新形势下无线网络室内覆盖系统的应用

随着移动通信技术的进步以及室内无线网络需求的增加,室内需要通过无线信号传输等方式进行大量的语音、视频、数据等的传输.区域覆盖必须对建筑物的屏蔽、吸收等问题进行有效解决,因此提高室内通信质量,从根本上提升移动网络的服务水平,是运营商非常关注的问题.本文围绕无线网络室内覆盖系统的应用,结合实际案例进行分析,旨在探索改善室内移动通信环境的优化方案,为推动移动网络优化工作提供参考价值.     

室内无线综合覆盖

移动通信和计算机网络的发展使得越来越多的无线业务需要室内信号覆盖,我国目前的覆盖方式是由每个运营商为其经营的业务信号单独建设室内覆盖系统,这种方式覆盖业务少,反复施工,浪费资源.文章提出建设无线综合覆盖的理念和实施方法,即"用一个宽带无线覆盖系统满足当今乃至未来可预见的各运营商对无线业务、容量和技术的要求,以及服务于整个楼宇用户的各种类型的无线应用需求".     

因地制宜选择3G室内覆盖方案

第三代移动通信的主要业务量将来自于室内,因此运营商必须提高室内覆盖能力. 实现3G室内覆盖的技术方案按信号来源一般可分为宏蜂窝无线接入、微蜂窝有线接入、无线直放站和BBU RRU这几种情况.     

多网合一室内分布系统的研究与应用

当前人们不仅需要室外的移动通信服务,同时还具有较高的室内移动通信技术要求,特别是在一些人口极为密集的大型现代建筑内,人们对室内移动通信技术的要求与日俱增.大型建筑在城市的分布较为密集,严重影响了无线信号的传递,增加了无线网络覆盖工作的难度,使得无线网络的覆盖更加复杂.     

基于EOC的家庭移动通讯覆盖技术的实现

随着移动通信建设步伐的不断加快、移动用户的飞速增加,在大中城市的室外地区已经基本可以做到无缝覆盖。为了提高网络质量、提高用户满意度、增加话务量,室内覆盖越来越成为网优的重点。本文主要论述了一种无线信号覆盖的接入系统,和现有的EOC设备相结合,利用CATV同轴电缆实现无线信号入楼或者入户的深度覆盖,提供了更好的室内移动通信环境。     

6.0-6.4GHz室内MIMO无线信道测量与传播特性分析

工作在6GHz以上高频段的多输入多输出(Multi-Input-Multi-Output,MIMO)无线通信系统是下一代无线移动通信的有力竞争方案.目前,对制约无线系统性能的高频段空时无线信道特性研究仍较少见.针对这一现状,采用基于网络分析仪的信道测量平台对典型办公环境下6.0-6.4GHz MIMO无线信道特性进行测量和分析.为了明确高频段为系统设计带来的新问题,将测量得到的高频段MIMO信道特性参数与低频段对比.对比结果表明,6.2GHz频段与2.45GHz频段MIMO信道传播特性存在较大差异.在对6.0-6.4GHz室内覆盖MIMO无线通信系统进行设计和评估时,需要基于6.0-6.4GHz频段无线信道传播的新特性对系统的关键技术和方案进行调整.     

GSM室内覆盖分布系统的设计

以广东省某市移动通信系统的室内覆盖基站为例,分析了有线传输方式及无线中继方式２种类型的室内覆盖站的设计方法及其优缺点,并从参数设备等方面讨论了室内覆盖站的设计原则及应注意的问题。     

WCDMA网络电梯内掉话的优化案例分析

随着移动通信的普及和3G网络的逐步商用,城市室内的深度覆盖越来越重要。室内深度覆盖一方面要建设室内覆盖系统,另一方面要对室内外无线信号进行联合优化,通过基站天线、参数调整结合室内分布系统的调整提高室内综合通信质量。电梯作为室内覆盖的一个特殊场景需要加以重点考虑。一、WCDMA室内覆盖组网概况     

LTE-Hi系统关键技术及发展方向

近年来,移动通信的数据量迅速增长,其中大部分发生在室内及热点场景。而到目前为止的移动通信技术主要是针对大覆盖的场景,缺乏室内分布系统的研究。因此,LTE室内覆盖优化方案不仅是3GPP标准化进程中的一个重要课题,也是国际运营商在网络优化中的重要考量。首先介绍了LTE-Hi系统的技术特征,然后比较其他常用室内覆盖方案,分析了该系统的优势,最后介绍了LTE-Hi技术的发展方向。     

关于无线通信室内覆盖集约化建设的分析

近年来,随着科学技术的发展,尤其是计算机技术和通信技术的发展,使得无线网络技术有了长足的发展,在人们的生活、学习和工作等方面实现了全面的覆盖和应用.每家运营商更加有意愿在人们活动相对集中的地区建立自身的无线网络覆盖区域,这样一来,导致了相应问题的出现,造成室内无线移动通信网络的重复覆盖.在这样的条件之下,无线通信室内覆盖集约化建设就尤为重要了,使资源浪费的现象得到相应的改善.     

An Investigation of MIMO Performance in the Indoor Ricean Environment

In this paper, we investigate the Multiple-Input Multiple-Output (MIMO) channel capacity in indoor Ricean channels based on MIMO channel measurements at 2.45 GHz. The measured data is analysed using a super resolution parameter estimation algorithm. Our results demonstrate that the line-of-sight (LOS) component in a Ricean scenario influences indoor MIMO performance through increased spatial correlation between array elements. We found that indoor channels with higher values of Ricean K factor have smaller numbers of effective multipath components and increased spatial correlation. Measurement results also showed that, the effect of varying antenna height on indoor MIMO capacity is also due to the spatial correlation of multipath propagation and has a close relationship with the separation between the transmitter and receiver. Zhongwei Tang is currently with the Wireless Technologies Laboratory at CSIRO. He was with Microwave and Wireless Technology Research Laboratory (MWTRL), Information and Communication Group, Faculty of Engineering of the University of Technology Sydney, Australia, where he pursued his Ph.D. Degree. His current research interests include RF propagation, MIMO Space-Time channel measurements, characterization and channel modelling, smart antennas, MIMO systems and array signal processing. Ananda S. Mohan is currently a member of the Faculty of Engineering, University of Technology, Sydney (UTS), Australia where he leads research on antennas, microwaves, wave propagation, and wireless technology. He received a Ph.D. degree in electrical communication engineering from the Indian Institute of Technology, Kharagpur, India and was a Scientist and Senior Scientist at the Research and Training Unit for Navigational Electronics, Hyderabad, India. At UTS, he directed the Sydney microwave design resource centre and was the associate program leader of the co-operative research centre for satellite systems. He currently directs the microwave and wireless technology research laboratory and a core member of the university research centre on health technologies. His current teaching and research interests include wireless mobile communications, microwaves and antennas, smart antennas and applications of microwave and wireless technology in medicine and has obtained many competitive research grants in these areas. Dr. Mohan was a co-recipient of the Priestly memorial award from the Institute of Radio and Electronic Engineers (IREE), Australia. He was a member of the organizing and technical Program Committees of the IEEE Globecom'98, APMC 2000, and International Symposium on Wireless Systems and Networks, 2003 and IASTED International Conference on Antennas, Radar, and Wave Propagation, for 2004 and 2005.     

基于DMT/QAM和STBC的室内MIMO光无线通信

针对室内漫射光无线通信问题,提出一种采用离散多音/正交幅度调制和空时块编码的多输入多输出(MIMO)光无线通信技术。基于离散多音/正交幅度调制技术,并通过考虑室内全光无线信道的脉冲响应和其噪声特性,建立起室内红外光无线链路的信道模型;再采用空时块编码技术,提出一种实现室内漫射光无线通信的MIMO无线通信系统,并通过分析得到接收机端重要的性能指标信噪比和误码率;仿真实验结果表明,提出的室内MIMO光无线通信技术与其他传统的技术方案相比,可以降低系统的误码率,获得更好的信噪比,降低所需要的发射光功率。     

Femtocell在校园3G覆盖中的应用

随着用户对网络覆盖要求的增加,成本以及部署的难易程度将会是移动通信室内覆盖的关键。从Femtocell的技术原理出发,介绍了其关键技术,通过与传统室分和无线局域网进行对比分析,并结合实际案例,从设计和优化两个角度详细介绍了Femtocell技术的应用,最后对其在LTE的应用前景展开设想。     

Cooperative MIMO channel models: A survey

Cooperative multiple-input multiple-output technology allows a wireless network to coordinate among distributed antennas and achieve considerable performance gains similar to those provided by conventional MIMO systems. It promises significant improvements in spectral efficiency and network coverage and is a major candidate technology in various standard proposals for the fourth-generation wireless communication systems. For the design and accurate performance assessment of cooperative MIMO systems, realistic cooperative MIMO channel models are indispensable. This article provides an overview of the state of the art in cooperative MIMO channel modeling. We show that although the existing standardized point-to-point MIMO channel models can be applied to a certain extent to model cooperative MIMO channels, many new challenges remain in cooperative MIMO channel modeling, such as how to model mobile-to-mobile channels, and how to characterize the heterogeneity and correlation of multiple links at the system level appropriately.     

MIMO无线通信系统研究现状及其技术路线

多输入多输出(MIMO)技术能在不增加带宽的情况下成倍地提高通信系统的容量和频谱利用率,是下一代移动通信系统中最富有竞争力的技术之一.本文分析了MIMO无线通信系统的空域相关性、信道建模以及信道估计研究现状,并提出了相应的技术路线,这些为更加深入地研究MIMO通信技术奠定了坚实的理论基础.     

MIMO无线通信系统的关键技术和应用前景

简单地描述了在平坦消失的无线信道中多输入多输出(MIMO)系统的基本工作原理;讨论了MIMO系统的三 大关键核心技术:MIMO无线信道建模、多天线空时编码和接收机设计;分析了MIMO技术的四大优点:阵列 增益、空间分集、空间复用和干扰减少。未来的第二代无线局域网和第四代移动通信系统等采用MIMO技术 将是大势所趋。     

Multiuser MIMO OFDM Based TDD/TDMA for Next Generation Wireless Communication Systems

Multiple-input multiple-output (MIMO) wireless technology in combination with orthogonal frequency division multiplexing (MIMO OFDM) is an attractive air-interface solution for next-generation wireless local area networks (WLANs), wireless metropolitan area networks (WMANs), and fourth-generation mobile cellular wireless systems. In this paper, one multiuser MIMO OFDM systems with TDD/TDMA was proposed for next-generation wireless mobile communications, i.e., TDD/TDMA 4G, which can avoid or alleviate the specific limitations of existing techniques designed for multiuser MIMO OFDM systems in broadband wireless mobile channel scenarios, i.e., bad performance and extreme complexity of multiuser detectors for rank-deficient multiuser MIMO OFDM systems with CDMA as access modes, extreme challenges of spatial MIMO channel estimators in rank-deficient MIMO OFDM systems, and exponential growth complexity of optimal sub-carrier allocations for OFDMA-based MIMO OFDM systems. Furthermore, inspired from the Steiner channel estimation method in multi-user CDMA uplink wireless channels, we proposed a new design scheme of training sequence in time domain to conduct channel estimation. Training sequences of different transmit antennas can be simply obtained by truncating the circular extension of one basic training sequence, and the pilot matrix assembled by these training sequences is one circular matrix with good reversibility. A novel eigenmode transmission was also given in this paper, and data symbols encoded by space–time codes can be steered to these eigenmodes similar to MIMO wireless communication systems with single-carrier transmission. At the same time,, an improved water-filling scheme was also described for determining the optimal transmit powers for orthogonal eigenmodes. The classical water-filling strategy is firstly adopted to determine the optimal power allocation and correspondent bit numbers for every eigenmode, followed by a residual power reallocation to further determine the additional bit numbers carried by every eigenmode. Compared with classical water-filling schemes, it can also obtain larger throughputs via residual power allocation. At last, three typical implementation schemes of multiuser MIMO OFDM with TDMA, CDMA and OFDMA, i.e., TDD/TDMA 4G, VSF-OFCDM and FuTURE B3G TDD, were tested by numerical simulations. Results indicated that the proposed multiuser MIMO OFDM system schemes with TDD/TDMA, i.e., TDD/TDMA 4G, can achieve comparable system performance and throughputs with low complexity and radio resource overhead to that of DoCoMo MIMO VSF-OFCDM and FuTURE B3G TDD.     

4×6 MIMO信道解码器的FPGA设计与实现

多输入多输出(MIMO)技术在现代无线移动通信系统中应用广泛,FPGA实现MIMO信道估计和解码是其实用化的关键。为保证系统性能,设计了一种OFDM-MIMO系统的并行流水浮点4×6 MIMO信道解码器,并在单片Xilinx Vertix6 FPGA芯片上进行了实现。实验结果表明,系统处理速率可以达到120 MHz,可以用于速率为1.485 Gbit/s的HDI高清视频的实时传输。     

室内MIMO无线信道模型和信道容量研究

本文从工程的实际出发,首先提出一种修正的室内MIMO无线信道模型,该模型有效地修正先前室内MIMO无线信道模型的不足,具有明显吻合室内实际通信环境的特点,然后分析天线方向性以及天线单元间的互耦对室内MIMO无线信道容量的影响.数值模拟验证了这种影响,并得到在一定条件下互耦导致的天线方向图畸变产生角度分集,提高信道容量,互耦对空域相关性无影响的条件以及室内丰富的多径使天线方向性对信道容量的影响不明显等结论.最后,实验也证实理论分析.     

Surveys on the intelligent surface: an innovative technology forwireless networks beyond 5G

With the rapid development of wireless communication technology and the explosive growth of mobile data traffic,more and more users are eager to get faster and better internet access. In order to meet the needs of users, energyand spectrum utilization are becoming more and more important as new challenges in wireless communicationnetworks. In recent years, reconfigurable intelligent surface ( RIS ) technology has been proposed in aprogrammable intelligent way to improve the performance and quality of wireless communication systems. Inaddition, the RIS performs better in terms of energy efficiency than other technologies. Therefore, the RIS hasbecome research hotspot rapidly because of its unique wireless communication ability. This paper aims to review theRIS, including channel model, design for transmitter and receiver, information theory, and the latest developmentof RIS-assisted multiple-input multiple-output (MIMO) systems. The applications of RISs in physical layersecurity, device to device (D2D) and cell coverage extension are also introduced in detail. In addition, we discussmajor research challenges related to the RIS. Finally, the potential research directions are proposed.