TD-LTE同频干扰抑制技术研究与应用

TD-LTE同频组网会使小区边缘重叠覆盖区域内产生同频干扰,严重影响小区边缘吞吐量.本论文创新提出一种干扰抑制技术,该技术基于GIS信息,通过泰森多边形原理构建蜂窝小区覆盖区域,精确计算小区覆盖面积,由小区覆盖面积求出小区覆盖等效半径,根据天线高度与覆盖半径之间的三角函数关系,确定基站天线的下倾角,在保证满足切换要求的连续性覆盖前提下,尽可能减小小区间的重叠覆盖,有效提升小区边缘吞吐量.     

小区间干扰协调技术研究

LTE(长期演进)系统中,由于同频组网,小区间的干扰问题成为LTE系统中不可忽略的问题,严重影响了用户感知。随着后期运营商大量放号,小区间的干扰问题会越来越严重,因此小区间干扰抑制技术变得尤为重要。文章着重研究ICIC(小区间干扰协调)技术对LTE网络质量的改善情况,通过测试分析,验证ICIC ON与ICIC OFF条件下网络的频谱效率的变化。最终验证得出ICIC ON对边缘用户的频谱效率提升较为显著。     

基于认知的LTE系统动态频谱分配

传统的软频率复用(SFR)无法适应长期演进(LTE)系统中业务的动态分布,可能导致小区中心和边缘区域频谱利用率不均。针对此问题,该文提出一种基于认知的LTE系统动态频谱分配方法(Cog-DSA)。该方法利用基站间的相互协作获得频谱使用状态信息,从而确定可用频谱集合,并评估来自邻小区的同频干扰,最终根据可用资源块的通信质量,对重负荷小区边缘进行频谱的动态借用和服务基站的灵活选择。仿真结果表明,所提方法能够有效改善频谱利用率,减少小区间干扰,显著提升边缘用户的传输速率。     

LTE网络优化技术

LTE（Long Term Evoludon）网络是继第三代移动通信网络之后国际上的新一代主流移动通信网络。介绍了LTE网络在特定场合采用的各种网络优化技术,包括在室内覆盖的家庭基站技术、在信号盲区和偏远地区覆盖的中继技术、在同频组网情况下抑制小区间干扰的小区间干扰协调技术,以及在小区边缘传输速率受限区域的多点协作技术。     

LTE网络优化技术

LTE(Long Term Evolution)网络是继第三代移动通信网络之后国际上的新一代主流移动通信网络.介绍了LTE网络在特定场合采用的各种网络优化技术,包括在室内覆盖的家庭基站技术、在信号盲区和偏远地区覆盖的中继技术、在同频组网情况下抑制小区间干扰的小区间干扰协调技术,以及在小区边缘传输速率受限区域的多点协作技...     

分层异构网络中基于进化博弈的小区附着机制

相比传统的宏蜂窝网络,分层异构网络是实现系统容量增强的一种很有前景的技术。尽管如此,由于家庭基站与宏基站同频部署,且它们被随机部署,异构网络中的干扰可能会更强。为了提升网络吞吐量,本文研究了一种新型的基于进化博弈的小区附着算法,为最小化小区间干扰,提高网络吞吐量提供了理论参考。     

基于扇区化的OFDM小区选择算法

首先给出了一种基于扇区化（Sectorizing）技术的OFDM蜂窝模型。该蜂窝模型利用定向天线的方向性特点,通过在小区内合理地分配频谱资源,减轻小区间的同频干扰,提高基站和移动终端间传输信号的载干比,从而提高网络总容量。然后将两种应用于全向天线蜂窝网络中的基于下行链路的小区选择模型应用在了该模型上,并通过仿真给出了性能分析结果。     

绿色蜂窝网络的频谱效率与能效函数

为了给绿色蜂窝网络的研究和设计提供一个基本的基准或判断依据,对存在多小区干扰和越区切换情况下蜂窝网络的网络传输能力(网络频谱效率)和能量效率函数(能效函数)进行了研究,揭示了蜂窝网络的功率开销与频谱效率之间的关系。首先,给出了蜂窝网络能效函数的定义,并在此基础上提出了小区干扰深度和越区切换的动力学模型,进而论证了存在多小区干扰和越区切换情况下的蜂窝网络频谱效率,并推证了数学表达式。最后,求解了蜂窝网络的能效函数,讨论了相关参数对它的影响和数值结果分析,为绿色蜂窝网络的研究和设计,提供了有益的分析依据和基础。     

小蜂窝网络中不活跃用户的最优能量效率资源分配方案

针对5G网络中因小区重叠覆盖区域的干扰问题,为缓解密集小蜂窝网络中移动用户的业务连续性,提高频谱资源利用率,进而最大化整个网络平均能量效率问题。该文提出一种基于不活跃用户的最优能量效率资源分配方案(EEI)。首先,该方案依据不活跃用户通知区域,建立以用户为中心的虚拟小区,小区内小蜂窝基站可协作为用户提供通信服务,提高用户通信质量,缓解小蜂窝同层干扰,减少切换信令开销。其次,基于Lyapunov优化理论,该方案将整体网络平均能量效率优化问题,转换为用户最优传输资源分配和最优功率分配两个子问题,在最大化系统平均能量效率同时保证系统队列稳定性。由于该文将原优化问题进行了松弛,所得结果是局部最优解,而不是全局最优解。仿真结果表明,该文提出的基于不活跃用户的最优能量效率资源分配算法,其系统能量效率优于对比算法而计算复杂度较高。     

基于部分频率复用的多小区协作方案及容量分析

针对无线蜂窝网中的小区间干扰问题,给出一种基于部分频率复用的多小区协作传输方案.该方案将小区用户划分为中心用户和边缘用户,中心用户采用频率复用因子为1的本地基站通信,边缘用户采用频率复用因子为3的多基站协作通信,并通过对多个小区的基站进行功率控制,达到抑制小区间干扰、提高系统容量的目的.数值分析表明,相对于传统多小区蜂窝系统(Traditional Multi-Cell System,TMCS)和广义分布式天线系统(Generalized Distributed Antenna System,GDAS),所提多小区协作蜂窝系统(Multi-Cell Cooperative System,MCCS)可以有效地克服小区间干扰,提高系统容量.     

一种新的基于3D有源天线组网的干扰协调方案

传统2D有源天线仅能进行水平维的波束调整,而3D有源天线能够结合垂直维的波束调整,提升系统的吞吐量.由于3D有源天线组网的干扰情况与2D完全不同,需要研究新的干扰协调方案,本文提出一种基于3D有源天线组网的干扰协调方案,通过相邻基站间交互各自对系统资源的使用信息,使得基站间可协调分配系统资源,降低了系统整体干扰水平.仿真结果表明,提出的方案可有效地抑制小区间干扰,提升边缘用户的性能乃至整个小区的平均吞吐量.     

Performance analysis of hexagonal cellular networks in fading channels

This paper analyzes the location‐dependent performance metrics of coverage probability and spectral efficiency in hexagonal cellular networks under Rayleigh fading with a general distribution for shadowing and also including two special cases of no shadowing and lognormal shadowing. The effects of system parameters such as frequency reuse factor, transmission probability of base stations, and signal‐to‐interference‐plus‐noise ratio gap from Shannon capacity are accurately characterized. The proposed approach is applied to fractional frequency reuse (FFR) scheme where the impact of FFR on spectral efficiency is evaluated. Numerical results show that (i) in a lognormal‐shadowed Rayleigh fading channel with the shadowing standard deviation of 12 dB, the cell area wide spectral efficiency is degraded by approximately 40% compared with when there is Rayleigh fading without shadowing; (ii) the improvement in spectral efficiency achieved by FFR over the universal frequency reuse increases as the transmission probability increases and the shadowing becomes less severe; and (iii) in Rayleigh fading without shadowing environment where all the base stations are actively transmitting, FFR achieves approximately 20% improvement in spectral efficiency in the cell edge area. Interestingly, this improvement increases to about 30% if a 3‐dB signal‐to‐interference‐plus‐noise ratio gap from Shannon capacity is further accounted. Copyright © 2015 JohnWiley & Sons     

无线通信系统小区间干扰控制技术

小区间干扰是蜂窝移动通信系统的一个固有问题,严重影响到系统的覆盖能力及系统容量。特别是对于小区边缘用户,将会直接导致他们出现频繁掉网或无法接入网络的情况。从现有的研究成果和各种标准化组织(LTE、IEEE802.16m、UMB)对小区间干扰控制的方案来看,小区间干扰控制主要包括包括干扰随机化、干扰抵消以及干扰协调3类方法。文章中主要分析了干扰协调中的3种典型技术——部分频率复用、多基站多输入输出(MIMO)和功率控制,并且介绍了这3种技术在各种标准化组织中的具体实现方案。     

16T16R技术在农村LTE网络中的应用研究

随着LTE网络建设工程的进行,满足农村地区LTE网络覆盖的要求势在必行。本文通过对农村地区LTE基站与GSM900基站共站址的可行性进行研究,对于部分农村山区,GSM站间距过大,TD-LTE与GSM共站无法保证有效覆盖,增加新站点又会加大投资成本的情况进行了分析,为了最大化的挖掘当前共站模式的潜力,提升广覆盖能力及边缘用户感知,提出了16T16R方案并对其进行了研究。通过实验证明16T16R方案的优势和可行性。进而向现网推行,增强农村网络覆盖能力和服务能力,提升边缘用户感知。     

采用部分频率复用的小小区网络建模与分析

小小区组网技术被认为是解决迅速增长的移动数据量需求的方法。然而,密集的小小区组网会导致严重的小区间干扰。传统的部分频率复用方法不能完全照搬用在部署不规则的小小区网络内,急需一种合理高效建模采用频率复用小小区网络的方法,对其性能进行评估。利用随机几何理论对小小区网络考虑部分频率复用场景进行建模,推导了考虑部分频率复用的小小区网络下行覆盖概率和网络吞吐量的表达式。数值仿真结果显示：部分频率复用技术可以提高小小区网络下行覆盖概率,但是会降低网络图吞吐量。在满足覆盖概率约束条件下,得到了使得网络吞吐量最大的频率复用因子的表达式。以上结果对未来采用频率复用技术的小小区组网的具体实施具有重要的指导意义。     

The analysis of coverage probability,ASE and EE in heterogeneous ultra-dense networks with power control

The ultra-dense network is a promising technology to increase the network capacity in the forthcoming fifth-generation (5G) mobile communication networks by deploying lots of low power Small Base Stations (SBSs) which overlap with Macro Base Stations (MBSs). The interference and energy consumption increase rapidly with the number of SBSs although each SBS transmits with small power. In this paper, we model a downlink heterogeneous ultra-dense network where a lot of SBSs are randomly deployed with MBSs based on the Poisson point process. We derive the coverage probability and its variance, and analyze the area spectral efficiency and energy efficiency of the network considering three Fractional Power Control (FPC) strategies. The numerical results and Monte Carlo simulation results show that power control can mitigate the interference and balance the performances of inner-user and edge-user equipments. Especially, a great improvement of energy efficiency is archived with a little loss of area spectral efficiency when FPC is adopted. Finally, we analyze the effect of base stations’ (BSs’) sleeping on the performance of the network when it is partially loaded.     

A downlink beamforming assisted by locally positioned communication devices

Recently, multiple cell types with overlapping coverage have been deployed simultaneously to increase cellular network capacity. Cross‐tier interference is one of the key technical challenges in the use of this method. A simple and practical beamforming scheme assisted by locally positioned communication devices for the downlink of a multi‐cell wireless hierarchical cell structure system is proposed in this paper to maximize the capacity of the embedded small cell and simultaneously ensure minimal impact on the performance of existing macrocells. The locally positioned communication devices can be implemented with low complexity and at low cost and can continuously provide helpful and accurate information to base stations for the proper configuration of geographical cell coverage, allowing neighboring cells to cooperate effectively with each other. Simulation results verify that the proposed scheme can provide a significant gain over conventional systems not using the proposed algorithm. Copyright © 2013 John Wiley & Sons, Ltd.     

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。     

Coverage and capacity optimization in LTE network based on non-cooperative games

As to provide the optimal coverage and capacity performance,support high-data-rate service and decrease the capital expenditures and operational expenditures(OPEX)(CAPEX) for operator,the coverage and capacity optimization(CCO) is one of the key use cases in long term evolution(LTE) self-organization network(SON).In LTE system,some factors(e.g.load,traffic type,user distribution,uplink power setting,inter-cell interference,etc.) limit the coverage and capacity performance.From the view of single cell,it always pursuits maximize performance of coverage and capacity by optimizing the uplink power setting and intra-cell resource allocation,but it may result in decreasing the performance of its neighbor cells.Therefore,the benefit of every cell conflicts each other.In order to tradeoff the benefit of every cell and maximize the performance of the whole network,this paper proposes a multi-cell uplink power allocation scheme based on non-cooperative games.The scheme aims to make the performance of coverage and capacity balanced by the negotiation of the uplink power parameters among multi-cells.So the performance of every cell can reach the Nash equilibrium,making it feasible to reduce the inter-cell interference by setting an appropriate uplink power parameter.Finally,the simulation result shows the proposed algorithm can effectively enhance the performance of coverage and capacity in LTE network.     

Multitier heterogeneous network using stochastic geometry and factorial moment approaches

The rapid growth of small cells is driving cellular network toward randomness and heterogeneity. Usually, cellular networks are modeled by placing each tier (eg, macro, pico, and relay nodes) deterministically on a grid. In such a heterogeneous cellular network, the rational approach to characterize the base stations (BSs), user, and relay locations is by using random spatial models. When calculating the metric performances such as coverage probability, these networks are idealized without consideration of interference. Therefore, interference modeling remains the key issue for the deployment of small cells. This paper developed a single and multitier cellular network model that captures the downlink heterogeneous cellular network with variable parameters such as the target signal‐to‐interference ratio (SIR), transmitted power, and deployment density. In particular, we model ‐tier transmission and compare it with a single‐tier and traditional grid model to obtain tractable coverage probability using stochastic geometry and factorial moment. The obtained results demonstrate the effectiveness and analytical tractability to study the heterogeneous performance.