Optimizing the optical/wireless interface for short-haul access networks

前传是指5G蜂窝基站和天线站点之间的通信（回程将5G数据从基站传输到互联网骨干网）。5G庞大的客户群和激进的数据速率带来了前所未有的前传要求。目前的研究为新兴的前传光传输找到了合适的解决方案，例如频谱效率低下的公共无线电接口（CPRI）。我们将解决如何在光/无线接口实现最佳功率和频谱效率的问题。如果我们要满足不断增长的需求，同时减少环境足迹，这些问题至关重要。这些网络将成为世界上70%使用移动的服务的人口的支柱，以及数十亿将构成物联网的设备。 ** 长距离光通信推动了光学元件和系统的创新。一旦技术成熟，降低价格点允许这些创新在成本敏感的短途网络中采用。然而，光纤无线电在长途传输中是不存在的。本研究计划的目标是利用最新的器件突破并将其用于光/无线接口。 项目将涵盖空间多路复用、相干检测和硅光子学，这是光通信中最热门的三个领域，以实现模拟（或数字）光纤无线电。** 空间复用的使用有望将光纤容量提高一个数量级。光纤中的多模或多芯可以携带独立的数据，就像无线中的多个天线一样。光纤芯之间的串扰或芯内的模式限制了光纤容量的增加。多输入多输出（MIMO）技术可以克服串扰并且通常在无线中采用。目前的研究测试MIMO在光学和MIMO在无线，假设都不会看到由于另一个性能下降。 我们将研究光纤和无线信道维斯于MIMO在端到端可靠性和/或容量方面的影响。**光通信设备以令人难以置信的速度发展，目前的飞跃集中在集成硅光子学的全套组件上。相干光检测的颠覆性采用，与现在接入网络中无处不在的直接检测相比，是硅光子学可以降低成本的一个例子。相干检测的灵敏度优势必须用于光纤无线电，同时避免使用高功耗的模数转换器和广泛的数字信号处理（长途传输中的必要条件）。

Fronthaul is the term given to communications between the 5G cellular base station and antenna site (backhaul takes 5G data from the base station to the internet backbone). The enormous client base and aggressive data rates for 5G brings unprecedented fronthaul requirements. Current research finds expedient solutions to burgeoning fronthaul optical transport, such as the spectrally inefficient common public radio interface (CPRI). We will address the lingering questions on how to achieve optimal power and spectral efficiency at the optical/wireless interface. These questions are crucial if we are to meet escalating demand while diminishing the environmental footprint. These networks will be the mainstays of the 70% of the world population using mobile services, and billions of devices that will comprise the internet of things. ******Long reach optical communications drive innovation in optical components and systems. Once technologies mature, dropping price points allow these innovations to be adopted in cost sensitive, short haul networks. Radio-over-fiber is, however, nonexistent in long haul. Taking the latest device breakthroughs and exploiting them for the optical/wireless interface is the objective of this research program. Projects will cover spatial multiplexing, coherent detection and silicon photonics three of the hottest areas in optical communications to enable analog (or digital) radio-over-fiber. ******The use of spatial multiplexing holds the promise of increasing fiber capacity by an order of magnitude. Multiple modes or multiple cores in the fiber can carry independent data, much like multiple antennas in wireless. Crosstalk among fiber cores, or modes within cores, limits the increase in fiber capacity. Multiple input, multiple output (MIMO) techniques can overcome crosstalk and are commonly employed in wireless. Current research tests MIMO on optical and MIMO on wireless, assuming that neither will see a performance degradation due to the other. We will examine the impact of optical and wireless channels vis-à-vis MIMO increases in end-to-end reliability and/or capacity.******Optical communications devices evolve at an incredible rate, with the current leap forward focusing on integrated silicon photonics for a panoply of components. The disruptive adoption of coherent optical detection, versus the omnipresent direct detection now in access networks, is one example of where silicon photonics can drive down costs. The sensitivity advantages of coherent detection must be harnessed for radio over fiber, while avoiding the power hungry use of analog to digital converters and extensive digital signal processing (de rigueur in long haul).