1. Introduction

Generally, antenna unit is a requisite of any on-air radio frequency system forming its service area and bandwidth capability. At present, implementing an active phased array antenna (PAA) [1] results in remarkably increased footprint and operation flexibility thanks to electronic beam steering function, which is realized by a beamforming network (BFN). Today, the global telecommunications industry is experiencing a stage of violent development associated with the becoming of the fifth-generation mobile communication networks (5G NR) [2–6], and it is planned that one of the milestones for 5G NR compared to available 4G LTE networks should be millimeter-wave (mmWave) communication with mobile radio terminals [7, 8]. This approach should lead to a newer network design technology using Radio-over-Fiber (RoF) building concept as well as PAA-assisted remote stations (RS) and user terminals (UT) [8, 9]. On this way, integrated and millimeter-wave (mmWave) photonics are extremely attractive technologies for realizing a PAA's interactive optical BFN due to its superior instantaneous operating bandwidth, immunity to electromagnetic interference, lightweight, and reconfigurability [3].

• It provides larger bandwidth, and hence, more number of UT can be

Design of Reconfigurable Multiple-Beam Array Feed Network Based on Millimeter-Wave…

• Its coverage is not limited to the line of sight (LoS) as first-order scatter paths

• Channel sounding feature is employed to take care of different types of losses at mmWave frequencies so that 5G network operates satisfactorily thanks to the measurement or estimation of channel characteristics, which helps in successful design, development, and deployment of 5G network with necessary

• Antenna size is physically small, and hence, a large number of antennas are packed in small volume. This leads to the use of massive multiple input, multiple output (MIMO), or beam-steerable PAA in RS to enhance the capacity

> Some superwide bandwidth cases in 5G access networks will require contiguous carrier bandwidths. To support them, additional carrier frequencies (below 6 GHz), as well as

Following the tendencies of expanding the available spectral bands and increasing user densification, mmWave 5G wireless network infrastructure can be erected with a lot of small cell sites controlled by the corresponding RSs. In order to avoid inter-interference inside these cells, one of the promising approaches is to equip the RS with beam-steerable PAA using hundreds of antenna elements to form multiple directional

Following the milestone of item 1, it is necessary to optimize the access network architecture so that at the same time it will provide high-quality communication with fixed and mobile users subject to low charges for the building and maintenance of networks. A promising candidate for solving the problem is a RoF's FiWi architecture, already tested in 4G LTE systems

mmWave RF carriers will be required

beams in omnidirectional space

accommodated.

DOI: http://dx.doi.org/10.5772/intechopen.89076

quality requirements.

(see item 2 of Table 1).

1 Radically expanding the available spectral bands

2 Using active antenna systems in mmWave communication

3 Establishing optimized access network architecture

Planned 5G NR spectrum allocations [12].

The milestones in the way to transform 4G LTE to 5G NR.

Table 1.

Figure 1.

111

No. Designation Short description

are viable.

Following it, recently we designed photonics-based BFNs for ultrawide bandwidth mmWave (57–76 GHz) antenna arrays [10]. Elaborating the direction, in this chapter, we review the worldwide progress referred to designing multiple-beam photonic BFN and highlight our last simulation results on design and optimization of millimeter-photonics-based matrix beamformers. Thus, in the rest of the sections, the following topics are under consideration. In particular, Section 2 reviews the specialties of mmWave photonics technique in 5G mobile networks of RoF technology based on fiber-wireless (FiWi) architecture. In addition, Section 3 presents theoretical background of array antenna multiple-beam steering using ideal models of matrix-based phase shifters and time delay lines. Section 4 includes a general analysis of radiation pattern sensitivity to compare updated photonics beamforming networks produced on phase shifter or true-time delay (TTD) approach. The principles and ways to optimized photonics BFN design are discussed in Section 5 based on the photonics BFN scheme including integrated 88 optical Butler matrix (OBM). All schemes are modeled using VPIphotonics Design Suite and MATLAB software tools. Finally, Section 6 concludes the chapter.
