3.5GHz固定无线接入系统干扰分析及其解决方法

本文分析了3．5GHz固定无线接入系统的同频、邻频干扰，以及与其他通信系统的干扰问题．并提出简单的计算和解决方法。     

40~50 GHz固定无线接入系统干扰共存分析

为了分析在40.5~42.3 GHz和48.4~50.2 GHz频段引入固定无线接入系统的可行性,对该频带固定无线接入系统与频率划分表中各主要业务系统间的共存问题进行了研究。通过计算机静态建模方法,分析了此频段内固定无线接入系统对固定、卫星固定、广播、射电天文等业务系统的干扰功率密度随距离变化情况,并根据相关业务的干扰保护准则获得对不同业务的隔离距离,从而证明在一定隔离距离条件下,固定无线接入系统不易对同频段的主要业务造成有害干扰,可以在该频段引入固定无线接入系统。研究成果可支撑我国无线电频谱管理部门对该频段业务的再次划分。     

3.5GHz频段LTE室内覆盖系统与卫星固定业务地球站同频共存分析

3.5GHz的频段规划需要研究LTE室内覆盖系统与卫星固定业务同频共存的场景。通过确定性分析以及系统仿真,本文给出了两系统共存所需的隔离距离和其他干扰规避措施建议。     

6G Hz频段IMT系统对卫星固定业务干扰分析

6 GHz作为移动宽带发展频谱使用有利于全球5G产业持续健康发展,为满足6 GHz频段国际移动通信(IMT)系统的使用需求,需要开展6 GHz频段下IMT与同频卫星固定(地对空)业务频谱共存研究,以保护该频段的卫星固定(地对空)业务的正常工作。首先分析IMT系统对卫星固定(地对空)业务的干扰场景,然后采用蒙特卡洛仿真方法计算IMT系统对卫星的集总干扰,最后分析干扰情况。结果表明,在智能制造室内场景和室外场景两种情况下,对于长期保护标准和短期保护标准,均无干扰,将6 GHz频段用于IMT系统能够与卫星固定(地对空)业务共存。     

无线接入系统和技术

无线接入是一个统称，可分为固定无线接入、移动无线接入，宽带接入、窄带接入，高速移动接入、低速移动接入等,因此蜂窝移动通信、集群移动通信、无绳电话、3.5GHz地面固定无线接入系统、本地多点分配业务（LMDS）和蓝牙（Bluetooth）技术，以及个人接入系统（无线市话）等都可划入无线接入的范畴。本文拟对最近两、三年来被看好的若干无线接入系统和技术作简要介绍，并提一些看法。１３．５GHz地面固定无线接入系统对3.5GHz地面固定无线接入系统，已进行了数年技术试验，体制成熟，可投入商用。为了鼓励竞争，促进无线接入市场的发展…     

3.5GHz因定无线接入系统

对MMDS系统进行了简要概述,认为3.5GHz固定无线接入系统对于中国来说是一个经济、高效、快速、理想的无线解决方案,并分析了3.5 GHz系统的三个构成部分.从覆盖范围、系统容量和业务能力等三个方面介绍了3.5 GHz系统的技术特性,最后强调固定无线接入的定位是有线接入的补充.     

固定宽带无线接入系统及其特点

介绍了常见固定宽带无线接入系统的基本情况,对LMDS接入技术、3.5GHz无线接入、MMDS接入技术、无线局域网技术、固定卫星接入技术以及不可见光纤无线系统的特点进行了分析说明。     

3.5 GHz频段5G系统对ATG系统干扰分析

为研究3.5 GHz频段地面5G系统对地空宽带通信(air to ground, ATG)系统同频同步干扰情况,对该频段中5G系统与飞机上ATG系统间的同频共存问题进行了系统间同频共存分析. 采用5G系统技术参数,在城区、城郊连续和郊区不同场景下,仿真5G系统基站(base station, BS)对机载ATG系统干扰情况及5G系统用户对ATG BS干扰情况,分别计算得到不同场景下5G系统BS对机载ATG系统及5G系统用户对ATG BS的平均干扰功率密度. 仿真结果表明,地面5G系统BS对机上ATG系统的同频干扰影响较小,可将该干扰视为可接受干扰. 同时,本文还给出了ATG BS的部署隔离距离参考值.     

TD-LTE与卫星广播系统干扰共存仿真研究

由于频谱资源的限制和不断增长的业务需求,未来在1.4GHz上很有可能出现TD-LTE室内覆盖系统与卫星广播业务（BSS）共存的情况,两系统在同一地理区域共存时产生的干扰会引起系统吞吐量的损失。针对这一问题,对TD-LTE室内覆盖系统与卫星广播系统在1.4GHz频段上的共存拓扑结构进行了重点分析,并通过确定性分析和系统级仿真两种方法评估了TD-LTE室内覆盖系统与BSS在同频和邻频两种情况下共存时的干扰状况,得到了两系统在不同地球站仰角下所需要的最小保护距离。通过仿真给出的相应结果和结论,对未来在1.4GHz频段上TDLTE室内覆盖系统与BSS系统的实际部署提出了合理建议。     

5G通信基站对邻频C波段卫星地球站干扰的分析与处置

为了解决5G通信基站对C波段单收地球站的干扰共存问题,选取一个干扰的实例作为研究对象,分析干扰成因,并通过实测数据得出带外抑制比ACLR是影响邻频干扰大小的主要因素。根据地球站的干扰保护准则并通过工程实践,可计算得出两系统邻频共存时需要保持的ACLR。     

27~29.5 GHz频段IMT-2020(5G)系统对卫星固定业务系统干扰分析研究

基于WRC-19 1.13议题研究框架和国内6 GHz以上第五代（the 5th Generation,5G）移动通信候选频段的兼容性分析要求,针对27~29.5 GHz频段国际移动通信-2020（International Mobile Telecommunications-2020,IMT-2020）系统对卫星固定业务（Fixed Satellite Service,FSS）系统的干扰进行研究.采用集总干扰评估方法,比较了FSS静止轨道卫星经度分别在东经59°、85°、113°时,IMT-2020（5G）系统基站对FSS上行链路的干扰情况.此外,还针对IMT-2020（5G）基站采用不同阵列配置进行了兼容性仿真研究.研究表明,在该频段IMT-2020（5G）系统不会对FSS产生有害干扰,特别是在IMT-2020（5G）基站采用大规模天线阵列的情况下.研究结果可为未来27~29.5 GHz频段IMT-2020（5G）系统频率规划实际部署及保护FSS系统提供技术依据.     

3.5GHz固定无线接入系统的典型技术与应用

对3.5GHz固定无线接入系统的应用背景和系统情况进行了叙述;介绍了广州3.5GHz FWA实验网方案和设计时考虑的问题。     

卫星移动业务C频段的干扰研究

分析了卫星移动业务与地面固定业务共用C频段时,对该频段地面固定业务的干扰情况。以世界无线电通信大会议题提出的卫星移动业务候选频段为背景,从理论上分析了卫星移动系统上行链路与下行链路对固定业务的干扰情况。利用国际电联相关建议搭建了干扰分析模型,并进行了仿真分析。通过分析,在假设的场景下,卫星移动业务的上行链路会对地面固定业务产生干扰,而上行链路不会产生干扰。     

Switchable-polarisation antenna for measuring polarisation dependence of multipath in 3.5 GHz FWA systems

A previous study has shown that circular polarisation reduces multipath delay spread in indoor radio systems. However, the effect is more difficult to measure in outdoor fixed wireless access (FWA) systems. Presented is a switchable-polarisation antenna that enables accurate comparison of linear against circular polarisation in outdoor measurements. Results show that circular polarisation reduces the multipath delay spread in suburban FWA systems at 3.5 GHz.     

Protection of FS receivers from the interference produced by HEO FSS satellites in the 18 GHz band: Effect of the roll‐off characteristics of the HEO system satellite antenna beams

This paper focuses on the protection of fixed service (FS) receivers from the aggregate interference produced by the satellites of multiple highly elliptical orbit satellite systems (HEOs). It analyzes the protection given to FS receivers operating in the 18 GHz frequency band by the power flux‐density (pfd) mask contained in Article 21 of the 2003 edition of the Radio Regulations [International Telecommunication Union, 2003.]. This mask establishes the maximum allowable value for the pfd produced by any of the satellites of a non‐geostationary system at the Earth's surface. The protection offered to FS receivers by this mask is analyzed in four interfering environments, each containing three identical HEO systems. Four types of HEO systems, with different orbital characteristics, are considered: three having satellites that operate only in the northern hemisphere and one having satellites that operate in both hemispheres. All satellite antennas are assumed to radiate 0.3° spot beams. Each HEO satellite is modelled so that the maximum pfd it produces at the Earth's surface just meets the RR Article 21 mask and the analysis takes into account the roll‐off characteristics of the satellite antenna beams. To reflect the multiplicity of possibilities concerning the geographical location and technical characteristics of the victim FS receiver (e.g. latitude, longitude, azimuth and elevation of its receiving antenna, antenna gain, receiver noise temperature, etc.) a number of cases were evaluated. The concept of interference in excess [Int. J. Satellite Commun. Networking 2006; 24 : 73–95] was used to combine the results corresponding to FS receivers located at the same latitude and having the same receiving antenna elevation angle but for which the location longitude and the azimuth of the pointing direction of its receiving antenna are randomly chosen. Results are expressed in terms of the cumulative distribution function of the interference in excess. Copyright © 2008 John Wiley & Sons, Ltd.     

INTERFERENCE AND SHARING CONSIDERATIONS BETWEEN THE SPACE OPERATIONS/SPACE RESEARCH SERVICE AND NEW APPLICATIONS OF THE FIXED SERVICE NEAR 2 GHz

Many satellite projects use radio frequencies in the bands 2025–2110 MHz and 2200–2290 MHz for spacecraft operations and data transmission. Frequencies below a few GHz are of particular interest because of favourable propagation conditions and attractive antenna designs. The above bands have to be shared with the fixed service and the mobile service. The fixed service has announced plans for the introduction of vast quantities of a new type of application, referred to as the point-to-multipoint system to be used for data distribution or local access systems. At International Telecommunications Union (ITU) meetings, scenarios assuming the worldwide deployment of more than one million new fixed service installations have been presented. This paper assesses the interference potential from point-to-multipoint systems to conventional direct links between spacecraft and earth stations. The interference into the space as well as into the ground segment has been investigated. Typical earth stations with a 15 m dish size have been assumed. Interference received at low earth orbiters as well as geostationary satellites has been evaluated. It is shown that sharing will not be possible without technical or operational constraints on the fixed service systems. © 1997 by John Wiley & Sons, Ltd.     

24.65～25.25 GHz频段IMT-2020（5G）系统对卫星广播系统干扰分析

基于WRC-19 1.13议题研究框架和国内6 GHz以上IMT-2020（5G）候选频段的兼容性分析要求,针对24.65～25.25 GHz频段IMT-2020（5G）系统对卫星广播系统的干扰进行研究。采用蒙特卡洛的仿真方法,比较了静止轨道卫星经度分别在东经59°、85°、113°时,IMT-2020（5G）系统基站对卫星广播系统上行馈线链路的集总干扰情况。通过仿真分析,评估了5G系统对不同轨位卫星两类载波的集总干扰水平。研究结果表明,在该频段,IMT-2020（5G）系统不会对卫星广播系统产生有害干扰,相关研究结果可为未来毫米波频段IMT-2020（5G）系统频率规划以及保护卫星广播系统提供技术依据。     

Potential interference and rain attenuation at 21.4–22 GHz downlink broadcasting satellite signals

World Radio Conference WRC-1992 has allocated the frequency band 21.4–22.0?GHz to regions 1 and 3 to be utilised to carry direct broadcasting satellite (DBS) services. This high-frequency band is more susceptible to rain attenuation, leading to degradation of the signal quality. Moreover, this frequency band is assigned to two different services, i.e. satellite broadcasting and fixed mobile services at the same regions; hence, the impact of intersystem interference in a depredated signal is a critical issue in the DBS receiver. In this study, the effects of rain attenuation on the DBS downlink signals as well as the impact of the potential interference on the reception quality will be estimated. An interference scenario will be introduced to investigate the system performance in both propagation mechanisms of clear-sky and rain conditions.     

On the protection of fixed service receivers from the interference generated by non‐GSO satellite systems operating in the 3.7‐4.2 GHz band

In this work, the current power‐flux density limits in Article 21 of the ITU‐R Radio Regulations for non‐geostationary satellite orbit (GSO) systems operating in the 3.7‐4.2 GHz band are analyzed. These limits aim the protection of fixed service receivers, operating in the same frequency band, from the interference produced by non‐GSO satellite systems. The analysis was motivated by Resolution 157 of the World Radiocommunication Conference 2015, that recognized the need for a revision of Article 21 with a view to enabling non‐GSO systems to operate in these fixed‐satellite service frequency bands while ensuring that existing primary services are protected. In the analysis, 5 different circular Walker Delta type satellite constellation structures, adequately chosen, are considered, and the results show that the current power‐flux density (pfd) limits may impose undue constraints to non‐GSO systems operating in this band. Therefore, a methodology to investigate a more adequate pfd limiting mask is presented and used to generate an alternative mask. An evaluation of the proposed pfd mask shows that it does not impose unnecessary constraints to the non‐GSO satellite systems. This, along with other facts, indicates that the proposed pfd limits are, indeed, much more adequate than the current ones.