The vision of next generation 5G wireless communications lies in providing very high data rates (typically of Gbps order), extremely low latency, manifold increase in base station capacity, and significant improvement in users’ perceived quality of service (QoS), compared to current 4G LTE networks. Ever increasing proliferation of smart devices, introduction of new emerging multimedia applications, together with an exponential rise in wireless data (multimedia) demand and usage is already creating a significant burden on existing cellular networks. 5G wireless systems, with improved data rates, capacity, latency, and QoS are expected to be the panacea of most of the current cellular networks’ problems. In this survey, we make an exhaustive review of wireless evolution toward 5G networks. We first discuss the new architectural changes associated with the radio access network (RAN) design, including air interfaces, smart antennas, cloud and heterogeneous RAN. Subsequently, we make an in-depth survey of underlying novel mm-wave physical layer technologies, encompassing new channel model estimation, directional antenna design, beamforming algorithms, and massive MIMO technologies. Next, the details of MAC layer protocols and multiplexing schemes needed to efficiently support this new physical layer are discussed. We also look into the killer applications, considered as the major driving force behind 5G. In order to understand the improved user experience, we provide highlights of new QoS, QoE, and SON features associated with the 5G evolution. For alleviating the increased network energy consumption and operating expenditure, we make a detail review on energy awareness and cost efficiency. As understanding the current status of 5G implementation is important for its eventual commercialization, we also discuss relevant field trials, drive tests, and simulation experiments. Finally, we point out major existing research issues and identify possible future research directions.

Next Generation 5G Wireless Networks: A Comprehensive Survey

Substrate-integrated waveguide (SIW) technology represents an emerging and very promising candidate for the development of circuits and components operating in the microwave and millimetre-wave region. SIW structures are generally fabricated by using two rows of conducting cylinders or slots embedded in a dielectric substrate that connects two parallel metal plates, and permit the implementation of classical rectangular waveguide components in planar form, along with printed circuitry, active devices and antennas. This study aims to provide an overview of the recent advances in the modelling, design and technological implementation of SIW structures and components.

Review of substrate-integrated waveguide circuits and antennas

With the demanding system requirements for the fifth-generation (5G) wireless communications and the severe spectrum shortage at conventional cellular frequencies, multibeam antenna systems operating in the millimeter-wave frequency bands have attracted a lot of research interest and have been actively investigated. They represent the key antenna technology for supporting a high data transmission rate, an improved signal-to-interference-plus-noise ratio, an increased spectral and energy efficiency, and versatile beam shaping, thereby holding a great promise in serving as the critical infrastructure for enabling beamforming and massive multiple-input multiple-output (MIMO) that boost the 5G. This paper provides an overview of the existing multibeam antenna technologies which include the passive multibeam antennas (MBAs) based on quasi-optical components and beamforming circuits, multibeam phased-array antennas enabled by various phase-shifting methods, and digital MBAs with different system architectures. Specifically, their principles of operation, design, and implementation, as well as a number of illustrative application examples are reviewed. Finally, the suitability of these MBAs for the future 5G massive MIMO wireless systems as well as the associated challenges is discussed.

Multibeam Antenna Technologies for 5G Wireless Communications

A novel slotted substrate integrated waveguide (SIW) leaky-wave antenna is proposed. This antenna works in the TE10 mode of the SIW. Leakage is obtained by introducing a periodic set of transverse slots on the top of the SIW, which interrupt the current flow on the top wall. It is seen that three modes (a leaky mode, a proper waveguide mode, and a surface-wave-like mode) can all propagate on this structure. The wavenumbers of the modes are calculated theoretically and are numerically evaluated by HFSS simulation. The leakage loss, dielectric loss, and conductor loss are also analyzed. A uniform slotted SIW leaky-wave antenna is designed that has good beam scanning from near broadside (though not exactly at broadside) to forward endfire. This type of SIW leaky-wave antenna has a wide impedance bandwidth and a narrow beam that scans with frequency. Measured results are consistent with the simulation and the theoretical analysis.

Substrate Integrated Waveguide (SIW) Leaky-Wave Antenna With Transverse Slots

A substrate integrated waveguide with square complementary split-ring resonators (CSRRs) etched on the waveguide surface is investigated in this paper. The proposed structures allow the implementation of a forward-wave passband propagating below the characteristic cutoff frequency of the waveguide. By changing the orientations of the CSRRs, which are incorporated in the waveguide surface and can be interpreted in terms of electric dipoles, varied passband characteristics are observed. A detailed explanation for the generation and variations of the passbands has been illuminated. The application of this waveguide and CSRR combination technique to the design of miniaturized waveguide bandpass filters characterized by transmission zeros is then illustrated. Filter design methodology is examined. These proposed filters exhibit high selectivity and compact size due to the employment of the subwavelength resonators and an evanescent-wave transmission. By slightly altering the configuration of the CSRRs, we find that the propagation of the TE10 mode can be suppressed and filters with improved selectivity and stopband rejection can be obtained. To verify the presented concept, three different types of filters are fabricated based on the standard printed circuit board process. The measured results are in good agreement with the simulation.

Substrate Integrated Waveguide Loaded by Complementary Split-Ring Resonators and Its Applications to Miniaturized Waveguide Filters

A novel dipole array omnidirectional high-gain antenna with a parallel feeding network is presented in this paper. The antenna comprises of four identical back-to-back radiating elements. The constructed prototype satisfies the required bandwidth. It covers the WCDMA system (1920MHz–2170MHz) with a good omnidirectional radiation pattern in the horizontal plane and a high gain. Details of the antenna design and the experimental results are presented.

A parallel feeding omnidirectional array antenna

This article presents the design of a wideband slot antenna for LTE indoor distribution system with simply shaped radiator element and wide-slot ground plane. By adjusting the slot's shape and modifying the surface current path and changing the electric field distribution inside the slot consequently, the antenna can operate in wideband and show compact structure. The relative bandwidth of the proposed antennas is 37% with the return loss less than -15dB, from 1890MHz to 2750MHz, covers the D (2500 ~ 2690MHz) and E (2300 - 2400 MHz) bands of the TD-LTE.

Wideband slot antenna for LTE indoor distribution applications

A novel printed side shaped elliptical monopole with ultra-wide bandwidth is presented in this paper. The antenna is simulated with CST software and fabricated on a Rogers 5880 dielectric substrate. The measured impedance bandwidth with VSWR<2 is from 0.8GHz to 6.3GHz. The short axis of the elliptical radiator is reduced for compact designation, and two notches at the sides of the ellipse are introduced for improving the radiation patterns.

Printed omni-directional wide-band monopole antenna with compact size

The invention relates to a multi-mode substrate integrated waveguide beam forming network which is applicable to microwave millimeter wave multi-beam antenna-feed systems and intelligent antenna systems The network has a planar circuit structure An upper metal copper-coated surface (1) and a lower metal copper-coated surface (2) are respectively positioned on two sides of a dielectric substrate(3) A metalized through hole (4) penetrates the dielectric substrate (3), and then is connected with the upper metal copper-coated surface (1) and the lower metal copper-coated surface (2) so as to form a multi-mode substrate integrated waveguide (5) and a substrate integrated waveguide phase shift network (6) The multi-mode substrate integrated waveguide (5) and the substrate integrated waveguide phase shift network (6) are directly connected to each other An input port (51) is positioned on one side of the multi-mode substrate integrated waveguide (5) An inner output port (52) is positioned on the other side of the multi-mode substrate integrated waveguide (5) and is connected with the inner side of the substrate integrated waveguide phase shift network (6) An outer output port (7)is connected with the outer side of the substrate integrated waveguide phase shift network (6)

Multi-mode substrate integration waveguide beam shaping network

A novel co-planar L-probe fed microstrip patch antenna is proposed. Unlike a conventional L-probe, the co-planar L-probe is a L-shaped strip which is printed entirely on a substrate. The probe's substrate is placed vertically beneath the patch's substrate. The antenna can be easily fabricated in PCB craftwork and integrated with RF circuits. A prototype of the antenna which is designed to operate at 2.5 GHz has been fabricated and measured. It is found that the antenna has 30.4% impedance bandwidth and an average gain of 8.1 dBi over 2.3–2.7 GHz. Details of the proposed design and experimental results are presented and discussed.

Zhenqi Kuai

Papers

A parallel feeding omnidirectional array antenna

Wideband slot antenna for LTE indoor distribution applications

Printed omni-directional wide-band monopole antenna with compact size

Multi-mode substrate integration waveguide beam shaping network

A novel co-planar L-probe designed to feed patch antenna