Hindawi Publishing CorporationEURASIP Journal on Advances in Signal ProcessingVolume 2009, Article ID 128516, 8 pagesdoi:10.1155/2009/128516
Research Article
Smart Antenna UKM Testbed for Digital Beamforming System
Mohammad Tariqul Islam,1 Norbahiah Misran,1, 2 and Baharudin Yatim1
1 Institute of Space Science (ANGKASA), National University of Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia2 Department of Electrical, Electronics & System Engineering, National University of Malaysia, 43600 UKM Bangi,Selangor Darul Ehsan, Malaysia
Correspondence should be addressed to Mohammad Tariqul Islam, [email protected]
Received 4 May 2008; Revised 11 November 2008; Accepted 6 January 2009
Recommended by Jiri Jan
A new design of smart antenna testbed developed at UKM for digital beamforming purpose is proposed. The smart antennaUKM testbed developed based on modular design employing two novel designs of L-probe fed inverted hybrid E-H (LIEH)array antenna and software reconfigurable digital beamforming system (DBS). The antenna is developed based on using thenovel LIEH microstrip patch element design arranged into 4 × 1 uniform linear array antenna. An interface board is designedto interface to the ADC board with the RF front-end receiver. The modular concept of the system provides the capability to test theantenna hardware, beamforming unit, and beamforming algorithm in an independent manner, thus allowing the smart antennasystem to be developed and tested in parallel, hence reduces the design time. The DBS was developed using a high-performanceTMS320C6711TM floating-point DSP board and a 4-channel RF front-end receiver developed in-house. An interface board isdesigned to interface to the ADC board with the RF front-end receiver. A four-element receiving array testbed at 1.88–2.22 GHzfrequency is constructed, and digital beamforming on this testbed is successfully demonstrated.
Smart antenna with digital beamforming (DBF) is regardedas one of the key components to meet the ever increasingappetite for higher data rates. Smart antenna technologydramatically improves the interference-suppression capa-bility and greatly increases frequency reuse, resulting inincreased capacity. Smart antenna with its beamformingcapability optimizes the signal-to-noise performance orpower consumption at both ends of the links. Advancementin powerful low-cost digital signal processor (DSP), general-purpose processors, field programmable gate array (FPGA),application-specific integrated circuits (ASICs), as wellas innovative software-based signal processing techniques(algorithms) or software-defined radio (SDR), has allowedthe development of smart antenna system to progressrapidly and make the smart antennas practical for cellularcommunications systems [1].
The beamforming is a key technology in smart antennasystem which is a process in which each user signal ismultiplied with a complex weight vectors that adjust the
magnitude and phase of the signal from each antennaelement [2–5]. Hence, the array forms a transmit beamin the desired direction and minimizes the output in theinterferer directions. A beamformer appropriately combinesthe signals received by different elements of an antennaarray to form a single output. The DBF system providesseveral advantages over analog beamforming techniques.First, analog array system uses expensive microwave phaseshifters and attenuators for each element. Second, the signalprocessing capability, such as adaptive beamforming, islimited. However, there are still challenges in the practicalimplementation of high-performance DBF array system [6].Classically, this is achieved by minimizing the mean squareerror (MSE) between the desired output and the actualarray output. This principle has its roots in the tradi-tional beamforming employed in sonar and radar systems[7–13].
Investigating the performance of highly sophisticatedwireless systems, in particular the smart antenna systems, isa difficult task. In most cases, this can only be performedvia simulation, which means modeling complex behavior
2 EURASIP Journal on Advances in Signal Processing
by simpler mathematical descriptions. Software simulation,for example, MATLAB software with its highly accuratedouble-precision numerical environment is on the onehand a perfect tool for the investigation of algorithms.On the other hand, many imperfections of the real-world are neglected [14]. A testbed is generally used forresearch which is a vehicle for further development, forverification of algorithms, or ideas under real-world orreal-time conditions. This results in the requirement forscalability, modularity, and extendibility [14]. The advantageof testbed is to reduce the investment risk of the newproduct in case the new technology would hide unforeseenchallenges.
Recently, there has been a great effort to build thesmart antenna system testbed (SATB) to meet the everdemanding channel capacity for the future generationbroadband mobile communication systems [15–17]. Thereare testbeds reported in the literature focusing on variouswireless technologies. The TSUNAMI project [18] in Europewas aimed at promoting research and development inadaptive antennas. The testbed reported by Virginia Techlab [19] is a 2 × 2 broadband MIMO. Iospan WirelessInc. and Stanford University also reported in [14] a smartantenna testbed one in downlink and another in uplink.These SATBs are designed based on narrowband antennasemploying conventional dipole, slots, TEM horns, reflectorsantenna, and so forth that made the antennas bulky andheavy. Aesthetic appearances of these structures are adverselyaffected by big bulky antennas. Microstrip technology meetsthe requirement of a compact and low-profile system due toits light weight, low production cost, ease of fabrication, andconformability with RF circuitry [20, 21]. However conven-tional microstrip antenna or array suffers from very narrowbandwidth. This set the design challenges of developing abroadband microstrip antenna that can cover the radio band(1.88–2.22 GHz).
The objective of this work is to reduce the antenna sizeand complexity of the system without compromising thedigital beamforming capability. Furthermore, microstrip slotantennas are selected for the design of the array due totheir compactness. The remainder of the paper is organizedas follows. Section 2 describes the system architecture andhardware implementation. Section 3 discusses the UKMtestbed measurement results, and finally Section 4 concludedthe paper.
2. System Architecture and HardwareImplementation
The novel SATB developed at UKM (UKM testbed) isdeveloped based on modular concept employing two noveldesigns of four-element microstrip patch antenna array andDSP-based DBS, which allows the exploitation of digitalbeamforming. The testbed is designed as a receiver unit. Ablock diagram of UKM testbed receiver system architectureis shown in Figure 1. The testbed receiver system composedof antenna system, radio unit, and digital signal processingbaseband section.
Customdesignedinterface
board
RFsection
RFsection
ADCTHS1206
ADCTHS1206
5–6 Kinterface
board
C6711DSP board
Figure 1: Block diagram of UKM testbed receiver.
Table 1: The LIEH-shaped MPA design specification.
RF parameter Values
Superstrate RT 5880 (εr1 = 2.2, h1 = 1.5748 mm)
Substrate Air (ε0 = 1, h0 = 16 mm)
Rectangular patchWidth and Length,{W ,L} = {79, 41}mm
Feed positionfp = 8.5 mm from bottom edge ofthe patch
Slots parameters (E) {ls, s,ws} = {37, 16, 1}mm
Slots parameters (H) {lh,wh, sh} = {18, 19, 2}mm
Probe length hp = 14 mm along y axis lp = 25 mmalong x axis
The radiating element, the LIEH-shaped microstrippatch antenna (MPA), is arranged in a 4 × 1 linear arrayconfiguration and with interelement spacing of 68 mm (or0.50 λ) at 2.2 GHz. The total dimension of the array is120 mm (width) by 285 mm (length) with the size of theground plane equals to 370 mm × 200 mm × 1 mm. Thedesign parameters for the LIEH-shaped MPA are shownin Table 1. The LIEH array antenna is constructed usingtwo dielectric layer arrangements, where a thick air-filledsubstrate was sandwiched between top-loaded dielectricsubstrate or superstrate with inverting radiating patch andan aluminum ground plane [22]. The array antenna isdesigned based on LIEH-shaped microstrip patch whichused contemporary design techniques, namely, the L-probe feeding, inverted patch, and slotted patch techniquesto meet the design requirement. The geometry of the4 × 1 uniform linear LIEH array antenna is shown inFigure 2.
A commercial electromagnetic simulator Sonnet Suite emsimulator was used to simulate the design. The fabricatedantennas were measured using the Agilent PNA E8358Anetwork analyzer, Agilent ESG-DP series E4436B signalgenerator, Advantest R3131A spectrum analyzer, and thestandard gain LPDA-0803 log periodic dipole antenna.Measurement was conducted in the open field. The arrayachieves an impedance bandwidth of 17.32% (at VSWR ≤1.5), maximum achievable gain of 11.9 ± 1 dBi and 20 dBcrosspolarization level [22].
EURASIP Journal on Advances in Signal Processing 3
Centreline
Inter element spacing
Inverted hybrid E-Hshaped patch
y,H
x,E
(a)
h1
h0
SMA
Superstrate (εr1)
Air (ε0)
L-probe
Silicon
Ground
Radiating patch
(b)
Figure 2: (a) Top view and (b) side view of the 4× 1 LIEH patch elements.
The radiation characteristics of the LIEH patch antennameasured in free space range are shown in Figure 3. Itshows the E-plane and H-plane radiation patterns of thehybrid patch at resonance frequency of 1.92 GHz and2.15 GHz. The experimental results agree well with thesimulation results (not shown in this paper). In the E-plane, the 3 dB beam width is 60◦ at 1.92 GHz and 50◦ at2.15 GHz. The peak crosspolarization is −25 dB at 1.91 GHzand −30 dB at 2.15 GHz. The radiation pattern is virtuallysymmetry in the H-plane but asymmetries in the E-plane.The asymmetry characteristic of the copolarization patternis clearly shown in Figure 3. The LIEH patch antenna showsthat the cross-polarization level increases with resonantfrequency and thickness [23]. The H-plane radiation patternshows a slightly broader 3 dB beamwidth about 75◦. Thepeak cross-polarizations are −11.87 dB and −9.82 dB at therespected resonant frequencies. The improvement in thecrosspolarization characteristics of the patch is due to theembedded parallel slot which reduces the current flow in H-plane direction as observed earlier. Noted in this figure, thecrosspolarization in the H-plane is considerably higher thanthe E-plane. Similar observations have been reported in theliterature [24]. This cross-polarization is generated by theleaky radiation of the slots [24] and also due to the substratethickness [25].
Figure 4 shows the measured coupling between theelements S12, S13, and S14 of the 4 × 1 LIEH array antenna,with element 1 taken as the reference element. It can beseen that the coupling between the reference element andother elements decays over elements spacing. As shown inthe figure, the magnitude of S12, S13, and S14 remains flat overthe pass band, and the maximum mutual coupling is betweenelement 1 and element 2 (S12) with the maximum value of−12.2 dB in the operating bandwidth. The minimum mutualcoupling is −41.83 dB between element 1 and element 4(S14). Table 2 shows the simulated and measured values ofthe interelement coupling between all elements of the array.
One of the fastest floating-point platforms available,the Texas Instruments (TI) TMS320C67 DSP capable of900 MFLOPS, was selected as the computational platformfor the DBS. The radio frequency (RF) receiver front-endsaccommodate a multichannel two-stage down conversion
Figure 3: Measured E- and H-plane normalized radiation patternsat two resonant frequencies of 1.92 GHz and 2.15 GHz.
Table 2: Interelement coupling for each element of 4× 1 LIEH.
S12 (2 GHz) S13 (2 GHz) S14 (2 GHz)
Simulated 15 dB 23 dB 34 dB
Measured 12 dB 21 dB 30 dB
between the RF section and the baseband section. Centerfrequency of 2040 MHz is used in the custom designed front-ends due to the propagation similarities compared to theworldwide 3G radio band (1.88 GHz–2.22 GHz) and theavailability of standard components at this frequency. TheDBS front-end is composed of four parallel RF channelswhich filtered, amplified, and downconverted the incomingsignal from the antenna into eight complex baseband signals(I&Q) using the I&Q demodulators. These signals are fedto the analog-to-digital conversion (ADC) board for dataconversion.
Figure 5 shows the simplified block diagram of RFfront-end of the UKM testbed. The RF section of thetestbed composes of four parallel RF channels whichare filtered and amplified by Trilithic RF BPFs centered
4 EURASIP Journal on Advances in Signal Processing
0
−10
−20
−30
−40
−50
Mag
nit
ude
(dB
)
1.86 1.93 2 2.06 2.13 2.2 2.27 2.33 2.4
Frequency, f (GHz)
S12
S13
S14
Figure 4: Measured coupling between element 1 and otherelements of the 4× 1 LIEH-shaped array.
at 2040 MHz and MiniCircuits ZHL-1724HLN low-noiseamplifiers, respectively. The incoming signal is downcon-verted by MiniCircuits ZEM-4300 MHz double-balancedmixers and Trilithic IF BPFs centered at 68 MHz. The eightcomplex baseband signals are generated using the ZFMIQ-70D demodulator. The LNA and IF amplifiers run on 15 voltsDC, and the power consumption per channel is measured at15.8 watts, which provided a combined power consumptionof 63.2 watts for the four-element RF front-end. The LOsignal for the mixers (13 dBm drive level) is driven from asingle source to keep the phase relationship constant betweenthe branches. An Agilent E4436B ESG series signal generatoris utilized to generate the 1972 MHz LO signal. The 1 to 4Mini-Circuits ZN4PD1-50 power splitter is used to deliverthe signal to the mixer. The Agilent 6653A DC power supplyis used to drive the amplifier.
The ADC is performed with the multichannel TITHS1206M EVM, which is mated to the Texas InstrumentsC67 DSP board through TI 5-6 K Interface board. Since an8-channel ADC board was not available on a single board,two 4-channel TI THS1206M EVM boards were placed ontop of another. The ADC board has been modified forstacking the two ADC boards to get eight baseband channels.Custom-designed boards were developed to interface withADC board. Figure 6 shows the developed RF front-endfor UKM testbed. The DBS consists of a four-layer rake.The dimension of each layer is 24 inches × 14 inches andmounted on an aluminum metal plate above the Perspex forgrounding and mechanical support. The bottom three layersare used to accommodate all the components and the toplayer for the screening purpose only. The power connectionsare run beside the board from the DC power supply.
The demodulated antenna signals are received fromSMA connector of MiniCircuits low-pass filter (LPF), butthe analog input of the ADC board is the combinationof header/socket. To feed the LPF signal into the analoginput of ADC, the header/socket connector is required tobe modified for complying with SMA connector of the
LPF filter. The analog input of the THS1206M EVM is a20-pin male header (2 rows × 10 pos). There is a 20-pinsocket on the bottom side and a 20-pin male header onthe top side of the THS1206M EVM. These are passing-through connectors (shorted top to bottom). The onlyoutput available from analog signal sources is from SMAmale connectors. Therefore, a female SMA connector isrequired to adapt to breakout the signal for THS1206MEVM board. A shielded ribbon cable is utilized with matingheader that fits on the 20-pin male header. These two maleheader connectors remain the same when THS1206M EVMis stacked on the 5-6 K Interface board. A 20-pin femalesocket which is connected by ribbon cable is used to plug intothe connector of the 5-6 K interface board. The other end ofthe ribbon cable is soldered to mate SMA connector.
In order to get the proper voltage level between 1.5 Vto 3.5 V for THS1206 M EVM, the voltage signal is shiftedto 2.50 V (REFM + REFP/2). Figure 7 shows the circuitdiagram of voltage level shifter circuit. The analog inputsignal is shifted to the analog input range of THS1206 (1.5 Vto 3.5 V) by using this circuit board. The op-amp is config-ured with a resistor divider as an inverting amplifier with aunity gain. Two units of 4-input TL084CN are employed inorder to get the 8 input signals. The output of the voltagedivider circuit is tapped into the noninverting input of theTL084CN op-amp. A high-resolution THS 1206 ADC andNyquist sampling technique are employed to solve signal dig-itization error. Figure 8 shows the developed UKM testbedsystem.
The developed UKM testbed is composed of 4 × 1LIEH array antenna, four RF branches, eight-channel ADC,TMS320C6711 DSP board, and Pentium host PC. The UKMtestbed receiver system implemented the DBF which is basedon the constant modulus algorithm (CMA) [8]. The DSPwith its beamforming algorithms generates the requiredweight vector based on the angle of arrival of the intendeduser. The CMA algorithm is simpler to implement and doesnot require any synchronization and reference signal. Thebeamforming algorithm is implemented on C67 floatingpoint DSP for the low-cost noncoherent testbed system.It does not waste the bandwidth for the training signal.A host PC is used to collect data in real-time and offlineprocessing. The data received from LIEH array antenna andthe processed RF front-end signal is recorded online utilizinghost PC. The data collected by the host PC is passed tothe MATLAB environment for postprocessing and displayin offline. Table 3 summarizes the specification of the UKMtestbed receiver.
3. Measurement Results and Discussions
A testbed is set up in the microwave lab to evaluate systemperformance. The DBF measurement result is presentedin this section. A single-tone test is performed for theevaluation of the UKM testbed performance. An Agilent54622 D-mixed signal digital oscilloscope is used after theLPF to observe the baseband signal waveform. Figure 9 showsthe experimental setup for the evaluation of beamformingalgorithm.
EURASIP Journal on Advances in Signal Processing 5
TM
S320
C67
11 D
SP
inte
rfac
e bo
ard
Ch1Ch2Ch3Ch4
Ch1Ch2Ch3Ch4
TH
S120
6AD
CT
HS1
206A
DC
Cu
stom
-des
ign
ed b
oard
SLP1.9
SLP1.9
LPF
LPF
LPF
LPF
ZHL-1724HLN
ZFL-1000GH
ZFL-1000H
ZEM-4300MH
ZHL-1724HLN
ZFL-1000GH
ZFL-1000H
ZEM-4300MH
SplitterZN4PD1-50
SplitterZMSC-4-1
I/Q demodZFMIQ -70D
I/Q demodZFMIQ -70D
I1
I4
Q1
Q4
5–6
K...
...
...
×
×
68 MHz1972 MHz
1972 MHz
10 MHzref
BPF68 MHz
BPF68 MHzBPF
2040 MHz
BPF2040 MHz
2040 MHz
2040 MHz
Figure 5: Simplified system block diagram of DBS system for the UKM testbed.
Analog inputconnector Voltage level
shifter circuitboard
2 ADC board
Splitter
TMS6711DSP
board
5–6 Kinterface
board
RF component
Figure 6: The developed RF front-end for UKM testbed.
Output 1
Output 2
Output 3
Output 4
Input 1 U2TL084
R6
+ V15V
R3R5
+ V25V
Input 2
Input 3
Input 4R2
R1
U1TL071
R10
R9 R8 R7
U3TL084
R11
R12
U4TL084
R13 R14
R15
R16 R17 R18
U5TL084
10 k
10 k
10 k
10 k10 k
10 k
10 k 10 k
10 k 10 k
10 k
10 k
10 k10 k
10 k
10 k 10 k
−+
−+
+−
+−
+−
Figure 7: Voltage level shifter circuit board.
6 EURASIP Journal on Advances in Signal Processing
A continuous wave of 2040.010 MHz RF signal is trans-mitted by transmitting the antenna. The signal is receivedby the 4 × 1 LIEH array at the front end of UKM testbedreceiver. The multichannel signal splitter is used to give inputto the mixer from LO. The RF tone is downconverted intoa 10 kHz baseband signal with an LO set at 1972 MHz. TheI and Q signals for different channels are recorded usingAgilent 54622 D digital oscilloscope from the LPF before theyare sent down to the ADC board.
Table 4 summarizes the amplitudes of I and Q signalsfor all four channels. In the measurement the phase of Isignal of channel 1 is considered as zero and the well-alignedphase front demonstrates a good broad side reception.The baseband signal is recorded as 10.10 kHz. There is nodisruption observed in the signal.
The signal received by the ADC after conversion usingcode composer studio (CCS) [26] is presented in Figure 10.In this figure, the first signal is I signal and the second signalis Q signal before DBF. These signals share the same shapesince both signals are from the same types of demodulator
Table 4: Measured I and Q signals amplitudes for 4 channels.
I (mV) Q (mV)
Channel 1 125 127
Channel 2 127 122
Channel 3 125 119
Channel 4 106 127
source. As can be seen from these figures, the amplitude ofboth types of signal is constant, and the phase differencebetween I and Q signal is 90◦. A small disruption is observedin the signal due to the signal generators and interchannelinterference, which is caused by the RF component and RFcable used for the measurement. There is no noticeable phasedifference observed between both channels. The original datasamples are shown along with the envelope.
The following results are carried out to demonstrate theUKM testbed as a beamforming system. The resulted weightvectors are used in MATLAB to plot the antenna responsepattern. The data is taken for a different angle of 0◦, 30◦,and −30◦ to plot the beampattern. The I and Q basebandsignals are digitized through ADCs and processed by DSP.The architecture is designed to retain all the amplitudeand phase information for each antenna element throughdownconversion and signal recovery, so that, DBF algorithmscan be applied. Once each channel data has been recovered,the DBF algorithm is calculating the weight vectors toform the antenna pattern. The DBF allows the antennaradiation pattern to be scanned over a wide range of angleswithout using the associated expensive RF attenuator andphase shifter hardware. Complex weighting coefficients aremultiplied with each channel data to synthesize the patternat the desired position.
Figure 11 demonstrates the baseband DBF radiationpattern at 0◦, 30◦, and−30◦. The 3 dB beamwidth is observedclose to 25◦. The side lobe levels are distributed unequallydue to asymmetry of the modification introduce in the patch.The first side lobe level is −20 dB at −50◦ and at 0◦ scanningangle. The peak side lobe level is −10 dB at −40◦ for thescanning angle of 30◦. For the scanning angle of −30◦, thepeak side lobe level is −15 dB at 10◦ correspondingly. Theantenna is used for a scan range as far as ±30◦. Beyond thisrange, the array degrades the antenna pattern due to themutual coupling.
4. Conclusion
This design and development of UKM testbed, capable ofperforming digital beamforming that employed LIEH arrayantenna operating at 1.88 GHz–2.22 GHz and DSP basedDBS, have been presented in this paper. The UKM testbedhas been designed in a modular manner, which simplifiesthe design, reduces the development time, eases hardwareupdate, and facilitates testing the various modules (e.g.,antenna hardware, beamforming unit, and beamformingalgorithms) in an independent manner. Custom-designedboards were developed to allow interface for the connector
EURASIP Journal on Advances in Signal Processing 7
Figure 10: Channel 1 demodulated I and Q signals using CCS.
0
−5
−10
−15
−20
−25
−30
−35
−40
−45
Gai
n(d
B)
−90 −60 −30 0 30 60 90
Angle (deg)
0 degree30 degree−30 degree
Figure 11: Baseband digital beamforming radiation pattern at theangles −30◦, 0◦, and 30◦.
and voltage level shifting for THS1206 EVM ADC boardto work properly. This paper also presented the antennabeampattern of different scanning angles. The capabilityof digital beamforming has been demonstrated successfullyon the UKM testbed. A DSP-based DBS system providedreconfigurability, rapid prototyping, and low-cost imple-
mentation. The novel low-cost SATB with its modulardesign and software reconfigurable approach provided a full3G band with small footprint and less weight. The low-cost implementation of the testbed system has proven tobe a small budget educational tool to enable researcherto understand practical implementation issues regardingsmart antenna system and demonstrate the efficacy of theapproach.
Acknowledgments
The authors would like to thank the IRPA Secretariat, Min-istry of Science, Technology and Environmental of Malaysia,IRPA Grant 04-02-02-0029, Institute of Space Science UKM,UKM Grant LL-001-2004, and Zamalah scheme of UKM forsponsoring this work.
References
[1] S. Ponnekanti, “An overview of smart antenna technology forheterogeneous networks,” IEEE Communication Surveys, vol.2, no. 4, pp. 14–23, 1999.
[2] B. G. Agee, “Blind separation and capture of communicationsignals using a multitarget constant modulus beamformer,”in Proceedings of IEEE Military Communications Conference(MILCOM ’89), vol. 2, pp. 340–346, Boston, Mass, USA,October 1989.
[3] H. Krim and M. Viberg, “Two decades of array signalprocessing research: the parametric approach,” IEEE SignalProcessing Magazine, vol. 13, no. 4, pp. 67–94, 1996.
8 EURASIP Journal on Advances in Signal Processing
[4] J. C. Liberti and T. S. Rappapoert, Smart Antenna forWireless Communications Is-95 and Third Generation CDMAApplications, Prentice-Hall PTR, Englewood Cliffs, NJ, USA,2002.
[5] S. Chen, N. N. Ahmad, and L. Hanzo, “Adaptive minimumbit-error rate beamforming,” IEEE Transactions on WirelessCommunications, vol. 4, no. 2, pp. 341–348, 2005.
[6] M. C. Wells, “Increasing the capacity of GSM cellular radiousing adaptive antennas,” IEE Proceedings: Communications,vol. 143, no. 5, pp. 304–310, 1996.
[7] J. D. Fredrick, Y. Wang, and T. Itoh, “A smart antenna receiverarray using a single RF channel and digital beamforming,”IEEE Transactions on Microwave Theory and Techniques, vol.50, no. 12, pp. 3052–3058, 2002.
[8] J. Litva and T. K. Y. Lo, Digital Beamforming in WirelessCommunications, Artech House, London, UK, 1996.
[9] L. C. Godara, “Applications of antenna arrays to mobilecommunications—part I: performance improvement, feasi-bility, and system considerations,” Proceedings of the IEEE, vol.85, no. 7, pp. 1031–1060, 1997.
[10] I. S. Reed, J. D. Mallett, and L. E. Brennan, “Rapid convergencerate in adaptive arrays,” IEEE Transactions on Aerospace andElectronic Systems, vol. 10, no. 6, pp. 853–863, 1974.
[11] M. W. Ganz, R. L. Moses, and S. L. Wilson, “Convergence ofthe SMI and the diagonally loaded SMI algorithms with weakinterference [adaptive array],” IEEE Transactions on Antennasand Propagation, vol. 38, no. 3, pp. 394–399, 1990.
[12] B. Widrow, P. E. Mantey, L. J. Griffiths, and B. B. Goode,“Adaptive antenna systems,” Proceedings of the IEEE, vol. 55,no. 12, pp. 2143–2159, 1967.
[13] L. J. Griffiths, “A simple adaptive algorithm for real-timeprocessing in antenna arrays,” Proceedings of the IEEE, vol. 57,no. 10, pp. 1696–1704, 1969.
[14] S. Caban, C. Mehlfuhrer, R. Langwieser, A. L. Scholtz, and M.Rupp, “Vienna MIMO testbed,” EURASIP Journal on AppliedSignal Processing, vol. 2006, Article ID 54868, 13 pages, 2006.
[15] F. Adachi, M. Sawahashi, and H. Suda, “Wideband DS-CDMAfor next-generation mobile communications systems,” IEEECommunications Magazine, vol. 36, no. 9, pp. 56–69, 1998.
[16] S. Choi and D. Yun, “Design of an adaptive antenna array fortracking the source of maximum power and its applicationto CDMA mobile communications,” IEEE Transactions onAntennas and Propagation, vol. 45, no. 9, pp. 1393–1404, 1997.
[17] S. Ohmori, Y. Yamao, and N. Nakajima, “The future gener-ations of mobile communications based on broadband accesstechnologies,” IEEE Communications Magazine, vol. 38, no. 12,pp. 134–142, 2000.
[18] C. M. Simmonds and M. A. Beach, “Downlink stabilityevaluations of the TSUNAMI (II) adaptive antenna testbed,” inProceedings of the 3rd ACTS Mobile Communications Summit,pp. 417–423, Rhodes, Greece, June 1998.
[19] R. Gozali, R. Mostafa, R. C. Palat, et al., “Virginia techspace-time advanced radio (VT-STAR),” in Proceedings of theRadio and Wireless Conferrence (RAWCON ’01), pp. 227–231,Waltham, Mass, USA, August 2001.
[20] K.-L. Lau, K.-M. Luk, and K.-F. Lee, “Design of a circularly-polarized vertical patch antenna,” IEEE Transactions on Anten-nas and Propagation, vol. 54, no. 4, pp. 1332–1335, 2006.
[21] Y. P. Zhang and J. J. Wang, “Theory and analysis ofdifferentially-driven microstrip antennas,” IEEE Transactionson Antennas and Propagation, vol. 54, no. 4, pp. 1092–1099,2006.
[22] M. T. Islam, N. Misran, and N. K. Jiunn, “A 4×1 L-probe fedinverted hybrid E-H microstrip patch antenna array for 3G
application,” American Journal of Applied Sciences, vol. 4, no.11, pp. 897–901, 2007.
[23] S. C. Gao, L. W. Li, M. S. Leong, and T. S. Yeo, “A novel dual-polarized, wide-band microstrip patch antenna with aperturecoupling,” in Proceedings of IEEE Antennas and PropagationSociety International Symposium, vol. 4, pp. 78–81, Boston,Mass, USA, July 2001.
[24] T. Huynh and K.-F. Lee, “Single-layer single-patch widebandmicrostrip antenna,” Electronics Letters, vol. 31, no. 16, pp.1310–1312, 1995.
[25] T. Huynh, K. F. Lee, and R. Q. Lee, “Crosspolarisationcharacteristics of rectangular patch antennas,” ElectronicsLetters, vol. 24, no. 8, pp. 463–464, 1988.
[26] Texas Instruments, “Code Composer Studio IDE,” November2008, http://focus.ti.com/docs/toolsw/folders/print/ccstudio.html.
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General Vice ChairCarles Antón Haro (CTTC)
Technical Program ChairXavier Mestre (CTTC)
Technical Program Co Chairsapplications as listed below. Acceptance of submissions will be based on quality,relevance and originality. Accepted papers will be published in the EUSIPCOproceedings and presented during the conference. Paper submissions, proposalsfor tutorials and proposals for special sessions are invited in, but not limited to,the following areas of interest.
Areas of Interest
• Audio and electro acoustics.• Design, implementation, and applications of signal processing systems.
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Technical Program Co ChairsJavier Hernando (UPC)Montserrat Pardàs (UPC)
Plenary TalksFerran Marqués (UPC)Yonina Eldar (Technion)
Special SessionsIgnacio Santamaría (Unversidadde Cantabria)Mats Bengtsson (KTH)
FinancesMontserrat Nájar (UPC)• Multimedia signal processing and coding.
• Image and multidimensional signal processing.• Signal detection and estimation.• Sensor array and multi channel signal processing.• Sensor fusion in networked systems.• Signal processing for communications.• Medical imaging and image analysis.• Non stationary, non linear and non Gaussian signal processing.
Submissions
Montserrat Nájar (UPC)
TutorialsDaniel P. Palomar(Hong Kong UST)Beatrice Pesquet Popescu (ENST)
Procedures to submit a paper and proposals for special sessions and tutorials willbe detailed at www.eusipco2011.org. Submitted papers must be camera ready, nomore than 5 pages long, and conforming to the standard specified on theEUSIPCO 2011 web site. First authors who are registered students can participatein the best student paper competition.
Important Deadlines:
P l f i l i 15 D 2010
Industrial Liaison & ExhibitsAngeliki Alexiou(University of Piraeus)Albert Sitjà (CTTC)
International LiaisonJu Liu (Shandong University China)Jinhong Yuan (UNSW Australia)Tamas Sziranyi (SZTAKI Hungary)Rich Stern (CMU USA)Ricardo L. de Queiroz (UNB Brazil)
Webpage: www.eusipco2011.org
Proposals for special sessions 15 Dec 2010Proposals for tutorials 18 Feb 2011Electronic submission of full papers 21 Feb 2011Notification of acceptance 23 May 2011Submission of camera ready papers 6 Jun 2011
