Future 5G Wireless Communication Research Articles

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.

Design and optimization of a transparent and flexible MIMO antenna for compact IoT and 5G applications

This work presents an optically transparent and flexible MIMO antenna that features two square patch elements placed in close proximity, aiming to meet the demands of compactness, flexibility, optical transparency, and visual appeal for IoT applications and future 5G wireless communication. The design includes a simple offset fed configuration to achieve the required isolation and impedance matching. It simplifies the process of creating closely spaced transparent MIMO antenna configurations. By optimizing and analyzing this structure, the antenna achieves better isolation and diversity gain performance, even when the patch elements are positioned very close to each other. To achieve optical transparency and flexibility, the antenna uses thin polyethylene terephthalate (PET) material as a substrate, which is a thermoplastic polymer resin from the polyester family. The wired metal mesh parameters for conducting parts of the MIMO antenna and offset position of the feed are carefully optimized to achieve required optical transparency, isolation, impedance matching and radiation performance without any complex decoupling or impedance matching network.

Deep neural network based resource allocation in D2D wireless networks

The increased complexity of future 5G wireless communication networks presents a fundamental issue for optimal resource allocation. This continuous, constrained optimal control problem must be solved in real-time since the power allocation should be consistent with the instantly evolving channel state. This paper emphasizes the application of deep learning to develop solutions for radio resource allocation problems in multiple-input multiple-output systems. We introduce a supervised deep neural network model combined with particle swarm optimization to address the issue using heuristic-generated data. We train the model and evaluate its ability to anticipate resource allocation solutions accurately. The simulation result indicates that the trained DNN-based model can deliver the nearoptimal solution.

Channel fading attenuation based on rainfall rate for future 5G wireless communication system over 38-GHz

In this paper, the effect of heavy rainfall on the propagation of a 38-GHz in a tropical region was studied and analyzed. Real measurement was collected, with a path length of 300 meters, for a (5G) radio linkage in Malaysia, installed at the Universiti Teknologi Malaysia (UTM) Johor Bahru campus. The employed system entails an Ericsson MINI-Link 38 E-0.6 mm, with a horizontal polarization (HP) antenna at the top integrated with a rain gauge and a data logger. Daily registered samples with a single minute span, for a full study period of 1 month, were collected and evaluated. The obtained rain rate was found as 56 mm/hr with a specific rain attenuation of 18.4 dB/km for 0.01% of the time. In addition to that, a calculated average rain attenuation of 5.5 dB for the transmission path of 300 meters length, was calculated. Based on these findings, a recommendation to update the International Telecommunication Union (ITU) specification of the rain attenuation for Malaysia is proposed. Based on the results, we suggest shifting the zone classification of Malaysia from zone P to zone N-P. Therefore, accurate design for future 5G systems would rely on more precise estimated attenuation levels leading to enhanced performance.

A Singly-Fed Dual-Band Microstrip Antenna for Microwave and Millimeter-Wave Applications in 5G Wireless Communication

The coexistence of microwave (MW) and millimeter wave (MMW) technologies is considered as the development tendency of the future 5G wireless communication system. In this paper, a single-port, single-layer, dual-band antenna with large frequency ratio is proposed to support the MW and MMW applications. This antenna mainly consists of a stub-loaded microstrip line in the center, two slot-loaded rectangular patches on the lateral sides, and two thin microstrip lines in-between which connect the former two. The stub-loaded microstrip line works as a series-fed MMW linear array at 26 GHz, and simultaneously it serves as the feed line for the MW patches operating at 4.85 GHz. The connection lines are elaborately designed to isolate the MW patches from the MMW signal, guaranteeing the radiation performance of the antenna at the two bands without requiring complicated filter. For verification, a prototype is fabricated and measured. The measured results show that the antenna has an impedance bandwidth of 3.1% and a peak gain of 8.93 dBi at the 4.85-GHz MW band, while an impedance bandwidth of 19% and a peak gain of 13.57 dBi at the 26-GHz MMW band.

60 GHz Broadband LTCC Antenna for 5G Mobile Communication Systems

This paper provides a numerical investigation in designing wideband circularly polarized 60 GHz antenna using Low-Temperature Co-fired Ceramic technology (LTCC). The LTCC provides high-density multilayer integration, low dielectric loss, and low costs. The use of LTCC technology is advantageous for easy and flexible 3D integration and freer vias distribution in the substrate. The designed antenna focuses on obtaining a better trade-off in terms of size, gain, circular polarization (CP), and large bandwidth. The circular polarization was chosen in order to minimize the transmission errors caused by polarization inconsistency between the transmitter and the receiver. The antenna geometry is developed taking into consideration the design rules of the LTCC with a layer thickness of 100 µm after firing and a metal layer thickness of 9 µm. A bandwidth of more than 33% centered at 60 GHz was obtained for this designed multilayer antenna. The results are obtained by using the High-Frequency Structure Simulator (HFSS). The proposed integrated antenna can be used in future 5G wireless communication systems and other 60 GHz spectrum applications.

A Dual-Polarized MIMO Array Antenna System for Future Smartphone

In this paper, a dual-polarization four antennas Multiple Input Multiple Output (MIMO) scheme is proposed. The four elements are arranged over a surface area of 67×139mm2 printed circuit board (PCB) using dielectric substrate FR-4 with epsilon 4.4 and thermal conductivity 0.025. A circular slot radiator is etched in ground plane in order to improve the radiation characteristics. To mitigate the mutual coupling in the proposed MIMO scheme, two rectangular parasitics with one open rib are embedded across square slot radiator. The proposed single antenna model covers a frequency range of 5.81-6.66 GHz at -10dB impedance bandwidth. However, the bandwidth is raised up to 1.47 MHz (5.48-6.95) GHz at -6dB. The results show that -20 dB return losses can be obtained, while -45 dB isolation was achieved for a dual microstrip line. The proposed antenna can be integrated with new smart-mobile devices for future 5G wireless communications.

A Wideband Differentially Fed Dual-Polarized Laminated Resonator Antenna

A wideband differentially fed dual-polarized laminated resonator antenna (LRA) is presented in this communication. Two differential pairs of L-probes are inserted into the LRA to excite degenerate dominant modes in LRA for dual-polarized operation. As a proof of concept, a prototype antenna centered at 5 GHz is designed, fabricated, and measured. The measured results agree well with the simulated ones. The experimental results show that the designed antenna achieves a wide bandwidth of 29% with differential reflection coefficient less than -10 dB. Moreover, it exhibits stable and symmetrical radiation patterns within the bandwidth. Benefiting from the differentially fed scheme, high port-to-port isolation better than 35 dB and low cross-polarization level less than -25 dB are achieved across the entire operating band. The proposed antenna is the first differentially fed dual-polarized LRA. Taking advantage of its planar structure integrated in the substrate, the proposed antenna is a promising candidate for future 5G wireless communications and antenna-in-package (AiP) solutions in millimeter-wave frequencies.

Design of Loop Antenna for 5G Wireless Communications

A design of a loop antenna is proposed for future 5G wireless communication. The radiating element is producing a second resonance at 38 laterally slimmed in a hemispherical manner to intensify the surface current density along the hemispherical contour, producing a second resonance at 55 GHz. In the previous paper, they implemented a wave antenna for communication. Using wave antenna for communication, the antenna size is very much small when compared to another antenna. In the wave antenna, the design of the antenna cannot increase bandwidth or wavelength, so that can get poor communication when transmitted. But using the loop antenna, this loop antenna can achieve system performance, directivity, radiation pattern. Loop antenna can be operated at 55 MHz for better communication. To reduce the distortion in the system, go for a loop antenna which can reduce distortion. There are many advantages to using the loop antenna. To reduce the problem previously, we go for a loop antenna, which can give good system operation. The antenna is centered on a single shielded loop inserted in the dielectric GIS window that tests the TEM mode propagation of PD currents. In conjunction with a trans-impedance amplifier, this paper outlines the related antenna parameters and antenna performance. The antenna sensitivity is within a few meters of the PD source, in the order of 1 pc. under laboratory conditions.

Joint uplink and downlink power allocation for maximizing the energy efficiency in ultra-dense networks

Ultra-dense network (UDN) is a promising solution to meet the huge data requirements of future 5G wireless communication systems. With many irregularly deployed small cell base stations (SBSs), it is very difficult to accurately measure network energy efficiency (EE) in UDN. Considering the necessity of saving energy in modern-day networks, in this paper, I present the EE evaluation of UDN based on the random spatial network model. In this considered system, the SBSs and the macro cell users (MUEs) are modeled as a homogeneous Poisson point process (PPP). Unlike the existing literature, I derive the simple closed-form expressions for the successful transmission probabilities of MUEs and small cells by Laplace transformation. Then, based on the obtained successful transmission probabilities, I derive the closed form expression for EE of the small cells in both uplink and downlink under some practical constraints. Further, to obtain the optimal SBS density in UDN, I propose a joint uplink and downlink power allocation (JUDPA) algorithm. The JUDPA algorithm obtains the maximum EE in small cells by iteratively optimizing the uplink and downlink powers. Our theoretical analysis and simulated results demonstrate the accuracy of the proposed model with better power allocation and less complexity than conventional solutions.

Higher order mode dielectric resonator antenna excited using microstrip line

In this paper, the square-shaped dielectric resonator antenna (DRA) operating on higher order (𝑇𝐸𝛿13) mode for the fifth generation (5G) communication applications is presented. The proposed DR antenna is excited by using a microstrip feed line and designed at the operating frequency of 28 GHz. The Rogers RT/Duroid 5880 material having a thickness of 0.254mm and a dielectric constant of 2.2 is used for the substrate. The commercial CST microwave studio (CST MWS) is used for the optimization and simulation of the antenna design. The reflection coefficient, antenna gain, radiation efficiency, VSWR and radiation pattern are studied. A -10dB bandwidth of 4.6% (1.3 GHz) for VSWR2 with a gain of 5 dBi and radiation efficiency of 89%. The proposed antenna design is suitable for future 5G wireless communication applications.

Joint measure matrix and channel estimation for millimeter-wave massive MIMO with hybrid precoding

Millimeter-wave (mmWave) massive multiple-input multiple-output (MIMO) with hybrid precoding is a promising technology for future 5G wireless communications. Channel estimation for the millimeter-wave (mmWave) MIMO systems with hybrid precoding can be performed by estimating the path directions of the channel and corresponding path gains. This paper considers joint measure matrix and channel estimation for a massive MIMO system. By exploiting the sparsity of a massive MIMO system, a channel estimation scheme based on a Toeplitz-structured measure matrix and complete complementary sequence (CC-S) is proposed. Moreover, analytic studies show that the measurement matrix based on CC-S yields either optimal performance or feasibility in practice than an independent identically distributed Gaussian matrix. The performance of the scheme is shown with numerical examples.

Hybrid Precoding Design Using MMSE Baseband Precoder for mm-Wave Multi-User MIMO Systems

For future 5G wireless communication networks, millimeter-wave (mmWave) cellular systems is considered to be the key enabling technology because of its high data rates, low latency, high system capacity, and huge available bandwidths. However, multiuser networks in mmWave frequency bands encounter high path loss and interference, thus degrading the performance. Applying large antenna arrays at the base stations (BS) in order to achieve high beamforming gains with the help of precoding techniques is an efficient way of improving the performance of the system. Although multi-user beamforming can improve spectral efficiencies, full digital beamforming strategies used in the conventional microwave systems increase the hardware cost and consumes high power for large number of antennas in mmW systems. In this paper, a low-complexity multi-user hybrid precoding structure is proposed for mmWave multiple input multiple output (MIMO) channels utilizing Minimum Mean Square Error (MMSE) precoders at the BS with perfect channel knowledge. Simulations show that the achievable rate obtained by the proposed hybrid precoding scheme is very close to the single-user rate and also performs better compared to other hybrid precoding approaches.

Clustering Algorithms and Validation Indices for a Wide mmWave Spectrum

Radio channel propagation models for the millimeter wave (mmWave) spectrum are extremely important for planning future 5G wireless communication systems. Transmitted radio signals are received as clusters of multipath rays. Identifying these clusters provides better spatial and temporal characteristics of the mmWave channel. This paper deals with the clustering process and its validation across a wide range of frequencies in the mmWave spectrum below 100 GHz. By way of simulations, we show that in outdoor communication scenarios clustering of received rays is influenced by the frequency of the transmitted signal. This demonstrates the sparse characteristic of the mmWave spectrum (i.e., we obtain a lower number of rays at the receiver for the same urban scenario). We use the well-known k-means clustering algorithm to group arriving rays at the receiver. The accuracy of this partitioning is studied with both cluster validity indices (CVIs) and score fusion techniques. Finally, we analyze how the clustering solution changes with narrower-beam antennas, and we provide a comparison of the cluster characteristics for different types of antennas.

Dual band omnidirectional millimeter wave antenna for 5G communications

ABSTRACTA planar dual band millimeter wave printed monopole antenna and a MIMO antenna are presented for 28/38 GHz future 5G wireless communications. The shape of the radiating element of the proposed antenna is derived from a 28 GHz rectangular monopole. The radiating element isproducing a second resonance at 38 laterally slimmed in a hemispherical manner to intensify the surface current density along the hemispherical contour, producing a second resonance at 38 GHz. The measured impedance bandwidth confirms its dual band characteristics, covering 26.65–29.2 and 36.95–39.05 GHz where . The measured radiation patterns are omnidirectional, with a peak gain value of 1.27 and 1.83 dBi at 28 and 38 GHz, respectively. Moreover, diversity performance of the proposed MIMO antenna is evaluated in terms of MIMO performance metrics. such as envelope correlation coefficient, diversity gain, isolation and channel loss capacity.

Non-Uniform Full-Dimension MIMO: New Topologies and Opportunities

Different from traditional massive MIMO arranging ULA only in the azimuth direction, FD-MIMO offers a practical means of realizing massive MIMO in limited space by equipping URA at the base station, which provides extra spatial degree of freedom in elevation domain and eliminates inter-cell interference considerably. Consequently, FD-MIMO draws much attention from both academia and industry for future 5G wireless communication systems. However, the spectral efficiency of URA is lower than its ULA counterpart when adopting the same number of antenna elements due to low resolution caused by the non-uniform distribution of users in the elevation domain. In this article, the concept of NUFD-MIMO is proposed for the first time, which inherits the advantages and is capable of handling the challenges of traditional FD-MIMO. Structured NURA is designed to enhance the spatial resolution of FD-MIMO in the elevation domain and the corresponding two-dimensional precoding is introduced as well. Moreover, some insights on actual NUFD-MIMO implementations in millimeter-wave systems are provided, including non-uniform multi-beam and two-layer phase shifter feeding network. Finally, future work

A Tutorial on Lossy Forwarding Cooperative Relaying

Lossy decode-and-forward (DF) relaying, also referred to as lossy forwarding (LF), can significantly enhance the transmission reliability and expand the communication coverage at the cost of a small increase in computational effort compared to its DF counterpart. Furthermore, it can further simplify the operations at the relay nodes by removing the error-detecting operation, e.g., cyclic redundancy check, which is used in the conventional DF systems. Due to these advantages, LF has been intensively investigated with the aim of its applications to various cooperative communication networks with different topologies. This paper offers a comprehensive literature review on the LF relaying strategy and makes comparisons between LF and DF. Five basic exemplifying scenarios are taken into consideration. These are the three-node network, the single-source multi-relay network with direct source-to-destination link, the multiple access relay channel, the two-way relay network, and the general multi-source multi-relay network. The paper includes not only theoretical performance limit analyses, but also performance evaluation by employing low-complexity accumulator aided turbo codes at the sources and relays as well as joint decoding at the destination. As expected, the performance enhancement in terms of outage probability, frame error rate, and $ {\epsilon }$ -outage achievable rate by LF over DF is significant, which is demonstrated in all the exemplifying scenarios in the literatures. Hence LF has a great potential to be applied to future 5G wireless communication networks, e.g., device-to-device, vehicle-to-vehicle, and machine-type communications, which are composed of the aforementioned exemplifying scenarios.

Compact Printed Ridge Gap Waveguide Crossover for Future 5G Wireless Communication System

The implementation of microwave devices using printed ridge gap waveguide (PRGW) technology is required as they are expected to play an essential role in millimeter wave applications. The proposed crossover is composed of four-arm PRGW sections and connected by a central rectangular junction. The size of the introduced crossover is $1.5 \lambda \times 1.5 \lambda $ at 30 GHz. This includes the first two rows of cells around the middle junction. The proposed design is fabricated and measured. The measured results demonstrate that the insertion loss is about 0.5 dB over 13.33% operating bandwidth. The measured and simulated results are in good agreement.

Caching hit probability and Compressive Sensing perspective for mobile cellular networks

Ever since the advent of wireless communications, there has been a tremendous growth in data traffic and service demand. Both of the above quantities are expected to explosively dominate wireless communication networks, as we move on to the future 5G wireless communication systems. This paper involves the so-called hit probability related to data caching, a technique that mainly alleviates backbone network congestion and reduces latency, by storing frequently accessed data in mobile users' cache (mobility-aware caching) and leaves the least popular data for recovery from base stations. The hit probability is defined in the literature as the probability of specific file request by a user together with the successful delivery of the data packet to the user/network node that made the request. Considering three distributions, the uniform, the well-established Zipf-like distribution and the normal distribution, we allow a varying number of cached filles and observe the curves representing the hit probabilities and perform comparison. We provide interpretation of the related to optimality results i.e. greatest achievable hit probability. In a pico-cell of a cellular network of minimum radius of 50 m and a maximum radius of 200 m, we derive the transmission power level and verify that it complies to the typical transmission power of a pico-cell. A final remark involves the Compressed Sensing sparsity concept, where considering that the possibility that a file is cached with probability p, and not cached with probability 1 − p, we examine the «sparsest» and «densest» scenario with respect to the number of cached files n opposed to the total N files in the aggregate users' cache, plotting the equivalent total probability. A final conclusion sets the issues of future work.

Histogram shifting-based blind watermarking scheme for copyright protection in 5G

In this article, we propose a novel robust and blind image watermarking scheme based on speeded up robust feature points for copyright protection of digital images in the fifth generation (5G) wireless communication. Encryption techniques have been already incorporated in the current wireless communication technologies. Similarly, copyright protection through watermarking can also be incorporated in future 5G wireless communication. The novelty of the proposed image watermarking scheme is that a new histogram shifting procedure has been introduced on the non-overlapping circular regions around the selected stable keypoints on the image. A new similarity measure based on longest common subsequence is also introduced to find the closeness between two watermark bit sequences even when they have different sizes. The proposed method outperforms the existing competing methods on standard image database (University of Southern California-Signal and Image Processing Institute) in terms of robustness, visual quality, and data embedding rate.