Spectrum decision is the ability of a cognitive radio (CR) to select the best available spectrum band to satisfy secondary users' (SUs') quality of service (QoS) requirements, without causing harmful interference to licensed or primary users (PUs). Each CR performs spectrum sensing to identify the available spectrum bands and the spectrum decision process selects from these available bands for opportunistic use. Spectrum decision constitutes an important topic which has not been adequately explored in CR research. Spectrum decision involves spectrum characterization, spectrum selection and CR reconfiguration functions. After the available spectrum has been identified, the first step is to characterize it based not only on the current radio environment conditions, but also on the PU activities. The second step involves spectrum selection, whereby the most appropriate spectrum band is selected to satisfy SUs' QoS requirements. Finally, the CR should be able to reconfigure its transmission parameters to allow communication on the selected band. Key to spectrum characterization is PU activity modelling, which is commonly based on historical data to provide the means for predicting future traffic patterns in a given spectrum band. This paper provides an up-to-date survey of spectrum decision in CR networks (CRNs) and addresses issues of spectrum characterization (including PU activity modelling), spectrum selection and CR reconfiguration. For each of these issues, we highlight key open research challenges. We also review practical implementations of spectrum decision in several CR platforms.

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Emerging Fifth-generation (5G) mobile networks and associated technologies are expected to provide multi-service wireless applications with diverse specifications intended to address not only consumer-based smartphone applications, but also the needs of various vertical industry markets (e.g., healthcare, education, energy, mining, agriculture, manufacturing, and so forth). This paper extends 5G networks' technology orientation towards attaining economic value for all key 5G stakeholders, including customers, mobile network operators (MNOs), equipment vendors, public institutions, private enterprises, digital business start-ups and other third parties. Although several surveys and tutorials have discussed business models in connection with 5G networks, there is no comprehensive study on business models for emerging 5G networks from the MNO's perspective. In this survey article, we present and investigate key advances on business models for 5G networks and 5G MNOs in particular, from industry, use cases and research community perspectives. The paper focuses the theoretical business model concept from both strategic management and technological innovation perspectives. Thereafter, we discuss conventional business models for MNOs before presenting particular disruptive business models which can be considered for rolling out 5G networks with an aim to improve business efficiency. Additionally, the paper explores the emerging network deployment concept of private 5G networks and their related business models. Finally, we present some of the open research challenges and provide possible guidelines for implementing 5G business models based on various countries' socio-economic status and relevant 5G use cases applicable in a specific context of emerging economies.INDEX TERMS 5G, business model, business model innovation, disruptive business model, mobile network operators, private 5G networks. I. INTRODUCTION 21The Fifth-generation (5G) of mobile networks have been 22 defined by the International Telecommunication Union (ITU) 23 via its Radio-communication sector (ITU-R) under the 24 umbrella name ''International Mobile Telecommunication-25 2020'' (IMT-2020) to support multi-service wireless appli-26 cations by offering: higher data rates (20 gigabits/second 27 peak data rate), a huge number of wireless connections 28 (1 million connections per square kilometer), higher spec-29 tral efficiency (3 times higher than 4G networks), improved 30 energy efficiency (100 times higher than 4G networks) and 31 (e.g., Advanced Mobile Phone System (AMPS) and Total 46 Access Communication System (TACS)); Second-generation 47 (2G) digital systems (e.g., Global System for Mobile Com-48 munication (GSM)); Third-generation (3G) digital sys-49 tems (e.g., Universal Mobile Telecommunication System 50 (UMTS)); Fourth-generation (4G) digital systems (e.g., Long 51 Term Evolution (LTE) -IMT-Advanced); and emerging 5G 52 digital systems (e.g., New Radio) [4]. Fig. 2 depicts the 53 evolution of wireless cellular networks.54 A. MOTIVATION 55 With...

National regulatory authorities (NRAs) in developing countries need an accelerated means to formulate technical regulations for the telecommunications sector. This will enable countries to gain maximum benefits from the rapid advances in technology. The existing regulation-making processes are time-consuming and do not cope with the emergence of global technological changes. This article presents an efficient and quicker approach to formulate regulatory framework to govern the wireless technologies that are based on the Dynamic Spectrum Access (DSA) technique. The approach utilises Multicriteria Decision Analysis (MCDA) tools. The article uses a case study to evaluate dominant Dynamic Spectrum Management (DSM) frameworks. Finally, a sustainable DSM framework that has potential to address the digital divide challenges in the context of developing countries is proposed.

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The global migration of television (TV) from analogue to digital broadcast will see a large amount of TV spectrum available (called TV white space -TVWS) for other services such as mobile and broadband wireless access (BWA). Leading spectrum regulation authorities, such as the Federal Communications Authority (FCC) and the Office of Communication (Ofcom) are already defined rules and policies for licence-exempt access of the TVWS for BWA, especially for rural areas. Key to these rules and policies are the transmission and operating parameters to ensure protection of TV incumbents from harmful interference that might be caused by the white space devices (WSD). In this paper we propose a framework for TVWS access and key transmission parameters for licence-exempt operation of WSD for providing rural BWA within the Southern African Development Community (SADC). These parameters are determined based on extensive studies and consultations completed by the FCC and Ofcom, but are optimized for the SADC rural environment. We believe that this paper will serve as an important guideline document for the SADC regulators to decide suitable technology and policies when opening TVWS for BWA, especially for the rural communities.

Geo-location white space spectrum databases (GL-WSDBs) are currently the preferred technique for enabling spectrum sharing between primary users and secondary users or white space devices (WSDs) in the very-high frequency (VHF) and ultra-high frequency (UHF) bands. This is true because technologies for making low-cost WSDs capable of autonomous sensing and detection of available white space (WS) spectrum are not yet feasible. This paper reviews the necessary enabling technical conditions to allow coexistence of primary and secondary systems in the VHF and UHF spectrum through a GL-WSDB approach. The practical implementation of South Africa's first GL-WSDB was performed. Results of WS channels available from five cities in South Africa calculated from the implemented GL-WSDB was compared with a commercially available GL-WSDB and was found to be 68% similar. Additionally, results from the implemented GL-WSDB were compared with measurements obtained from field spectrum scanning campaigns at two different locations in Cape Town, South Africa, and was found to be 64% similar.