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Transcript of Cognive BeamformingforSpectral! …newyork.ing.uniroma1.it/IC0902/4th-Workshop/Technical... ·...
Cogni've Beamforming for Spectral
Coexistence of Satellite and Terrestrial Networks
Shree Krishna Sharma ([email protected])
Dr. Symeon Chatzinotas Prof. Björn O8ersten
SnT, University of Luxembourg
9-‐11 Oct 2013, Rome, Italy
Outline
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q Introduc'on Ø CogniLve SatComs Ø Beamforming
q Proposed Scenarios q Receive Beamforming Ø Signal Model Ø Applicable Techniques Ø Results
q Transmit Beamforming Ø Signal Model Ø Applicable Techniques Ø Results
q Numerical Results q Conclusions
IntroducLon
q Mo'va'on Ø Increasing Spectrum demand Ø Temporal and spaLal variaLons
q Current Status Ø Spectrum segmenta'on Ø Sta'c frequency allocaLon
q Future Solu'ons: Source: NTIA Ø Dynamic Spectrum Access Ø Primary/secondary cogniLon
q Cogni've Radio Techniques: Spectrum Sensing, Underlay, Overlay, Database
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CogniLve SatComs
q Hybrid Satellite Terrestrial Coexistence
q Dual Satellite Coexistence
q S. K. Sharma, S. Chatzinotas, and B. O8ersten, “Cogni've Radio Techniques for Satellite Communica'on Systems” in proc. IEE VTC fall , Las Vegas, NV, 2013.
Operator 1 Satellte
Operator 2Satellite
Gateway 1Gateway 2
Cognition
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Beamforming
q Spectral sharing opportunity in the angular domain (same Lme, frequency and geographical locaLon)
q Underlay CR
q Beamforming Types: depending on how beamforming weights are chosen. Ø Data independent beamforming Ø Sta's'cally op'mum beamforming: Weights are chosen based on the staLsLcs of
the received data at the array. § MulLple Side-‐lobe Canceler (MSC) § Minimum Variance Distor'onless Response (MVDR) § Linearly Constrained Minimum Variance (LCMV)
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Proposed Scenarios Uplink Coexistence with Receive Beamforming Downlink Coexistence with Transmit Beamforming
q Shree K. Sharma, Symeon Chatzinotas, and B. O8ersten, “Spa'al Filtering for Underlay Cogni've SatComs”, in proc. PSATS , Toulouse, France, June 2013.
q Shree K. Sharma, Symeon Chatzinotas, and B. O8ersten, “Transmit Beamforming for Spectral Coexistence of Satellite and Terrestrial Networks”, in proc. CROWNCOM 2013, Washington DC, USA, July 2013.
Satellite
Terrestrial BS
Terrestrial Terminals
Weak
Interfering
Link
Strong Interfering Link
Primary Link
Secondary Link
Satellite Terminals
Satellte
Terrestrial BS
Terrestrial Terminals
Weak reception links
Strong Interfering Link
Primary Link
Secondary Link
Satellte Terminals
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Proposed Receive Beamforming
q Unique Propaga'on characteris'c of satellite terminals q SpaLal Filtering (Receive Beamforming) at terrestrial BS q The angular sector in which interfering satellite terminals are located is known to the beamformer. q The number of interfering terminals and their exact loca'ons are not known. q Objec've: to miLgate interference coming from whole angular sector and to maximize SINR of desired user.
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Signal Model
q M: number of antennas in the BS array, K: total number of users (one SU+(K-‐1) PU) q Received Signal y at BS
q Signal Direc'onal Matrix (SDM)
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MVDR and LCMV
q SINR of the kth desired user
q MVDR Problem and Solu'on
q LCMV Problem and Solu'on
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SimulaLon Parameters
q GEO satellite q Satellite terminals at azimuth range of 10◦
to 85 ◦ seen from the BS. q A single desired user at -‐30 ◦. q The considered interfering sector is
quanLzed in the interval of 5◦ and consider one terminal in each quanLzed angle.
q Number of interferers=16
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Numerical Results
Fig. SINR comparison of LCMV and MVDR
beamformers in the proposed scenario (M=20, K=17)
q LCMV provides similar SINR as that of MVDR beamformer towards the desired user and can provide very low SINR towards the interfering sector than the MVDR.
q LCMV can reject the
interference more effecLvely than MVDR in the considered scenario.
-150 -100 -50 0 50 100 150-200
-150
-100
-50
0
A zimuth angles (degrees)
SINR
indB
L C MVMVDR
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Numerical Results
Fig. SINR versus number of interferers for the proposed scenario
with beamformer designed for M=18, K=17.
q The SINR for both decreases as the number of interfering users increases in the considered interfering sector.
q LCMV shows beTer
performance compared to MVDR for low number of interferers (< 9 in Fig.) and for higher number interferers, MVDR shows beTer performance than the LCMV. 2 4 6 8 10 12 14 16
-20
-15
-10
-5
0
5
10
15
20
Number of interferers
SINR
indB
L C MVMVDR
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Proposed Transmit Beamforming
q Transmit Beamforming at terrestrial BS
q Objec'ves: Ø to miLgate interference towards the considered angular sector and to maximize SINR of a desired user.
Ø To miLgate the interference which may be picked up by the backlobe of the satellite terminals located beyond the sector of interest
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Satellite Terminals
·∙
Satellite
N
S
EW
BS
SAT Terminal
TerrTerminal
Dish Receiving interference with main lobe
Dish Receiving interference with back lobe
Signal Model
q M: number of antennas in the BS array, K: total number of PUs in the considered sector, one SU.
q Received Signal at the desired user (SU)
q Array Response Vector
q Interfering signal at the pth PU terminal
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Proposed Techniques
q Scaled LCMV:
q Modified LCMV
q SU Rate Maximiza'on Problem
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Numerical Results
Fig. SINR comparison of the modified LCMV and standard LCMV for the considered scenario
q Modified LCMV beamformer reduces the SINR towards the direc'on of the satellite terminal located at DoA of −15◦, thus protecLng the satellite terminal from secondary interference (IT -‐80 dB below the maximum gain).
q The reduced value of the SINR in
the direcLon of the primary satellite terminal depends on the choice of the parameter IT. -150 -100 -50 0 50 100 150
-180
-160
-140
-120
-100
-80
-60
-40
-20
0
Azimuth angles (degrees)
SIN
R (d
B)
Standard LCMVModified LCMV
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Numerical Results
Fig. Transmit power in the desired direcLon versus power threshold
q PU terminals from 45◦ to 85◦ with each terminal at 5◦ interval and SU rate maximiza'on approach.
q Tx power in the desired user’s
direc'on is the maximum when the constrained threshold power is kept at −10dBW for all the cases.
q Tx power in the desired direcLon
increases as the angular difference between the desired SU and the considered sector becomes large (i.e., maximum at 0◦ in Figure).
-80 -70 -60 -50 -40 -30 -20 -10 011.8
12
12.2
12.4
12.6
12.8
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Constrained power threshold in the directions of PUs (dBW)
Tx p
ower
to th
e de
sire
d us
er (d
BW
)
SU-rx at 30o
SU-rx at 20o
SU-rx at 10o
SU-rx at 0o
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Numerical Results
Fig. Worst case SU rate versus PU distance from BS Fig. Worst SU rate versus PU distance and angular deviaLon from the sector of interest
01
23
45
0
10
20
308
10
12
14
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Distance (Km)Angular deviation (degrees)
SU ra
te (b
its/s
ec/H
z)
1 2 3 4 5 6 7 8 9 1014.02
14.03
14.04
14.05
14.06
14.07
14.08
14.09
14.1
Distance to PU (Km)
Wor
st c
ase
SU
rate
(bits
/sec
/Hz)
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Conclusions q The performance of LCMV is much be8er in terms of rejecLng interference from the sector
of interest (even in case of DoA uncertainty of interfering signals). q MVDR beamformer is beTer suited for a large number of interfering terminals. and LCMV beamformer is be8er suited for the case of DoA mismatch of the desired signals. q Modified LCMV can miLgate the interference towards the specific angular sector by also
providing sufficient protec'on towards PU terminals located beyond the sector of interest.
q The worst case SU rate is dependent on the PU distance, the permissible interference threshold at the PU terminals as well as the angular devia'on of the desired user from the considered angular sector.
q The choice of a technique in the considered scenario depends on the desired performance level as well as the flexibility of applying different constraints to the opLmizaLon problem.
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References q Shree K. Sharma, Symeon Chatzinotas, and B. O8ersten, “Spa'al Filtering for Underlay Cogni've SatComs”, in proc. 5th Int. Conf. Personal
Satellite Services (PSATS), Toulous, France, June 2013. q Shree K. Sharma, Symeon Chatzinotas, and B. O8ersten, “Transmit Beamforming for Spectral Coexistence of Satellite and Terrestrial
Networks”, in proc. CROWNCOM 2013, Washington DC, USA, July 2013. q Shree K. Sharma, Symeon Chatzinotas, and B. O8ersten, “Interference Alignment for Spectral Coexistence of Heterogeneous Networks”,
EURASIP Journal on Wireless CommunicaIons and Networking, vol. 2013:46, 2013. q Shree K. Sharma, Symeon Chatzinotas, and B. O8ersten, “Satellite Cogni've Communica'ons: Interference Modeling and Techniques
Selec'on”, in Proc. ASMS/SCPC 2012, Baiona, Spain, Sept. 2012. q Shree K. Sharma, S. Chatzinotas, and B. O8ersten, “Cogni've Beamhopping for Spectral Coexistence of Mul'beam Satellites”, in proc.
Future Network Mobile Summit 2013, Lesbon, Portugal, July 2013. q Shree K. Sharma, S. Chatzinotas and B. O8ersten, “Cogni've Radio techniques for Satellite Communica'on Systems”, in proc. VTC-‐fall
2013, Las Vegas, CA, Sept. 2013, invited paper. q S. Chatzinotas, Shree K. Sharma, and B. O8ersten, “Frequency packing for interference alignment-‐based cogni've dual satellite systems”,
in proc. VTC-‐fall 2013, Las Vegas, CA, Sept. 2013. q Shree K. Sharma, S. Chatzinotas, and B. O8ersten, “Exploi'ng Polariza'on for Spectrum Sensing in Cogni've SatComs,” in CROWNCOM
Conference, Stockholm, Sweden, June 2012. q Shree K. Sharma, S. Chatzinotas, and B. O8ersten, “Spectrum Sensing in Dual Polarized Fading Channels for Cogni've SatComs,”in Proc.
IEEE Global CommunicaIons Conference, Anaheim, CA, December 2012. q Shree K. Sharma, Symeon Chatzinotas, and B. O8ersten, “Satellite Cogni've Communica'ons and Spectrum Regula'on”, in Proc. of
InternaIonal RegulaIons of Space CommunicaIons Workshop, Luxembourg, 24-‐25 May 2012. q S. Chatzinotas, Shree K. Sharma, and B. O8ersten, “Mul'antenna Signal Processing for Cogni've Communica'ons”, in proc. ChinaSIP 2013,
Beijing, China, July 2013, invited paper. q Shree K. Sharma, Symeon Chatzinotas, and B. O8ersten, “Effect of Noise Correla'on on Frac'onal Sampling based Spectrum Sensing”, in
proc. ICC 2013, Budapest, Hungary, June 2013. q Symeon Chatzinotas, Shree K. Sharma, and B. O8ersten,”Asympto'c Analysis of Eigenvalue based Blind Spectrum Sensing”, in proc. ICASSP
2013, Vancouver, Canada, May 2013. q Shree K. Sharma, Symeon Chatzinotas, and B. O8ersten, “Eigenvalue Based Sensing and SNR Es'ma'on for Cogni've Radio in Presence of
Noise Correla'on,” IEEE TransacIons on Vehicular Technology, vol. 62, no. 8, pp. 1-‐14, 2013. q Shree K. Sharma, Symeon Chatzinotas, and B. O8ersten, “SNR Es'ma'on for Mul'-‐dimensional Cogni've Receiver under Correlated
Channel/Noise,” to appear in IEEE Trans. Wireless CommunicaIon, 2013.
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Thank you for your a8enLon!