## 5 Discussions and Conclusions  
There have been several research studies for JCRS in the past, with a focus on waveforms and network possibilities [1; 2; 4; 5; 8; 14]. However, a comprehensive survey on the RF hardware comprising of front-ends, antenna, beamformers, and packaging along with the related system perspectives has been missing in the literature. This article aims to fill that gap, while focusing more on the mmWave implementation of such systems.  
JCRS is a power technology, which will increase the resilience and security of almost all verticals. However, much research is still ahead, especially for full-duplex operation. To design compact RF hardware, achieving high bandwidth and self-interference cancellation will be the next milestone in enabling high throughput and high resolution JCRS systems for future 5G/6G ecosystems. However, depending on the figure-of-merits, the nature of integration will vary. The introduction of the 802.11 bf standard [98] for Wi-Fi sensing will play an important role as a starting point. The high bandwidth available in ultra-wide band (UWB) standards can play a role as UWB sensing to support presence detection and environment mapping. The first generations of JCRS systems may have only minor modifications over the traditional RF hardware, mostly due to the missing demand from the users. However, as discussed in this paper, the path to solve the challenges for a co-designed system, optimized for hardware reuse, needs to be paved without additional power and area overheads. The main research activities should focus on the realizability of a low power compact mmWave solution that can address KPIs for both communication and sensing. The benefits are limited if the two systems are working only in cooperation. Hardware reuse and a co-designed reconfigurable RF hardware will provide the right impetus towards making RaaS a reality. The opportunities are limitless, whether it is the coordination of radars in the context of V2X or to build context aware communication systems enabling 6G networks.  
Standardization process will be another milestone in reaching spectrum sharing, synchronization, localization, and other KPIs such as the other systems of radar-assisted communication, communication assisted radar, Radar as a Service, etc. The effort will ensure the seamless co-existence of communication and radar sensing systems, bringing more resilience for smart cities, smart factories, and other verticals. The success of 802.11 bf systems will also a play a role in understanding the first usage of integrated communication and radar sensing using the same band. However, it is of paramount importance to verify the possible hardware architectures for JCRS systems as inputs to the standardization and case study discussions in order to facilitate the integration of this powerful feature/technology in 6G and beyond communication networks.  
Conceptualization, P.S. and A.H.; methodology, P.S., A.H., M.U. and S.K.; investigation, P.S., A.H., M.U. and S.K.; writing--original draft preparation, P.S., A.H., M.U. and S.K.; writing--review and editing, P.S., A.H., M.U. and S.K. All authors have read and agreed to the published version of the manuscript.  
This work is financed on the basis of the budget passed by the Saxon State Parliament.  
No new data were created or analyzed in this study. Data sharing is not applicable to this article.  
The authors would like to acknowledge the contribution of [PERSON] and [PERSON] to this work.  
The authors declare no conflict of interest.