Millimeter-wave Mobile Broadband: Unleashing 3-300GHz Spectrum

Millimeter-wave Mobile Broadband:

Unleashing 3-300GHz Spectrum

Farooq Khan & Jerry Pi

Samsung

March 28, 2011

1Copyright 2011 by the authors. All rights reserved.

Outline• Introduction

– Mobile broadband growth

– The myth of traffic and revenue gap

– The national broadband plan

• mmW spectrum

– History of millimeter wave communications

– Unleashing 3-300GHz spectrum

– LMDS and 70/80/90 GHz bands

• mmW Propagation characteristics

– Free Space Propagation

• MMB air-interface design

– Duplex and multiple access schemes

– Frame Structure

– Channel coding and modulation

• Dynamic beamforming with miniature antennas

– Beamforming fundamentals

– Baseband beamforming

– Analog beamforming

– RF beamforming

– Beamforming in fading channels– Free Space Propagation

– Material penetration loss

– Oxygen and water absorption

– Foliage absorption

– Rain absorption

– Diffraction

– Ground reflection

• mmW Mobile Broadband (MMB) network

architecture

– Stand-alone MMB system

– MMB base station grid

– Hybrid MMB + 4G systems

– Deployment and antenna configuration

– Beamforming in fading channels

• Radio frequency components design and

challenges

– RF transceiver architecture

– MMB RF transceiver requirement

– mmWave Power amplifier

– mmWave LNA

• MMB system performance

– Link budget analysis

– Link Level performance

– Geometry distribution

– System throughput analysis

• Summary






• mmW spectrum








– Frame Structure






– RF beamforming





– Rain absorption

– Diffraction



architecture







challenges




– mmWave LNA






• Summary


Mobile Subscriber Growth

30

40

50

60

70

80

90

100

Pe

r 1

00

in

ha

bit

an

ts

Global ICT developments, 2000-2010*

Mobile cellular telephone subscriptions

Internet users

Fixed telephone lines

Mobile broadband subscriptions

Fixed broadband subscriptions

Year 2010

• 6.9 billion world population

• 5.3 billion mobile users

• 2.1 billion Internet users

• 940 million mobile broadband users

0

10

20

30

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010**Estimates

Source: ITU World Telecommunication /ICT Indicators database

4

Mobile Internet traffic pushes the limit of

mobile broadband networks …

5

The exciting (and yet concerning) future

A much larger (and growing)

portion of the IP traffic to

become mobile

6

The myth of mobile data traffic revenue gap

1000

1500

2000

2500

3000

3000

4000

5000

6000

7000

8000

mo

bile

da

ta r

eve

nu

e (

$B

/yr)

Mo

bile

dat

a tr

affi

c (P

B/m

o)

2000

3000

4000

5000

6000

400

600

800

1000

1200

1400

Co

mp

ute

r p

rice

ind

ex

CP

U g

ate

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un

t (m

illio

ns)

The yawning gap between mobile data traffic and revenue

But, we have seen this before …

0

500

1000

0

1000

2000

3000

2010 2011 2012 2013 2014 2015m

ob

ile d

ata

re

ven

ue

($

B/y

r)

Mo

bile

dat

a tr

affi

c (P

B/m

o)

Mobile data traffic Mobile data revenue

0

1000

0

200

400

2000 2002 2004 2006 2008 2010

Co

mp

ute

r p

rice

ind

ex

CP

U g

ate

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t (m

illio

ns)

CPU gate count Computer price index

Expon. (CPU gate count)

Also available in many other occasions:

• Transistor counts per IC – Moore’s Law

• The hard disk storage – Kryder’s Law

• Network capacity – Butter’s Law of Photonics, Nielsen’s Law

• The Great Moore’s Law Compensator – Wirth’s Law


1000

1000

10000

mo

bile

da

ta r

eve

nu

e (

$B

/yr)

Mo

bile

dat

a tr

affi

c (P

B/m

o)

100

1000

100

1000

10000

Co

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ute

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rice

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Looking from another perspective, our gap seems to be actually quite small, if any

The myth of mobile data traffic revenue gap

100100

2010 2011 2012 2013 2014 2015

mo

bile

da

ta r

eve

nu

e (

$B

/yr)

Mo

bile

dat

a tr

affi

c (P

B/m

o)

Mobile data traffic Mobile data revenue

1010

2000 2002 2004 2006 2008 2010

CPU gate count Computer price index

Expon. (CPU gate count)

The moral of the story

• Your eyes may fool you

• “Yawning gap” already exists in many (yet thriving) ICT industries

• If there is a gap between mobile data traffic and revenue, get used to it.

Need technology to provide >100x capacity with similar cost as cellular


US Frequency Allocation Chart

9

National Broadband Plan

Part of the American Recovery and Reinvestment Act passed in February 2009

Published on March 15, 2010

Ambitious goals

•Goal 1: At least 100 million U.S. homes should have affordable access to actual download speeds of at least 100 megabits per second and actual upload speeds of at least 50 megabits per second.

•Goal 2: The United States should lead the world in mobile innovation, with the fastest and most extensive wireless networks of any nation.

•Goal 3: Every American should have affordable access to robust broadband service, and the means and skills to subscribe if they so choose.

•Goal 4: Every community should have affordable access to at least 1 Gbps broadband service to anchor institutions such as schools, hospitals and government buildings.

•Goal 5: To ensure the safety of Americans, every first responder should have access to a nationwide public safety wireless network.

•Goal 6: To ensure that America leads in the clean energy economy, every American should be able to use broadband to track and manage their real-time energy consumption.


The gist of NBP - 500MHz more spectrum

Make 500 megahertz of spectrum newly available for broadband within 10 years

300 megahertz (between 225MHz and 3.7GHz) should be made available for mobile use within five years

• 20 MHz of Wireless Communications Spectrum (WCS) in the 2.3GHz range• 20 MHz of Wireless Communications Spectrum (WCS) in the 2.3GHz range

• 10 MHz D Block of 700MHz band re-auction for "commercial use” that is compatible with public safety services

• 60 MHz of Advanced Wireless Spectrum (AWS) in the 1900MHz and 2000MHz range

• 90 MHz of Mobile Satellite Spectrum to be used for terrestrial purposes in regions where it is difficult to deploy cellular

• 120 MHz of reallocated TV broadcast spectrum (TV broadcasters are rallying against it)






• mmW spectrum








– Frame Structure






– RF beamforming





– Rain absorption

– Diffraction



architecture







challenges




– mmWave LNA






• Summary


Wavepropagation

Eletric field

Magnetic field

The Electromagnetic Waves

A changing electric field generates an oscillating magnetic field

A changing magnetic field generates another changing electric field

These oscillating fields forms electromagnetic waves that

λλλλ

electromagnetic waves that propagates at speed of light


What is Millimeter-wave?

Micro-wave

• Frequency 300 MHz ~ 300 GHz (Wavelength 1mm ~ 1m)

Millimeter-wave (the high-end of the micro-wave frequencies)

• Frequency 30 GHz ~ 300GHz (Wavelength 1mm ~ 1cm)

• In this tutorial, we refer to frequencies between 3GHz and 300GHz as millimeter-wave in our effort to explore new spectrum for mobile broadband communication

Current applications of millimeter-wave

• Radio astronomy, wireless backhaul, inter-satellite link, high resolution radar, security screening, amateur radio


The History of Millimeter-wave

1864 :• The existence of electromagnetic waves was predicted by James Clerk Maxwell from his equations.

1888:

• Heinrich Hertz was the first to demonstrate the existence of electromagnetic waves by building an apparatus that produced and detected microwaves in the UHF region. The design necessarily used horse-and-buggy materials, including a horse trough, a wrought iron point spark, Leyden jars, and a length of zinc gutter whose parabolic cross-section worked as a reflection antenna. 1888: length of zinc gutter whose parabolic cross-section worked as a reflection antenna.

1894:• J. C. Bose publicly demonstrated radio control of a bell using millimeter wavelengths, and conducted

research into the propagation of microwaves.

1931:

• the first, documented, formal use of the term microwave: "When trials with wavelengths as low as 18 cm were made known, there was undisguised surprise that the problem of the micro-wave had been solved so soon." Telegraph & Telephone Journal XVII. 179/1


Unleashing the 3-300GHz Spectrum

With a reasonable assumption that about 40% of the spectrum in the mmW bands can be made available over time, we open the door for possible 100GHz new spectrum for mobile broadband

• More than 200 times the spectrum currently allocated for this purpose below 3GHz.


LMDS and 30/40 GHz bands

A total of 1.3GHz spectrum available in the LMDS bands

Possibly, a total of 3.4GHz spectrum available in the 38GHz (38.6–40GHz) and 40GHz (40.5-42.5) bands


70/80/90 GHz (E-band)

A total of 12.9GHz bandwidth available in the E-band


Spectrum Identified for MMBBand Frequency range

[GHz]

Available Spectrum [GHz]

23GHz 22.55-23.55 1.0

LMDS

27.50-28.35,

29.10-29.25,

31.075-31.225

1.3

38GHz 38.6-40.0 1.4

40GHz 40.50-42.50 2.040GHz 40.50-42.50 2.0

46GHz 45.5-46.9 1.4

47GHz 47.2-48.2 1.0

49GHz 48.2-50.2 2.0

E-band

71-76

81-86

92-95

12.9

Others --

Total 23.0






• mmW spectrum








– Frame Structure






– RF beamforming





– Rain absorption

– Diffraction



architecture







challenges




– mmWave LNA






• Summary


Propagation Loss

Transmission loss of mmW is accounted for principally by the free space loss

Free-space loss (Isotropic antennas)

• LFSL, dB = 92.4 + 20logf + 20logR

• f is the carrier frequency in GHz• f is the carrier frequency in GHz

• R is distance in km

Other factors

• Atmosphere Gaseous Losses

• Precipitation attenuation

• Foliage blockage

• Scattering

• Bending


Solid Angle

2Area r=

rr

r

• One radian is defined as the plane

angle with its vertex at the center of

a circle of radius r that is subtended

by an arc of length r

• 2π radians in a full circle

• One square radian (or steradian) is

defined as the solid angle with its

vertex at the center of a sphere of

radius r that is subtended by a

spherical surface of area r2

• 4π steradians in a closed sphere

Copyright 2011 by the authors. All rights reserved. 22

24A rπ=2C rπ=

Beam Area (or Beam Solid Angle) [1/2]

z0θ =

θ

θ

sinr

θ

sinr dθ φ

rdθ2 sindA r d dθ θ φ=

θ

x

y

φ

0φ =φ

dφr

rdφ

θdθ

2( )( sin )

sin

dA rd r d r d

d d d

θ θ φ

θ θ φ

= = Ω

Ω =

Where Solid Angle subtended by the areadΩ = dA


Beam Area (or Beam Solid Angle) [2/2]

• The beam area (or beam solid angle) of an antenna is given by the integral

of the normalized power pattern over a sphere:

( )

( )

2

0 0

, sin

,

A nP d d

P d

φ π θ π

φ θ

θ φ θ θ φ

θ φ

= =

= =

Ω =

Ω = Ω

∫ ∫

∫∫

2

sin 4d d

φ π θ π

θ θ φ π= =

= ∫ ∫

• The beam area is the solid angle through which all of the power radiated

by the antenna would stream if P(θ, φ) maintained its maximum value

over ΩΑ and was zero elsewhere.

( )4

,A n

P dπ

θ φΩ = Ω∫∫ 0 0φ θ= = ∫ ∫

Power radiated = ( , ) AP θ φ Ω


Directivity and Gain of an Antenna( )( )

( )

( )

( ) ( )

max

max

2

0 0

max max

,

,

,

1, sin

4

, ,

av

PD

P

PD

P d d

P PD

φ π θ π

φ θ

θ φ

θ φ

θ φ

θ φ θ θ φπ

θ φ θ φ

= =

= =

=

=

= =

∫ ∫

( )

( )

( )

( )

( )( )

( )

max max

4 4

4

4 max

, ,

1 1, ,

4 4

4 4 4

,,

,

An

P PD

P d P d

DP dP

dP

π π

π

π

θ φ θ φ

θ φ θ φπ π

π π π

θ φθ φ

θ φ

= =

Ω Ω

= = =Ω Ω

Ω

∫∫ ∫∫

∫∫∫∫

( )

Antenna Gain

where k= efficiency factor 0

Gain is less than directivity due to ohmic losses in the antenna

G kD k= ≤ ≤


Antenna Aperture

AΩ

aE rE

eA

r

2

a er

a

E AE

r

EP A

λ=

=

4

A

Dπ

=Ω

0

22

0

2 22

0 0

2 2 22

2 2

0 0

2

ae

rA

a re A

a a ee A

A

e

EP A

Z

EP r

Z

E EA r

Z Z

E E AA r

Z r Z

A

λ

λ

=

= Ω

= Ω

= Ω

Ω =

2

2

2

4

4

4

A

A

A

e

e

e

D

A

D A

AD

π

λ

π λ

π

λ

Ω

Ω =

Ω =

=

=

2

2

41 Isotropic Antenna

4

e

e

AD

A

π

λ

λ

π

= =

=


Pathloss with Isotropic Antennas

2

2

2

Area of receive antenna

of a sphere 4

Area of an ideal isotropic antenna, 4

Formula, 4

r r

t

r

r

P A

P Area r

A

PFriis

P r

π

λ

π

λ

π

= =

=

⇒ =

rA

r

24A rπ=

4t

P rπ

• For isotropic antennas, path loss increases with frequency


Pathloss with directional antennas

4 effeff effAP A Aπ

eff

tA eff

rA

tP

rPt t

PG

2 2 2

2 2

4

4 4

1

effeff eff

tr r rt

t

eff eff

t rr

t

AP A AG

P r r

A AP

P r

π

π λ π

λ

= =

= ⋅

• Receive power improves with frequency!!

• 31.5 dB more gain at 90GHz compared to 2.4GHz if antenna size is kept constant


Foliage Losses

At 80GHz frequency and 10 meters foliage penetration, the loss can be about 23.5dB which is about 15dB higher compared to the loss at 3GHz frequency.

Foliage losses for millimeter waves are significant and can be a limiting impairment for propagation in some cases.

( ) ( )0.3 0.6

5fol

f DL =


Rain Attenuations

Light rain at a rate of 2.5mm/hour yields just over 1 dB/km attenuation while heavy rain at the rate of 25 mm/hour can result in over 10 dB/km attenuation at E-band (70/80/90 GHz) frequencies

More severe rain such as Monsoon at a rate of 150mm/hour can jeopardize communications with up to tens of dBs of loss per km at millimeter wave frequencies.

Therefore, a mechanism such as supporting emergency communications over cellular bands when mmW communications are disrupted by heavy rains should be considered as part of the MMB system design.


Attenuations for different materials

Attenuation [dB]

MaterialThickness

[cm]

2.5GHz

[7]

40GHz

[8]60GHz [7]

Drywall 2.5 5.4 - 6.0

Office Whiteboard 1.9 0.5 - 9.6

Clear Glass 0.3/ 0.4 6.4 2.5 3.6

Mesh Glass 0.3 7.7 - 10.2

Chipwood 1.6 - 8.6 -

Wood 0.7 - 3.5 -

Plasterboard 1.5 - 2.9 -

Mortar 10 - 160 -

Brick wall 10 - 178 -

Concrete 10 - 175 -


Diffraction (Fresnel Zones)

1 2

1 2

n

n d dr

d d

λ=

+

Higher frequencies have smaller Fresnel

zone radii and hence can pass through

narrow gaps with lower loss


Ground Reflection [1/3]

( ) ( )2 22 2

2 1

2 2

2 2

1 1

21 11 1

2 2

t r t r

t r t r

t r t r t r

d d h h d h h d

h h h hd

d d

h h h h h hd

d d d

∆ = − = + + − − +

+ − ∆ = + − +

+ − ∆ ≈ + − + =

22,

2

t rd

c

h h

d c f

π θπθ τ

λ λ π∆

∆

∆ ∆= = = =

The “Free-space” path loss exponent at

mmW frequencies is likely going to be

smaller than the lower RF frequencies

for coverage distances of interest


Ground Reflection [2/3]The field strength can be calculated by adding

the direct and reflected ray accounting for

phase difference θ∆

( )

( )

( )

( ) ( )( )

2

2

2

1

1

1 1

1 cos sin

j

T i

j

j

E E e

P e

P e

P j

θ

θ

θ

ρ

ρ

ρ

θ θ

∆

∆

∆

−

−

−

= +

∝ +

∝ − = −

∝ − +

For grazing incidence ρ = -1

( ) ( )( )

( ) ( )

( )( )

2

2 2

2

2

2

2 2 2

2 2 2

1 cos sin

1 cos sin

1 cos4 sin

2

4 sin 4sin cos2 2 2

4sin sin cos2 2 2

P j

P

P

P

P

θ θ

θ θ

θθ

θ θ θ

θ θ θ

∆ ∆

∆ ∆

∆

∆

∆ ∆ ∆

∆ ∆ ∆

∝ − +

∝ − +

−∝ +

∝ +

∝ +

24sin2

Pθ∆

∝


Ground Reflection [3/3]






• mmW spectrum








– Frame Structure






– RF beamforming





– Rain absorption

– Diffraction



architecture







challenges




– mmWave LNA






• Summary


MMB Network

Packet Data Server

Gateway #1

F

GK

L

Cell Site 2

Cell Site 3

Cell Site 4

MS3

MS2

TX/R

XRX/

TX

TX

High-gain Tx/Rx beamforming

• significantly suppress other-cell interference and

• creates overlapping

Packet Data Server

Gateway #2

B

C

DE

AH

I

J

K

Cell Site 1

Cell Site 5

Cell Site 6

Cell Site 7

MS1

MS2

TX/RX

RX/TX• creates overlapping

coverage of MMB base stations

mmW in-band inter-base station backhauling

• enable deployment without fixed-line high-speed backhaul


An interference limited cellular network

Clear cell boundaries and cellular footprint for each cell due to inter-cell interference

Many base stations are not Many base stations are not visible to mobile station due to strong interference from a few dominant serving/interfering base stations

Mobile station only communicate with one serving cell (or few serving cells) at a time (All other cells generate interference that works against the communication)


An MMB base station grid

Inter-cell interference significantly suppressed due to strong Tx/Rx beamforming (Large spatial multiplexing capability)

Base stations are visible to Base stations are visible to the mobile station as long as link budget permits

Large overlap of base station coverage area (No clear cell boundary)


SINR comparison

An interference limited cellular network

2

2

0

ik i

ik

jk j

j i

h P

N h Pρ

≠

=+∑

2

0jk j

j i

h P N≠

>>∑

Copyright 2011 by the authors. All rights reserved. 40

An MMB network

( ) ( )

( ) ( )

2

2

0

ik i i ik k ik

ik

jk j j jk k jk

j i

h P

N h P

α θ β φρ

α θ β φ≠

⋅ ⋅=

+ ⋅ ⋅∑

Serving cell TxBF

enhances signal strength

RxBF enhances

signal strength

RxBF suppresses

interferencesOther cells TxBF increases interference variation

Increased channel capacity

MMB Overlay on Cellular

Users are served by MMB opportunistically

Fall back to cellular when mmWavechannel conditions are not suitable

Achieved via dual-mode MMB and 4G Achieved via dual-mode MMB and 4G deployment

•Separate MMB and 4G systems share cell sites

•Inter-RAT handover to achieve fallback

Or heterogeneous MMB+4G networks

•MMB integrated into existing 4G system (e.g., as an extension carrier)

•Users are dynamically scheduled in the MMB carriers when suitable


Heterogeneous MMB+4G Networks

Packet Data Server

Gateway

MS1

MBS_0

MBS_1 MBS_2

MBS_3

MBS_4

MBS_5 MBS_6

CBS_A

CBS B


MS2

MS3

MBS_9

MBS_7

MBS_8MBS_10

MBS_11

MBS_12

MBS_13

MBS_14

Cellular Base Station (CBS)

MMB Base Station (MBS)

MMB communication link

cellular communication link

CBS_B

CBS_C

Fixed line between MBS and CBS

Fixed line between CBS / MBS and

Packet Data Server / Gateway

MS4

MMB In-band Dynamic Backhauling

Packet Data Server

Gateway

MS2

BS_A

mmWave L

ink 1

mmWBe

am 1

Beam

0Beam 5

Base stations are connected via mmWave link

Dynamic beamformingenables dynamic backhauling via multiple

MS1

MS3

Cellular Base Station

mmWave communication link

cellular communication link

BS_B

BS_C

Fixed line between BS and Packet

Data Server / Gateway

mmWave Link 2

Wave Link 3

Beam 2

Beam 3

Beam 4


backhauling via multiple routes

• Increased throughput

• Congestion mitigation

• Improved robustness

Backhaul link and access link share the same mmWave band

• Maximize spectrum utilization

• Minimize infrastructure cost

MMB Deployment Scenario

Carrier frequency

• Can be deployed between 3GHz and 300GHz

• Achievable transmission power and efficiency decrease as carrier frequencies increase (limited by existing mmWave integrated circuit technology)

Deployment scenariosDeployment scenarios

• Urban Macro (Site-to-site distance 1km – 5km, BS Tx Power ~ 50dBm)

• Urban Micro (Site-to-site distance 200m – 1km, BS Tx Power ~40dBm)

• Urban Pico (Site-to-site distance 50m – 200m, BS Tx Power ~30dBm)

• Femto (Site-to-site distance < 50m, BS Tx Power ~20dBm)

Mobility

• Support mobility up to 350kmph for carrier frequencies between 3GHz and 30GHz

• Support mobility up to 120kmph for carrier frequencies between 30GHz and 90GHz


Antenna Configurations

Base station antenna configurations

• 12 horn antennas per cell with each horn covers 30o field of view

• 17 – 23 dB antenna gain

• 6 antenna arrays per cell with each array

Base station horn antenna

• 6 antenna arrays per cell with each array covers 60o field of view

• 64 – 1024 antenna elements for each array


Mobile station antenna configurations

• Antenna arrays with 4 – 64 antenna elements each


Mobile station phase antenna array

Base station phase antenna array


Base Station with Horn Antennas

12 horn antennas per base station

Each horn antenna serves one mobile station at a time

Mobile stations perform antenna selection

Mobile stations employ multi-antenna array

Mobile stations perform Tx and Rx beamforming


Base Station with Horn Antennas

17dB Tx

Antenna Gain

~12dB Rx

Antenna Gain

MMB Sector

Antenna Gain

16 Elements (4x4) array

2cm


Horn antennas at base station

Antenna array at mobile station

Mobile station Tx beamforming for uplink

Mobile station Rx beamforming for downlink

( )

( )

2

2

0

ik i k ik

ik

jk j k jk

j i

h P

N h P

β φρ

β φ≠

⋅=

+ ⋅∑

Downlink SINR

Base Station with Antenna Arrays

Antenna Arrays arranged in a hexagon structure with each array covering 600

Each antenna array can serve multiple mobile stations at a time

Mobile stations perform antenna array selection

Dynamic joint Tx-Rx beamforming with narrow beams within each sector


Base Station with Antenna Arrays


Antenna array at base station

Antenna array at mobile station

MS TxBF and BS RxBF for uplink

MS RxBF and BS TxBF for downlink

Downlink SINR

( ) ( )

( ) ( )

2

2

0

ik i i ik k ik

ik

jk j j jk k jk

j i

h P

N h P

α θ β φρ

α θ β φ≠

⋅ ⋅=

+ ⋅ ⋅∑





• mmW spectrum








– Frame Structure






– RF beamforming





– Rain absorption

– Diffraction



architecture







challenges




– mmWave LNA






• Summary


Duplex schemesFDD (Frequency Division Duplex)

• Requires DL and UL carriers (DL and UL can have different bandwidth)

• Good coverage and link throughput

• More RF/mmW hardware (separate antennas/arrays or frequency duplexers/filters) higher cost

TDD (Time Division Duplex)

• DL and UL transmissions occur in the same carrier but in different time slots• DL and UL transmissions occur in the same carrier but in different time slots

• Tradeoff between downlink and uplink (in terms of both coverage and throughput)

• Less RF/mmW hardware (DL and UL share antennas/arrays) lower cost

• For MMB, the delay performance is expected to be comparable to FDD because of the short slot duration (125 us)

SDD (Spatial Division Duplex)

• DL and UL transmissions (to and from different mobile stations) occur in the same time-frequency resources but in different beams

• Require separation of Tx/Rx circuits at the base station

• SDD from the base station point of view

• TDD from the mobile station point of view


Spatial Division Duplex

Tx

RxR

x

Base station transmit and receive in the same time-frequency resource

The transmission and reception are spatially separated (via Tx and Rx beamforming) R

x


beamforming)

Base stations coordinate the downlink and uplink transmissions to minimize interferences

Both uplink and downlink channel state information required at the base station for proper scheduling and coordination

Multiple Access

Flexible choice of multiple access schemes

• Supports TDMA, SDMA, OFDMA, and SC-FDMA

• Configurable based on hardware and deployment scenarios

MMB DownlinkMMB Downlink

• TDMA at slot level (OFDM or single-carrier transmission)

• SDMA/OFDMA within a slot

MMB Uplink

• TDMA at slot level

• SDMA/OFDMA/SC-FDMA within a slot


Time-domain Channel Selectivity

3 10 30 60 90

3 8.33 27.78 83.33 166.67 250.00

30 83.33 277.78 833.33 1666.67 2500.00

120 333.33 1111.11 3333.33 6666.67 10000.00

350 972.22 3240.74 9722.22 19444.44 29166.67

3 10 30 60 90

3 120.00 36.00 12.00 6.00 4.00

Doppler

(Hz)

Carrier Frequency (GHz)

Mo

bile

spe

ed

(km

ph

)

Coherence Time (ms)Carrier Frequency (GHz)

Doppler calculated based on worst case scenario

•The direction of velocity aligned with the direction of beamforming

Design choice: MMB to support Doppler up to 10kHz (Coherent time ≥≥≥≥ 100us)

•Different numerology can be developed to support mobility with higher Doppler (e.g., due to either higher speed or higher frequency)

3 120.00 36.00 12.00 6.00 4.00

30 12.00 3.60 1.20 0.60 0.40

120 3.00 0.90 0.30 0.15 0.10

350 1.03 0.31 0.10 0.05 0.03

Mo

bile

spe

ed

(km

ph

)


Frequency-domain Channel Selectivity

Millimeter wave propagation characteristics in a mobile communication environment is not well understood

• Most literature reports RMS delay ~ 10ns and maximum delay spread ~ 100ns

• For cellular waves in a 1km cell, the maximum delay spread should mostly be within a few microseconds (1km ~ 3.3us)

• High gain antennas and beamforming of mmW should significantly reduce the delay spread

• As the cell size gets smaller, LOS will occur more frequently, which also reduce the delay • As the cell size gets smaller, LOS will occur more frequently, which also reduce the delay spread and frequency selectivity

Best guesstimate (at this point) is the maximum delay spread of mmW in a mobile environment should mostly be less than 1us for cell radius < 1km

• Equivalent to 333-meter difference among the travel distance of the rays that arrive at the receiver via the narrow beams formed by the transmitter antennas and receiver antennas

Design choice: MMB to support delay spread up to 1us (Coherent bandwidth ≥ 1MHz)


OFDM/Single-Carrier numerology

Subcarrier spacing and Cyclic Prefix

• Two important design parameters that pertain to many issues

• Wide subcarrier spacing leads to sensitivity to frequency selectivity, and high CP overhead

• Narrow subcarrier spacing leads to sensitivity to Doppler, frequency offset, and require more expensive VCOs and VCXOs

• Larger CP provides protection against inter-symbol-interference due to multipath channel

• Shorter CP incurs less overhead and leads to a more efficient system design• Shorter CP incurs less overhead and leads to a more efficient system design

Subcarrier spacing = 270 kHz

• OFDM/SC symbol length is ~3.7 us

• Possible to support a coherence time of 100 us (350kmph @ 30 GHz, 120kmph @ 90 GHz)

1/8 and 1/4 CP

• Both 1/8 and 1/4 CP are supported

• 1/8 CP = 463 ns, low overhead

• 1/4 CP = 926 ns, ensure good performance in deployment with larger cells (1~5 km)


OFDM/SC numerology (short CP)

Short CP Configurations

System Bandwidth (MHz) 62.5 125 250 500 1000

Sampling rate (MHz) 69.12 138.24 276.48 552.96 1106

Subcarrier spacing (kHz) 270

OFDM symbol length (FFT size) 256 512 1024 2048 4096

OFDM symbol duration (us) 3.70OFDM symbol duration (us) 3.70

CP length 32 64 128 256 512

CP duration (us) 0.46

Slot duration (us) 125

Number of OFDM symbols per slot 30

Subframe duration (ms) 1

Number of slots per subframe 8

Frame duration (ms) 10

Number of subframes per frame 10


OFDM/SC numerology (long CP)

Long CP Configurations

System Bandwidth (MHz) 62.5 125 250 500 1000

Sampling rate (MHz) 69.12 138.24 276.48 552.96 1106

Subcarrier spacing (kHz) 270

OFDM symbol length (FFT size) 256 512 1024 2048 4096

OFDM symbol duration (us) 3.70OFDM symbol duration (us) 3.70

CP length 64 128 256 512 1024

CP duration (us) 0.93

Slot duration (us) 125

Number of OFDM symbols per slot 27

Subframe duration (ms) 1

Number of slots per subframe 8

Frame duration (ms) 10

Number of subframes per frame 10


Frame Structure (Short CP)

CP

CP

CP

CP


Resource Channelization – Subbands

Each subband consists of 4 RBs

• Bandwidth = 4 × 4.86 = 19.44 MHz

• The number of subbands for different system bandwidth

• 3 (62.5 MHz), 6 (125 MHz), 12 (250 MHz), 24 (500 MHz), 48 (1 GHz)

Number of occupied subcarriers

• 216 / 58.6 MHz (for 256-point FFT / 62.5 MHz)

• 432 / 116.9 MHz (for 512-point FFT / 125 MHz)

• 864 / 233.6 MHz (for 1024-point FFT / 250 MHz)

• 1728 / 466.8MHz (for 2048-point FFT / 500 MHz)

• 3456 / 933.4MHz (for 4096-point FFT / 1 GHz)


Resource Channelization – Resource Block

8

9

10

11

12

13

14

15

16

17

Each RB includes 18 subcarriers

•1 RB = 18 ×270kHz = 4.86 MHz = 540 REs

•24 symbols used

Time

Freq

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

0

1

2

3

4

5

6

7

8

Control channel RE

Control channel RS

Data channel RE

Data channel RS

•24 symbols used for data, 1 RB carries 432 data REs

•The number of RBs for different system bandwidth

•12 (for 62.5MHz)

•24 (for 125MHz)

•48 (for 250MHz)

•96 (for 500MHz)

•192 (for 1GHz)


Channel Coding

Regular protograph LDPC codes

• Highly structured simple decoder design

• High degree of parallelism high throughput

• low decoding complexity low power consumption

• Gbps decoder with power consumption on the order of 100mW• Gbps decoder with power consumption on the order of 100mW

Data channel FEC

• Length-1728 and Length-432 code with code rate (1/2, 5/8, 3/4,13/16)

• Length-1728 codes lifted from the length-432 codes

Control channel FEC

• Length-432 LDPC code with code rate (1/2, 5/8, 3/4,13/16)

• Lower code rates achieved by shortening


LDPC0 1 0 1 1 1 0 0

1 1 1 0 0 0 1 0

0 0 1 0 0 1 1 1

1 0 0 1 1 0 0 1

H

=

14, 2,

2

cr c

r

ww w r

w= = = =

Low Density Parity Check codes

• Linear block codes

• Row and column weights << dimension of the parity check matrix

• “Capacity-approaching”

• Iterative decoding with linear decoding complexity (e.g., belief propagation)


HARQ

A combination of FEC and ARQ

Support both incremental redundancy (IR) and chase combining (CC)

Effective in combating fast fading, interference variation, and increasing throughput

Buffer management is critical for effective HARQ in MMB

• 1ms buffering = 1M information bits @ 1Gbps, = 16M information bits @ 16Gbps


Modulation and Coding Schemes

MCS Modulation Code rate Repetition Data rate (Mbps) Spectral Efficiency

0 π/2−BPSK 1/2 4 415 0.08

1 π/2−BPSK 1/2 2 829 0.17

2 π/2−BPSK 1/2 1 1659 0.33

3 π/2−BPSK 5/8 1 2074 0.41

4 π/2−BPSK 3/4 1 2488 0.50

5 π/2−BPSK 13/16 1 2696 0.54

6 QPSK 1/2 1 3318 0.66

*Data rate is calculated assuming 5 carriers with 1GHz bandwidth each, 1/8 CP, and 20% control channel overhead

6 QPSK 1/2 1 3318 0.66

7 QPSK 5/8 1 4147 0.83

8 QPSK 3/4 1 4977 1.00

9 QPSK 13/16 1 5391 1.08

10 16QAM 1/2 1 6636 1.33

11 16QAM 5/8 1 8294 1.66

12 64QAM 1/2 1 9953 1.99

13 64QAM 5/8 1 12442 2.49

14 64QAM 3/4 1 14930 2.99

15 64QAM 13/16 1 16174 3.23






• mmW spectrum








– Frame Structure






– RF beamforming





– Rain absorption

– Diffraction



architecture







challenges




– mmWave LNA






• Summary


MMB Beamforming

The “most critical” technology for MMB

Beamforming Options

• Baseband Digital Beamforming

• Baseband Analog Beamforming (phase shifters)• Baseband Analog Beamforming (phase shifters)

• RF Beamforming (phase shifters)

Challenges

• Beam pattern/codebook design

• Beam training signal/procedure/algorithm design

• Beam tracking signal/procedure/algorithm design

67

Copyright by the authors, all rights reserved

Array of 2 Point Sources [1/3]

θ

r

cos2

dθ

cos2

dθ

1 2

2 2cos cos

2 20 0

2 2cos cos

2 2

022

d dj j

d dj j

E E E

E E e E e

e eE E

π πθ θ

λ λ

π πθ θ

λ λ

−

−

= +

= +

+=

Same amplitude, same phase

20

0

0

2

22 cos cos

2

Assuming 2 1 and / 2

cos cos2

dE E

E d

E

πθ

λ

λ

πθ

=

= =

=



θ

r

cos2

dθ

cos2

dθ

1 2

2 2cos cos

2 20 0

2 2cos cos

2 2

022

d dj j

d dj j

E E E

E E e E e

e eE E

π πθ θ

λ λ

π πθ θ

λ λ

−

−

= −

= −

−=

Same amplitude, opposite phase

20

0

0

2

22 sin cos

2


sin cos2

dE jE

jE d

E

πθ

λ

λ

πθ

=

= =

=



1 2

2 2cos cos

2 2 2 2

0 0

2 2cos cos

2 2 2 2

022

d dj j

d dj j

E E E

E E e E e

e eE E

π δ π δθ θ

λ λ

π δ π δθ θ

λ λ

− + +

− + +

= +

= +

+=

Same amplitude, arbitrary phase difference

θ

r

cos2

dθ

0

0

0

22

22 cos cos

2 2


cos cos2 2

E E

dE E

E d

E

π δθ

λ

λ

π δθ

=

= +

= =

= +


cos2

dθ

Dynamic Antenna Array [1/2]

)

)+

∆

)

3co

sθ

+∆

)

4co

sθ

+∆

θ(

)

cos

d

θ

+∆

d

22 cosj d

e

πθ

λ−2

cosj d

e

πθ

λ−

( )s t( )s t( )s t( )s t

22 cosj d

e

πθ

λ+

2cosj d

e

πθ

λ+

( )s t

∆(2

cos

d

θ+

∆

(3co

sd

θ

(4co

sd


Dynamic Antenna Array [2/2]

A dynamic antenna array can point in any direction to maximize the received signal

Enhanced receiver/transmitter antenna gain (reduced PA power, LNA gain)

Improved diversity

Reduced multi-path fadingReduced multi-path fading

Null/ Suppress interfering signals

Spatial power combining:

• Less power per PA

• Simpler PA architecture


BB Digital Beamforming

( ) ( )1Ms t

− ( ) ( )1Nr t

−

( )1s t 1

tw

1

rw ( )2r t

( )0s t 0

tw0

rw ( )1r t

M

Optimal capacity for all channel conditions: min(M,N) data streams

Can support a variety of MA schemes (TDMA / OFDMA / SC-FDMA / SDMA)

High hardware complexity: M(N) full transceivers

High system power consumption

( ) ( )1M − ( ) ( )1Nr t

−

( )1

t

Mw

−( )1

r

Nw

−


BB Analog Beamforming

1

tw

1

rw( )s t

0

tw0

rw

( )r tM

1 data stream, antenna weights applied at “analog” baseband

Achieves high antenna gain in an arbitrary direction

Intermediate hardware complexity: M(N) RF mixers

Intermediate power consumption

( )1

t

Mw

−( )1

r

Nw

−


RF Beamforming

1

rw( )s t

0

rw

( )r tM

1

tw

0

tw

Σ

1 data stream, RF phase shifters only, digitally controlled

Achieves high antenna gain in an arbitrary direction

Low hardware complexity: N RF phase shifters

Low system power consumption

No (or limited) support simultaneous transmissions to multiple users (e.g. OFDMA / SC-FDMA / SDMA)

( )1

r

Nw

−( )1

t

Mw

−


Long Term Fading of mmWave Channel

Beamforming is a transmission / reception scheme that can be used to adapts to the long-term statistics of the channel

Question to answer: Will the long-term channel fading for mmWave varies much faster than that of cellular waves?mmWave varies much faster than that of cellular waves?

Let’s look at the determinants of the long-term fading of a wireless channel

• Pathloss

• Penetration loss

• Absorption due to atmosphere and/or precipitation

• Reflection, diffraction, and blocking


Long Term Fading of mmWave Channel

Pathloss

• Change depends on change of the location of the MS and the distance travelled – not the carrier frequency

Penetration loss

• Change depends on change of the location of the MS and blockages in the path travelled – again not depend on the carrier frequency

AbsorptionAbsorption

• Change depends on change of the location of the MS and distance travelled, not the carrier frequency

Reflection, diffraction, blocking

• Change depends on change of the location of the MS and the path travelled, not the carrier frequency

Observation

• The long term fading of mmWave channel induced by communication medium and environment should not be significantly faster than that of the cellular waves


Beamforming and Channel Fading

Beamformingenhances the gain of the strongest paths while suppresses others

The good

Beamformingincreases the sensitivity of channel condition to channel fading

The bad



The spatial selectivity of beamforming

• Use horn antenna as an example for analysis

• Gain of a horn antenna G ≈ 10log10(4.5AeλAhλ)

• 3 dB beamwidth of a horn antenna

• θ = 56 / A , • θ3dB, E-plane = 56 / Aeλ,

• θ3dB, H-plane = 67 / Ahλ

• Assume θ3dB = θ3dB, E-plane = θ3dB, H-plane

• G ≈ 42.27 - 20log10θ3dB

Tradeoff between beamforming gain and beam adaptation overhead and robustness of the channel

• The larger the Tx/Rx beamforming gain, the narrower the beamwidth

• Increased sensitivity to mobility

• More frequent beamforming adaptation needed



For BS Tx/Rx beamforming with < 30 dB antenna gain

• θ3dB ≈ 4.1 degree

• 7.2 meters wide @ 100 meter distance

• It takes 73.7 ms (589 MMB slots) for an MS moving at 350kmph to travel 7.2 meters

For MS Tx/Rx beamforming with < 20 dB antenna gainFor MS Tx/Rx beamforming with < 20 dB antenna gain

• θ3dB ≈ 13 degree

• 22.5 meters wide @ 100 meter distance

• It takes 231.1 ms (1849 MMB slots) for an MS moving at 350kmph to travel 22.5 meters

Observation

• The increased long term channel variation due to Tx/Rx beamforming in MMB is on the order of tens of milliseconds or slower (hundreds of MMB slots or more)






• mmW spectrum








– Frame Structure






– RF beamforming





– Rain absorption

– Diffraction



architecture







challenges




– mmWave LNA






• Summary


RF Transceiver

Transceiver key RF components

• Antenna, Filters, Power Amplifier (PA), Low-Noise Amplifier (LNA), Oscillator (VCO), Mixer and Data converters (DAC/ADC)


Nonlinear Device

In the most general sense, the output response of a nonlinear circuit can be modeled as a Taylor series in terms of the input signal voltage

2 3

0 0 1 2 3

where the Taylor Coefficients are defined as

i i iv a a v a v a v= + + + +L

( )0 0

01

2

02 2

where the Taylor Coefficients are defined as

0

0

0

and higher order terms

ii

ii

a v

dva

vdv

d va

vdv

=

==

==

iv ov


Gain Compression

Consider the case where a single frequency sinusoid is applied to the input of a nonlinear device such as a power amplifier

0 0

2 2 3 3

0 0 1 0 0 2 0 0 3 0 0

cos

cos cos cos

iv V t

v a a V t a V t a V t

ω

ω ω ω

ω

=

= + + + +

+

L

2 00 0 1 0 0 2 0

3 3 0 03 0 0 3 0

2 3

0 0 2 0 1 0 3 0 0

2

2 0 0 3

1 cos 2cos

2

cos cos 21cos

2 4

1 3cos

2 4

1 1cos 2

2 4

tv a a V t a V

t ta V t a V

v a a V a V a V t

a V t a

ωω

ω ωω

ω

ω

+ = + + +

+ + +

= + + + +

+

L

3

0 0cos3V tω +L

0

3

1 0 3 02

1 3 0

0

3

Voltage gain at frequency

334

4

is negative in most practical amplifiers

a V a V

G a a VV

a

ω

+= = +


Intermodulation Distortion

Consider two-tone input voltage consisting of two closely spaced frequencies

2 1ω ω−1 22ω ω−

2 12ω ω−

1ω2ω

12ω22ω

2 1ω ω+

13ω23ω

2 12ω ω+1 22ω ω+

( )

( ) ( ) ( )

( ) ( )

0 1 2

2 32 3

0 1 0 1 2 2 0 1 2 3 0 1 2

2 2

0 1 0 1 1 0 2 2 0 1 2 0 2

2 2 3

2 0 1 2 2 0 1 2 3 0 1

cos cos

cos cos cos cos cos cos

1 1cos cos 1 cos 2 1 cos 2

2 2

3 1cos( ) cos( ) cos cos3

4 4

i

o

o

v V t t

v a a V t t a V t t a V t t

v a a V t a V t a V t a V t

a V t a V t a V t

ω ω

ω ω ω ω ω ω

ω ω ω ω

ω ω ω ω ω ω

= +

= + + + + + + +

= + + + + + +

+ − + + + +

L

3

1 3 0 2 2

3 3

3 0 2 1 2 1 2 3 0 1 2 1 2 1

1 2

3 1cos cos3

4 4

3 3 3 3 3 3cos cos(2 ) cos(2 ) cos cos(2 ) cos(2 )

2 4 4 2 4 4

Output spectrum consists of harmonics of the form

,

t a V t t

a V t t t a V t t t

m n m n

ω ω

ω ω ω ω ω ω ω ω ω ω

ω ω

+ +

+ + − + + + + − + + +

+ =

L

0, 1, 2 3,

These combinations of the two input frequencies are called intermodulation products

± ± ± L

2 1 1 22ω ω−2 12ω ω− 2 1

2 12ω ω+1 22ω ω+


Third-Order Intercept Point (IP3)

1

1 2

2 2

1 0

2

2 2 6

2 3 0 3 0

1

2

1 3 9

2 4 32

These two powers are equal at the third-order IP

P a V

P a V a V

ω

ω ω−

=

= =

1 0

2 2 2 6

1 3

1

2

32 2 1

3 1

3

These two powers are equal at the third-order IP

Let input signal voltage at the IP be

1 9

2 32

4

3

21

2 3IP

IP

IP IP

IP

V V IP

V

a V a V

aV

a

aP P a V

aω =

=

=

= = =


Mixer

IFf

LOf

RF LO IFf f f= ±RFf

LOf

IF RF LOf f f= ±

IFfLOf

LO IFf f+

LO IFf f−

0

RF LO IFf f f− =

RF LOf f+LO

f0 RFf

( ) ( ) ( )

( ) ( ) ( )

cos 2 cos 2

cos 2 cos 22

RF LO IF LO IF

RF LO IF LO IF

v t K v t v t K f t f t

Kv t f f t f f t

π π

π π

= =

= − + +

( ) ( ) ( )

( ) ( ) ( )

cos 2 cos 2

cos 2 cos 22

IF LO RF LO RF

IF RF LO RF LO

v t K v t v t K f t f t

Kv t f f t f f t

π π

π π

= =

= − + +


Image Frequency

IFfLOf

RF LO IFf f f= +

0

IM LO IFf f f= −

IFfLOf

IM LO IFf f f= +

0

RF LO IFf f f= −

2IF

f 2IF

f

-fIF is mathematically identical to fIF because the frequency spectrum of any real signal is symmetric about zero frequency , and thus contains negative as well as positive frequencies

A received RF signal at the image frequency fIM is indistinguishable at the IF stage from the desired RF signal of frequency fRF

( )

( )

IF RF LO LO IF LO IF

IF IM LO LO IF LO IF

f f f f f f f

f f f f f f f

= − = + − =

= − = − − = −

( )

( )

IF RF LO LO IF LO IF

IF IM LO LO IF LO IF

f f f f f f f

f f f f f f f

= − = − − = −

= − = + − =


Homodyne (Zero-IF) Receiver

( )

( )

( )

2

2

1 cos 2cos cos cos

2

After low pass filtering

1

2

1 cos 2sin sin sin

2

After low pass filtering

1

RFRF RF RF

RFRF RF RF

tI t t t t

I t

tQ t t t t

ωω ω ω

ωω ω ω

+= = =

=

−= = =

( )1

2Q t =


Benefits Drawbacks

Less hardware LO Leakage

Low power consumption DC offset errors

No IF stage and hence no image filter I/Q mis-match

Flicker (or 1/f) noise

Super-heterodyne Receiver

LOf

IFf


Benefits Drawbacks

Good sensitivity High Q filter

Good selectivity High performance oscillator

LNA output impedance matched to 50 ohm is

difficult

Integration of HF image reject filter is a major

problem

Wideband-IF Receiver

( )sinIF

tω

( )cos IF tω

LOω

( )I t

( )Q t

( )'I t

( )cos IF tω

( )Q t

( )'Q t


Benefits Drawbacks

Image cancellation by IR mixer IR Mixer

Image rejection from the RF front-end pre-

selection filter

Good phase noise performance

Wideband-IF Receiver (Image Rejection)

( ) ( ) ( )

( ) ( ) ( ) ( )

( ) ( ) ( )

cos cos cos

1 1cos cos cos cos

2 2

cos cos sin

RF RF IM IM LO

RF IF RF LO IM IF IM LO

RF RF IM IM LO

I t x t x t t

x t t x t t

Q t x t x t t

ω α ω β ω

ω α ω ω α ω β ω ω β

ω α ω β ω

= − + −

= − + + − + + + + −

= − + −

Low-side injection

Signal of interest

Image

RF LO LO IM IFω ω ω ω ω− = − =

( )cos cos cos sin sinRF RF RF RF RF RF

x t x t x tω α α ω α ω− = +

( )cos cos cos sin sinIM IM IM IM IM IMx t x t x tω β β ω β ω− = +

( ) ( ) ( )

( ) ( ) ( )

cos cos sin

1 1sin sin sin sin

2 2

RF RF IM IM LO

RF IF RF LO IM IF IM

Q t x t x t t

x t t x t

ω α ω β ω

ω α ω ω α ω β ω

= − + −

= − − + + − + + + ( )

( ) ( ) ( ) ( ) ( ) ( )

( ) ( ) ( ) ( )

( ) ( ) ( )

After low-pass filtering

1 1cos cos , sin sin

2 2

1 1' cos sin cos cos 2

2 2

1 1' sin cos sin sin 2

2 2

LO

RF IF IM IF RF IF IM IF

IF IF RF IM IF

IF IF RF IM

t

I t x t x t Q t x t x t

I t I t t Q t t x x t

Q t I t t Q t t x x

ω β

ω α ω β ω α ω β

ω ω α ω β

ω ω α ω

+ −

= − + + = − − + +

= − = + +

= + = + ( )

( ) ( )

After low-pass filtering

1 1' cos , ' sin

2 2

IF

RF RF

t

I t x Q t x

β

α α

+

= =


Low-IF Receiver

( )2sin 2 LOf tπ

( )2cos 2 LOf tπ

( )2cos 2 LOf tπ


Benefits Drawbacks

Potential advantages of both heterodyne and

homodyne receivers.

ADC dynamic range

The IF frequency is just one or two channels

bandwith away from DC, which is just enough to

overcome DC offset problems.

Image reject mixer which is implemented in

digital baseband

Downlink RF Transceiver Requirement

Base station transmitter

•Transmit antennas / antenna arrays

• 20 – 30 dB antenna gain, horn antennas or phase antenna arrays (64 – 1024 elements)

•Power amplifier

• 20 – 50 dBm, >20% efficiency, EVM < 5% for OFDM waveform

• Packaging

• Integrated solution of antenna array / PA / MMIC / RFIC to minimize transmission loss• Integrated solution of antenna array / PA / MMIC / RFIC to minimize transmission loss

Mobile station receiver

• Receive antenna arrays

• 6 – 18 dB antenna gain, phase antenna arrays (4 – 64 elements)

• Receiver sensitivity < -80dBm

• Total Rx chain Noise Figure < 7dB

• Similar solutions exist today!

• 60GHz CMOS RFIC with phase antenna array (BWRC)

• 60GHz Single-chip integrated antenna and RFIC (GEDC)

• Packaging

• Integrated solution of antenna array / LNA / MMIC / RFIC to minimize transmission loss

94


Uplink RF Transceiver Requirement

Mobile station transmitter

• Transmit antenna arrays

• 6 – 18 dB antenna gain, phase antenna arrays (4 – 64 elements)

• Power amplifier

• 20 – 23 dBm, >20% efficiency, EVM < 5% for 16QAM single-carrier waveform

• Packaging• Packaging

• Integrated solution of antenna array / PA / MMIC / RFIC to minimize transmission loss

• Power consumption on the order of 100mW ~ 1W

Base station receiver

• Receiving antennas / antenna arrays

• 20 – 30 dB antenna gain, horn antennas or phase antenna arrays (64 – 1024 elements)

• Receiver sensitivity < -95 dBm

• Total Rx Noise Figure < 5dB

• Packaging

• Integrated solution of antenna array / PA / MMIC / RFIC to minimize transmission loss

95


Travelling Wave Tube (TWT) Power Amplifier

TWT amplifiers have been extensively used for high power applications at millimeter wave frequencies

• Provides KWs to MWs power for satellite and radar

• Cost in 10K’s of US$ (too expensive for cellular)

Need to consider solid-state amplifier design for MMB


Solid-state Power Amplifier

Gallium-Nitride based power amplifier

• Wide bandgap materials such as gallium nitride (GaN) or silicon carbide (SiC) have much larger bandgapsthan conventional semiconductors

• Gallium-nitride High Electron Mobility Transistor (GaN HEMT) devices have breakdown voltages 10 times higher than GaAs HEMT devices, allowing GaN HEMT devices to operate with much higher voltages

97

Source: “Gallium Nitride

(GaN) Microwave

Transistor Technology

For Radar Applications”,

Microwave Journal,

January 2008

Solid-state Power Amplifier

State-of-the-art for solid-state mmWave PAs

• 11 Watts at 34 GHz (D. C. Streit, et. al., “The future of compound semiconductors for aerospace and defense applications”, CSIC 2005)

• 842 mW at 88 GHz (M. Micovic, et. al., “W-Band GaN MMIC with 842mW output power at 88 GHz”, IMS 2010)

• 5.2 Watts at 95 GHz with a 12-way radial-line combiner (James Schellenberg, et. al., “W-Band, 5W solid-state power amplifier/combiner”, IMS 2010)

98

Source: “Gallium Nitride

(GaN) Microwave

Transistor Technology

For Radar Applications”,

Microwave Journal,

January 2008

Cascaded Constructive Wave Amplifier

• Forward wave is amplified as it propagates along the transmission line

• Backward wave is attenuated as it propagates

• Distribution of N cascaded traveling wave stages

• Active devices along the transmission line provide feedback

• Relative phase of transmission line and active device determines amplification/

attenuation.

Source: J. Buckwalter and J. Kim, ISSCC 2009

Low-Noise Amplifier [1/2]

Single Stage 60 GHz LNA

Source: Javier Alvarado, PhD thesis, May 2008

Gain 12 dB

Noise Figure 5 dB over 57 – 64 GHz

Power Consumption 4.5mA from a 1.8 V source

1-dB compression point +1.5dBm

Efficiency 17.4%

Process IBM0.12 μm, 200 GHz fT, SiGe technology.

Low-Noise Amplifier [2/2]

Two Stage 23–32GHz LNASource: El-Nozahi et al,

IEEE JOURNAL OF SOLID-STATE CIRCUITS, FEB 2010

Gain 12 dB

Noise Figure 4.5–6.3dB over 23–32 GHz

Power Consumption 13mW from a 1.5 V source

IP3 -4.5dBm to -6.3dBm [stage1=-2dBm, stage2=7dBm]

Efficiency NA

Process Jazz Semiconductor 0.18 m BiCMOS

1

3, 3,1 3,2

1 1

tot

G

IP IP IP= +





• mmW spectrum








– Frame Structure






– RF beamforming





– Rain absorption

– Diffraction



architecture







challenges




– mmWave LNA






• Summary


MMB downlink budget

MMB link downlink budget analysis Case 1 Case 2 Case 3 Case 4 Case 5 Case 6 Case 7 Case 8

Transmit Power (dBm) 35.00 40.00 35.00 40.00 35.00 40.00 35.00 40.00

Transmit Antenna Gain (dBi) 17.00 17.00 23.00 23.00 17.00 17.00 23.00 23.00

Carrier Frequency (GHz) 28.00 28.00 28.00 28.00 28.00 28.00 28.00 28.00

Distance (km) 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50

Key system configuration parameters

•Base station Tx power: 35dBm – 40dBm

•Base station Tx antenna gain: 17 dB – 23 dB

•Mobile station Rx antenna gain: 3 dB – 10 dB

Distance (km) 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50

Propagation Loss (dB) 115.32 115.32 115.32 115.32 115.32 115.32 115.32 115.32

Other losses 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00

Receive Antenna Gain (dB) 3.00 3.00 3.00 3.00 10.00 10.00 10.00 10.00

Received Power (dBm) -80.32 -75.32 -74.32 -69.32 -73.32 -68.32 -67.32 -62.32

Bandwidth (MHz) 500 500 500 500 500 500 500 500

Thermal Noise PSD (dBm/Hz) -174.00 -174.00 -174.00 -174.00 -174.00 -174.00 -174.00 -174.00

Noise Figure 7.00 7.00 7.00 7.00 7.00 7.00 7.00 7.00

Thermal Noise (dBm) -80.01 -80.01 -80.01 -80.01 -80.01 -80.01 -80.01 -80.01

SNR (dB) -0.31 4.69 5.69 10.69 6.69 11.69 12.69 17.69

Implementation loss (dB) 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.00

Spectram Efficiency 0.37 0.95 1.12 2.23 1.31 2.50 2.78 4.29

Data rate (Mbps) 186.08 474.53 559.37 1117.08 653.70 1250.93 1390.35 2145.23


Path loss formula: PL = 141.3 + 20log10d with d in km (free-space loss + 20dB)

MMB uplink budget

MMB uplink budget analysis Case 1 Case 2 Case 3 Case 4 Case 5 Case 6 Case 7 Case 8

Transmit Power (dBm) 20.00 23.00 20.00 23.00 20.00 23.00 20.00 23.00

Transmit Antenna Gain (dBi) 3.00 3.00 3.00 3.00 10.00 10.00 10.00 10.00

Carrier Frequency (GHz) 28.00 28.00 28.00 28.00 28.00 28.00 28.00 28.00

Distance (km) 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50

Key system configuration parameters

•Mobile station Tx power: 20dBm – 23dBm

•Mobile station Tx antenna gain: 3 dB – 10 dB

•Base station Rx antenna gain: 17 dB – 23 dB

Distance (km) 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50

Propagation Loss (dB) 115.32 115.32 115.32 115.32 115.32 115.32 115.32 115.32

Other losses 20.00 20.00 20.00 20.00 20.00 20.00 20.00 20.00

Receive Antenna Gain (dB) 17.00 17.00 23.00 23.00 17.00 17.00 23.00 23.00

Received Power (dBm) -95.32 -92.32 -89.32 -86.32 -88.32 -85.32 -82.32 -79.32

Bandwidth (MHz) 50 50 50 50 50 50 50 50

Thermal Noise PSD (dBm/Hz) -174.00 -174.00 -174.00 -174.00 -174.00 -174.00 -174.00 -174.00

Noise Figure 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.00

Thermal Noise (dBm) -92.01 -92.01 -92.01 -92.01 -92.01 -92.01 -92.01 -92.01

SNR (dB) -3.31 -0.31 2.69 5.69 3.69 6.69 9.69 12.69

Implementation loss (dB) 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.00

Spectram Efficiency 0.20 0.37 0.67 1.12 0.80 1.31 1.98 2.78

Data rate (Mbps) 9.92 18.61 33.32 55.94 39.92 65.37 98.96 139.03


Path loss formula: PL = 141.3 + 20log10d with d in km (free-space loss + 20dB)

Link Budget Analysis Summary

MMB downlink budget

• Low end: 35 dBm Tx power, 17 dB Tx antenna gain, 3 dB Rx antenna gain, 5 dB implementation loss 180 Mbps on 500 MHz bandwidth at 500 meters

• High end: 40 dBm Tx power, 23 dB Tx antenna gain, 10 dB Rx antenna gain, 5 dB implementation loss) 2145 Mbps on 500 MHz bandwidth at 500 meters

MMB uplink budgetMMB uplink budget

• Low end: 20 dBm Tx power, 3 dB Tx antenna gain, 17 dB Rx antenna gain, 5 dB implementation loss 9.92 Mbps on 50 MHz bandwidth at 500 meters

• High end: 23 dBm Tx power, 10 dB Tx antenna gain, 23 dB Rx antenna gain, 5 dB implementation loss 139 Mbps on 50 MHz bandwidth at 500 meters

Conclusion

• Assuming free-space plus 20dB path loss, MMB can provide 100 Mbps ~ 2 Gbpscell-edge throughput on the downlink and 10 Mbps ~ 100 Mbps cell-edge

throughput on the uplink at 28 GHz for cell radius of 500 meters.


Link Level Performance

Length-432 and Length-1728 LDPC

Code rate 1/2, 5/8, 3/4, 13/16

Layered decoding

Maximum number of iterations


System Level Performance

19 cells wrap-around

12 sectors per cell

1 horn antenna per sector

20 dB antenna gain

• 17.5o 3-dB beamwidth in azimuth domain

• 10o 3-dB beamwidth in elevation domain

• 30 dB front-to-back ratio

Base station Tx power = 13, 16, 19, 22 dBm/MHz

Mobile station uniformly dropped in the coverage area


Geometry with Single Rx Antenna

Site-to-site distance = 500 meters

Single Rx antenna with -1 dB antenna gain

0.7

0.8

0.9

1

Interference

limited

3dB worse 5%-tile

geometry than cellular

No Rx beamforming

PLF1: PL = 141.3 + 20log10d with d in km

12dB Lognormal shadowing

•8dB Lognormal shadowing for cellular

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

-12.00 -9.00 -6.00 -3.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00

Cellular, 33dBmPerMHz 13dBmPerMHz, PLF1, NoBF

16dBmPerMHz, PLF1, NoBF 19dBmPerMHz, PLF1, NoBF

22dBmPerMHz, PLF1, NoBF


Geometry with Single Rx Antenna

0.7

0.8

0.9

1


Single Rx antenna with -1 dB antenna gain

2 – 6 dB worse 5%-tile


0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

-12.00 -9.00 -6.00 -3.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00

Cellular, 33dBmPerMHz 13dBmPerMHz, PLF2, NoBF

16dBmPerMHz, PLF2, NoBF 19dBmPerMHz, PLF2, NoBF

22dBmPerMHz, PLF2, NoBF


No Rx beamforming



•8dB Lognormal shadowing for cellular

1

2

3

4

30

60

90

120

150

RxBeam 1

RxBeam 2

RxBeam 3

RxBeam 4

Mobile station Rx beamforming

=

+=

2sin

2sin

cos

ϕ

ϕ

θφϕ

N

AF

kd

210

240

270

300

330

180 0

4-element uniform linear array

N=4, d=λ/2, k=2π/λ

4 fixed beams (φ=0, π/2, π, 3π/2)

Mobile station orientation is random ~ U[0, 2π)

Mobile station selects the beam that maximizes geometry

2


Geometry with Rx Beamforming

0.7

0.8

0.9

1


4-element antenna array with -3 dB antenna gain per element

Interference

limited

The same 5%-tile

geometry as cellular

0

0.1

0.2

0.3

0.4

0.5

0.6

-12.00 -9.00 -6.00 -3.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00

Cellular, 33dBmPerMHz 13dBmPerMHz, PLF1, RxBF

16dBmPerMHz, PLF1, RxBF 19dBmPerMHz, PLF1, RxBF

22dBmPerMHz, PLF1, RxBF


Rx beamforming



• 8dB Lognormal shadowing for cellular

Geometry with Rx Beamforming

0.7

0.8

0.9

1


4-element antenna array with -3 dB antenna gain per element

0-3dB worse 5%-tile


0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

-12.00 -9.00 -6.00 -3.00 0.00 3.00 6.00 9.00 12.00 15.00 18.00

Cellular, 33dBmPerMHz 13dBmPerMHz, PLF2, RxBF

16dBmPerMHz, PLF2, RxBF 19dBmPerMHz, PLF2, RxBF

22dBmPerMHz, PLF2, RxBF


Rx beamforming



• 8dB Lognormal shadowing for cellular

System Throughput AnalysisMMB system performance analysis assumptions

Number of cells 19

Number of sectors per cell 12

Site to site distance 500 meters

Carrier frequency 28 GHz

System bandwidth 500 MHz

Path loss model141.3 + 20log10d,

or 157.4 + 20log10d

Base station Tx power 40, 43, 46, or 49 dBmBase station Tx power 40, 43, 46, or 49 dBm

Base station Tx antenna configuration Single horn antenna

Base station Tx antenna gain 20 dB

Log-normal shadow fading STD 12 dB

Mobile station Rx noise figure 7 dB

Mobile station Rx antenna configurationSingle antenna, or Rx beamforming

with 4-element ULA

Mobile station Rx antenna gain-1 dB for single antenna case,

-3 dB for ULA case

System overhead (cyclic prefix, control channels, etc.) 40%

Transceiver implementation loss 3 dB


System Throughput

4000

4500

5000

5500

6000

Ce

ll t

hro

ug

hp

ut

(Mb

ps)

PLF1, NoBF

PLF2 provides higher

system throughput

than PLF1

30x LTE cell throughput (4Tx MIMO per sector, 3-sector cell, 20MHz system bandwidth)

2000

2500

3000

3500

4000

40 43 46 49

Ce

ll t

hro

ug

hp

ut

(Mb

ps)

Base station transmit power per sector (dBm)

PLF1, NoBF

PLF2, NoBF

PLF1, RxBF

PLF2, RxBF


RxBF significantly

improves system

throughput

system bandwidth)

Cell-edge performance

80

100

120

140

ed

ge

th

rou

gh

pu

t (M

bp

s)

PLF1, NoBF

PLF1 allows better cell-

edge throughput than

PLF2

0

20

40

60

40 43 46 49

cell

-ed

ge

th

rou

gh

pu

t (M

bp

s)

Base station transmit power per sector (dBm)

PLF1, NoBF

PLF2, NoBF

PLF1, RxBF

PLF2, RxBF


RxBF significantly

improves system

throughput





• mmW spectrum








– Frame Structure






– RF beamforming





– Rain absorption

– Diffraction



architecture







challenges




– mmWave LNA






• Summary


SummaryMillimeter wave spectrum (3-300GHz) can potentially provide the bandwidth required for mobile broadband applications for the next few decades and beyond.

•Opportunity to open 200 times the spectrum currently allocated for cellular below 3GHz.

Propagation and other losses due to rain, foliage and penetration through building materials needs better understandingbuilding materials needs better understanding

Millimeter waves are also attractive for mobile application due to small component sizes such as antennas.

•Further research is needed towards components and devices that meets mobile application demand of higher power and efficiency

Wireless community should take on the growing data demand by exploiting millimeter wave spectrum paving the way for multi-Gbps mobile broadband.


Documents

Millimeter-wave Mobile Broadband: Unleashing 3-300GHz Spectrum