Antenna Arrays with Parasitic Elements: a Technology - CiteSeerX
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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
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Papadias, Alrabadi, Kalis: Parasitic Antenna Arrays for Compact MIMO Systems 2/93
• 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
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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
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Conventional MIMO
Transmission
Future MIMO
Transmission
The Vision
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Review of MIMO Technology
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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
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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 ( )
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• 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] )
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• 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′
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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
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First Experimental MIMO Testbed (Bell Labs, 1996)
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Transmit & Receive Arrays
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Over-the-air Typical Received Signal
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Over-the-air Processed Signals
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• 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]
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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]
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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
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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])
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• 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]
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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
∞
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3G1X (cdma2000) voice performance
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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
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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]
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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
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IST Mobile Summit, Aveiro, Portugal, June 2003, EU-FP6 Project FITNESS
HSDPA MIMO Video Transmission PrototypeDemonstrating Multi-User Uplink Processing
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MMDS MIMO Prototype
Originally developed by Iospan & Stanford University for fixed wireless point-to-point MIMO links
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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]
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MIMO in WiMAX (802.16e): an Overview
• Transmission modes:– Beamforming– Space-time coding– Spatial Multiplexing– Adaptive MIMO [Li06]
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Uplink Collaborative MIMO
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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
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Review of
PARASITIC ANTENNA ARRAYS
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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
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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.
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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.
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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.
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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
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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.
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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
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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).
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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
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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?
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BeamSpace (BS) MIMO
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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
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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.
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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.
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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
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BS-MIMO: A New Formulation
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BS-MIMO Formulation Continued
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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.
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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.
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BS-MIMO forPARASITIC ARRAYS
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A Single-Active Single-Passive Array
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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Control Circuit
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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.
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All PSK Modulation Schemes
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Model Extension
Planar Symmetrical Topology:
An Orthonormal Basis of 3 functions
is obtained.
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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.
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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.
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Mutual Information Analysis: Open-Loop
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Simulation Results
Gaussian Signaling is assumed
rather than PSK
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Average Mutual Information for Discrete PSK Input
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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.
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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.
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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)
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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.
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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.
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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.
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SM via AS, Cont.
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Control Circuit Design
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Mutual Information Analysis
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Spatial Demultiplexing
I/Q Separation
Beam-Switching at twice the symbol rate
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Some Design Considerations
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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
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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.
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Bandwidth Expansion
Ideal Transition
Slow Transition
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Applications
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Devices
Mobile Equipments:
Cellular Phones, PDA’s, Laptops
Access Points
Motivation:
The Capacity of a 2x2 system is greater than the ∞x1
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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
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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)
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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.
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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.
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Satellite Communications
Motivation:The need for light (small weight), Adaptive and low-DC Power Consuming Array.
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Biosensor Networks
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Thank you!
Special thanks to Osama Alrabadi, Antonis Kalis and Nicola Marchetti for providing valuable material for this presentation
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[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.
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