5G Antenna for Homes and Offices
Sarthak Pandit, Hitesh Pariani, Kartik Parsodkar, Aaditya Patil
Role of Antennas:
With the significant wireless evolution from 1G to 5G, technologies and network capacities are evolving to meet rapidly increasing customer demands. The antenna designs have made significant technological advancements as these demands are steadily rising.
The 5G mobile communication standard introduced significant technological advancements in terms of reliability, capacity, availability, and latency. As a result, regulatory bodies like the European Telecommunication Standards Institute (ETSI) and 3rd Generation Partnership Project (3GPP) also established antenna requirements and specifications for 5G systems.Because 5G mobile networks may operate at multiple frequencies, separate antennas are required for each frequency band. Specialised antennas and antenna ideas are necessary because different frequencies are employed to transmit a signal for different applications. So, one reason for the requirement for extra antennas is the diversity of frequency bands used for communication. This involves the development of unique technologies for 5G mobile antennas.
Antenna Design:
A 5G mobile antenna should be small and compact, while meeting bandwidth and radiation efficiency criteria. The mm-wave spectrum has additional path loss due to higher frequency air attenuation and absorptions. To combat route loss, 5G antennas should have a high gain and enhanced directivity.
Antenna arrays and beam-steerable antennas are key enablers for the 5G mobile and broadband communication due to their ability to reduce path losses, improve spatial coverage, and achieve high directivity and gain. MIMO technology has recently undergone extensive research for 5G communication in order to meet the higher capacity requirement and for a wider coverage area.
Because of the physical propagation constraints of radio signals, most of the frequencies proposed for 5G are only appropriate for a short range. These frequency bands, however, offer a significant bandwidth potential. Low-power base stations known as femtocells can be utilised to power mobile radio hotspots with extremely high data rates. This necessitates the installation of extra base stations. As a result, streetlamps may one day provide not just light but also access to mobile Gigabit internet by hosting base stations for femtocells.
Radio Frequency Integrated Circuit
When operating in the microwave spectrum, the Radio Frequency Integrated Circuit (RFIC), antenna, and modem chips are grouped as separate design blocks, and the entire radio system establishes a horizontal integration known as a multiple-chip module. This configuration expands the chip area, which limits the applicability of this strategy for cellular and other wireless devices because the size of these devices is continuously getting smaller as technology advances.
Impedance should be matched at the antenna circuit interface to ensure maximum power transfer from one component to the other because the antenna must interface with the electronic circuitry, whether in a discrete or integrated manner. To create a reliable feeding network, standard interconnect components like coaxial cables, C-clips, and RF switches with a certain impedance value (50) are used. However, at mm-wave frequencies, the RFIC components’ signal attenuation properties drastically deteriorate, which has had a negative impact on the noise figure. For 5G mm-wave devices, the antennas should essentially be placed close to the RFIC, in contrast to the current mobile antennas. Antenna in package (AiP) and Antenna on Chip(AoC) are the two main groups of highly integrated and compact antenna packaging schemes for 5G mm-wave mobile antennas
Integrated antennas for 5G handheld devices
As the mm-wave 5G antennas are expected to be compatible with the previous technologies such as 4G/LTE, therefore, integrated or co-existing 4G/LTE and mm-wave 5G antennas will be an effective solution for long and short-range communication. However, because of the enhanced coupling effects between tightly packed antennas, designing such antennas is extremely difficult. Recent research has revealed antenna configurations for portable devices in which 4G/LTE and mm-wave 5G antennas coexist on the same substrate board. The suggested integrated antenna solution consists of a two-element MIMO microwave antenna system and a mm-wave array. The suggested planar antenna system is intended for smartphone devices. As an integrated antenna solution for handheld devices, a MIMO antenna structure operating at microwave frequencies and an mm-wave tapered slot antenna array are proposed.
Advanced Antenna System (AAS)
The advanced antenna system (AAS) is a hybrid technology that unifies and enhances all previous mobile communications generations. It opens up new opportunities in a variety of fields, including IoT and realistic methods for real-time cloud computing.
So what is AAS exactly?
A combination of AAS features, such as MIMO and beamforming, are combined with an AAS radio to make an AAS. An active antenna system, in which the active transceiver array and the passive antenna array are cleverly merged into one hardware piece, is a key part of the AAS. The AAS can be significantly reduced in size because of this integration, which also improves communication throughput, lowers cable losses, and uses less power. Along with the algorithms to facilitate the execution of the AAS features, the AAS also includes the hardware and software needed to process radio signals.
Multiple signals may be simultaneously received or transmitted with different radiation patterns using AAS.
Features of AAS:
- Multi-antenna technology:
Beamforming and MIMO are two multi-antenna approaches that are referred to as AAS features. In today’s LTE networks, such characteristics are already employed with traditional systems.
2. Beamforming:
When transmitting, beamforming is the ability to direct radio energy through the radio channel toward a specific receiver(As shown in the figure below)
Constructive addition of the corresponding signals at the UE(user equipment) receiver can be accomplished by altering the phase and amplitude of the transmitted signals, which boosts the received signal strength and, consequently, the throughput for end users. Similarly, beamforming is the capacity to gather the signal energy from a particular transmitter when receiving. An AAS’s beams are continuously adjusted to their environment to provide exceptional performance in both UL and DL.
Even though it is frequently incredibly efficient, energy transmission in only one direction is not always the best option. It is advantageous to send the same data stream along several different paths, with phases and amplitudes controlled so that they add positively at the receiver, in multi-path scenarios where the radio channel comprises multiple propagation paths from transmitter to receiver due to diffraction around corners and reflection against buildings or other objects. We call this generalised beamforming(As shown in figure below).
3. MIMO(Multiple input, multiple output) in 5G:
The ability to broadcast multiple data streams utilizing the same time and frequency resource while allowing each data stream to be beamformed is known as spatial multiplexing, or MIMO for short. MIMO’s main objective is to boost throughput. The foundation of MIMO is the idea that many data streams with lower power per stream are preferable to a single stream with full power.(MIMO works for both UL and DL)
a. SU-MIMO
Single-user MIMO (SU-MIMO) refers to the ability to send one or more data streams, known as layers, from a single transmitting array to a single user. The number of layers that may be supported, referred to as the rank, is determined by the radio channel. A UE must have at least as many reception antennas as there are DL layers to distinguish between them. By delivering distinct layers with different polarizations in the same direction, SU-MIMO may be obtained.
SU-MIMO can be achieved by sending different layers on different polarizations in the same direction. SU-MIMO can also be achieved in a multipath environment, where we send different layers on different propagation paths(as shown in figure below)
b. MU-MIMO
The AAS simultaneously transmits many layers in independent beams to various users utilizing the same time and frequency resource in multi-user MIMO (MU-MIMO), hence boosting network capacity. The system must identify two or more users who require simultaneous data transmission and reception in order to employ MU-MIMO. Additionally, little user interference is necessary for effective MU-MIMO. This can be done by utilizing generalized beamforming with null forming, whereby nulls are produced in the directions of the other concurrent users when a layer is sent to one user.
For MU-MIMO to achieve its efficiency improvements, each layer must be received with a good signal-to-interference and noise ratio (SINR). Similar to SU-MIMO, the total DL power is divided among the several levels; as a result, the power (and thus SINR) for each user decreases as the number of MU-MIMO users increases. Additionally, due to user interference, the SINR will continue to decline as the user numbers expands. As a result, as the number of MIMO layers rises, the network capacity usually increases as well, to the point where power sharing and user interference cause gains to gradually reduce and even cause losses.
4. Antenna array structure
To enable high-gain beams and enable steering of those beams over a variety of angles, a rectangular antenna array is used. Both in UL and DL, the gain is attained by constructively combining the signals coming from several antenna elements. The gain increases with the number of antenna elements.
Smaller pieces of the antenna array’s amplitude and phase are independently controlled to achieve steering ability. Typically, to do this, the antenna array is divided into so-called sub-arrays (groups of non-overlapping elements), as shown in section C, and two dedicated radio chains are applied to each sub-array (one for each polarisation), as shown in section D.
5. Deployment scenarios:
It requires a combination of knowledge about the scenario, potential site constraints, and available AAS features, particularly the requirement for vertical beam steerability, the applicability of reciprocity-based beamforming, and the benefit from MU-MIMO, to determine what kind of AAS configuration is most suitable and cost-effective for a specific deployment scenario.
We have selected three common use cases — rural/suburban, urban low-rise, and dense urban high-rise — to highlight various elements of AAS implementation. The scenarios are shown below, along with pertinent details, possible AAS setups, and performance potential.
Conclusion
This chapter describes the specifications and requirements for 5G wireless communication. Moreover, essential design considerations for 5G are also discussed briefly. It is described in detail how these antennas are utilising key enabling technologies such as arrays and MIMO to improve the radiation characteristics of the 5G antennas. In addition, recently reported integrated 4G/LTE and 5G antenna systems for handheld devices are also discussed. A major technology that will be the integral part of the 5G system will be Advanced Antenna System(AAS).
AAS enables state-of-the-art beamforming and MIMO techniques that are powerful tools for improving end-user experience, capacity and coverage.In dense urban high-rise scenarios with tall buildings and high subscriber density, an AAS with beamforming capabilities in both vertical and horizontal directions is the most beneficial option. In suburban/rural settings, where vertical beamforming is rarely required, the performance of a less expensive AAS with fewer radio links is sometimes sufficient. A small number of AAS variations offer considerable benefits across a wide range of deployment circumstances, allowing mobile network operators to reap the benefits of cost-effective AAS across their networks.
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