on the assignment of terminal stations (TS) to base stations (BS). The Broadband Fixed Wireless Access (BFWA) systems operate at high carrier frequencies. In this frequency range wave propagation is highly influenced by precipitation. Applying site diversity can mitigate rain attenuation effects. Present contribution provides a special site diversity method adopting genetic algorithm to adaptively optimize TS-BS assignments from point of view of the interference in BFWA service area. Rain events are generated with a Markov modeled simulation of the rain cell translations.     

Multipath propagation model of spatio-temporal dispersion observed at base station in urban areas

This paper presents a multipath propagation model for microcells in urban areas. The proposed model is a statistical geometric model that describes the propagation characteristics for propagation loss, power delay profiles, and power azimuth spectra. The applicable target of the proposed model is long-term characteristics such as the characteristics that depend on the height of a base station (BS) and the distance between the BS and a mobile station. Calculated power delay profiles and power azimuth spectra based on the model are similar to those of the power function. In order to verify the validity of the model, the power delay profiles and power azimuth spectra are measured. The measurement results agree well with the simulation results based on the model and the validity of the model is confirmed.