Since 1990’s, the demand on wireless devices, mobile and wireless networks, has experienced unprecedented growth which makes the frequency bands more and more crowded.
Experimental results show that SDR as the central unit extends the functions of the network, re-configurability, and also provides interoperability in the heterogeneous network. Software-defined radio (SDR) has been used as the central unit whose function is to sense the spectrum and connect the IoT devices. An attempt is made to design, and implement a preliminary step called sensing control layer which is the first step out of the framework of CIoT. CR has the capabilities to implement artificial intelligence schemes to provide learning features and automatic reconfiguration. The reason for deploying CR as the central device is to manage and provide an interface to different users. The Cognitive Internet of Things (CIoT) has emerged as an equipping technology, which focuses on the functions of CR and its potential contribution to IoT. Due to the diversification of applications, embedding the IoT technology with cognitive capability aids intelligence and improves the overall performance of the system. Cognitive radio (CR) that has connectivity to the Internet strengthens the concept of “Internet of Things”.
IoT devices are interconnected in heterogeneous networks, which have interference, and hardware–software interconnection problems. The exponential growth of Internet of Things (IoT) leads to spectrum-related issues such as Spectrum Allocation and Management. The review also revealed that for mid-band 5G communication, the commonly used electronic switching such as PIN diodes have sufficient isolation loss to provide the required beam performance. The review provides new insights on pattern reconfigurable antenna where such antennas are categorized as beam steering antenna and beam shaping antennas where the operation modes and purposes are clearly investigated. A variety of design configurations have also been critically studied for their compatibilities to be operated in the mid-band communication systems. The various adaptation techniques of radiation pattern reconfigurable planar antennas and the understanding of its antenna design approaches has been investigated for its radiation pattern enhancement. This review begins with an overview of the underlying principals in reconfiguring radiation patterns, followed by the presentations of the implemented innovative antenna topologies to suit particular advanced features. They represent the key of antenna technology for materializing a high rate transmission, increased spectral and energy efficiency, reduced interference, and improved the beam steering and beam shaping, thereby land a great promise for planar antennas to boost the mid-band 5G. This paper presents a comprehensive review of reconfigurable antennas, specifically in terms of radiation patterns for adaptation in the upcoming Fifth Generation (5G) New Radio frequency bands.
New requirements in communication technologies make it imperative to rehash conventional features such as reconfigurable antennas to adapt with the future adaptability advancements.
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