6G-REFERENCE: 6G haRdware Enablers For cEll fRee cohEreNt Communications & sEnsing

在城市地区，6 G需要依靠可持续的解决方案来科普不断增长的交通需求和人口密集化，同时提供颠覆性的能力，如物联网的实现。6 G-REFERENCE设想的解决方案包括用于联合相干通信和厘米波感知的超密集无小区部署，这平衡了6 GHz以下（例如降低路径损耗）和毫米波（例如宽带宽）范围的优势。这些系统面临五个基本挑战：（i）分布式无线电单元之间精确同步的需要;（ii）前传数据分发;（iii）感测能力的集成;（iv）低复杂度/成本/消耗无线电;以及（v）与其他服务共存。6 G-REFERENCE将开发解决所有这些问题的集成电路和天线组件解决方案。设计了频率/时间同步电路和一种新的基于全双工的连续同步框架。事实上，全双工使能解决方案将针对这种方案以及级联无线电单元之间的有效前传数据分发进行开发，并用于实现集成的单基地雷达感测。除此之外，在传感领域，6 G-REFERENCE将探索集成在天线中的环境传感器，重新使用同步框架进行精确定位，并开发新的阵列解决方案，如频率调制，以控制成本和功耗提供空间超分辨率。后者也将有针对性的时间调制阵列提供有效的单射频链多波束操作以及可重新配置的智能表面扩展功能的小型FMA/TMA阵列.最后，将开发动态IF和天线滤波，以实现高效的频谱共存方案。6 G-REFERENCE的最终目标是开发硬件使能器，最终构成未来6 G分布式无线电的参考设计。

In urban areas, 6G will need to rely on a sustainable solution to cope with the ever-increasing traffic demands and population densification, while providing disruptive capabilities like the materialization of the internet of sense. The solution envisioned by 6G-REFERENCE consist of ultra-dense cell-free deployments for joint coherent communications and sensing at cm-waves, which balance the benefits of sub-6GHz (e.g. reduced pathloss) and mm-wave (e.g. wide bandwidth) ranges. These systems face five fundamental challenges: (i) the need of accurate synchronization among distributed radio units; (ii) fronthaul data distribution; (iii) integration of sensing capabilities; (iv) low complexity/cost/consumption radios; and (v) coexistence with other services. 6G-REFERENCE will develop integrated circuit and antenna component solutions addressing all of them. It will design frequency/time synchronization circuits and a new continuous synchronization framework based on full-duplex. Indeed, full-duplex enabling solutions will be developed targeting such scheme as well as efficient fronthaul data distribution among cascaded radio units, and for enabling integrated monostatic radar sensing. Besides these, on the sensing domain, 6G-REFERENCE will explore environmental sensors integrated in the antenna estates, reuse the synchronization framework for accurate localization, and develop new array solutions like frequency modulation providing spatial superesolution at a contained cost and power consumption. The latter will be also targeted by time modulated arrays providing efficient single-RF chain multibeam operation as well asreconfigurable intelligentsurfaces extending the capabilities ofsmall FMA/TMA arrays. Finally, dynamic IF and antenna filtering will be developed to enable efficient spectrum coexistence schemes. The ultimate goal of 6G-REFERENCE is to develop hardware enablers that could end up constituting a reference design of future 6G distributed radios.