Antenna Arrays with Parasitic Elements: a Technology - CiteSeerX

Papadias, Alrabadi, Kalis: Parasitic Antenna Arrays for Compact MIMO Systems 1/93

Antenna Arrays with Parasitic Elements:a Technology for Compact MIMO Systems

Dr. Constantinos B. Papadias

Co-authors: O. Alrabadi & A. Kalis

Broadband Wireless & Sensor Networks Group (B-WiSE)

Athens Information [email protected]

Talk given at the 2nd International Symposium on AppliedSciences in Biomedical and Communication Technologies

Bratislava, Slovak Republic, Nov. 24-27, 2009


• Motivation / Vision• Review of MIMO technology

– Basic features & techniques– Main benefits & Limitations

• Review of parasitic antenna arrays:– Fix directive transmission– Beam / null steering– Pattern / angular diversity

• Beam-space MIMO– A new formulation for conventional MIMO systems– Spatial multiplexing with parasitic antenna arrays

• Design issues • Applications

Outline

Papadias, Alrabadi, Kalis: Parasitic Antenna Arrays for Compact MIMO Systems 3/93www.ait.edu.gr

Classical MIMO

i. High Cost due to Expensive RF components

ii. High Spatial Correlation for Spacing less than λ/2

iii. Reduced Antenna Efficiency due to Strong Mutual Coupling

iv. High Consumption of DC Power as Multiple IF/RF Front-ends are used

Designing a Low Cost, High Performance Compact MIMO Transceiver Seems Contradictory Using Classical MIMO.

No Capacity Gain (Over SISO) for D=λ/4 or less

Motivation


Conventional MIMO

Transmission

Future MIMO

Transmission

The Vision


Review of MIMO Technology


Single antenna links: Shannon capacity

“It is dangerous to put limits on wireless” Guglielmo Marconi, 1932

• The information-theoretic capacity of single-antenna links is limited by the link’s signal to noise ratio according to Shannon’s celebrated formula• Capacity grows logarithmically with the Tx power (i.e. to go from 1bps/Hz to 11 bps/Hz, the Tx power must be roughly increased by ~1000 times!)

•Disclaimer:

TX RX2log (1 SNR ) [bps/Hz]C = +s k( ) x k( )

C. ShannonBell Laboratories Technical Journal, 1950


Multiple antenna links

• Keeping the game fair: total Tx power should remain the same

• Questions: (1) What is the corresponding capacity?(2) How should we transmit from the different antennas? (3) How should the receiver operate?

TX 1 RX 1

TX 2 RX 2

TX M RX N

s k1( )

s k2 ( )

s kM ( )

x k1( )

x k2 ( )

x kN ( )


• We are primarily interested in the case where:– The transmitter only knows the channel statistics but not the

channel realization H. This is sometimes referred to as ‘‘open-loop’’ operation

– We also assume a coherent receiver that knows perfectly the MIMO channel H

• The mutual information with equal power transmission from each antenna (a pragmatic popular approach), is

‘‘Open-loop’’ MIMO

†2log det T

o Nn

PC IMσ

⎧ ⎫= +⎨ ⎬

⎩ ⎭HH

(see [Foschini ’96] [Foschini & Gans ’98][Telatar ’99] )


• The capacity can be written equivalently as:

• This leads to the following equivalent representation of the MIMO channel in terms of independent component channels (often called ‘‘spatial modes’’):

The Spatial Multiplexing Effect

2 221 1

SNRlog 1 log 1r r

To i i

i in

PCM M

λ λσ= =

⎛ ⎞ ⎛ ⎞= + = +⎜ ⎟ ⎜ ⎟⎝ ⎠⎝ ⎠

∑ ∑where are the eigenvalues of the channel matrix and is the rank of .

'siλ†HHr

H

r

1 ( )s k′1λ + 1 ( )x k′

( )rs k′rλ +

( )rn k′

( )rx k′

1 ( )n k′


Rayleigh i.i.d. MIMO (open-loop) Outage CapacitiesSP

ECTR

AL

EFFI

CIE

NC

Y (b

ps/H

z)

NUMBER OF UNCORRELATED ANTENNAS (M=N)

0 10 20 30 40 50 60

150

100

50

24dB18 dB 12dB

6 dB

0 dB

SPECTRAL EFFICIENCY vs. NUMBER ANTENNASAT 1% OUTAGE

1×N OptimumCombining at 24 dB

Predicted capacities


First Experimental MIMO Testbed (Bell Labs, 1996)


Transmit & Receive Arrays


Over-the-air Typical Received Signal


Over-the-air Processed Signals


• V-BLAST*

• simple (1D) coding• fairly simple receiver• short of capacity• “per antenna rate control” (PARC)

mode achieves capacity with multi-rate feedback

• D-BLAST

• more demanding coding• more complex receiver• achieves capacity with

single rate feedback

Two Basic Transmission Methods

...

... ...

.........

* BLAST stands for Bell labs Layered Space Time architecture, see [Foschini ’96, Foschini & Gans ’98]


V-BLAST vs. Capacity (Rayleigh i.i.d Channel)

SNR: 10 dBSNR: 10 dB

V-BLAST is capable of attaining a significant portion of the available MIMO capacity

0 5 10 15 20 25 30 35 40 45 500

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1M=16, N=16, ρ=10 dB

capacity [bps/Hz]

Pr.(

capa

city

>abc

issa

)

(1,1)

(1,2)

(1,4)

(1,8)

(1,16)

V-BLAST(16,16)

open-loop(16,16)

See [Papadias & Foschini ’02]

[10% outage capacities]


SIMPLE CASE: (1,N) DIFFICULT CASE: (M,1)

H1

H2

HN

TX

H1

H2

HM

Capacity is easilyachieved with 1-D codecs (MRC)

Capacity is not easily achieved with 1-D codecs

RX TX

RX

Maximizing the Throughput: Two Extreme Cases


Space-time Block Coding Transmit Architecture

ENCODER Space-TimeBlock Code/ Mapping

Input Data Stream

TX 1

TX M

%( )b i ( )b i 1( )s k

( )Ms k

… …

• The original bit stream is first encoded• The encoded data are then mapped onto blocks of vector data that

are then transmitted out of the antennas • In this fashion, encoding and spatial multiplexing are decoupled:

encoding is a time-only operation, whereas the block code determines how the encoded data samples are mapped onto different antenna elements

… …

Encoded Input Stream

(See [Tarokh et al. ’99])


• have double length but are used for 2 sub-streams, no redundancy

• and are odd and even samples from the same user’s data

An application to 2.5/3G voice: Space-Time Spreading

• Based on Alamouti coding [Alamouti ’98]• Each user’s sub-streams are multiplexed as follows:

1 ( )s i

c2

c1

2 ( )s i 2 2( )s i∗ c

1 1( )s i c

1 2( )s i∗ c

2 1( )s i c 2 1 1 2( ) ( )s i s i∗−c c

1 1 2 2( ) ( )s i s i∗+c c

B2

B2

DD

b i( )

1( )s i

c c1 2, ⇒2 ( )s i

[Hochwald, Marzetta, Papadias 2001]


Alamouti Space-Time Code: Capacity

0 2 4 6 8 10 12 14 16 18 200

1

2

3

4

5

6

7

8

9

SNR [dB]

capa

city

[b/s

/Hz]

10% outage capacities

2x2 open-loop2x2 Alamouti

x1 log-det8x1 log-det4x1 log-det2x1 Alamouti1x1

∞


3G1X (cdma2000) voice performance


MIMO in 3G: UMTS high speed downlink data

• Assumptions:– Turbo coding– 20 codes– 3km/hr– flat fading– known channel– ML / symbol

5 10 15 20 25 30 35 4010

-4

10-3

10-2

10-1

100

3km/hr

Ior/Ioc (dB)

FER

(4,4)(2,2)

10.8Mbps 64QAM

14.4Mbps 16QAM

10.8Mbps 8PSK

10.8Mbps 4PSK

14.4Mbps 4PSK

21.6Mbps 8PSK

(1,1)Dashed:VBLASTSolid: ML


10 15 20 25 30 350

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Throughput, Mbits/s

Pro

b(T

hrou

ghpu

t < x

-axi

s)"B"-channel, 16-QAM, 4320 bits per slot, 10ms frame

Benchmark 1 Benchmark 2 Benchmark 3 Proposed solution

2x2 MIMO in WiFi: “B” channel, (3-9)m distance

Almost doubledthroughput

can be achieved

[Kuzminskiy et al. 05]


HSDPA 4x4 MIMO Test-Bed [Lucent, 2002]

Rx-Rad

io I

nter

face

UMTS-MIMO Frontend

MIM

O I

nter

face

Pre-

Proc

essing Timing Recovery

Baseband Processing

MIMO Decoder:• ML• BLAST• MMSE• ZF• Hybrid R

LP-In

terf

ace

Rx-Rad

io I

nter

face

UMTS-MIMO Frontend

MIM

O I

nter

face

Pre-

Proc

essing Timing Recovery

Baseband Processing

MIMO Decoder:• ML• BLAST• MMSE• ZF• Hybrid R

LP-In

terf

ace

UMTS-Transmitter

UMTS-Transmitter

UMTS-Transmitter

UMTS-Transmitter

Tx-

Radio

Inte

rfac

e

Radi

o Co

ntro

ller

Inte

rfac

e

Radio

Radio

UMTS-Transmitter

UMTS-Transmitter

UMTS-Transmitter

UMTS-Transmitter

Tx-

Radio

Inte

rfac

e

Radi

o Co

ntro

ller

Inte

rfac

e

Radio

Radio

Radio

Radio

• Featuring the world’s first MIMO ASIC• Achieving 19.2 Mbps over a 5 MHz UMTS carrier

UMTS BTS User Equipment


IST Mobile Summit, Aveiro, Portugal, June 2003, EU-FP6 Project FITNESS

HSDPA MIMO Video Transmission PrototypeDemonstrating Multi-User Uplink Processing


MMDS MIMO Prototype

Originally developed by Iospan & Stanford University for fixed wireless point-to-point MIMO links


MIMO in LTE (Rel. 8): an Overview

• Transmission modes:– Downlink Single User Transmit Diversity– Downlink Spatial Multiplexing & Closed-Loop MIMO– Downlink Multi-User MIMO– Uplink Multi-User MIMO [3GA09]


MIMO in WiMAX (802.16e): an Overview

• Transmission modes:– Beamforming– Space-time coding– Spatial Multiplexing– Adaptive MIMO [Li06]


Uplink Collaborative MIMO


IEEE Trans. on Information Theory, Special Issue on Space-Time Transmission, Reception, Coding and Signal Design, Vol. 49, No. 10, Oct. 2003.

IEEE Journal on Selected Areas in Communications, Special Issue on MIMO, March 2003.IEEE Trans. on Signal Processing, Special Issue on Signal Processing for Communications, Vol.50,

No. 10, Oct. 2002.EURASIP Journal on Applied Signal Processing, Special Issue on Space-Time Coding and Its

Applications – Part I, Vol. 2002, No. 3, Mar. 2002.EURASIP Journal on Applied Signal Processing, Special Issue on Space-Time Coding and Its

Applications – Part II, Vol. 2002, No. 5, May 2002.EURASIP Journal on Applied Signal Processing, Special Issue on MIMO Communications and Signal

Processing, Vol. 2004, No. 5, May 2004.A. Tulino and S. Verdu, Random matrix theory and wireless communications, Foundations & Trends

in Communications & Information Theory, Vol. 1, No. 1, 2004.A. Paulraj, R. Nabar and D. Gore, Introduction to Space-Time Wireless Communications, Cambridge

University Press, Cambridge, UK, 2003. Alex Gershman, Editor, Space-Time Processing for MIMO Communications, Wiley 2005.T. Kaiser and A. Bourdoux, Editors, Smart Antennas – State of the Art, EURASIP Hindawi Book

Series, 2004.H. Bolcskei, D. Gesbert, C. Papadias, A. J. Van der Veen, Editors, Space-Time Wireless Systems:

From Array Processing to MIMO Communications, Cambridge University Press, 2006

Further Reading on MIMO


Review of

PARASITIC ANTENNA ARRAYS


Yagi-Uda Antenna : Single Step Design

Mainly designed and optimized using NEC2.

Excitation can be an incident plane wave as in TV Rx or a voltage source.

The Ladder Antenna

Passive DirectorsDriven DipolePassive Reflector

S. Uda ‘’On the Wireless Beam of Short Electric Waves’’, Journal of the institute of Electrical Engineers of Japan’’, March 1926-July 1929


Harrington’s Reactively Controlled Array

A Single Active Dipole Surrounded by Six Parasitic Dipoles Loaded with Reactances.

Harrington Array

Harrington, R. Reactively controlled directive arrays. IEEE Trans Antennas Propag 1978; 26(3): 390-395.


Switched Parasitic Arrays (SPA)After 1978

Dinger, R. Reactively steered adaptive array using microstrip patch elements at 4 GHz. IEEE Trans Antennas Propag 1984; 32(8): 848-856.Dinger, R. A planar version of a 4.0 GHz reactively steered adaptive array. IEEE Trans Antennas Propag 1986; 34(3): 427-431.Preston, S. L., Thiel, D. V., Smith, T. A., O’Keefe, S. G., Lu, J. W. Base-station tracking in mobile communications using a switched parasitic antenna array. IEEE Trans Antennas Propag 1998; 46(6): 841-844.Vaughan, R. Switched parasitic elements for antenna diversity. IEEE Trans Antennas Propag 1999; 47(2): 399-405.


Seven-Element ESPAR

ESPAR is a modified version of the Harrington Array in the sense that monopoles rather than dipoles are used, and the variable reactive loads are integrated in the ground plane.

Gyoda, K., Ohira, T. Design of electronically steerable pasive array radiator (ESPAR) antennas. Proc. IEEE Antennas Propag Soc Int Symp, 2000, 922-955.


Different Configurations

T. Ohira and K. Gyoda, “Electronically Steerable Passive Array Radiator Antennas for Low-Cost Analog Adaptive Beamforming”, IEEE International Conference on Phased Array Systems and Technology, 2000. pp. 101 – 104

N-Element ESPAR


Monopoles and Dipoles

3D PatternE-Plane

By approximating the H-Plane to be omnidirectional, the array factor AF is easily found by the superposition of the currents induced on thedipoles/monopoles.


Analog Adaptive Beamforming: Only via ESPAR

C. Sun, A. Hirata, T. Ohira, N. C. Karmakar, “Fast Beamforming of Electronically Steerable Parasitic Array Radiator Antennas:Theory and Experiment”, IEEE Transactions on Antennas ond Propagation, vol. 52, no. 7, July 2004, pp 1819-1832


Three Element ESPAR

A 3-element ESPAR was mainly

introduced for Pattern Diversity.

Inter-element spacing of λ/4 and λ/20 was used

The configuration is quite attractive for mobile terminal for mitigating the fading effect.

T. Sawaya, K. Iigusa, M. Taromaru, and T. Ohira, “Reactance Diversity: Proof-of-Concept Experiments in an Indoor Multipath-Fading Environment with a 5-GHz Prototype Planar Espar Antenna”, Consumer Communications and Networking Conference, 5-8 Jan. 2004, pp. 678 – 680.M. Taromaru and T. Ohira, “Electronically Steerable Parasitic Array Radiator Antenna − Principle, Control Theory and its Applications −”, 28th General Assembly of International Union of Radio Science (URSI GA 2005).


Coordinated T/R Beamforming: A Simple Approach

Chen Sun; Hunziker, T.; Taromaru, M. ‘’Wireless Communication Systems’’, 2005.2nd International Symposium on 7-7 Sept. 2005 Page(s):581 - 585


Till Now

Parasitic arrays have been used for

1. Designing fixed directive antennas

2. Reconfigurable arrays for

i. Beam and Null Steering

ii. Providing Reactance Diversity (Pattern or Angular Diversity)

What about true MIMO (i.e. spatial multiplexing?)

Can a compact parasitic array function as a MIMO terminal?


BeamSpace (BS) MIMO


Classical MIMO

i. High Cost due to Expensive RF components

ii. High Spatial Correlation for Spacing less than λ/2

iii. Reduced Antenna Efficiency due to Strong Mutual Coupling

iv. Interference Among the Parallel RF Chains

v. High Consumption of DC Power as Multiple IF/RF Front-ends are used

Designing a Low Cost, High Performance Compact MIMO Transceiver Seems Contradictory for Conventional MIMO.

Compact Multi-Element Arrays

C. Waldschmidt,, S. Schulteis, and W. Wiesbeck, “Complete RF System Model for Analysis of Compact MIMO Arrays”, IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL. 53, NO.3, MAY 2004


Capacity Motivation

The Capacity of a 2x2 system is greater than the ∞x1

C. B. Papadias, ``On the spectral efficiency of space-time spreading schemes for multiple antenna CDMA systems," Thirty-Third Asilomar Conference on Signals, Systems, and Computers, vol.1, 24-27 Oct. 1999.


Deploying Complex Decoupling Networks for Mitigating the Mutual Coupling Effect (Multi-port Conjugate Matching)

Increased Complexity, Cost and Size Antenna BW Reduction

Some Limited Solutions

Narrowband

Wideband

J. Weber, C. Volmer, K. Blau, R. Stephan, and M. A. Hein, ``Miniaturized antenna arrays using decoupling networks with realistic elements," IEEE Trans. Microwave Theory Tech., vol.54, no.6, pp.2733-2740, June 2006.


Polarized ArraysDeploying Polarized Arrays

Drawbacks:

1. Multiple Front-ends

2. Sub-channels Power Imbalance as the XPD is Environment and Handset Orientation Dependent.

3. Large Size e.g. Two Cross-Polarized Array Elements require an Area of λ2/4 .

λ/2

λ/2


BS-MIMO: A New Formulation


BS-MIMO Formulation Continued


AF of 2-element λ/2 array (QPSK Signaling)

C. Oestges and B. Clerckx,``MIMO Wireless Communication, From Real-World Propagation to Space-Time Code Design," pages 227-230, First Edition, 2007.


Till Now

• In classic MIMO systems we map symbols on orthonormal functions in the antenna domain (on antenna elements).

• We have considered mapping symbols directly on the wavevector domain.

• This is a Beamspace-MIMO system.

• We propose to use parasitic antennas to transmit different symbol pairs simultaneously towards different Angles of Departure at the transmitter, with a single active element.


BS-MIMO forPARASITIC ARRAYS


A Single-Active Single-Passive Array


Spatial Multiplexing (SM) via Beamforming (BF)

ON-OFF Keying

A. Kalis, A. G. Kanatas, M. Carras, A. G. Constantinides, ``On the performance of MIMO systems in the wavevector domain,“ IST Mobile & Wireless Communications Summit, 5-8 June 2006, Mykonos, Greece.


BPSK SM via BFE(Θ)=s0A(Θ)

A. Kalis, A. G. Kanatas, C. Papadias, ``An ESPAR antenna for beamspace-MIMO systems using PSK modulation schemes," IEEE International Conference on Communications 2007, Glasgow, UK, June 24-28, 2007.


Tx1

Tx2

Tx3

Rx1

Rx2

Rx3

h11

h33

θR,1

θR,3

θT,1

θT,2

θT,3

θR,2

describe the coupling between the jth orthogonal basis radiation pattern of the Tx antenna with the ith orthogonal basis radiation pattern of the Rx antenna.

( , )VH i j

The Virtual Channel

ˆ ˆ ˆ

HR V T

H HR R b T T

R R b T bs

bs V bs bs

= +

= +

= +

= +

= +

y Hx n

A H A x n

A A H A A x n

A A H B x ny H x n

% %

% %

%

A. M. Sayeed, ``Deconstructing multiantenna fading channels," IEEE Trans. Signal Processing, vol. 50, pp. 2563-2579, Oct. 2002.


Troubles

1. Changing the driving point impedance when changing the loads.

2. The obtained pattern may not be a pure linear combination ofthe desired functions.

3. Can hardly be scaled to higher order modulation schemes.


Pattern Decomposition: A Novel Approach

Example: BPSK Signaling

O. N. Alrabadi, A. Kalis, C. Papadias and A. Kanatas, ``Spatial Multiplexing by decomposing the far-field of a compact ESPAR antenna," IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 15-18 Sept 2008.


Circuit Relations of the 3-element ESPAR

O. N. Alrabadi, A. Kalis, C. Papadias and A. Kanatas, ``Spatial Multiplexing by decomposing the far-field of a compact ESPAR antenna," IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 15-18 Sept 2008.


Three-Element ESPAR Far-Field

O. N. Alrabadi, C. B. Papadias, A. Kalis, N. Marchetti and R. Prasad ``MIMO Transmission and Reception Techniques Using Three-Element ESPAR Antennas," IEEE Communications Letters, Vol.13, Issue 4, April 2009 Page(s):236-238.


A Basis of Two Angular Functions

AF

O. N. Alrabadi, C. B. Papadias, A. Kalis, N. Marchetti and R. Prasad ``MIMO Transmission and Reception Techniques Using Three-Element ESPAR Antennas," IEEE Communications Letters, Vol.13, Issue 4, April 2009 Page(s):236-238.


Control Circuit


All PSK Modulation Schemescos(kdcos(Θ)) 1 As d 0

d=λ/16 and less ~0

Non-linear Mapping from the Reactance Space (XL) to the Signal Space S

O. N. Alrabadi, C. B. Papadias, A. Kalis and R. Prasad ``A Universal Encoding Scheme for MIMO Transmission Using a Single Active Element for PSK Modulation Schemes," IEEE Transactions on Wireless Communications.


All PSK Modulation Schemes


Model Extension

Planar Symmetrical Topology:

An Orthonormal Basis of 3 functions

is obtained.


Channel Model

Parametric Channel Model

J. Fuhl, A. F. Molisch and E. Bonek, ``Unified channel model for mobile radio systems with smart antennas," Ins. Elect. Eng. - Radar Sonar Navigation, vol. 145, pp. 32-4, Feb. 1998.


Channel Estimation

O. N. Alrabadi, A. Kalis, C. Papadias and A. Kanatas, ``Spatial Multiplexing by decomposing the far-field of a compact ESPAR antenna," IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 15-18

Sept 2008.


Mutual Information Analysis: Open-Loop


Simulation Results

Gaussian Signaling is assumed

rather than PSK


Average Mutual Information for Discrete PSK Input


Performance Evaluation

V. Barousis, A. G. Kanatas, A. Kalis, C. Papadias, ``A Limited Feedback Technique for Beamspace MIMO Systems with Single RF Front-end," IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 15-18 Sept 2008.


Lack of Orthogonality

Correlation may not be always zero among the basis when considering channels with narrow angular spread

O. N. Alrabadi, C. B. Papadias, A. Kalis and R. Prasad ``A Universal Encoding Scheme for MIMO Transmission Using a Single Active Element for PSK Modulation Schemes," to appear at IEEE Transactions on Wireless Communications.


Optimal Loads

At [jX1 jX2]=[-j5 -j62]Ω ηM=95%, and Power Imbalance between B1(Θ) and B2(Θ) about -0.22 dB (0 dB is Optimal)


Spatial Multiplexing (SM) via Antenna Switching (AS)

Motivation

1. Next generation wireless terminals (e.g. LTE and WIMAX) will use most probably a single antenna for uplink versus four antennas for downlink.

Hence: There is no real MIMO for the uplink Transmission

2. We at AIT have some experience in designing an antenna switch system on the node level.Hence: A MIMO (SM or STBC) can be implemented using a switch antenna system during transmission whereas antenna selection diversity is used during reception.

O. N. Alrabadi, C. B. Papadias, A. Kalis, N. Marchetti and R. Prasad ``Spatial Multiplexing via Antenna Switching," Accepted on 13 June 2009 at the IEEE Communications Letters.


Motivation, Cont.

Energy Saving in WSN’s

Motivation: Total Energy Saving is done by integrating a MIMO Transceiver for Transmitting on lower Power Level, Keeping the Same Data Rate and the Same Link Performance of SISO.


SM via AS, Cont.

O. N. Alrabadi, C. B. Papadias, A. Kalis, N. Marchetti and R. Prasad ``Spatial Multiplexing via Antenna Switching," Accepted on 13 June 2009 at the IEEE Communications Letters.


SM via AS, Cont.


Control Circuit Design


Mutual Information Analysis


Spatial Demultiplexing

I/Q Separation

Beam-Switching at twice the symbol rate


Some Design Considerations


Driving Impedance Variations

C. Sun, A. Hirata, T. Ohira, N. C. Karmakar, “Fast Beamforming of Electronically Steerable Parasitic Array Radiator Antennas: Theory and Experiment”, IEEE Transactions on Antennas ond Propagation, vol. 52, no. 7, July 2004, pp 1819-1832

Port impedance varies according to loads usedIncreasing number of parasitic elementsincreases the resolution and directivity of the antenna but spread of port impedance values increases Frequency response and centre frequencydepend on matching of port impedance to feed network

One technique is to use dynamic (variable) matching instead of constant matchingAddition of variable impedance to active elementMatching performed based on value of imaginary part of port impedance to maintain efficiency


Design Considerations

While varactor can give a large reactive range,

their switching rate is slower than other switches

like PIN Diodes

M. D.~Migliore, D. Pinchera and F. Schettino, ``Improving Channel Capacity Using Adaptive MIMO Antennas," IEEE Transactions on Antennas and Propagation, vol.54,Nov 2006.


Bandwidth Expansion

Ideal Transition

Slow Transition


Applications


Devices

Mobile Equipments:

Cellular Phones, PDA’s, Laptops

Access Points

Motivation:

The Capacity of a 2x2 system is greater than the ∞x1


DevicesWireless Sensor Nodes

Motivation: Total Energy Saving is done by integrating a MIMO Transceiver for Transmitting on lower Power Level, Keeping the Same Data Rate of a SISO system.

AIT’s SENSA


Ad-hoc Networks

The performance of peer-to-peer communication links between 2 nodes equipped with 3-element ESPAR antennas is shown in the Figure beside.

Etot(Θ,Φ)


Multi-User MIMO: Base-Station Capacity Enhancement

Motivation:Number of Simultaneously Served Users is Upper-bounded by

the Number of BS-Antennas Proposed Idea:Surround Each Active Antenna with two or three parasitic

elements (PE), and external control circuitRequirement:Each Array (the single active and its PE) should be placed at

sufficient distance from each other, so no mutual coupling among the arrays takes place.

Proposed Topology:Collinear Topology Precoding Matrix (W):A block-diagonalizing matrix is proposed, so that the

orthonormality of the basis is not destroyed.


Cognitive Radios (CR)By integrating Compact and Cheap Parasitic Arrays in the user’s

handhelds, the spatially aware terminals can enhance the whole system capacity via

1. Interference reduction via null steering is controlled via cheap varactors.

2. Robust performance is done via space-time coding, and adaptive modulation.

3. Capacity attainment is done via spatial multiplexing and high M-array signaling.

4. Low-cost receiver diversity is done via angular diversity.5. Beam-steering or beam-selection is implemented under poor

MIMO channel conditions.6. Hidden Terminal Problem is Solved by Scanning the Space

Using a Directive Rotating Beam.

Broadband ESPAR Arrays and Multi-band Parasitic Arrays are already Available.


Satellite Communications

Motivation:The need for light (small weight), Adaptive and low-DC Power Consuming Array.


Biosensor Networks


Thank you!

Special thanks to Osama Alrabadi, Antonis Kalis and Nicola Marchetti for providing valuable material for this presentation


[Alamouti ’98] S. M. Alamouti, “A Simple Transmit Diversity Technique for Wireless Communications", IEEE JSAC, vol. 16, Oct. 1998, pp. 1451-58.[Bolcskei et al. 06] H. Bolcskei, D. Gesbert, C. Papadias, A. J. Van der Veen, Editors, Space-Time Wireless Systems: From Array Processing to MIMO Communications, Cambridge University Press, 2006.[Foschini ’96] G.J. Foschini, "Layered space-time architecture for wireless communication in a fading environment when using multielement antennas," Bell Labs Tech. J., pp. 41-59, 1996. [Foschini & Gans ’98] G. J. Foschini and M. J. Gans, ‘‘On limits of wireless communications in a fading environment when using multiple antennas,’’ Wireless Personal Communications, vol. 6, pp. 311-335, 1998.[Hochwald et al. ’01] B. Hochwald, T. Marzetta and C. Papadias, ‘‘A transmitter diversity scheme for wideband CDMA systems based on Space-Time Spreading,’’ IEEE Journal on Selected Areas in Communications (J-SAC), special issue on wideband CDMA (II), vol. 19, No. 1, pp. 48-60, Jan. 2001.[Kuzminskiy et al. 05] A. Kuzminskiy, H. Karimi, D. Morgan. C. Papadias, D. Avidor and J. Ling, “Downlink Throughput Enhancement of IEEE 802.11a/g Using SDMA with a Multi- Antenna Access Point,” EURASIP Signal Processing, special issue on Advances in Signal Processing-assisted cross layer Designs, No. 86, Issue 2, pp. 1896-1910, Dec. 2005. [Li06] Kuo-Hui Li, (Intel Mobility Group), “IEEE 802.16e-2005 Air Interface Overview,” June 5, 2006, available on-line.[Papadias ’09] C. Papadias, “On the Spectral Efficiency of Space-Time Spreading Schemes for Multiple Antenna CDMA Systems,” 33rd Asilomar Conference on Signals, Systems and Computers, Pacific Grove, CA, Oct. 24-27, 1999. [Papadias & Foschini ’02] C. Papadias and G. Foschini, ``On the capacity of certain space-time coding schemes,’’ EURASIP Journal on Applied Signal Processing, special issue on Space-Time Coding and its Applications, pp. 447-458, vol. 5, May 2002.[Tarokh et al. ’99] V. Tarokh, H. Jafarkhani and A. R. Calderbank, ‘‘Space-time block codes from orthogonal designs,’’ IEEE Trans. on Information Theory, vol. 45, No. 5, pp. 1456 – 1467, July 1999.[Telatar ’99] E. Telatar, ‘‘Capacity of multi-antenna Gaussian channels,’’ European Transactions on Telecommunications, vol. 10, No. 6, pp. 585-595, Nov. / Dec. 1999.[3GA’09] 3G Americas, “MIMO Transmission Schemes for LTE & HSP Networks,” June 2009, available on-line.

References

Antenna Arrays with Parasitic Elements: a Technology - CiteSeerX

Documents

Transcript of Antenna Arrays with Parasitic Elements: a Technology - CiteSeerX