6G Wireless Networks: Vision, Requirements, Applications and Challenges

Reconfigurable Intelligent Surfaces (RIS) are emerging as a key enabler of 6G wireless networks by dynamically controlling and optimizing RF environments. RIS consists of programmable meta- surfaces that enhance signal propagation through beamforming, interference reduction, and energy efficiency. This paper explores the technical foundations of RIS, its role in overcoming limitations of traditional RF systems, and its advantages in 6G use cases. Deployment strategies, including hybrid and collaborative RIS systems, are analyzed to ensure optimal performance. The paper concludes with insights into the future trajectory of RIS technology and its integration into next-generation wireless networks. Keywords – Reconfigurable Intelligent Surfaces, 6G, RF Signal Enhancement, Beamforming, Wireless Networks.

Energy efficiency (EE) is one of the most important metrics for the beyond fifth generation (B5G) and the future sixth generation (6G) wireless networks. Reconfigurable intelligent surface (RIS) has been widely focused on EE enhancement for wireless networks because it is power-saving, programmable, and easy to be deployed. However, RIS is generally passive and thus difficult to obtain corresponding full channel state information (CSI), which severely impacts the EE enhancement of RIS-assisted wireless communications. To solve this problem, in this paper we propose the new single-active-antenna combined RIS transmitter structure, which can replace traditional multiple antennas to reduce hardware cost and power consumption. Based on the single-active-antenna combined RIS structure, we develop the Dumb RIS-Assisted Random Beamforming (Darb)-based Joint RIS-Elements and Transmit-power optimizAtion (Jeta) scheme, where dumb RIS randomly changes its phase shift according to isotropic distribution only depending on the CSI feedback from users to RIS-assisted transmitter. Then, we jointly design the number of RIS elements and optimize the transmit power to maximize the EE of RIS-assisted wireless communications. Simulation results show that compared with the traditional multi-antenna system, our developed Darb-based-Jeta scheme can significantly increase the EE without the full CSI.

This paper presents a comprehensive literature review on applications of economic and pricing theory for resource management in the evolving fifth generation (5G) wireless networks. The 5G wireless networks are envisioned to overcome existing limitations of cellular networks in terms of data rate, capacity, latency, energy efficiency, spectrum efficiency, coverage, reliability, and cost per information transfer. To achieve the goals, the 5G systems will adopt emerging technologies such as massive multiple-input multiple-output, mmWave communications, and dense heterogeneous networks. However, 5G involves multiple entities and stakeholders that may have different objectives, e.g., high data rate, low latency, utility maximization, and revenue/profit maximization. This poses a number of challenges to resource management designs of 5G. While the traditional solutions may neither efficient nor applicable, economic and pricing models have been recently developed and adopted as useful tools to achieve the objectives. In this paper, we review economic and pricing approaches proposed to address resource management issues in the 5G wireless networks including user association, spectrum allocation, and interference and power management. Furthermore, we present applications of economic and pricing models for wireless caching and mobile data offloading. Finally, we highlight important challenges, open issues and future research directions of applying economic and pricing models to the 5G wireless networks.

Unleashing the potential of sixth generation (6G) wireless networks in smart energy grid management: A comprehensive review

The contention-based bandwidth request and power management mechanisms aim to improve the spectral efficiency and power consumption in Fifth Generation (5G) wireless networks to support massive Internet of Things (IoT) devices. However, when these mechanisms as combined together, they exhibit increased access delay with contention bandwidth request and response delay during power management. This tradeoff is due to the improper selection of contention window during backoff mechanism, and the duration and position of listen interval during power management. Here, the suitability of message and code-based mechanism for single hop and two-hop 5G wireless relay networks has been investigated. In single hop network, the devices set their contention window either by message or code based base station assisted backoff along with combined cyclic binary exponent power saving mechanism. In two-hop wireless network, devices set their contention window by multi-layered bandwidth request with combined power saving class mechanism. Simulations are carried out under high mobility conditions to validate the proposed mechanisms.

In this paper we present a method to assess measurements for link quality estimation in wireless networks. Quality of service (QoS) is increasingly important in 3G wireless networks. Commonly, the end to end QoS is defined by delay and error rate. To meet the end-to-end QoS requirements it is very important to control the error rates on the air interface. The error rates can be controlled by change the energy per bit on the air interface. A mismatching energy assignment will either result in a waste of capacity or in a violation of the error rate requirements for the air interface. Thus, the link quality estimation is critical for performance and capacity of wireless networks. In this paper we present a method to evaluate the value of possible measurements for link quality estimation. This method supports the selection process of appropriate measurements and allows the comparison of their performance. As an example, we apply the presented method to an UMTS 12.2 kbps connection.

As the demand for higher speed data transmissions continues to increase exponentially beyond the speed-limit of the fourth generation (4G) wireless networks due to the rapid spectrum depletion of the microwave frequency bands below 6 GHz, it has become quite evident that the existing wireless communication systems will eventually be constrained from meeting the huge throughput requirements for various emerging applications beyond 4G wireless networks. In order to sustain the future market dominance of wireless communications, the narrowness of wireless bandwidths in the existing systems, which has become a key issue for the upcoming wireless systems, needs to be addressed by looking beyond the traditional microwave spectrum domain through the exploitation of the huge bandwidths available in the millimeter wave bands. In this work, we have conducted the review for a series of measurements at various microwave bands, below 6 GHz and above, to study the behavior of ultra-wideband (UWB) channels, typically in different indoor and outdoor environments. These measurements have been used to gain a useful insight into the path loss and time dispersion parametric behaviors of the 5G channel and to investigate the channel characterization of the UWB signals within spatially restricted locations. Moreover, these measurements have been used to evaluate the newest channel model and channel prediction which have proposed for 5G.

EGHR: Efficient group-based handover authentication protocols for mMTC in 5G wireless networks

<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Low-density parity-check</i> (LDPC) codes that allow for encoding-decoding have been adopted in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">fifth-generation</i> (5G) network to support high-throughput and low-latency communications. To meet new user requirements of the beyond 5G and future <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sixth-generation</i> (6G) wireless networks, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">reconfigurable intelligent surface</i> (RIS) has been proposed as a promising solution to enhance the communication quality. In this letter, we investigate the performance of a RIS-assisted wireless communication system where the signal transmitted from the transmitter is protected by LDPC codes. We derive the analytical upper and lower bounds on the bit error probability of the RIS-assisted wireless system with LDPC-coded source signals. Through Monte Carlo simulations, we validate the accuracy of our derived bounds for various numbers of RIS reflecting elements.

Caching content of small base stations (SBSs) is a promising approach in the fifth generation (5G) wireless networks for decreasing the transmission delay and energy consumption. The key issue in caching is effective cooperation among SBSs for full usage of the caching to reduce the systems cost. In this paper, we first introduce the architecture of wireless cellular networks with caching in 5G. We divide the caching space into two parts: One caches the fixed content purchased by telecom operators from the remote service providers, and the other one caches contents for wireless transmission. Then, we propose the cooperative caching scheme based on content-exchanged, where each user can get its demanded data from either local SBS or purchasing the contents stored in the neighboring cooperative SBSs. We further prove the concavity of system costs regarding to the proportion between the two parts. We also propose a mechanism to search for the minimal system costs. Finally, by simulations, we prove that the performance of our proposed cooperative caching scheme is better than that of the traditional cache schemes without purchasing the contents between SBSs.

5G wireless networks must have a high data rate, a large channel capacity, good quality, and a low Peak-to- Average Power Ratio (PAPR). The fifth generation (5G) technology improved communication systems. Filtered OFDM (F-OFDM) is seen as a candidate approach for 5G wireless communication networks. Impulsive noise's presence and impact were considered in this study. Modeling is done using the Middleton Class A model for impulsive noise. In the simulation, the Bit Error Rate (BER) performance enhancement for F- OFDM over OFDM is seen. The discovery supports the use of F- OFDM in the PLC and WSN portions of the whole network, which ensure that the integration of these heterogeneous networks occurs more quickly and smoothly while reducing BER. Those solutions may facilitate the 5G network deployment in Bangladesh; hence, those solutions are needed. When the numFFT in F-OFDM is raised while the QAM is lowered, the BER performance is shown to improve. On the impulse noise channel, QPSK modulation and numFFT=2048 yield the best results. This experiment demonstrated that higher modulation orders had low PAPR but also found that for 16-QAM, the value of PAPR is much higher and the PAPR for F-OFDM modulation rose when the FFT size was raised.

Extremely large aperture arrays (ELAAs) and reconfigurable intelligent surfaces (RISs) are candidate enablers to realize connectivity goals for the sixth-generation (6G) wireless networks. For instance, ELAAs can provide orders-of-magnitude higher area throughput compared to what massive multiple-input multiple-output (MIMO) can deliver through spatial multiplexing, while RISs can improve the propagation conditions over wireless channels but a passively reflecting RIS must be large to be effective. Active RIS with amplifiers can deal with this issue. In this paper, we analyze the distortion generated by nonlinear amplifiers in both ELAAs and active RIS. We derive analytical expressions for the angular directions and depth of nonlinear distortion in both near-field and far-field channels. These insights are then used in a distortion-aware scheduling scheme that predicts the beamforming directions of the distortion and strategically allocates users in frequency to minimize its impact. Numerical results validate our theoretical analysis and compare distortion-aware and distortion-unaware scheduling methods, highlighting the benefits of accounting for nonlinearities. We conclude that nonlinearities can both create in-band and out-of-band distortion that is beamformed in entirely new directions and distances from the transmitter.

With increasing interest in the concept of 5G wireless networks and the popularization of mobile devices, users gradually watch videos through mobile devices in streaming mode rather than off-line mode. However, the latency and lags of mobile networks will reduce the quality of service. In HTTP live streaming services, when there are multiple sources for the same content stored in the streaming servers, the suited quality content is able to be selected for playing according to the networking bandwidth conditions between servers and user equipment, and the users can obtain appropriate streaming quality automatically. However, the selection policy is difficult to be approved between 5G wireless communication networks and SDNs. In this study a buffer-aware HTTP live streaming approach is proposed, which evaluates the weights of media segments to decide the transmitting priorities based on the current playing time and adjust the appropriate transmission path through the decision making network controller according to the utilization and stability of the routers and switches in SDN. Finally, the experimental results proved that the approach is able to correct the overall streaming source sequence with the buffer status to effectively upgrade overall streaming service quality, as well as maintain a certain level of streaming quality for SDN-enable 5G wireless networks.

The advent of the wireless communications systems augurs new cutting-edge technologies, including self-driving vehicles, unmanned aerial systems, autonomous robots, the Internet-of-Things, and virtual reality. These technologies require high data rates, ultra-low latency, and high reliability, all of which are promised by the fifth generation of wireless communication systems (5G). Many research groups state that 5G cannot meet its demands without artificial intelligence (A.I.) integration as 5G wireless networks are expected to generate unprecedented traffic giving wireless research designers access to big data that can help in predicting the demands and adjust cell designs to meet the users' requirements. Subsequently, many researchers applied A.I. in many aspects of 5G wireless communication design including radio resource allocation, network management, cyber-security. In this paper, we provide an in-depth review of A.I. for 5G wireless communication systems. in this respect, the aim of this paper is to survey A.I. in 5G wireless communication and networking by discussing many case studies, discuss the challenges, and shed new light on future research directions for leveraging A.I. in 5G wireless communications.

In this chapter, we present a comprehensive end-to-end (E2E) network slicing framework for fifth-generation (5G) wireless and core networks and provide our vision on network slicing for beyond 5G (B5G) networks using artificial intelligence (AI) technologies. We first give an introduction on the 5G communication networks by specifying distinct 5G networking characteristics. As the key features of 5G pose challenges on quality-of-service (QoS)-oriented resource provisioning, a new concept of network slicing is presented, based on software-defined networking (SDN) and network function virtualization (NFV) technologies, to enhance the overall resource utilization while guaranteeing QoS isolation among services. We focus on developing specific network slicing solutions for both 5G wireless networks and core networks. In addition, the evolution of B5G networks is discussed in terms of a potential networking paradigm shift with new service key performance indicators (KPIs). To satisfy B5G service requirements, a framework of AI-assisted network slicing lifecycle is developed to automate the slice creation with reduced slice management complexity. A case study is presented to demonstrate the effectiveness of the proposed E2E network slicing solutions.Keywords5G communication networksNetwork slicingWireless networksRadio resource slicingCore networksComputing and transmission resource slicingBeyond 5G networksAI-assisted network slicingQoSE2E delay