A Channel Sharing Scheme for Cellular Mobile Communications

This paper presents a channel sharing scheme, Neighbor Cell Channel Sharing (NCCS) , based on region partitioning of cell coverage for wireless cellular networks. Each cell is divided into an inner-cell region and an outer-cell region. Cochannel interference is suppressed by limiting the usage of sharing channels in the inner-cell region. The channel sharing scheme achieves a traffic-adaptive channel assignment and does not require any channel locking. Performance analysis shows that using the NCCS scheme leads to a lower call blocking probability and a better channel utilization as compared with other previously proposed channel assignment schemes.     

卫星移动通信的信道模拟技术

信道的计算机模拟是数字卫星通信在探索，研究和发展过程中的重要手段和必比阶段，本文基作者经验的总结，圣卫星通信计算机模拟的方法论给出一个简要而系统的介绍，重点放在移动卫星信道上。其内容包括：等效复基带表示法，一种信道分析和模拟研究所采用的非常方便珠数学形式。     

A Geometric-Statistic Channel Model for THz Indoor Communications

The eventual practical deployment of a terahertz (THz) wireless communication system requires a proper channel model. By considering the unique characteristics of THz propagation, this paper proposes a geometric-statistic channel model for system-level simulation. This work also provides an evaluation methodology for investigating the system performance. Numerical results reveal that the proposed channel model is not only suitable to describe the physical characteristics of the THz channel, but also to investigate system-level performance.     

第3代移动通信系统中的信道编码技术研究

第3代移动通信系统IMT2000是当前的研究热点,而信道编码又是其关键技术之一.第3代移动通信系统中的业务范围和数据传输速率都大有提高,因此信道编码在语音业务上除了继承第2代系统的前向纠错(FEC)卷积编码技术外,还采纳了以Turbo码为代表的纠错能力更强的、先进的编码技术.讨论了CDMA2000[1]系统中的纠错编码技术,尤其是Turbo码在其中的应用.     

移动通信的用户移动和呼叫模型

依据移动通信的特性,阐述了流体流模型、马尔可夫模型、重力模型、运动轨迹模型等几种用户移动和呼叫模型,并进行了比较,为建立通用的流量模型做一初步的探讨。     

一种适用于非城市区域的卫星移动信道统计模型

本文提出了一种适用于非城市区域的卫星移动信道统计模型—莱斯 K模型 ,采用K 分布来描述由于遮蔽引起的接收信号包络的缓慢变化 ,用莱斯分布来描述包含直视信号分量 (主径 )在内的多径快衰落 ,得到了接收信号包络的概率分布和误比特率 .在此基础上 ,本文利用样本矩对莱斯 K模型参数进行了估计并对参数估计性能进行了评价 .最后 ,本文利用实测数据对模型进行了验证 .     

三维MIMO信道物理模型的统计特征

提出以散射矩阵来概括并简化电波传播过程中散射体对电磁波的影响,并对传统的距离分集和极化分集多入多出（MIMO）信道模型进行扩展,建立了一种可以应用于各种分集情况的三维通用MIMO物理信道模型。再以此模型为基础,对三维环境中的MIMO信道统计特征进行了研究,推导出任意情况下交叉极化鉴别度（XPD）和子信道间相关性的计算方法,并进行了仿真验证。仿真结果表明从文中所提出信道模型提取得到的统计特征与理论分析的结果是相符的。     

A Comparison of Some Channel Assignment Strategies in Large-Scale Mobile Communications Systems

When more than one radio channel is available to serve a mobile customer in a large-scale mobile communications system the strategy used to make the assignment has an effect on system performance. Performance characteristics for five different assignment strategies obtained from a computer simulation are compared in this paper. It was found that the strategy that chooses a channel to be assigned at a base station so that the distance to the next base station using the same channel is a minimum, performs better than a strategy that minimizes the mean square distance to the next "in use" base stations on both sides. Also, it was found that choosing the first available channel encountered in a channel search is a strategy that produces reasonably good system performance.     

一种基于几何统计的卫星移动MIMO信道模型

结合统计模型复杂度低和几何模型精确度高的优点,提出了一种基于几何统计的双极化卫星移动多输入多输出(MIMO)系统的信道建模理论。该模型总体上使用几何模型的建模思路,采用射线追踪方法对信道中传输的射线进行追踪,重点关注各条射线的各种小尺度参数,在实际计算中引入统计学方法对各种小尺度参数进行建模与处理,同时考虑信道环境造成的信号衰减以及信道环境对射线极化的影响,完成了信道模型的建立。根据已完成的建模理论,利用Matlab实现极化卫星移动MIMO信道的建模与仿真。通过与增强型统计模型仿真结果进行比较,得出了此几何统计模型是正确的,并可在一定程度上提高建模准确性的结论。     

移动通信终端NS-IOT测试解析

对于运营商来说,终端质量至关重要。当4G到来时,用户对高速畅游满怀期待;而移动互联网众多杀手级的应用也蓄势待发;终端侧的整机数据性能对于整个4G产业链都有着非同一般的重要性。本文介绍了NS-IOT测试的测试背景、测试定义、测试系统构成、测试原理以及常见问题。     

B3G空中接口技术分析--MIMO信道测量

在多径信道中,使用多天线的MIMO无线系统能够比单天线系统提供更高的信道容量,而信道测量是决定通信性能的一个重要因素。对目前国际范围内现有的MIMO信道测量进行了研究,并做了归纳和分类。此外,对MIMO信道测量方法进行了分析,并给出了一些针对MIMO信道测量系统设计的建议,为B3G空中接口技术研究提供了技术支持。     

Angle and Time of Arrival Statistics for a 3-D Pie-Cellular-Cut Scattering Channel Model

In this paper, investigated a 3-D pie-cellular-cut (PCC) scattering channel model for microcell environments, that idealizes the mobile station (MS) located inside of a 3-D scattering semispheroid and base station (BS) employing a directional antenna at the center of the semispheroid. The joint probability density functions (PDFs) and marginal PDFs of Angle of arrival (AOA) and Time of Arrival (TOA) seen at the BS and the MS in correspondence with azimuth and elevation angles are derived. The results show that the proposed 3D scattering channel model performs better compared with previously proposed 2D models for outdoor and indoor environments, which promotes the research of the statistical channel models.     

A Generalized Model for the Spatial Characteristics of the Cellular Mobile Channel

In this paper, we present an intensive study of the spatial characteristics of the cellular mobile channel for picocell, microcell, and macrocell environments. We review the previous physical channel models and make appropriate comments/corrections wherever needed. We find that almost all physical channel models proposed so far are specific to particular cellular environments and that no general model exists in the literature. Thus, we propose a generalized physical channel model, referred to as the eccentro-scattering model, and derive the expressions for the probability density function (pdf) in an angle of arrival (AoA) of the multipath signals at a base station (BS) for the picocell, microcell, and macrocell environments using the two most commonly used scatterers' distributions, i.e., uniform and Gaussian. The derived formulas, in closed form, can be further used in designing beamwidth and channel tracking algorithms and assessing the performance of smart antennas. We discuss the relations between the results obtained for different cellular environments in the uniform and the Gaussian scattering and investigate the effects of the standard deviation of the scatter density and size of the scattering disc on the pdf of AoA at the BS. Previous work on the AoA statistics considering either the shape of the scattering regions or the distribution of scatterers within that region can more easily be reproduced using the provided general formula. We prove that assuming the scatterers to be either uniformly or Gaussian distributed in sparsely populated areas gives almost the same distribution of AoA of multipaths at the BS.     

宽带移动卫星通信信道模型研究

从多径衰落、阴影效应和多普勒效应三个方面研究宽带移动卫星通信信道的频率色散特性和多普勒功率谱非对称特性。基于WSSUS模型提出宽带移动卫星通信信道的统计模型。采用蒙特卡洛仿真方法对农村地区和城市地区两种信道的冲激响应和误码率特性进行仿真。仿真结果表明该信道模型能够真实反映宽带移动卫星通信信道的特性,对卫星通信系统关键技术设计具有参考价值。     

PRS开启第三代移动通信之门

1移动通信的发展历程 进入90年代,在第二代数字移动通信迅猛发展的同时,人们对第三代移动通信提出了新的要求。它应该能实现全球漫游,同时应具备宽带的数据通信能力。1996年,FPLMTS被正式更名为IMT-2000(国际移动通信系统),工作于2000MHz频段。 IMT-2000不但要满足多速率、多环境、多业务的要求,还应能将现有的通信系统集成为统一的可替代系统。因此,它应具有以下特点：提供全球无缝覆盖和漫游;能提供窄带和宽带多媒体业务;适应多种运行环境,如陆地、航空和海域;服务质量达到固定网水平,收费合理;系统管理和配置灵活,业务组织灵活;移动终端轻便,成本低;支持系统平滑升级和现有系统的演进;频谱利用率高等。     

一种适于移动视频通信的运动估值算法

在视频通信中，由于移动终端的处理能力、电池容量和存储空间的限制，降低视频编码计算量成为实时视频通信急需解决的问题。运动估值作为视频编码算法中最耗时的模块，直接影响着整个编码算法的性能和重建视频质量。本文在分析低码率压缩码流运动矢量场以及误差曲面性质的基础上，提出一种基于时空预测的快速运动估值方法。仿真结果表明：与MVFAST相比，本文方法不需要另增存储开销，将计算复杂度降低了35％以上，而视频质量仅下降0．1dB左右。同时它结构简单，比较易于硬件实现。     

一种用于移动终端的联合信道译码器

对移动终端中使用的信道译码技术进行了介绍，指出未来的移动终端需要支持多种通信标准。设计了一种用于移动终端的联合信道译码器，可支持多种通信标准，达到最大限度利用共享资源，从而节省总体成本。     

A Transmit and Receive Multi-Antenna Channel Model and Simulator for Communications from High Altitude Platforms

The interest of the scientific and industrial communities on the application of high altitude stratospheric platforms to communications is increasingly growing. Several research projects and field trials are being carried out by international consortia and specific portions of the electromagnetic spectrum have been allocated by the International Telecommunications Union (ITU) for communications applications. The channel experienced by such systems plays a key role for the provision of reliable communications services but, unfortunately, its inherent characteristics are substantially different from those of other channel typologies. Therefore, in order to design and simulate effective propagation impairment mitigation techniques such as adaptive modulation and coding or adaptive beamforming and equalization algorithms, an ad hoc channel model and simulator is definitively required. In this paper a novel channel model and a related channel simulator especially tailored for HAP-based communication systems are presented. The model is conceived for link-level simulations of point-to-point communication links, wherein both the transmitter and the receiver may be equipped with an array of antennas. Peculiar physical effects of the stratospheric channel are taken into account as well as impairments due to the possible presence of scatterers and relative movement of both transmitting and receiving stations. The structure of the channel simulator has been conceived to maintain the computational burden at required by the channel simulator is kept low by an efficient tapped delay line implementation. This work is supported by the CAPANINA project (FP6 IST-2003-506745): Communications from aerial platform networks delivering broadband communications for all, http://www.capanina.org.

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