Future 5G Communication Systems Research Articles

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.

Design of high gain base station antenna array for mm-wave cellular communication systems

Millimeter wave (mm-Wave) wireless communication systems require high gain antennas to overcome path loss effects and thereby enhance system coverage. This paper presents the design and analysis of an antenna array for high gain performance of future mm-wave 5G communication systems. The proposed antenna is based on planar microstrip technology and fabricated on 0.254 mm thick dielectric substrate (Rogers-5880) having a relative permittivity of 2.2 and loss tangent of 0.0009. The single radiating element used to construct the antenna array is a microstrip patch that has a configuration resembling a two-pronged fork. The single radiator has a realized gain of 7.6 dBi. To achieve the gain required by 5G base stations, a 64-element array antenna design is proposed which has a bore side gain of 21.2 dBi at 37.2 GHz. The 8 × 8, 8 × 16, and 8 × 32 antenna array designs described here were simulated and optimized using CST Microwave Studio, which is a 3D full-wave electromagnetic solver. The overall characteristics of the array in terms of reflection-coefficient and radiation patterns makes the proposed design suitable for mm-Wave 5G and other communication systems.

Design and Simulation of Rectangular Microstrip Patch Antennas (45 GHz and 60 GHz) for V-band Applications

In this article, two wideband microstrip rectangular patch antennas have been designed and simulated for V band communication systems at resonant frequencies 45 GHz and 60 GHz. Rogers RO4730G3 is used as substrate dielectric with dielectric constant 2.98. The dimensions of the antennas are 6.23mm*6.7mm*0.7mm and 6mm*6.4mm*0.7mm respectively, with very simple geometrical configuration. To investigate the performance, the designs were then simulated using (CST) Studio Suite software package. The dimensions have been well studied and optimized to obtain acceptable results of Voltage Standing Wave Ration (VSWR), return loss, gain, bandwidth (BW) and radiation pattern. The 45 GHz antenna provides a gain of 6.73 dBi with the BW of 5.5 GHz and 1.03 of VSWR. Meanwhile, the 60 GHz design offers 6.92 dBi of gain with BW of 11.57 GHz and 1.05 of VSWR. The achieved results illustrate that both designs provide a good performance and are applicable for future 5G communication systems or any applications in the V band region.

A digital SIW-slot antenna array with FPGA implementation of beamforming

The future satellite platform and 5G communication systems place high demands on antennas, in which the antenna should offer low-cost, lightweight, electronically steerable features. In this paper, the design of a digital slot antenna element based on substrate integrated waveguide (SIW) is proposed. SIW guides the microwave inside the substrate confined with planar metallic covers and through-hole synthetized side-walls in conventional applications, and can also radiate the microwave towards free space in antenna applications through opening slots in its metallic covers. The slot antenna element is realized by implementing PIN diodes across the gaps on both sides of the pad in the center of the slot antenna, to provide the switching freedom of the slot antenna element between radiating and non-radiating states. Besides, radial decoupling stubs are introduced into the bias line so as to reduce the leakage of the energy in the SIW structure. Applying a series of on/off states to the diodes produces various radiation patterns, thus wide range scanning is possible supposing that enough array elements are equipped. Finally, a digital SIW-slot array composed of 8 by 4 elements with tunable field programmable gate array circuits are fabricated and measured. The measured results validate the reconfigurable characteristics for the radiation pattern of the proposed digital SIW-slot antenna array without heavy engineering of phase shifter in conventional antenna arrays. The antenna is consisted by 4 by 8 elements and its dimension, simulated gain and radiation efficiency are 145 mm times 127 mm times 1.524 mm, 15 dBi and 53.5%, respectively. Our designed SIW antenna has the advantage of both size and weight. Furthermore, its digitalized control of beamforming allows a programming-friendly interface for smart antenna development.

Analysis of Propagation Characteristics for Various Subway Tunnel Scenarios at 28 GHz

In order to meet the higher data transmission rate requirements of subway communication services, the millimeter wave (mmWave) broadband communication is considered as a potential solution in 5G technology. Based on the channel measurement data in subway tunnels, this paper uses ray-tracing (RT) simulation to predict the propagation characteristics of the 28 GHz millimeter wave frequency band in different tunnel scenarios. A large number of simulations based on ray-tracing software have been carried out for tunnel models with different bending radiuses and different slopes, and we further compared the simulation results with the real time measurement data of various subway tunnels. The large-scale and small-scale propagation characteristics of the channel, such as path loss (PL), root mean square delay spread (RMS-DS), and angle spread (AS), for different tunnel scenarios are analyzed, and it was found that the tunnel with a greater slope causes larger path loss and root mean square delay spread. Furthermore, in the curved tunnel, the angle spread of the azimuth angle is larger than that in a straight tunnel. The proposed results can provide a reference for the design of future 5G communication systems in subway tunnels.

Compact Photonic-Crystals Based Isolator Using Ni–Zn Gyromagnetic Ferrite Posts

A Faraday rotation isolator is conventionally achieved by connecting a matched load to a three-port circulator. It obtains superior performance (isolation > 20 dB) at the inevitable cost of non-ideal size. In order to adapt to the miniaturizations and integrations required for future 5G communication systems, it is particularly important to reduce the size of the devices. This work demonstrates a photonic crystal-based isolator design, comprising a unique reflecting cavity and a built-in fan-shaped coupler, where four Ni–Zn ferrite posts achieve the rotations. The design with the compact size of about 46.6 × 41.6 × 4.32 mm3 obtains excellent forward transmission efficiency and reverse isolation of 0.50 dB and 44.20 dB, respectively.

A Compact, Dual-Band Antenna with Defected Ground Structure for 5G Applications

In this paper, a novel dual-band monopole planar antenna is presented. The antenna is operated in 28/38[Formula: see text]GHz and has a bandwidth of 0.5/0.7[Formula: see text]GHz to operate in 5G frequency bands. Additionally, it exhibits a stable omni-directional radiation pattern with high gain characteristics, which helps to improve the performance of future 5G communication devices. The radiation efficiency achieved more than 94% throughout its operating bands. The numerical analysis has been carried out using a three-dimensional (3D) full-wave electromagnetic solver (ANSYS HFSS). In order to validate the numerical analysis, the proposed antenna has been fabricated and shows a good agreement with simulated results. The antenna has been designed and fabricated on Roger RT/Duroid 5880 dielectric substrate. This paper paves a new idea to design dual-band, simple and miniaturized single-element monopole planar antennas, which would be a good candidate for future millimeter-wave 5G communication systems.

A High Gain and Wideband Narrow-Beam Antenna for 5G Millimeter-Wave Applications

A wideband antenna with a high gain and narrow beam-width for future 5G communication systems is presented in this research. The antenna operates in 28 GHz 5G band with a large 35.53% bandwidth ranging from 23.41-33.92 GHz. The array has 4-elements arranged in a linear fashion to attain a high gain of 10.7 dBi. It radiates along its end-fire direction and provides a very narrow beam-width of 14.6° in its H-plane. A corporate feed network specifically designed for thin substrates was used in order to excite the array elements. It is built upon thin 0.254 mm Rogers substrate to minimize transmission losses and attain high radiation efficiencies of more than 90% throughout its operating frequency range. It has a compact structure bearing low cost and is easy to fabricate. This antenna fulfills necessary requirements of 5G communication and is therefore a good candidate to be used in the millimeter-wave range.

Wideband magneto‐electric dipole antenna with a claw shaped reflector for 5G communication systems

AbstractA wideband magneto‐electric dipole antenna with a claw‐shaped reflector is presented for future 5G communication systems. A pair of E‐shaped radiating patches is used to form an electric dipole, while two folded patches, which are shorted to the ground, are used as the magneto dipole. Four inverted‐L parasitic branches are introduced on the four corners of the ground, producing new resonant points. The four parasitic branches along with the ground plane form a claw‐shaped reflector for the antenna to obtain stable directional radiation patterns. This antenna is fed by a modified feeding structure to improve the matching of the working band. The measured results show that the reflection coefficient is less than ‐10 dB in a relative bandwidth of 103.6% (1.18‐3.72 GHz). The average gain in the working band is around 7.6 dBi. As a result, the proposed antenna can be a favorable candidate for future 5G communication systems.

Integration of millimeter-wave and optical link for duplex transmission of hierarchically modulated signal over a single carrier and fiber for future 5G communication systems

Integration of optical and millimeter-wave systems provide a promising solution for future giga-bits per second wireless communication systems. We have proposed and simulated full-duplex transmission of a hierarchically modulated signal carrying data for two different users at a combined rate of 1.5 Gbps. Analogue modulation of the optical carrier is used for the transmission of downlink data while the same carrier is re-used by digitally modulating it with the uplink data. The use of optical analogue and digital modulation schemes allow the transmission of duplex data over a single optical fiber. A millimeter-wave channel $$\hbox {NYUSIM}\_{\mathrm{v1}}\_4$$ is integrated with the optical link. The performance of the downlink and uplink signals are evaluated in terms of error vector magnitude and bit-error rate measurements, respectively. The effect of fiber length, received optical power and data rates on the performance has also been evaluated. It is shown that for a fiber length of 10 km, the lowest error vector magnitude obtained for the hierarchically modulated signal after transmission through a 14 m millimeter-wave link is 9.5%.

A broadband wire hexagon antenna array for future 5G communications in 28 GHz band

AbstractA broadband antenna array for 28 GHz 5G communications is presented in this paper. The antenna array has dimensions of 45 × 20 mm2 and has a measured operating band in 25.052‐34.923 GHz frequency range. A 4‐way feed network to excite its array elements was designed and optimized for the operating band. The single element consists of two co‐centric wire hexagons backed by another hexagonal ground loop of larger radius. The resulting monopole is surrounded by vias arranged in an inverted U‐shape manner for better performance. The antenna array has a minimum radiation efficiency of 85% with peak gain of 12.15 dBi. The antenna has narrow beam‐widths of 44.3° and 12.5° in two of its respective planes. The antenna is fabricated on an ultra‐thin Rogers substrate. The proposed antenna is deemed suitable for future 5G communication systems due to its simple design, compact size and low fabrication cost.

60 GHz Substrate-Integrated-Waveguide-Fed Patch Antenna Array With Quadri-Polarization

This communication presents a new design of a quadri-polarization-agile aperture-coupled patch antenna array for 60 GHz applications. Four polarization states, namely, vertical linear polarization, horizontal linear polarization, left-hand circular polarization (LHCP), and right-hand circular polarization (RHCP) can be flexibly reconfigured by dynamically switching the excitation of the corresponding port. More importantly, as the LP and CP radiations are achieved by using differential feeding and sequential-rotation feeding, respectively, the array exhibits wide impedance and axial ratio (AR) bandwidths, high polarization purity as well as symmetrical pattern with the main beam fixed at boresight. The −10 dB impedance bandwidths are better than 11.6% (57–64 GHz) for the four polarization states. The measured AR bandwidths are from 58 to more than 64 GHz for both the LHCP and RHCP. The good radiation performance together with the quadri-polarization-agile capability of this new array, as demonstrated in the communication, underlines its suitability for the future 5G communication systems, especially in a multipath propagation environment.

Green resource allocation method for intelligent medical treatment‐oriented service in a 5G mobile network

SummaryDue to the development of mobile transmission techniques, more exciting services can be launched that may change our daily lives in more easy and comfortable ways. The introduction of device‐to‐device (D2D) service in future 5G communication systems can extend the service coverage of intelligent medical treatment from hospitals to anywhere inside the network coverage area, which can save precious time and medical resources. As one of the key techniques in a 5G system, D2D technology has attracted extensive attention from academia and industry due to its system performance improvement, user experience enhancement and service extension. However, the introduction of D2D service will tremendously pollute the system transmission environment due to the induced interference, especially in the downlink direction where the interferer is very strong. This situation brings new challenges for effective and green resource utilization. To solve this problem, a green spectrum resource allocation strategy based on the Hungarian method is proposed in this paper to optimize system spectrum efficiency while considering the fairness among users under the assumption that all resources are fully shared by traditional cellular and newly introduced D2D users. To validate the performance of the proposed algorithm, a system‐level Monte Carlo simulation is also conducted, which shows the favorable performance of the proposed algorithm over the traditional greedy algorithm.

Precoded Chebyshev-NLMS-Based Pre-Distorter for Nonlinear LED Compensation in NOMA-VLC

Visible light communication (VLC) is one of the main technologies driving the future 5G communication systems due to its ability to support high data rates with low power consumption, thereby facilitating high speed green communications. To further increase the capacity of VLC systems, a technique called non-orthogonal multiple access (NOMA) has been suggested to cater to increasing demand for bandwidth, whereby users’ signals are superimposed prior to transmission and detected at each user equipment using successive interference cancellation. Some recent results on NOMA exist which greatly enhance the achievable capacity as compared with the orthogonal multiple access techniques. However, one of the performance-limiting factors affecting VLC systems is the nonlinear characteristics of a light emitting diode (LED). This paper considers the nonlinear LED characteristics in the design of pre-distorter for cognitive radio inspired NOMA in VLC, and proposes singular value decomposition-based Chebyshev precoding to improve performance of nonlinear multiple-input multiple-output NOMA-VLC. A novel and generalized power allocation strategy is also derived in this paper, which is valid even in scenarios when users experience similar channels. Additionally, in this paper, analytical upper bounds for the bit error rate of the proposed detector are derived for square $M$ -quadrature amplitude modulation.

Interference coordination in full-duplex HetNet with large-scale antenna arrays

Massive multiple-input multiple-output (MIMO), small cell, and full-duplex are promising techniques for future 5G communication systems, where interference has become the most challenging issue to be addressed. In this paper, we provide an interference coordination framework for a two-tier heterogeneous network (HetNet) that consists of a massive-MIMO enabled macro-cell base station (MBS) and a number of full-duplex small-cell base stations (SBSs). To suppress the interferences and maximize the throughput, the full-duplex mode of each SBS at the wireless backhaul link (i.e., in-band or out-of-band), which has a different impact on the interference pattern, should be carefully selected. To address this problem, we propose two centralized algorithms, a genetic algorithm (GEA) and a greedy algorithm (GRA). To sufficiently reduce the computational overhead of the MBS, a distributed graph coloring algorithm (DGCA) based on price is further proposed. Numerical results demonstrate that the proposed algorithms significantly improve the system throughput.

The Effect of Power Adjustment on Handover in High-Speed Railway Communication Networks

In future 5G communication systems, supporting high-quality wireless communications in high-mobility scenarios becomes very essential. Although many existing works indicate that increasing transmit power is able to reduce the handover failure probability (referred to as the power greedy scheme) through improving the radio condition or received signal strength, it goes against the requirement of green system design. In this paper, we investigate the effect of power adjustment on handover performance from the perspective of reducing the “uncertainty” in handover procedure in high-speed railway communications systems by embedding it into the existing handover procedure. It is shown that, with power adjustment, the handover performance can be improved without increasing extra energy consumption. The power adjustment-assisted handover scheme is applied to a high-speed railway scenario with distributed antenna system (DAS) cells. Both the blanket transmission-based handover scheme and the remote antenna unit selection transmission-based handover scheme are discussed for DAS cells. To evaluate the performance, the handover probability, handover failure probability, and communication interruption probability associated with two handover schemes are analyzed. Moreover, two new performance metrics, named handover occurrence probability and handover failure occurrence probability, are defined to efficiently evaluate the handover performance versus the position of the train. Both the analytical and the numerical results show that introducing power adjustment into handover gives ability to achieve a better performance compared with the current existing ones. Moreover, the power adjustment-assisted handover scheme is capable of achieving the similar system performance to existing power greedy scheme but without increasing energy consumption.

A Techno-Economic Framework for 5G Transport Networks

Wireless heterogeneous networks (HetNets) are a cost- and energy-efficient alternative to provide high capacity to end users in the future 5G communication systems. However, the transport segment of a RAN poses a big challenge in terms of cost and energy consumption. In fact, if not planned properly, its resulting high cost might limit the benefits of using small cells and impact the revenues of mobile network operators. Therefore, it is essential to be able to properly assess the economic viability of different transport technologies as well as their impact on the cost and profitability of a HetNet deployment (i.e., RAN plus transport). This article first presents a general and comprehensive techno-economic framework able to assess not only the TCO but also the business viability of a HetNet deployment. The framework is then applied to the specific case study of a backhaul-based transport segment. In the evaluation work two technology options for the transport network are considered (i.e., microwave and fiber) assuming both a homogeneous (i.e., macrocells only) and a HetNet deployment. Our results demonstrate the importance of selecting the right technology and deployment strategy in order not to impact the economic benefits of a HetNet deployment. Moreover, the results also reveal that a deployment solution with the lowest TCO does not always lead to the highest profit.

Distributed resource allocation in ultra-dense networks via belief propagation

Ultra-dense networking is widely accepted as a promising enabling technology to realize high power and spectrum efficient communications in future 5G communication systems. Although joint resource allocation schemes promise huge performance improvement at the cost of cooperation among base stations, the large numbers of user equipment and base station make jointly optimizing the available resource very challenging and even prohibitive. How to decompose the resource allocation problem is a critical issue. In this paper, we exploit factor graphs to design a distributed resource allocation algorithm for ultra dense networks, which consists of power allocation, subcarrier allocation and cell association. The proposed factor graph based distributed algorithm can decompose the joint optimization problem of resource allocation into a series of low complexity subproblems with much lower dimensionality, and the original optimization problem can be efficiently solved via solving these subproblems iteratively. In addition, based on the proposed algorithm the amounts of exchanging information overhead between the resulting subprob-lems are also reduced. The proposed distributed algorithm can be understood as solving largely dimensional optimization problem in a soft manner, which is much preferred in practical scenarios. Finally,the performance of the proposed low complexity distributed algorithm is evaluated by several numerical results.

Antenna‐height‐dependent delay spread model under indoor stair environment for small cell deployment in future mobile communications

A novel measurement‐based antenna‐height‐dependent statistical root‐mean‐square (RMS) delay spread model under indoor stair environment is proposed. In this model, the RMS delay spread is described as a log‐normal random variable with antenna‐height‐dependent parameters in both line‐of‐sight (LOS) and the non‐LOS (NLOS) areas. The environmental independence of the RMS delay spread distribution is shown first. Then, the parameters of the proposed model are extracted using least‐squares and maximum likelihood estimation. The accuracy of the proposed model is verified by the extensive measured data, and the mean values of the RMS delay spread are compared with those in other related works. Finally, the interdependence of RMS delay spread and the coherence bandwidth is investigated. The proposed model can be applied to the physical layer designs of small cells in future 5G and ubiquitous mobile communication systems. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.