Dr.P.H.RaoScientist

SAMEER-Center for ElectromagneticsChennai

RF and Antenna Design Challenges in

Indigenous 5G Test bed Development

OUTLINE

TOPICS

5G Challenges

Indigenous 5G Test Bed

Antenna Design ChallengesBeamformer design challenges

Conclusions

Introduction

5G RF System and Antenna Testing

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● No matter how 5G will ultimately be implemented, higher data-rates, more capacity and many more connected “things” will be parts of the wireless future.

● The emerging definition of 5G envisions dramatic performance improvements in network capacity, mobile connections, latency, cost, data rates and coverage

● The 5G requirements for high data rates and low latency demand the implementation of technologies with large bandwidth in sub 6GHz and mm wave bands.

RF and antenna developments and challenges specific to "Indigenous 5G test bed" both for sub 6GHz and mm wave bands. ● Complex RF and Antenna technologies ● Compact and small form factor ● The interface issues● RF integration and fabrication issues● The MIMO antennas at sub 6GHz● Phased array and Hybrid beam forming developments at mm wave ● Alternative solutions in mm wave antenna developments for 1D and 2D beam switching

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Introduction

● 5G Technology development and implementation

○ Enable true human-centric and connected machine-centric networks to redefine end user mobility along with the entire landscape of the global telecoms industry.

● 5G will herald an even greater rise in the prominence of mobile access for realizing total ICT network growth and expansion.

A changing telecoms landscape

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Heterogeneous Network

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● As with any major advance in communications technology, 5G presents a whole new set of technical RF challenges.

● Unprecedented bandwidth, with carriers up to 100 MHz wide in FR1 and 400 MHz in FR2 and new waveforms will generate very high peak-to power ratios.

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• Implementation of Massive MIMO • Beam steering to deliver multi-gigabit

data rates.• An escalation in bandwidth, demand

for high linearity in RF systems.• MIMO and beam former measurements

Challenges and Requirements

● For many handsets, the change will mean a substantial increase in RF content, signal-routing complexity, and antenna bandwidth.

● mm wave antennas and RF need complex designs for beam forming.

● It will be challenging to squeeze even more content into already crowded space allocated to the RF front end, and highly integrated solutions will be needed to minimize solution size and increase performance.

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Challenges and Requirements : Hand set

Dual Connectivity : RF Interference Challenges

● NSA will continue to present challenges for handset RF design over at least the next decade, until all mobile operators convert to SA.

● Dual connectively can create extremely complex RF challenges.

● The NSA specification also allows the handset to transmit on one or more LTE bands while receiving on the 5G band.

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5G: RF and Antenna Testing

Top challenges testing 5G NR device throughput include :● Configuring 5G NR frame structures for higher

throughput.● Configuring 5G NR devices for optimal link adaptation.● Optimizing 5G NR beamforming performance at

mmWave frequencies.

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5G: RF and Antenna Testing

Beamforming performance at mmWave frequencies:

● Beam acquisition and tracking ● Beam refinement ● Beam feedback ● Beam switching

Source Keysight document

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5G: RF and Antenna Testing

Top challenges testing mmWave beamforming include:

• Issues testing mmWave devices in the far-field

• OTA test methodologies are still being defined

Indigenous 5G Testbed

Ø Dual Polarized, high isolation Antennas

Ø MIMO and Massive MIMO Antenna development

Ø C-Ran and Massive MIMO antennas@ 2.4GHz

Ø RF Front End system integration

Ø UE Antenna development

FR1 : RF System

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SAMEER-Responsibility and Activities : Fr2Indigenous 5G Testbed

Ømm wave Beam steered phased arrayØPhased array design and developmentØBeam forming RF Network designØRF and Antenna on a multilayer stack upØHybrid beam forming Antennas ØSwitched beam arrays @ Fr2Ø UE antennas

FR2 : mmWave RF System

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Indigenous 5G Testbed

Ø 4x4 Array antenna

Ø Dual Polarised

Ø Printed planar feed configuration to enable the integration with RF board

FR1 : MIMO System

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Feed network simulation

T Line LOSS (dB)

GCPW - 1 0.648

GCPW - 2 0.321

GCPW - 3 0.318

GCPW - 4 0.140

GCPW - 5 0.177

TOTAL 1.604

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Design challenges

General● Components availability at 28 GHz● 3GPP compliance [EIRP]● Antenna and RF Integration

Antenna

● Antenna element design● Element spacing● Polarization● Feeding methods

Beamforming errors ● Cross talk● Antenna mutual

coupling● Impedance mismatch● Phase control resolution

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Design challenges

RF designPCB substrate selection● For printed antenna● For RF circuits● Substrate Losses (Tan D)● Board thickness● Prepreg property● Surface roughness

EM Simulation● Multi layer design [10 Layers]● Thin substrate [8 mils]● High frequency operation● Large number of Vias● Complex design ● PCB artwork to EM simulation● Simulation time

Power supply filtering and power supply layersVia design at 28 GHz

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Layout constraints

Layout designAvailability of PCB laminatesAvailability and compatibility of bonding material [PTFE, teflon non stick]Design for manufacturability [DFM]Track width, clearance, via sizeCost of fabrication

SI/PI design - Tx and RX switching currentEMI issues PCB stackup details and stackup issues

Addressing the challengesStart with single chip design, simple configuration Part by part Design and simulation [X Microwave]

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● Components availability● Integration with antenna● Layout constraints● Polarization● Power output and EIRP● Components assembly and testing

a. Small components, Handling issuesb. ESD sensitive

● EM Simulationa. Multi layer design (Import from PCB software)b. Thin substratec. High frequencyd. Large number of viase. Complex designf. Layout conversion between PCB design and EM simulation

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Design Challenges

Layout constraints

Thermal design challengesHeat dissipation (Approximate) - 16 Devices

Tx mode : 42 Watts, Rx mode : 26 WattsAverage : 32 Watts

Heat dissipation through solder ballsHeat sink designThermal Via design

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● As with any major advance in communications, 5G presents significant RF challenges for mobile devices and infrastructure, and will require innovative new solutions. When making technology choices, the cost and complexity of adding 5G content will be weighed against the performance benefits.

● 5G is designed to work with diverse application and the complexity is one of the major challenges to address. Since 5G is a platform for many wireless technologies to co-exist, technology providers has to overcome challenges in terms of signal spectrum, transmission protocols, security and network compatibility etc… Due to huge demand for a smarter network, 5G standard has been evolving faster than expected timeline.

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Conclusions

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1. Outlook: Visions and research directions for the Wireless World, WWRF, Oct 2011

2. Roadmap and workplan on future technologies(2020) from 3GPP, ITU, WRC, APT, CJK, China IMT2020, etc. Radiation blockage reduction in Antennas using Radio Frequency cloaks” IEEE-AP magazine: June2018.

3. "Miniaturisation of switched beam array antenna usingphase delay properties of CSRR-loaded transmissionline,“ IET Microw. Antennas Propag.,2018,Vol.12 Iss.12,pp.1960-1966.

4. "Full-Duplex Communications for Future Wireless Networks,” 2018 IEEE Global CommunicationsConference Globecomm-2018.