New Antennas for Mobile Technology

Bob Giometti Vice President R&D and Engineering, SkyCross [email protected] Presented at the Antenna Systems Conference December 12-13, 2013 Las Vegas, NV

Contents 1. Introduction 2. LTE-A and the Mobile Device Antenna 3. LTE-A: Impact on the Antenna System a. Requirements b. Carrier Aggregation c. Drivers for Antenna Tuning 4. Enabling Technologies a. Aperture Tuning a b. Tunable Match Network c. Hybrid Approach d. Co-location of antennas e. Isolated Mode Antennas (iMAT) - Beam Forming Application 5. Summary

Introduction

Background/Bio - Over 20 years experience in the wireless industry - Mobile phone product development at Motorola/Google - Electrical design lead for the original RAZR - BSEE/MSEE Illinois Institute of Technology - Joined SkyCross as VP of R&D and Engineering Jan. 2013

Page 4

LTE- A and the Mobile Device Antenna

LTE-A: Squeezing Even More Into The Mobile Device • Many bands (40+ and counting….) – – – – – – –

700 MHz in US (sub-bands for AT&T and Verizon) AWS (2.1/1.7 GHz) in US 790-862 MHz in Europe 2.6 GHz FDD – mainly in Europe 2.6 GHz TDD – China, Europe 2.3 GHz TDD – China, Korea, India 600MHz on the way!

• GPS, BT, FM, NFC,… • WiFi (Dual Band) • Tx Diversity • MIMO 2x2, 3x3, 4x4,… • Carrier Aggregation – Low/Low, Low/High, High/High Page 6

Challenges facing today’s Mobile Device Antenna Engineer Traditional antenna performance is inadequate to meet market demands for: )  Increasing number of frequency bands (4G/LTE  Increased data traffic clogged networks )  Real life use cases (head, hand, slider phone  Thinner phones Smaller antennas  Quality of Service challenges Bands of Interest vary by:  Country / Region  Network provider  Protocol  Need

for advanced adaptive antenna/RF solutions

Page 7

“Advanced Smart Antennas” provide improved RF Performance & Increased Flexibility

Page 8

LTE-A: Impact on the Antenna System

LTE- A 2013 to 2016 Higher Capacity/Throughput and/or Efficiency •Wider Radio Channels: 20 MHz •Carrier Aggregation: up to 100 MHz •Advanced Antenna Configurations •More Advanced MIMO (Higher Order, Multi-User, Higher Mobility) •Coordinated Multipoint Transmission •Het-nets (Microcells/Picocells/Femtocells)

Enables more users, more applications, and a better experience LTE 2010 to 2012 •5 or 10 MHz Radio Channels •2X2 Multiple Input Multiple Output (MIMO)

Page 10 Source: Rysavy Research/4G Americas, 2012

Carrier Aggregation Considerations • Easiest way to arrange aggregation: use contiguous component carriers within the same operating frequency band (as defined for LTE), so called intra-band contiguous. • May not always be possible, due to frequency allocation scenarios. • For non-contiguous allocation it could either be intra-band, i.e. the component carriers belong to the same operating frequency band, but are separated by a frequency gap, or it could be inter-band, in which case the component carriers belong to different operating frequency bands.

Page 11

LTE-A Drivers for Antenna Tunability • LTE smartphones are challenged to achieve tightening carrier performance expectations – 4G LTE speeds/capacity require MIMO (multiple LTE antennas) – Growing number of operating frequency bands (number of antennas) – Aggressively styled device form-factors (constrained space)

• OEMs seeking new technical solutions to address challenges – Tunable antenna solutions seen as the desired approach – Progressive OEMs already initiating smartphone architectures that support tunable antenna modules

• LTE-A Requirements – Carrier Aggregation – Higher Levels of MIMO – Tx Diversity Page 12

Antenna Tuning Technologies

Tunable vs. Passive Antennas • Integrates tuning elements, antenna, and interface

• Supports Carrier Aggregation requirements

• Smaller size (smaller than • Primary/secondary antennas can conventional passive antennas at be co-located for greater space same efficiency) or higher gain in reduction same size to reduce Tx power consumption (increased battery • Potential to simplify filter circuits life) • Separate from and complementary to feed-point impedance matching

• Simple 1 or 2 bit interface and control

Page 14

Motivation for Tunable Antennas 1.

Greater band coverage +MIMO in accepted form factor allocated space

2.

Smaller Antenna: 1000 cubic millimeters or less (handset OEMs)(need more tuning states)

3.

Head/Hand Effect mitigation (requires sensor and algorithm) (Operators)

4.

Higher ASP stemming from integration of antenna and tuning elements/control (Antenna Suppliers)

5.

Lower VSWR (PA Suppliers)

6.

Reduced Filter Requirements (Filter suppliers) Page 15

Aperture Tuning (AT) vs. Tunable Matching Network (TMN) Aperture Tuning

Tunable Matching Network

• Integrates tuning element, antenna, and interface

• Used to improve VSWR match to antenna.

• Antenna resonance is changed directly by the tuning element.

• Not considered as producing optimal radiation efficiency compared to Aperture Tuning

• Allows antenna to be made smaller or cover more bands than with passive antenna • Simple interface and control to achieve open loop coverage on a band-by-band basis • Often used with tuning devices such as switches or DTCs for open or closed loop control. • Can be thought of as a “coarse tuner”

• Improves power coupled to antenna over frequency of operation and under varying usage or environmental conditions • More complex interface generally with 6 or more bits of control • Can use analog tuning devices such as BST and Varactor diodes, may be open or closed loop • Can be thought of as a “fine tuner”

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Efficiency Comparison Between Passive Broad Band and State-Tuned-Aperture Antennas Significant improvement in low band performance

Minimal impact to high band performance

Low Bands

High Bands

~0.8 dB >2 dB

State 1 State 2 Broad Band

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Hybrid Approach: Aperture + Match Tuning

RF (Port 2)

Tunable Matching Network (Fine Tuner) Optimize Performance

Diversity Aperture Tuned Antenna (Coarse Tuner) Band Selection

Flash Memory

MIPI RFFE

Microcontroller

GPIO Control

Control Algorithm

RF (Port 1)

Tunable Matching Network (Fine Tuner) Optimize Performance

Diversity Aperture Tuned Antenna (Coarse Tuner) Band Selection

Page 18

Antenna Co-Location

Antenna Proximity Problem • Far apart – Negligible coupling between antennas – spatial separation makes antenna patterns unique – How far: generally more than about half wavelength (17 cm at 900 MHz) – size not feasible for many consumer products

• Close together - coupling between antennas may -

be a problem (RX saturation or desense, TX distortion) coupling hurts radiation efficiency as power goes into neighboring antenna and not to far field patterns lose uniqueness and are highly correlated (loss of MIMO capacity or loss of diversity gain) Reality of many consumer products

Antenna starts to couple more to its neighbor than to the far-field

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The MIMO Antenna Solution for 4G

: Isolated Mode Antenna Technology • iMAT is a patented technology that allows a single antenna structure to behave like multiple antennas through the use of multiple feed points. • Each feed point accesses the single antenna as if it consisted of 2, 3, or more independent antennas that are highly isolated with superior link performance gain. • This compact solution is applicable to any mobile device! iMAT supports legacy networks and is essential for next generation protocols that require diversity or MIMO. Patented Technology

Page 21

Enables Multiple Antennas in Small Spaces The iMAT solution offers high efficiency, superior isolation, and low correlation coefficient while maintaining equivalent return loss, with a single antenna!

Conventional Smart Antenna Approach

SkyCross iMAT Solution SkyCross Antenna Technology Breakthrough!

d 1

d 2

3...

3...

1

-10 -20 -30

60 50

EFF

40 30

Frequency

0

EFF

-10 -20 -30

60 50

ISO

40 30

Efficiency %

ISO

Isolation dB

0

Efficiency %

Isolation dB

2

Technology Applications • WiFi and/or WiMAX • 4G/LTE • HSDPA / HSUPA • 1XEVDO • 802.11n, 802.11ac • Mobile video (CMMB, T-DMB, DVB-H) Antenna Requirements • Diversity/MIMO • High isolation • High radiation efficiency • Low correlation coefficient • Small size

Frequency Page 22

iMAT: Far-Field Patterns • Each resonance mode has a unique far field pattern • With iMAT approach each antenna port couples to a different combination of the two fundamental modes • The resulting far-field patterns are also unique to each other resulting in low ECC Combination

Common Mode

+

=

Farfield pattern from Port 1

Differential Mode

-

=

Farfield pattern from Port 2

Pattern phase reversal Page 23

iMAT: Concurrency of Isolation and ECC • With iMAT Port-to-port isolation and low far-field correlation are obtained from the same design optimization at the same frequency • Both result from the condition where the near fields associated with Port 1 are orthogonal from those associated with Port 2

Port-to-Port Coupling

frequency

Pattern Correlation

• The proper conditions are achieved through resonance and so are inherently optimized to a particular frequency band or bands frequency

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SkyCross ST-iMAT™ (State-Tuned iMAT Antenna Module for Smartphone)

VersiTune-LTE™ Tunable Antenna Module Smartphone Implementation

iMAT Radiating Elements

Tunable Antenna Module

State 1

State 2

• Aperture tuning in SkyCross tunable antenna modules permits the actual radiating elements to be configured for optimal performance at each desired frequency band • SkyCross ST-iMAT and Aperture Tuning deliver:    

Smaller size Improved device performance Network improvement (fewer dropped calls, increased network capacity) Superior performance versus simple feed-point matching Page 25

Tunable iMAT “Isolation Notch” Drives Multiband Antenna Performance • Isolation is a measure of signal interference separation from one feed point to the other • Correlation coefficient is the degree to which the two RF signals are distinct from each other

iMAT d e s ig n a llows “c o n tro l” o f th e is o la tio n b e twe e n p o rts . Drive s h ig h e r e ffic ie n c y a n d lo we r c o rre la tio n c o e ffic ie n t Page 26

LTE-700 Corner to Corner Conventional Antenna Design

VSWR: 0.8

-4dB

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iMAT LTE-700 Antenna Design

VSWR