Design Challenges and Possible Solutions for 5G SIW MIMO and Phased Array Antennas: A Review

Abstract

With the increasing demand for high-speed data, rapid deployments of the 5G terrestrial heterogeneous wireless networks are expected worldwide in the next decade. In such networks, sub-6 GHz macro-cells overlapped by mmWave small-cells are being used to cater to densely populated regions. As a result, several challenges arise with the antenna design technologies used at the mobile terminal, access points, or backhaul/front haul levels. These challenges are being addressed using multiple-input multipleoutput (MIMO), massive-MIMO, and phased array antenna technologies. In order to implement these antenna technologies, considering the expanding 5G scenario, substrate integrated waveguide (SIW) offers a viable solution due to its low-cost, low-profile, high-power handling, low transmission loss, and ease of integration with the radio circuits; therefore, the SIW plays a vital role in developing the modern radio systems. The proposed study aimed to provide a comprehensive overview of SIW MIMO and phased array antennas operating in the 5G sub-6 GHz and mmWave bands. It deliberates the specific issues related to the band of operations and challenges in designing different antenna structures. After careful investigation and detailed analysis, this paper identified existing research gaps and suggested possible antenna design solutions for prospective researchers who intend to explore further the aforementioned promising area and present future research directions.INDEX TERMS 5G New Radio (NR), millimeter-wave (mmWave), multiple-input multiple-output (MIMO), planar antennas, substrate integrated waveguide (SIW), sub-6 GHz. I. INTRODUCTIONThere is rapid growth in the deployments of 5G heterogeneous wireless networks to cater to the increasing demands of high-speed data communication in the modern wireless system [1,2]. In such a scenario, the microwave and mmWave networks overlap (See Fig. 1) to serve the mobile units, access points, backhaul, and fronthaul wireless links, supported by MIMO, massive MIMO, and phased array antennas [1,2]. In order to realize these antennas, substrate integrated waveguide, a well-established planar technology, is a suitable choice [3]. A. MIMO ANTENNAThe multiple-input multiple-output (MIMO) antenna is the key enabling technology for fourth-generation (4G), fifth-generation (5G), and beyond 5G (B5G) wireless communication systems. In 4G communication, MIMO primarily supports average download speeds for mobile users. Whereas, in 5G, the MIMO at the user equipment (UE) side and massive MIMO at the base station (BS) promise to deliver high data speeds for enhanced mobile broadband (eMBB) access and enable a wide range of services, including internet of thing (IoT) and critical machine-to-machine communications [1].As per Shannon's channel capacity theorem, the direct way to enhance the date rate is by increasing the bandwidth and/or signal-to-noise ratio (SNR) [4]; however, these are not under the control of the antenna designer and are fixed by the cellular operator. Therefore, multiple antenna...

A Critical Review of Interconnect Options for SIW Technologies

“…The SIW cavity behaves identically to a conventional metallic cavity when d/s ≥ 0.5 and d/λ o ≤ 0.1 [23]. Furthermore, conditions such as d < s < 2d must be satisfied to avoid the bandgap effect [6], [23]- [25], which arises due to periodic structures of vias in SIW.…”

A Millimeter Wave Air Filled SIW Horn Antenna with Tilted Beam

“…Where, w 1 is the width of dielectric-filled regions of the AFSIW region, (see Figure 1), c is the light's speed, and ϵ r is the dielectric constant. The via diameter and separation between the center-to-center of the vias used in the AFSIW is determined using the technique described in [10]- [12]. Substrates 1 and 3 can be utilized to realize baseband or digital circuits for a more cost-effective wireless system solution.…”

Advances in MIMO Antenna Design for 5G: A Comprehensive Review

“…Parasitic elements, neutralization lines, slots/stubs, decoupling structures, defective ground structures, slot etching, metamaterials, unit cells, etc. are the most widely used isolation techniques [ 85 , 86 , 87 , 88 , 89 , 90 ]. The parasitic element approach is where an isolating element is placed in between antenna elements to reduce the effects of coupling.…”