Future Wireless Communication Systems Research Articles

Self‐attention convolutional neural network optimized with Remora Optimization Algorithm for energy aware resource management in Non‐orthogonal Multiple Access networks

SummaryNon‐orthogonal multiple access (NOMA) is an efficient technology for future wireless communication systems. The resource management on NOMA networks is flattering for improving energy efficiency (EE) of systems. Therefore, self‐attention convolutional neural network (SACNN) optimized with Remora Optimization Algorithm (ROA) for energy aware resource management in NOMA network (SACNN‐ROA‐EE) is proposed in this paper for solving user allocation, channel allocation, and power allocation problems. The Matching‐Coalition approach is considered to face the user allocation issue, and the SACNN is considered to face the channel allocation and power allocation problems. SACNN does not adopt any optimization methods to determine the optimal parameters in channel allocation and power allocation. Therefore, the ROA is applied to optimize the SACNN weight parameters. The proposed technique is activated in MATLAB, and its efficacy is analyzed with under performances metrics, such as minimum user rate, sum rate, energy, and spectral performance. The proposed SACNN‐ROA‐EE attains 24.35%, 27.84%, and 38.58% better sum rate and 27.45%, 43.28%, 30.56% better EE compared with existing methods, such as EE utilizing communication deep neural network optimized with power allocation optimization (PAO‐CDNN‐EE), EE under deep transfer deterministic policy gradient along deep deterministic policy gradient approach (DPPGA‐DTDPPG‐EE), and EE utilizing deep reinforcement learning with baseline algorithms (BA‐DRL‐EE), respectively.

Machine Learning Strategies for Reconfigurable Intelligent Surface-Assisted Communication Systems—A Review

Machine learning (ML) algorithms have been widely used to improve the performance of telecommunications systems, including reconfigurable intelligent surface (RIS)-assisted wireless communication systems. The RIS can be considered a key part of the backbone of sixth-generation (6G) communication mainly due to its electromagnetic properties for controlling the propagation of the signals in the wireless channel. The ML-optimized (RIS)-assisted wireless communication systems can be an effective alternative to mitigate the degradation suffered by the signal in the wireless channel, providing significant advantages in the system’s performance. However, the variety of approaches, system configurations, and channel conditions make it difficult to determine the best technique or group of techniques for effectively implementing an optimal solution. This paper presents a comprehensive review of the reported frameworks in the literature that apply ML and RISs to improve the overall performance of the wireless communication system. This paper compares the ML strategies that can be used to address the RIS-assisted system design. The systems are classified according to the ML method, the databases used, the implementation complexity, and the reported performance gains. Finally, we shed light on the challenges and opportunities in designing and implementing future RIS-assisted wireless communication systems based on ML strategies.

Impact of memory on beamforming optimization for DDPG-assisted RIS-multi-user system

Recently, reconfigurable intelligent surfaces (RIS) have garnered considerable attention as indispensable components driving the evolution of future 6G wireless communication systems. This heightened interest is primarily attributed to notable advancements in programmable meta-material fabrication, which enable the creation of highly versatile and adaptable surfaces. These surfaces, often referred to as intelligent reflecting arrays, represent a significant departure from the conventional capabilities of massive multiple-input multiple-output (MIMO) systems, thereby catalyzing the emergence of intelligent radio environments characterized by enhanced flexibility and efficiency. Our study is dedicated to the comprehensive exploration of coordinated design strategies that encompass both the transmission beamforming matrix at the base station and the phase shift matrix at the RIS. Leveraging recent breakthroughs in deep reinforcement learning (DRL), our approach harnesses the power of a Long Short-Term Memory (LSTM) based DRL algorithm. This algorithm orchestrates the joint design process through iterative interactions with the environment, strategically guided by predefined rewards operating within a continuous framework of states and actions. While recent research has underscored the efficacy of LSTM-based architectures in bolstering the learning capacity of reinforcement learning (RL) algorithms and simplifying the search process, our investigation reveals a nuanced insight. Contrary to prevailing trends, we find that the integration of memory into the Deep Deterministic Policy Gradient (DDPG) with LSTM (DDPG-LSTM) algorithm yields unexpected consequences, negatively impacting the system's overall performance. Through preliminary simulation results, we empirically demonstrate the adverse effect of memory on DDPG performance when applied to RIS systems. This finding not only sheds light on the complexities of optimizing 6G wireless communication systems but also underscores the importance of careful algorithmic design and parameter tuning in achieving desired outcomes in emerging technologies.

MH-SIA: multi-objective handover using swarm intelligence algorithm for future wireless communication system

MH-SIA: multi-objective handover using swarm intelligence algorithm for future wireless communication system

Improved End-to-End Wireless Transmission Integrating NOMA and DL-Based Autoencoder

The field of wireless communication systems has experienced significant advancements in recent years, leading to the emergence of two promising technologies: non-orthogonal multiple access (NOMA) and deep learning (DL)-based autoencoders (AE). Through power allocation, NOMA enables multiple users to share a single frequency band, while AE can compress and decompress data with high precision. Integrating NOMA and AE enables end-to-end (E2E) transmission with a superior signal-to-noise (SNR) ratio. To further enhance the wireless network's block error rate (BLER) performance, the multiple-input, multiple-output (MIMO) technique is also incorporated into the newly proposed system. With the incorporation of the MIMO signal, the system is abbreviated as the MIMO-NOMA-AE system. The suggested technique for detecting MIMO-NOMA-AE signals has demonstrated a remarkable performance gain in SNR surpassing the traditional successive interference cancellation (SIC)-based NOMA system. The proposed system also performs better than previously utilized deep neural network (DNN)-based SISO-NOMA-AE communication systems. While this method shows potential for future wireless communication systems, further research and testing are necessary to evaluate its practical feasibility and effectiveness.

Photonics-based all-dielectric horn antenna for millimeter waves in 5G and 6G applications

This work introduces a cost-effective photonics-based approach for fast-implementing horn antennas operating in millimeter-wave frequencies (mm-waves). Instead of using conventional metallic guiding structures, we employed an all-dielectric quarter-wave stack Bragg mirror photonic design. As a proof-of-concept, we used five semi-spherical air-polylactic acid bilayers stacked with a conical (horn-like) aperture fabricated through a one-step 3D printing process. The prototype, with a bandwidth of 2.6 GHz (from 24.96 to 27.50 GHz), was fed by the WR28 standard waveguide mechanism with measured gain ranging from 10.6 to 13.9 dBi (between 25 and 27 GHz). These outcomes demonstrate our idea's suitability for alternative design of high-frequency antennas for future 5G and 6G wireless communications systems, overcoming the precision constraints of traditional manufacturing methods.

Performance Analysis of SNR in MIMO OFDM Downlink System

The goal of future wireless communications systems is to provide a wide variety of high quality high-rate services with minimum requirements on spectrum, power consumption and hardware complexity. Toward this end, proper system structures as well as robust system designs are required to meet the challenges in wireless transmissions, such as multipath fading, limited spectrum resource, and interference. Recent research results have unveiled the multiple-input multiple-output (MIMO) system as a potential candidate to play a key role in future wireless. A MIMO wireless system is commonly deployed by using multiple transmit and receive antennas. Early work on multi-antenna systems involves the use of antenna arrays at the receiver to provide spatial diversity against the random destructive effect of fading. There is a recent rich literature on employing multiple antennas at the transmitter and achieving diversity through space-time coding when there is no channel state information at the transmitter (CSIT), or through transmit beam forming when there is perfect CSIT.

Peak-to-average power ratio reduction using companding algorithm for NOMA waveform

Future wireless communication systems can accommodate huge connections and improve spectrum efficiency by using the non-orthogonal multiple access (NOMA) multiple access approach. High Peak-to-Average Power Ratio (PAPR) levels can, however, negatively affect NOMA, resulting in decreased system performance and more complicated power amplifiers. This study suggests PAPR reduction in NOMA utilising companding methods for 512, 256, and 64 sub-carriers to address this problem. The high peak power of NOMA signals may be effectively compressed by using nonlinear companding techniques, such as μ -law and A-law companding, which reduces distortion and improves overall system dependability. Simulations are used to assess the effectiveness of the suggested companding methods, and the findings show a significant reduction in PAPR, assuring increased Bit Error Rate (BER) effectiveness and transmission resilience in NOMA-based communication systems. The suggested method is contrasted with the conventional A-Law (C-A-Law) and μ-law (C- μ-law).

Graphene-enabled chiral metasurface for terahertz wavefront manipulation and multiplexing holographic imaging

The ability of metasurfaces to simultaneously manipulate both the spin and phase of circularly polarized (CP) incident waves has attracted considerable attention from researchers. Here, we propose a reconfigurable double circular split rings (DCSRs) chiral metasurface. By introducing graphene and changing the Fermi level of graphene, dynamic circular dichroism (CD) can be achieved. The calculation results show that when the Fermi level of graphene is increased from 0.1 eV to 1 eV, the CD decreases from 0.72 to 0.09 at 0.839 THz, which provides a CD-tunable spin-controlled method. In addition, based on the graphene-enabled DCSRs, we design two metasurface arrays combining Pancharatnam-Berry (PB) phase and coding metasurface theory to realize terahertz CP wave switchable focusing and spin-controlled multi-pencil beam generation. Furthermore, we demonstrate the application of reflective holography for multiplexing circularly polarized waves. The results of this paper are expected to play a significant role in the future terahertz wireless communication system, multi-spectral imaging, and information encryption fields.

An optically semi-transparent liquid antenna with slot-coupled feeding for future wireless communication systems

To meet the needs of optically transparent camouflage and concealment in the military field, as well as to improve the aesthetics and flexibility of wireless electronic devices. In this paper, a rectangular wideband liquid antenna with medium transparency and a hollowed-out center is proposed. The antenna is fabricated by using 3D printing technology and is primarily composed of a hollowed-out rectangular resin container, a transparent ionic liquid, and a non-transaprent slot-coupled feeding structure. By removing the center of the resin container and filling it with air, a resonator is formed that merges a rectangular ring with air. This method decreases the equivalent relative permittivity of the entire resonator and expands the operating bandwidth. Experimental results show that the antenna has an impedance bandwidth of 7 GHz-8.25 GHz, a relative bandwidth of 16.4%, a optical transparency of 84.57% and a maximum gain of 9.5dBi at 8 GHz. The proposed antenna has potential applications in electronic countermeasures, multimode composite guidance, 5G communication, and transparent electronic devices.

Towards artificial intelligence-aided MIMO detection for 6G communication systems: A review of current trends, challenges and future directions

In recent times, artificial intelligence (AI) has gained considerable attention as a highly promising technology for enhancing the performance of multiple-input multiple-output(MIMO) detection in wireless communication networks. AI approaches such as deep learning and reinforcement learning have enabled MIMO receivers to learn and adapt to complex channel conditions and interference scenarios, significantly improving throughput and error rate performance. This study provides a detailed review of the existing status of AI-aided MIMO detection and discusses the potential of this technology for future wireless communication systems, such as 6G. The study also discusses the challenges and opportunities associated with integrating AI techniques into MIMO detection and emphasizes the necessity for additional research in this field.

A breakthrough for temperature and linearity stability from device to circuit-level with 14 nm junctionless SOI FinFET: Advancing K-band LNA performance

SOI junctionless (JL) FinFETs are well-suited for future wireless communication systems; however, they suffer from the self-heating effect (SHE), which diminishes performance at higher temperatures. We proposed a novel structure called p-layer JL-FinFET (pL-JL-FinFET) to improve high-frequency performance at high temperatures. The Ge p-layer beneath the Silicon Fin increases electron current density and enhances device performance. Two high thermal conductivity 4H-SiC boxes are placed below the source and drain regions to overcome SHE. The pL-JL-FinFET exhibits the maximum transconductance of 148 μS, unity gain cut-off frequency of 455 GHz, and maximum available gain of 28.6 dB, which are improved by 208 %, 26 %, and 35 %, respectively, compared to regular JL-FinFET. Temperature analysis demonstrates suppressed SHE and better thermal stability than the regular JL-FinFET. Also, the pL-JL-FinFET shows superior thermal behavior in different fin shapes. The pL-JL-FinFET with a rectangular fin shape shows excellent linearity and high-frequency performance, achieving unconditional stability and minimum noise figure (NFmin) of less than 1 dB. An extracted small signal model is used to design a K-band low noise amplifier (LNA) with maximum NF and gain values of 0.75 dB and 18.7 dB. The pL-JL-FinFET opens opportunities for reliable, high-performance RF circuits while effectively managing thermal behavior.

DGT-based pulse shaping filter for Generalized Frequency Division Multiplexing system

The future wireless communication systems belonging to the next generation will encounter many diverse demands, like the need for data rates that surpass the capabilities of fifth-generation networks, ultra-low power consumption to cater to battery-operated communication sensors, and extremely short response times essential for control applications. A unified physical layer waveform is envisaged to address these flexible requirements, introduced as Generalized Frequency Division Multiplexing (GFDM) for beyond 5G (B5G) communication systems. One of the important features of GFDM is the utilization of flexible pulse shaping filtering in the time domain, resulting in improved performance. In this paper, a pulse-shaping filter is designed for the GFDM system using discrete Gabor representation, discrete biorthogonality condition and Wigner distribution. An analytical expression for the analysis window is derived using the biorthogonality condition. Further, the performance of the GFDM system is analyzed in terms of out-of-band (OOB) radiation and symbol error rate (SER). The results are presented for the Quadrature Amplitude Modulation (QAM) scheme over Additive White Gaussian Noise (AWGN), Rayleigh, Nakagami-m, two wave with diffuse power (TWDP), and Nakagami-q fading channels. The detailed analysis shows that the OOB radiation and SER performance exhibit strong dependence on the choice of the pulse shaping filter.

Provably Energy Efficiency and Lower Power Consumption Based on HOA in 5G MIMO-NOMA Systems

The rapid expansion of 5G communication networks necessitates improved energy efficiency and reduced power consumption. This article explores the integration of Hybrid Optimization Algorithms (HOA) in 5G MIMO-NOMA systems, aiming to enhance energy efficiency and minimize power usage. The proposed methodology leverages MIMO technology and Non-Orthogonal Multiple Access (NOMA). We introduce a new power consumption model based on HOA, recognizing MIMO-NOMA as pivotal in future wireless communication systems. HOA allows simultaneous service for more users, leading to heightened energy efficiency and reduced power consumption compared to conventional MIMO or NOMA systems. A streamlined user admission scheme is presented, admitting users based on ascending power requirements to meet Quality of Service criteria. Numerical results demonstrate the efficacy of HOA and the power allocation strategy in enhancing energy efficiency and user admission. Comparative analysis shows lower power consumption and approximately a 10% increase in energy efficiency compared to traditional methods and other algorithms like GA, PSO, SPPA, and the water-filling algorithm.

Reconfigurable and multiple beam steerable non-orthogonal-multiple-access system for optical wireless communication

The ability to reconfigure and adapt to different application scenarios plays an important role in future wireless communication systems. Here, a beam dividable and steerable optical wireless communication (OWC) system adopting a spatial light modulator (SLM) is presented. The reconfigurable multiple beam splitter as well as the adjustable splitting ratio are demonstrated. Experimental results show the proposed system can nearly evenly partition the input beam into up to five spots and can have the adjustable splitting ratio for the two-spot case. Combining non-orthogonal multiple access (NOMA) and wavelength division multiplexing (WDM), the proof-of-concept experimental demonstration shows the proposed system can provide 320.08 Gbit/s and 179.68 Gbit/s for the single-user scenario without beam steering and with steering of about 4°, respectively. Moreover, the data rates pairs of (92.20 Gbit/s, 119.17 Gbit/s) and (51.50 Gbit/s, 124.78 Gbit/s) can be achieved for the two-user scenario at different beam steering angles, respectively. The flexibility of data rate allocation for multiple users is also discussed. The OWC system under evaluation can satisfy the pre-forward error correction bit-error rate limit (pre-FEC BER = 3.8 × 10−3).

Fuzzy-based optimization of AODV routing for efficient route in wireless mesh networks

The performance of any communication system heavily relies on the efficient routing of interventions. This article addresses the significant issue of routing protocol selection for optimal path determination in networks. Particularly, when wireless communication occurs among mobile nodes with limited resources, such as batteries, the routing problem becomes even more challenging. This article proposes the Fuzzy Control Energy Efficient (FCEE) routing protocol to overcome these challenges. The FCEE protocol combines the Ad-Hoc On-Demand Distance Vector (AODV) protocol with fuzzy logic techniques to enhance network lifetime and performance. The proposed approach introduces a memory-based channel integrated with fuzzy logic methodologies, which effectively restricts the forwarding of unnecessary broadcast packets based on the energy availability of the operating node. Through extensive simulations, demonstrate the promising capabilities of FCEE as a routing protocol for wireless mesh networks. To further assess the effectiveness of the FCEE protocol, the proposed article compares it with two existing routing protocols: AODV and Intelligent Routing AODV (IRAODV). The simulation results shows that the FCEE routing protocol significantly enhances the reliability of the conventional AODV, providing improved link connectivity and longer route lifetimes. Additionally, our proposed protocol enhances the quality of service (QoS) for mesh routing, with an average throughput of 351.374 (Kbps) compared to 90 (Kbps) for IRAODV and 39 (Kbps) for AODV. Moreover, FCEE exhibits superior energy efficiency with an average energy consumption of 14, while IRAODV and AODV consume 40 and 90 joules, respectively. In conclusion, the FCEE routing protocol demonstrates its potential to address the challenges of efficient routing in wireless mesh networks. By leveraging fuzzy logic and integrating it with AODV, FCEE enhances network lifetime, performance, and energy efficiency, making it a promising solution for future wireless communication systems.

Design and analysis the performance of triangular patch antenna for THz applications

Modern technology advancement requires a more extensive data rate to convey information more rapidly than ever. Improved bandwidth can satisfy the need for high-speed transmission demand. In order to achieve significantly increased bandwidth for a high data rate communication, the antenna design at the THz band is essential. The microstrip patch antenna is one of the most prominent antennas for THz band applications such future 5G communication systems and advanced wireless communication system. This paper proposed a triangular patch antenna for THz applications where FR4 is used at the substrate as an insulator and Graphene at the patch as a conductor. Moreover, we improve the performance of the proposed antenna by modifying the shape of the patch and ground (GND) layer. We modify the patch shape by cutting the corner edge of the triangular patch. Moreover, the GND layer is modified with horizontally partial ground. The size of the proposed antenna is set to 160×120 µm2. We analyze the performance of the proposed antenna using CST simulation software. Based on the simulation results, the proposed antenna with a modified patch and GND shape shows wide bandwidth of 1.27 THz and minimal return loss of -33.22 dB at a resonant frequency of 2.28 THz. Additionally, the gain and efficiency of the suggested antenna show good improvement. Therefore, the proposed triangular patch antenna with a modified patch and GND shape is expected to be suitable for high-speed THz applications.

Terahertz wireless communication systems: challenges and solutions for realizations of effective bidirectional links

Wireless communication systems have evolved through a pursuit for broader bandwidths and a drive to higher frequencies. The drive has continued to present day and is now approaching the terahertz (THz) spectrum, where there exists great potential for broadband communication—and equally great challenges. Of note are the challenges of mobility for conventional THz transmitters, which have low transmitted powers, large sizes, and high power consumption. The proposed work recognizes these challenges and introduces the concept of retro-modulation in passive THz transceivers to have them establish passive THz links. Conventional (active) THz transceivers and links are contrasted to the proposed (passive) THz transceivers and links, with experimental and theoretical results given for THz retro-modulators having corner-cube and spherical retroreflectors with optical and electrical modulators. Ultimately, the findings show that passive THz links with high-frequency electronic transmitters and detectors and the proposed THz retro-modulators are capable of operation with signal-to-noise ratios between 10 to 20 dB at 300 GHz. Such findings open the door to future bidirectional THz wireless communication systems with mobile THz transceivers.

On the Capacity of Communication Channels With Memory and Sampled Additive Cyclostationary Gaussian Noise

In this work we study the capacity of interference-limited channels with memory. These channels model non-orthogonal communications scenarios, such as the non-orthogonal multiple access (NOMA) scenario and underlay cognitive communications, in which the interference from other communications signals is much stronger than the thermal noise. Interference-limited communications is expected to become a very common scenario in future wireless communications systems, such as 5G, WiFi6, and beyond. As communications signals are inherently cyclostationary in continuous time (CT), then after sampling at the receiver, the discrete-time (DT) received signal model contains the sampled desired information signal with additive sampled CT cyclostationary noise. The sampled noise can be modeled as either a DT cyclostationary process or a DT almost-cyclostationary process, where in the latter case the resulting channel is not information-stable. In a previous work we characterized the capacity of this model for the case in which the DT noise is memoryless. In the current work we come closer to practical scenarios by modelling the resulting DT noise as a finite-memory random process. The presence of memory requires the development of a new set of tools for analyzing the capacity of channels with additive non-stationary noise which has memory. Our results show, for the first time, the relationship between memory, sampling frequency synchronization and capacity, for interference-limited communications. The insights from our work provide a link between the analog and the digital time domains, which has been missing in most previous works on capacity analysis. Thus, our results can help improving spectral efficiency and suggest optimal transceiver designs for future communications paradigms.

A Broadband Filtering Circularly Polarized Folded Transmitarray Antenna Based on Metasurface

This letter presents a broadband filtering circularly polarized (CP) folded transmitarray antenna (FTA) with a linearly polarized (LP) feed antenna based on metasurface (MS). The whole antenna mainly consists of two MSs located on the top and bottom layers and an LP feed antenna. LP to CP wave (LP-CP) conversion and phase compensation are achieved across the entire X-band with the designed top MS. The top bandpass MS is also used as a spatial filter, utilizing its out-of-band suppression characteristics and high passband edge selectivity. A fabricated prototype was measured, and the results reveal that its maximum gain is 27.8 dBi at 10.2 GHz with an aperture efficiency of 40%. It also achieves a 3-dB gain bandwidth of 24.5% and a 3-dB axial-ratio (AR) bandwidth of 41.1%, which is in good agreement with the simulation results as well. The proposed broadband CPFTA achieves a bandpass filtering response while also retaining the advantages of low profile, high gain, and low cost, which illustrates great application potential in future wireless communication systems.