面向5G云无线接入网的光纤MIMO和无线MIMO融合的传输技术研究

The transmission system of wireless signals between central stations and antenna towers (i.e. front-haul systems), is a bottleneck in achieving broadband and high speed wireless access. With the development of big data, internet of things and 5G wireless mobile communications, it is essential and more important to have high speed and broadband cloud wireless access networks with support of wireless MIMO signal transmission and distribution. Therefore, a less complexity front-haul transmisison system, which must support wireless MIMO, is required to be obtained, which is considered a key technical challenge at present and in the near future. In this project, the combination of optical fiber mode disvision multiplexing (i.e. optical fiber MIMO) with radio over fiber (ROF) will be explored, to achieve low-complexity front-haul transmission systems and support high capacity wireless MIMO signal transmission and distribution. For this project, we will conduct the following researches: (1) investigate and analyze mode coupling in multi-mode fibers, and determine the high-order modes that lead to less mode coupling; (2) investigate chromatic dispersion of the high-order modes and its impact on and limitations of wireless signal transmision that is based on radio over fiber;(3) investigate and find the technical methods for the reduction of the impact of mode coupling and high chromatic dispersion of the high order modes;(4) investigate the applicability and limitations of various multimode fibers to optical fiber MIMO short-hual transmission and find appropriate technical solutions to tackle the technical limitations; and finally (5) investigate and analyze the application of radio over fiber front-haul transmission systems with optical fiber MIMO to support wireless MIMO signal transmission, and establish the design guidelines of low complexity front-haul transmission systems.

从中心站到天线塔的无线信号传输系统（即前传系统）是实现宽带高速无线接入的瓶颈。随着大数据、物联网及5G移动通信等技术的发展，适用于无线MIMO信号传输的宽带高速云无线接入网的重要性日益突出，支持无线MIMO信号的传输前传系统是当前和今后亟待研究和解决的关键技术问题。本项目研究光纤模式复用（即光纤MIMO）与无线MIMO融合的传输技术，结合光载无线电技术，旨在为实现低复杂、大容量的无线MIMO前传系统奠定基础。项目将首先研究和分析光纤模式之间的耦合，确定模式耦合较小的高阶模，研究高阶模式内色散及其对传输的影响，研究降低模式耦合和色散影响的技术方法，研究各种多模光纤在光纤MIMO短距离传输中的技术限制和可能的解决方案，最后研究和提出融合光纤MIMO与无线MIMO技术的光载无线电前传传输系统设计指南。

从中心站到天线塔的无线信号传输系统（即前传系统）是实现宽带高速无线接入的瓶颈。随着大数据、物联网及5G移动通信等技术的发展，适用于无线MIMO信号传输的宽带高速云无线接入网的重要性日益突出，支持无线MIMO信号的传输前传系统是当前和今后亟待研究和解决的关键技术问题。.本项目研究光纤模式复用（即光纤MIMO）与无线MIMO融合的传输技术，结合光载无线电技术，旨在为实现低复杂、大容量的无线MIMO前传系统奠定基础。项目首先研究和分析光纤模式之间的耦合，确定模式耦合较小的高阶模，研究高阶模式内色散及其对传输的影响，研究降低模式耦合和色散影响的技术方法，提出了4种不同结构的模式转换器。然后针对光纤MIMO和无线MIMO融合传输系统中微带线传输中的辐射泄漏，提出3种射频封装技术。最后，针对光纤和MIMO融合的传输系统中天线技术，研究支持5G MIMO系统的宽频带、多频段天线和MIMO天线，提出了几种光纤MIMO和无线MIMO融合的传输系统的MIMO天线技术。