Cognitive radio (CR) network has emerged as a potential solution to the under-utilization problem of the allocated radio spectrum, where spectrum sensing (SS) plays a key role to enable the coexistence between primary and secondary users. It has attracted research interests, and several works have been reported in the literature. Nevertheless, the assumptions and simplifications introduced during the modeling of the communication system often yield misleading conclusions each time relevant aspects of their implementation on a testbed are omitted. Hence, prototypes are built to study their behaviour under real-world conditions, therefore software defined radio (SDR) has emerged as an ideal vehicle to allow researchers to experiment with prototypes of these CR approaches. In this survey, we provide an overview of the latest works in CR networks related to the spectrum awareness approaches and taking into account their implementation on testbeds. These approaches are classified from a practical point of view, where a detailed review of the existing works for each category is provided. A review of the existing SDR platforms is also exposed highlighting the main components and features of current architectures employed for experimental evaluation of CR approaches. Next, the challenges to implement current spectrum awareness approaches on SDR platforms are detailed. Finally, at the light of these reviews, research challenges and open issues are identified for future research directions.
INDEX TERMSCognitive radio, spectrum sensing, SDR platforms, hardware impairments.
The migration of TCMS communications to a Wireless Train Backbone (WLTB) is one of the main goals of CONNECTA-2 and Safe4RAIL-2 projects of Shift2Rail initiative. In this paper the suitability of 5G technology for a WLTB is analyzed, both for infrastructure-based and V2X networks. Obtained results indicate that 5G technology is suitable for a WLTB, but in order to cover a large number of consists either high-end 5G configurations need to be used (e.g. 4x4 MIMO in millimeter waves) or the requirements for the WLTB need to be scaled down.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.