Wi-Fi is still by far the most common and cheapest wireless technology to deliver Internet services to users and digital devices, which are dramatically increasing in terms of quantity and the quality of services they require. As a result, Wi-Fi networks are the most congested wireless technology. This issue incentivised many researchers to propose radio resource management solutions in unlicensed frequency bands to alleviate that problem. Nonetheless, these solutions lack coordination among the network operators who utilise wireless spectrum and hence, they do not efficiently solve the problem. In this work we propose a ‘win-win’ platform based on Software Defined Wireless Networking (SDWN) that facilitates a trusted and accountable Wi-Fi network access trading among networks operators, to solve the congestion problem in a collaborative manner that is beneficial for everyone. The platform enables Wi-Fi networks operators to both improve their users' satisfaction and earn incentives hence, achieving the ‘win-win’ equilibrium. Evaluation results in a dense Wi-Fi network environment show how the ‘win-win’ platform significantly improves satisfaction and achieved data rates for the cooperating networks operators' users in comparison to the standard approach.

The dawn of near 100% global coverage and Tbps data rates is not far as the six generation (6G) networks official roll out is expected around 2030. To match these expectations, new paradigm shifts in terms of global coverage and utilised spectrum are currently under investigation. Space-Air-Ground Integrated Networks (SAGINs) are envisaged to be an integral part of 6G networks to achieve network connectivity anywhere on earth using terrestrial, aerial, and satellite communications. However, the provision of end-to-end routes in SAGIN is very complex given its multi-dimensional, multi-tier, and heterogenous nature. Moreover, satisfying the Quality of Service (QoS) requirements and security of these routes is not trivial in SAGINs. In this paper, a novel hybrid Software Defined Networking (SDN)-based architecture for secure and QoS aware routing in SAGINs is proposed. Using Multiple SDN controllers at different levels in SAGINs, the architecture follows a hierarchical structure with different routing provisioning layers, at different levels, to exploit the heterogeneity of SAGINs to find multiple routes that satisfy the security and QoS requirements. To illustrate its efficiency, a case study of Vehicle-to-Everything (V2X) technology is used to show how an end-to-end charging service, for an electric vehicle, can be built on top of the proposed architecture.

Cooperation to access wireless networks is a key approach towards optimizing the use of finite radio spectrum resources in overcrowded unlicensed bands and to help satisfy the expectations of wireless users in terms of high data rates and low latency. Although solutions that advocate this approach have been widely proposed in the literature, they still do not consider a number of aspects that can improve the performance of the users’ connections, such as the inclusion of (1) cooperation among network operators and (2) users’ quality requirements based on their applications. To fill this gap, in this paper we propose a centralized framework that is aimed at providing a “win‐win” cooperation among Wi‐Fi and cellular networks, which takes into account 5G technologies and users’ requirements in terms of Quality of Service (QoS). Moreover, the framework is supported by smart Radio Access Technology (RAT) selection mechanisms that orchestrate the connection of the clients to the networks. In particular, we discuss details on the design of the proposed framework, the motivation behind its implementation, the main novelties, its feasibility, and the main components. In order to demonstrate the benefits of our solution, we illustrate efficiency results achieved through the simulation of a smart RAT selection algorithm in a realistic scenario, which mimics the proposed “win‐win” cooperation between Wi‐Fi and cellular 5G networks, and we also discuss potential benefits for wireless and mobile network operators.

Abstract As we enter a new era of next-generation wireless systems represented by Fifth Generation (5G) New Radio (NR) technology, it is essential to grasp the recent progress in their standardization and development. This article offers a concise survey of the 5G NR system design that aims at introducing its features according to the relevant Third Generation Partnership (3GPP) specifications. Our focus is set on the flexibility of 5G NR, which refers to its capability to support novel services and technologies, such as enhanced Mobile Broadband (eMBB) and Internet of Things (IoT) for massive Machine Type Communications (mMTC) while satisfying the underlying quality requirements. The key enablers of the 5G NR operation are scalable numerology, ultra-lean and beam-centric design, support for low latency, spectrum extension, and forward compatibility. This work summarizes these important features by studying the overall 5G architecture and the user-/control-plane protocol stacks specified by 3GPP. Furthermore, the impact of scalable numerology on system performance is discussed. Finally, we also consider open challenges and future research directions.

Current interference management solutions for dense IEEE 802.11Wireless Local Area Networks (WLANs) rely on locally measuring the cumulative interference at the Acess Point (AP) in charge of adjusting the spectrum resources to its clients.These solutions often result in coarse-grained spectrum allocation that often leaves many wireless users unsatisfied and increases the spectrum congestion problem instead of easing it.In this paper, we present a centralized interference management algorithm that treats the network-wide interference impact of each channel individually and allows the controller to adjust the radio resource of each AP while it is utilised.This coordinated allocation takes into account the Quality of Service (QoS) requirements of downlink flows while minimizing its effect on neighbouring APs.Therefore, this paper proposes a novel approach for quantifying the interference impact of each employed channel and jointly addressing the user-side quality requirements and the network-side interference management.The algorithm is tailored for operatoragnostic Software-Defined Networking (SDN)-based Radio Resource Management (RRM) in dense Wireless Fidelity (Wi-Fi) networks and adopts a fine-grained per-flow approach.Simulation results show that our algorithm outperforms existing solutions in terms of reducing the overall interference, increasing the capacity of the wireless channel, and improving the users' satisfaction.

This paper presents a novel Access Point (AP) selection strategy based on a potential game played at a centralized controller. The proposed approach relies on Software Defined Networking (SDN), which has long been considered in the literature as a method to control management functionalities for Wi-Fi networks. The use of SDN provides a global view of the network, which guarantees an efficient distribution of Wi-Fi users among the APs. The centralized potential game proposed in this paper is based on the Fittingness Factor (FF) concept, which is a metric reflecting the suitability of the available spectrum resources to the application requirements. This paper describes the development of a new SDN-based framework that implements the potential game-based algorithm relying on the FF for efficient AP selection. The simulation campaign illustrates the important gains, both in terms of data rates assigned to the Wi-Fi users and their satisfaction compared against the AP selection suggested by the IEEE 802.11 standards and another algorithm proposed in the literature.

This paper addresses the problem of Access Point (AP) selection in large scale IEEE 802.11 Wireless Local Area Networks (WLANs) through the study of a shopping mall use-case. We investigate through simulations the impact of a smart AP association algorithm including two strategies based on the Fittingness Factor (FF) concept, which considers the suitability of the requirements for different stations accessing the network, on the performance of the WLAN studied in this use-case. The proposed AP selection algorithm is implemented in a framework based on Software Defined Network (SDN), which handles the APs distributed in the WLAN of the considered shopping mall use-case. The simulation campaign illustrates the important gains, both in terms of users' satisfaction and assigned throughput compared against the AP selection suggested by the IEEE 802.11 standards. Moreover, this result gives to the service providers a trade-off between efficiency and complexity delivered by the proposed strategies included in our smart AP selection algorithm when the SDN framework is used to manage large WLANs.

In spite of the enormous popularity of Wi-Fi-enabled devices, the utilisation of Wi-Fi radio resources (e.g. RF spectrum and transmission power levels) at Access Points (APs) is degraded in current decentralised Radio Resource Management (RRM) schemes. Most state of the art centralised control solutions apply configurations in which the network-wide impacts of the involved parameters and their mutual relationships are ignored. In this paper, we propose an algorithm for jointly adjusting the transmission power levels and optimising the RF channel assignment of APs by taking into account the flows' required qualities while minimising their interference impact throughout the network. The proposed solution is tailored for an operator-agnostic and Software Defined Wireless Networking (SDWN)-based centralised RRM in dense Wi-Fi networks. Our extensive simulation results validate the performance improvements of the proposed algorithm compared to the main state of the art alternative by showing more than 25% higher spectrum efficiency, satisfying the users' demands and further mitigating the network-wide interference through flow-based and quality-oriented power level adjustment.

This paper addresses the problem of access point (AP) selection in large Wi-Fi networks. Unlike current solutions that rely on received signal strength to determine the best AP that could serve a wireless user's request, we propose a novel framework that considers the quality of service (QoS) requirements of the user's data flow. The proposed framework relies on a function reflecting the suitability of a Wi-Fi AP to satisfy the QoS requirements of the data flow. The framework takes advantage of the flexibility and centralised nature of software defined networking (SDN). A performance comparison of this algorithm developed through an SDN-based simulator shows significant achievements against other state-of-the-art solutions in terms of provided QoS and improved wireless network capacity.

This paper illustrates a Universal Software Radio Peripheral (USRP)-based real-time testbed that is able to evaluate different spectrum management solutions that exploit the Cognitive Radio (CR) paradigm. The main objective of this testbed is to provide an accurate and realistic platform by which the performance of innovative spectrum management solutions for a wide set of scenarios and use cases in the context of Opportunistic Networks (ONs) and Cognitive Radio Networks (CRNs) can be entirely validated and assessed before their implementation in real systems. Real-time platforms are essential to carry out significant studies and to accurately assess the performance of innovative solutions before their implementation in the real world. This work provides a comprehensive description of the testbed, highlighting many interesting implementation details and illustrating its applicability for different studies that rely on the CR paradigm. Then, a particular application in a realistic Digital Home (DH) scenario is also illustrated, which allows demonstrating the effectiveness of the real-time testbed and assessing its practicality in terms of user-perceived end-to-end Quality of Experience (QoE) in a realistic environment.

Dynamic Spectrum Access, based on the Cognitive Radio (CR) paradigm, is a promising solution to improve the currently inefficient spectrum utilization. In this respect, this paper deals with the spectrum selection problem when a number of radio links has to be established in a CR network. A novel strategy based on a Partially Observable Markov Decision Process (POMDP) is proposed combining partial observations of the interference state together with a statistical characterization of the interference dynamics. In this context, the use of an efficient observation strategy is a key element to account for the trade-off between achieved performance and measurement requirements. For that purpose, the aim of the paper is to propose and evaluate different observation policies for the POMDP-based spectrum selection framework. Results show that the proposed framework is able to achieve very similar performance than a strategy operating under full knowledge of the interference state requiring much less associated signaling.

The demand for higher data rates, capacity and better Quality of Service (QoS) is constantly growing; therefore, there is a pressing need for efficient use of wireless network resources. In this context, the application of Cognitive Radio (CR) principle has emerged as a solution to the problem of spectrum scarcity. In this respect, this paper presents an algorithm that enables multi-band spectrum selection for wireless applications under interference variations in the available spectrum blocks. The algorithm is formulated as a Partially Observable Markov Decision Process (POMDP) targeting the maximization of a reward function that captures how suitable each allocated spectrum block is for the data transmission in each radio link depending on the application bit rate requirements.

Multimedia broadcast multicast services (MBMS), introduced by Third Generation Partnership Project (3GPP) in universal mobile telecommunications system (UMTS) release 6 specification, have the aim to support downlink streaming and game services to groups of users. MBMS can supply users with resources in two different modalities: point-to-point (PtP) and point-to-multipoint (PtM). The power consumed by the network is an important topic to discuss when considering the presence of MBMS services. The UMTS system is, in fact, interference- limited; thus, the power available to Node B is limited and it must be enough to serve any user under its coverage. Therefore, the choice of the most efficient transport channel in terms of power consumption is a key aspect for the MBMS, since a wrong transport channel selection for the transmission of the MBMS data could adversely affect the overall capacity of the system. In this paper we search for the most efficient transport channel to convey MBMS data, by comparing the performance of the high speed downlink shared channel (HS-DSCH), the dedicated channel (DCH), and the forward access channel (FACH), for given transmission power levels and cell coverage size.