TD-SCDMA Femto小区与宏网的双向重选

TD-SCDMA Femto是一种毫微微基站,在实际使用过程中,TD-SCDMA Femto小区和宏网之间的自动双向切换重选一直是一个较为困难的问题。笔者对TD-SCDMA Femto小区和宏网之间的自动双向重选机制进行了分析,并提出了相关解决方案。     

TD-SCDMA网络优化增加邻区时的扰码规划方案

由于CDMA网络可以支持单频组网,所以扰码规划很重要。TD-SCDMA网络频率规划时需要做频点、扰码整体规划。在实际优化过程中,会发生已经运行一段时间的在密集市区的TD-SCDMA小区需要添加邻区的情况,本文给出了优化增加邻区时的扰码检查方法及新的扰码筛选方法。     

无线通信系统异构网络的自动邻区关联方法

主要提出一种宏小区与毫微微小区混合组网的异构无线通信网络,从而设计了一种用于异构无线通信网络中的基站间自动邻区关联的方法,并阐述了具体实施步骤。该方法支持异构网络中的基站自组织功能,基站能够在自动邻区关联的过程中正确地获得邻区基站的ID,从而成功构造邻区关系且无需人工配置,克服了已有方法存在的缺陷。同时,该方法无需修改空口信令,也不会增加空口信令开销。     

TD-SCDMA Femto系统部署存在的问题及解决方案

本文分析总结了TD-SCDMA Femto网络部署中存在的一些问题并提出了解决方案,如怎样解决Femto基站与宏蜂窝小区之间的重选和切换,如何实现Femto基站的时间同步,如何降低宽带回传网络时延以提升质量,网络部署初期如何实现跨地区接入。     

TD-SCDMA系统中“类adjacentPN干扰”优化方法浅析

0引言 TD—SCDMA系统由于时延扩展、信号延迟、码的非完全正交性等原因存在大量频率码字干扰。2个距离较近的小区,如果配置的扰码相关性大,不论是否同频,都会导致干扰。在实际TD网络优化过程中,频率资源有限,频点（B频段9个频点）调整较困难,而扰码（128个）调整相对灵活,通过扰码优化可以有效规避干扰,从而达到预期的优化目的。     

TD-SCDMA Femto支撑网建设技术方案探讨

1网络管理支撑网 1.1网络管理支撑系统结构 Femto网络管理支撑系统架构如图1所示。整个网络管理系统由Femto基站Manage、Femto网关Manage两部分构成。●Femto基站Manager：Femto基站Manager基于TR-069,负责为Femto提供配置参数,实现Femto的位置认证功能,     

TD-SCDMA系统中的扰码分析

TD-SCDMA网络已历经七期的网络工程,基站密度越来越大,邻区关系越来越复杂,小区间信号的穿插覆盖情况比较严重,以往对复合码零时延相关特性的分析已不再适用,对复合码的时延相关性特性的分析已显得日益重要。文章重点介绍复合码时延相关特性的分析方法及扰码优化方案与案例,期望对业界技术人员提供一定的帮助,对现网存在的大量网络问题提供一种新的分析方法。     

TD-SCDMA同频组网中扰码性能分析及同频干扰的解决方法

本文简要回顾了TD-SCDMA物理层的帧结构,介绍了多频点的特性及多频点系统的同频组网方式,指出多频点系统并没有解决TD-SCDMA系统短扰码相关性能不佳的问题.分析扰码的互相关性,得出12个最大不相关组的结论,从理论上证明热点地区难以保证邻小区都选择互相关性最好的扰码,同时通过外场测试报告也证明了问题的存在.因此本文给出了一种基于路损的、利用多频点的频率参数分配信道的策略,从无线资源管理的角度缓解热点地区因扰码相关性问题引起的同频干扰,并给出了该方法经局部外场验证后的结果.     

WCDMA网络扰码规划研究

扰码规划是WCDMA网络规划的一部分,文章对WCDMA扰码规划的原理进行了阐述,分析了小区搜索、扰码规划的不同方案和需要注意的扰码复用距离问题。良好的扰码规划对于获得最优的网络性能很重要,在进行扰码规划的时候,要结合实际的网络情况,选择合理的扰码复用距离和邻区扰码组的分配,以达到最好的网络性能。     

TD-SCDMA系统中小区关系分类算法及其实现

分析了TD-SCDMA系统中小区关系分类对扰码规划的意义,提出了以小区经纬度、方向角作为已知条件,用与小区方向角的垂直方向作为参考坐标系取代正北方向,来对小区的关系进行分类,从而判断小区之间是否为紧密邻区的算法,给出仿真测试结果,最后在扰码规划软件中实现了提出的算法.     

Power control and clustering in heterogeneous cellular networks

Recently, it is widely believed that significant coverage and performance improvement can be achieved through the deployment of small cells in conjunction with the well-established macro cells. However, it is expected that the high density of base stations in such heterogeneous cellular networks will give rise to multiple design problems related to both co-tier (small-to-small) and cross-tier (between small and macro cells) interference. Fortunately, cooperation between base stations will play a major role to cope with these problems and hence to enhance the users’ data rates. In this paper, we consider a two-tier cellular network comprised of a macro cell underlaid with multiple small cells where both co-tier and cross-tier interference are taken into account. We study the scenario where the small cell base stations seek to maximize a common objective by forming multiple clusters through cooperation. These base stations have also to allocate power to their associated users and, at the same time, control the total aggregate interference caused to the macro cell user which has to be kept below a threshold prefixed by the macro cell base station. We consider two utility functions: the overall sum rate of the small cell network and the minimum data rate of the small cell users. We formulate the studied problems as mixed integer nonlinear optimization problems and we discuss their NP hardness. Therefore, due to the complexity of finding the optimal solution, we design heuristic algorithms which resolves efficiently the tradeoff between computational complexity and performance. We show through simulations that the designed heuristics approach the optimal solution (obtained using the complex exhaustive search algorithm) with highly reduced computational complexity.     

On-Demanded Multicast Zone Configuration in CDMA Network Systems

Focusing on enriched multimedia broadcast/multicast opportunities of a wireless communication network, we build multicast cell configurations in a CDMA based network. In a CDMA based wireless network, a terminal can get significant signal quality enhancement by the combining of data streams from multiple base stations. To combine the data streams, the base stations have to be operated with a common time schedule. The cells whose base stations are operated as such are called soft-combine cells. A terminal can take advantage of signal quality enhancement, if the terminal is in a soft-combine cell and at least one neighbor cell supports soft-combine. Our problem is to find a limited number of soft-combine cells under the computing burden of the network controller, while the benefit of soft-combine is maximized. We build a combinatorial optimization model and solution methods for the dynamic reconfigurations of soft-combine supporting cells.     

Concentrated multicast zone configuration in CDMA network systems

Focusing on enriched multimedia broadcast/multicast opportunities of a wireless communication network, we build a multicast cell configuration in a CDMA-based network. In a CDMA-based wireless network, a terminal can significantly reduce the bit error rate by the combining of data streams from multiple base stations. To combine the data streams, multiple base stations have to be operated with a common time schedule. The cells whose base stations are operated as such are called soft-combine cells. A terminal can take advantage of error rate reduction, if the terminal is in a soft-combine cell and at least one neighbor cell supports soft-combine. Our problem is to find a limited number of soft-combine cells under the heavy computational burden of a network controller, such that the benefit of the soft-combine is maximized.     

自组织技术在TD-SCDMA和TD-LTE网络的引入研究

SON是解决未来网络配置和优化工作,提高网络服务质量并大幅降低网络维护成本的有效途径。本文从现网维护和优化所面临的挑战出发,分析了SON技术在TD-SCDMA和TD-LTE网络维护和优化中发挥的重要作用,并结合目前已有的研究和标准化成果,研究了基站自启动、自动邻区关系等SON功能在TD-SCDMA和TD-LTE网络中的应用解决方案。     

Small Cell Planning: Resource Management and Interference Mitigation Mechanisms in LTE HetNets

In an attempt to address the huge data demand of indoor mobile users and poor signal strength from outdoor base stations to indoor environments, opertaors have started deploying variety of small cells likes Femtos, picos and micro cells. In this work, we used Femtos as small cells. Femto cells are low-cost, low-power consuming cellular base stations which operate only in licensed spectrum and are designed for both outdoor and indoor communication. Although small cells can be used for enhancing network capacity and coverage, arbitrary deployment of large number of small cells can lead to increase in operators expenditure and may create severe interference issues for cell edge users. In this paper, we look into optimal placement of small cell solutions to improve data rates of users in LTE HetNets using Femtos. Besides, these solutions address the main concerns of interference and resource management by proposing mechanisms for optimal placement of Femtos (OptFP, MinNF), dynamic power control and bandwidth allocation in Femtos (SOPC) and dynamic offloading. We provide a comparison of placement solutions and the applicability of each proposal keeping the operators’ revenue in mind.

     

Green cell association for multimedia transmission in cognitive heterogeneous networks

With the introduction of low‐powered pico/femto‐base stations and relay nodes into the macro‐cell, recent heterogeneous networks provide an attractive approach for future wireless communication. Although it may achieve better coverage and higher capacity, several problems remain unsolved before practical deployment. For example, how to select the proper cell from neighbor low‐powered cells and then occupy the radio resource without interference on macro‐users is both important and challenging, especially for rigorous multimedia applications. The traditional cell access algorithms and quality‐control parameters such as delay or throughput no longer suit well in this complex environment. An effective approach should be pursued. In this paper, we investigate this interesting cell association problem and propose a complete green resolution on the basis of thorough discussions about the multimedia transmission under these concerns. Cognitive radio is introduced to share spectrum between macro‐cell and low‐powered cells while securing the transmission of authorized macro‐users. We also bring forth the concept of ‘interference balance’ to better manage the overall interference and energy consumption in the network. Restless bandit model is formulated on the basis of channel state, data rate, interference control, and the carefully chosen intra‐refreshing rate for multimedia traffic. Then the cell association scheme is designed to be efficient and practical because of the simple index property of our model output. Simulation results have proven the performance of our proposed resolution compared with existing algorithms on interference constraint, multimedia distortion, and overall network energy consumption balance. Copyright © 2013 John Wiley & Sons, Ltd.     

基于4G数据识别5G室内外同频干扰的方案研究

目前中国移动主要基于2.6GHz频端开展5G网络建设,由于室分系统和宏站共用100MHz频谱,因此室内外同频干扰会对5G用户感知产生不利影响。本文提出了一种基于4G测量报告快速识别室外5G高干扰小区的技术方案,可用于识别5G室内外高干扰小区。研究分析和测试验证表明：该方案可快速发现并定位室内外同频干扰覆盖问题,有助于辅助制定网络优化措施。     

Precoding and channel state information sharing in cooperative macro base stations and femto sites

Femto cell technology is a promising solution for indoor coverage of cellular systems. The interference between macro and femto cells can be mitigated via cooperation between the macro base station (BS) and the inside femto sites (FSs). In this paper, the idea of multi‐cell multi‐input and multi‐output is introduced, whereby the macro BS shares the same frequency band with the inside FSs in support of the femto users. Both single‐user and multi‐user precoding at the macro BS are proposed to support the cooperative transmission between the macro BSs and FSs. In single‐user precoding and multi‐user precoding without power allocation, only the angle information of the FS‐user channels is required to be sent from the users to the macro BS. If the magnitude information is also sent by each user, multi‐user precoding with power allocation can be employed to support cooperation between macro BSs and FSs, which is an extension of the classical water‐filling optimization problem. Theoretical derivations and an iterative algorithm are both presented to solve this optimization problem. Analytical and simulation results with respect to the signal received with interferences validate the effectiveness of cooperation between the macros BSs and FSs.Copyright © 2012 John Wiley & Sons, Ltd.