research article performance analysis of a six-port...

Research ArticlePerformance Analysis of a Six-Port Receiver in a WCDMACommunication System including a Multipath Fading Channel

A O Olopade and M Helaoui

Intelligent RF Radio Technology Laboratory (iRadio Lab) Department of Electrical and Computer EngineeringSchulich School of Engineering University of Calgary Calgary AB Canada T2N 1N4

Correspondence should be addressed to A O Olopade aoolopaducalgaryca

Received 4 October 2013 Accepted 20 November 2013 Published 23 January 2014

Academic Editor Alexander Koelpin

Copyright copy 2014 A O Olopade and M Helaoui This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

Third generation communication systems require receivers with wide bandwidth of operation to support high transmission ratesand are also reconfigurable to support various communication standards with different frequency bands An ideal software definedradio (SDR) will be the absolute answer to this requirement but it is not achievable with the current level of technology This paperproposes the use of a six-port receiver (SPR) front-end (FE) in aWCDMAcommunication system AWCDMAend-to-end physicallayer MATLAB demo which includes a multipath channel distortion block is used to determine the viability of the six-port basedreceiver The WCDMA signal after passing through a multipath channel is received using a constructed SPR FE The basebandsignal is then calibrated and corrected inMATLABThe six-port receiver performance is measured in terms of bit error rate (BER)The signal-to-noise ratio (SNR) of the transmitted 119868119876 data is varied and the BER profile of the communication system is plottedTheeffect of the multipath fading on the receiver performance and the accuracy of the calibration algorithm are obtained by comparingtwo different measured BER curves for different calibration techniques to the simulated BER curve of an ideal receiver

1 Introduction

Third generation (3G) mobile communication systems intro-duced in recent years are a huge step in increasing wirelesstransmission capacity fidelity and efficiency The increasingnumber of cellular standards together with the variety of fre-quency bands these standards use in different regions of theworld demands a high degree of reconfigurabilityThe idea ofreconfigurability applies not only to the baseband processingbut also to the RF front-end As a result reconfiguration hasbecome the key issue in the design of wireless terminals [1]The implication is that the receiver front-end (FE) is requiredto have a wide bandwidth to support a high data transmissionrate and it should also be multimode and multistandard tosupport fast and constantly evolvingmodern communicationsystems This enables forward and backward compatibilityPower requirement fidelity size and cost are also paramountproperties to consider in a receiver front-end design

An example of 3G mobiles communication standard isthe WCDMA communication systems which compared to

the second generation systems have a larger system capacityand greater coverage area to provide higher transmission rateand more services to consumers

An ideal software defined radio (SDR) will be theoptimum solution to satisfy the listed requirements on thereceiver FE The SDR radio directly digitizes the output froman antenna and all the receiver blocks (filters amplifiersfrequency down converters power detectors etc) are imple-mented in the application software or the embedded systemsFigure 1 describes the structure of an ideal SDR

However due to the required high sampling frequencyand power dissipation of the analog-to-digital converter(ADC) the ideal SDR has not been feasible with the currenttechnology Receiver FEs such as direct conversion receivers(DCR) and subsampling receivers have been close candidatesto an ideal SDR but however have their peculiar challengesThe DCR is able to do away with the surface acoustic wave(SAW) filter which is typical of superheterodyne receiversthus reducing size cost and complexity This also enablesan integrated single chip solution However design of such

Hindawi Publishing CorporationJournal of Electrical and Computer EngineeringVolume 2014 Article ID 198261 7 pageshttpdxdoiorg1011552014198261

2 Journal of Electrical and Computer Engineering

Antenna

ADC DSP

BasebandIQ data

Figure 1 Ideal Software Defined Radio Configuration

low-cost SAW-less single chip multiband receivers posessignificant challenges The required thresholds on the noisefigure (NF) second-order intermodulation intercept point(IIP2) third-order intermodulation intercept point (IIP3)and local oscillator (LO) phase noise are quite challenging toattain Also the voltage-control oscillator (VCO) frequencytuning range and analog-to-digital converter (ADC) signal-to-noise ratio (SNR) and dynamic-range requirements toenable a multiband and multimode operation are quitechallenging to achieve [2] DC offset 119868119876 mismatch and LOleakage are some of the drawbacks when these requirementsare not met The subsampling receiver on the other handhas a highly reconfigurable structure because bulk of thedemodulation process is done in the digital domain It how-ever has limitation on bandwidth Typical design challengesassociated with the RF subsampling receiver include the trackand hold thermal noise folding effects aliasing and aperturejitter noise generated from the sampling clock phase noise [3]

Perez-Duenas et al [4] proposed a six-port based rakereceiver for direct sequence ultrawideband systems (DS-UWB) which has been considered a type of physical layer(PHY) suitable for high-speed wireless personal area net-works (WPANs) in IEEE 802153a The six-port receiver(SPR) is an alternative direct conversion receiver whosestructure is composed of a passive six-port wave correlatorand four diode power detectors While the SPR is typicallybroadband and highly reconfigurable its performance isdegraded due to the nonidealities in the wave correlatorcircuit and the limited dynamic range of the diode powerdetectors This necessitates driving the detectors outside oftheir square law region and a suitable calibration techniqueto mitigate these structural drawbacks to achieve goodperformance across a broad frequency band at the cost ofincreasing the computation complexity The SPR is evenmore appealing in concurrent dual band receiver operationwhich uses the same architecture as in the single band casethus avoiding hardware component duplication which istypical in state-of-the-art concurrent dual band receivers [5]While previous work investigated some SPR configurationsrequiring low power consumption and no calibration for lowpower applications such as millimeter-wave (especially inthe 60GHz band) this work proposes the use of a six-portreceiver (SPR) FE for a WCDMA communication systemThe SPR is implemented as the receiver FE and the bit errorrate of the received signal is used as an index to measurethe fidelity of the communication system The remainder ofthis paper is structured as follows Section 2 introduces thesix-port receiver theory and discusses its implementation in

the WCDMA communication system Section 3 describesthe measurement setup Section 4 details the results of thereceiver and Section 5 concludes the paper

2 Six-Port Receiver (SPR) Technique

21 Six-Port Receiver Theory Among the first use of the six-port technique for a receiver application is the work of Liet al in [6] Due to its simplicity and broad bandwidth alot of work has been done to improve its performance andextend its usage [4ndash12] A six-port receiver comprises of asix-port wave correlator and four envelope power detectorsAs shown in Figure 2 the wave correlator is configured usingthree quadrature hybrid couplers and a power divider Diodepower detectors (D3 to D6) are typically used as the envelopedetectors of the output at ports P3 to P6 The LO signaland the RF have the same center frequency for homodyneoperation and are fed through ports P1 and P2 respectivelyThe SPR operates using an addictive mixing of the RF andLO signal in the SPR wave correlator and then a square lawprocessing by the diode power detectorsThe wave correlatorhas predefined phase-shifts and attenuations for the LO andthe RF signals such that these two input signals generatedifferent amplitudes and phases at the four output ports [7]

The 119868119876 information can be recovered from the four diodemeasurement at the output ports Equation (1) gives the diodeoutput power (119875

119894) expression in terms of the 119878-parameters of

the six-port wave correlator as follows

119875119894=

10038161003816100381610038161198781198941 (119886LO) + 1198781198942

(119886RF)1003816100381610038161003816

2 for 119894 = 3 4 6 (1)

where 119886LO = (1radic2)|119886LO|119890119895(120596119905+0LO) is the LO signal and

119886RF = (1radic2)|119886RF|119890119895(120596119905+0RF) is the RF signal

Expanding (1) the difference equation between two diodeoutputs is given by

119875119894minus 119875119895= (

100381610038161003816100381611987811989411003816100381610038161003816

2minus

100381610038161003816100381610038161198781198951

10038161003816100381610038161003816

2

)1003816100381610038161003816119886LO

1003816100381610038161003816

2

+ (10038161003816100381610038161198781198942

1003816100381610038161003816

2minus

100381610038161003816100381610038161198781198952

10038161003816100381610038161003816

2

) (119868RF2minus 119876RF

2)

+ 2119868RF1003816100381610038161003816119886LO

1003816100381610038161003816 10038161003816100381610038161198781198941

1003816100381610038161003816

100381610038161003816100381611987811989421003816100381610038161003816 cos (ang119878

1198942minus ang1198781198941

minus 0LO)

minus cos (ang1198781198952

minus ang1198781198951

minus 0LO)

minus 2119876RF1003816100381610038161003816119886LO

1003816100381610038161003816 10038161003816100381610038161198781198941

1003816100381610038161003816

100381610038161003816100381611987811989421003816100381610038161003816 sin (ang119878

1198942minus ang1198781198941

minus 0LO)

minus sin (ang1198781198952

minus ang1198781198951

minus 0LO)

(2)

As mentioned earlier the ideal six-port wave correlatorhas specific predefined phase and amplitude relationshipfor optimum performance in the demodulation processThese conditions must be constant and valid over the entirebandwidth of operation of the SPR [8]

Journal of Electrical and Computer Engineering 3

BPF RF

Port2

Six-port correlator

Port1 LO

minus

minus

+

+

QC1

QC2

QC3

D4

D3

D

Vcc

Vcc

LNA

D6

D5

IEST

QEST

(a)

DSP

LO

RFBPF

Port1Port 2

Six-port correlator

QC1

QC2

QC3

D4

D3

D

ADC

ADC

ADC

ADC

LNA

D6

D5

IEST + jQEST

(b)

Figure 2 (a) SPR architecture using quasi-ideal component (b) SPR architecture with DSP estimation

(i) The conditions on the wave correlator are as follows

(1) |11987841| = |11987831| and |119878

51| = |11987861|

(2) |11987842| = |11987832| and |119878

52| = |11987862|

(3) ang11987841

= ang11987831

+ 90∘ and ang119878

32= ang11987842

+ 90∘

(4) ang11987851

= ang11987861

+ 90∘ and ang119878

62= ang11987852

+ 90∘

(5) ang11987842

minus ang11987831

minus 0LO = 2119899120587 119899 = 0 1 2 (6) ang119878

52minus ang11987861

minus 0LO = (2119899 + 12)120587 119899 = 0 1 2

where 119878119894119895are the 119878-parameters of the wave correlator and 0LO

is the initial phase of the LO signalIn addition all four diode detectors must operate within

their square law region (119875119894= 119870119894119881119894 119894 = 3 4 sdot sdot sdot 6) at all times

and they must have identical response that is 119870119894is the same

for 119894 = 3 4 sdot sdot sdot 6Considering Figure 2(a) which depicts an SPR using

quasi-ideal component the In-phase (119868) component of the RFsignal is proportional to the difference between diode voltageoutputs 119881

3and 119881

4while the quadrature (119876) component is

proportional to the difference between 1198815and 119881

6 Equations

(3a) and (3b) below give the expression to estimate the 119868 and119876 data using architecture the following

119868EST =1198611198681198702(1198814minus 1198813)

4100381610038161003816100381611987831

1003816100381610038161003816

1003816100381610038161003816119878321003816100381610038161003816

1003816100381610038161003816119886LO1003816100381610038161003816

(3a)

119876EST =1198611198761198701(1198815minus 1198816)

4100381610038161003816100381611987851

1003816100381610038161003816

1003816100381610038161003816119878521003816100381610038161003816

1003816100381610038161003816119886LO1003816100381610038161003816

(3b)

119861119868and 119861

119876are the gains of the differential amplifiers in

the 119868 and 119876 recovery paths respectively Using differenceamplifiers as depicted in Figure 2(a) the 119868 and 119876 data arereceived directly However the assumption of the outlinedideal condition is only valid at the design frequency Thisrestricts the SPR to a narrow band receiver as a shift fromthe optimum conditions will result in DC offset and 119868119876

mismatch thus reducing the fidelity of the receiver Fig-ure 2(b) shows an architecture which digitizes the output ofthe diode detectors and uses suitable calibration technique to

estimate the 119868119876 data A lot of research has been done in SPRcalibration using both analog and digital techniques [6ndash8 13ndash15] with varying degree of complexity and performance Onesuch calibration technique is a linear combination of all fourdiode outputs for the 119868119876 data estimation as given in thefollowing expressions

119868EST =

6

sum

119894=3

120572119894119875119894 (4a)

119876EST =

6

sum

119894=3

120573119894119875119894 (4b)

Hasan and Helaoui in [8] proposed a modified memorypolynomial modeling technique for the SPR which simul-taneously compensates for the six-port wave correlator anddiode detectors nonidealities The following equation is theproposed 119868119876 estimation algorithm

(119868 + 119895119876)EST (119899) =

6

sum

119889=3

119872

sum

119902=0

119873

sum

119901=1

119860119901119902119889

V119901119889[119899 minus 119902] (5)

where 119860119901119902119889

are the complex predetermined calibrationconstants from a training signal 119872 is the memory depthand 119873 is the nonlinearity order of the modified memorypolynomial for the 119899th symbol The error vector magnitude(EVM) of the received signal as compared to the transmittedsignal was used as the metric to measure the performanceof the calibration technique This calibration technique wasreported to have a better performance than the conventionallinear calibration techniques

22 Six-Port Receiver in a WCDMA System Figure 3 showsa MATLAB demo of theWCDMA end-to-end physical layerIt simulates the downlink (DL) path of the frequency divisionduplex (FDD) downlink physical layer of the WCDMAwireless communication system with the inclusion of thereceiver FE which is the focal point of this work The modelhas 8 main subsystems listed in Table 1 below with a briefdescription of their functions


DTCH

DCCH

BERerror countsamples

BERblock error rate (BLER)

BLER

Node B (BS-base station)

UE (user equipment)

Channel

blocks

Simulation time


Wcdma UE Rxantenna

Wcdma UE Rxantenna

Wcdma DL Txchannel coding scheme

Wcdma Tx channel coding scheme

Wcdma Txphysical channel mapping

Wcdma TxPhCh mapping

Wcdma Rx physical channel demapping

Wcdma RxPhCh demapping

Wcdma DL Rxchannel decoding scheme

Wcdma Rxchannel decoding scheme

Wcdma channel model

Wcdma BS Txantenna

Wcdma BS Txantenna

Receiver FE

Modelparameters

synd2

synd1

synd2synd1

error rate calculation

TxRx

error ratecalculation

TxRx

Bernoullibinary

Bernoullibinary

BLERcalculation

dtchdtch

dtch

dcchcctrch dpch

synd1

synd2

cctrch Tx signal

dtch

dpch

Rx signal

dtch Txdtch Rx

dcch Txdcch Rx

1234

Multipath + AWGN multipath-AWGN channel

dtch Rx

dcch Rx

dtch Tx

dcch Tx

Homodyne receiver

Figure 3 MATLAB Simulink WCDMA end-to-end physical layer demo

Table 1 WCDMA end-to-end physical layer subsystems

Subsystem Function1 WCDMA DL Tx channel coding scheme Transport channel encoding and multiplexing2 WCDMA Tx physical mapping Physical channel mapping3 WCDMA BS Tx antenna spreading and modulation Modulation and spreading4 WCDMA channel model Channel model5 Receiver front-end RF signal reception and frequency demodulation6 WCDMA UE Rx antenna Despreading and demodulation7 WCDMA RX physical channel decoding scheme Physical channel demapping8 WCDMA RX channel demapping Transport channel demultiplexing and decoding

Detailed description of the subsystems can be found in[16] A constructed SPR is used as the receiver FE as depictedin the model A detailed description of the setup for the SPRis given in Section 4

The DL channels of the demo were set to 384 kbps withthe default transport block size of [3840 100] The number offilter taps for the root raised cosine filter was set to 96 andthe number of coefficient for the channel estimation filterswas 21 The oversampling factor was set to 8 The channelis a multipath channel block with four multipath channelsand an additive white Gaussian noise (AWGN) source blockThe multipath delay channels were set with relative delays of0 secs 260119890 minus 9 secs 521119890 minus 9 secs and 781119890 minus 9 secs Thecorresponding vector of the average power for the delay pathsis [0 minus3 minus6 minus9] dB The speed of the terminal to model theDoppler Effect was set to 120KmphThe signal-to-noise ratio

of the AWGNwas varied between minus15 dB and 5 dB in steps of25 dB to plot the BER profile of the receiver system

3 SPR FE Implementation

The SPR test bench is assembled as in Figure 4 The six-port wave correlator is constructed using three quadraturehybrid couplers 1198761 to 1198763 and a Wilkinson combiner Four8472B Schottky detectors from Agilent Technologies Incwere used as the power detectorsThe generated baseband 119868119876

data at the output of the channel subsystem of the MATLABSimulink model is up-converted to 25GHz RF using a signalgenerator (E4438C ESG from Agilent Inc) The LO signalalso at 25 GHz is generated using a second signal generator(E8247C from Agilent Technologies) The RF and LO signals


Table 2 Estimated EVMs of receiver FE at all SNRs

SNR (dB) Matlab wo multipathBER ()

Matlab w multipathBER ()

SPRmp w multipath(119873 = 2 119872 = 4)

BER ()

SPRc w multipath(119873 = 1 119872 = 0)

BER ()minus15 047180 04697 04687 04707minus125 047000 04695 04686 04701minus10 046910 04633 04636 04625minus75 045900 04122 04135 04167minus5 030040 02301 02346 02357minus25 0022310 004113 004258 0044860 153119890 minus 05 000154 000165 000194525 0 1021119890 minus 5 3064119890 minus 5 4085119890 minus 5

5 0 5106119890 minus 6 5106119890 minus 6 5106119890 minus 6

Agilent E4438CESG vector signalgenerator

Agilent E8247CPSG signalgenerators

DSP platform

Agilent (89600series) dual-channel VSA

Six-portwave

correlator Diode powerdetectors

GPI

Bin

terfa

ce

Figure 4 Test bench setup for the SPR Front-End

are passed into the SPR and the voltages generated by thediode detectors are captured and digitized a four channeledmixed signal oscilloscope (infiniium MSO9404A from Agi-lent Technologies) The captured voltages are imported toMATLAB and using (5) the transmitted 119868119876 data is recoveredThe estimated 119868119876 data is hence transmitted to the UE sectionof the MATLAB Simulink model as depicted in Figure 3 forfurther demodulation process to recover the transmitted bit

4 Measurement Results

The performance of the communication system with an SPRfront end is evaluated using the bit error rate (BER) ofthe communication system The test bench was set up asdescribed in Section 4 The RF input power to the SPR FEwas 7 dBm while the LO power was set to 10 dBm 15 362048 119868119876 data points were generated from the WCDMA end-to-end physical layer MATLAB model and sent at an RFfrequency of 25 GHz with the signal generator 2500 samplesof the generated 119868119876 data were used in calibrating the SPR andthe estimated calibration constants were used to recover theremaining 119868119876 data points from the RF signal To enable a plotof the BER characteristics of the receiver the signal-to-noise

ratio of the generated 119868119876 data point was varied betweenminus15 dB and 5 dB in steps of 25 dB Measurements were takenfor the following scenarios and the corresponding referencesin brackets are used in the BER plot legend

(i) complete MATLAB simulation without a receiverFE and without multipath channel fading (Mat-lab wo multipath)

(ii) complete MATLAB simulation without a receiver FEwith a multipath fading channel (Matlab w multi-path)

(iii) SPR homodyne receiver FE simulation with a mul-tipath fading channel with memory polynomial cal-ibration technique (SPRmp w multipath) using (5)

(iv) SPR homodyne receiver FE simulation with a mul-tipath fading channel with linear combination esti-mation technique (SPRc w multipath) using (2) (4a)and (4b)

The first two cases are complete MATLAB simulationswhich skip the homodyne receiver block It assumes a perfectreceiver FE which does not introduce any distortion ornoise to the received signal In the third and fourth casethe implemented six-port receiver front-end of Figure 4 isused and along with the signal generation and demodulationin MATLAB Table 2 shows the measured BER and theestimated EVM of the receiver at different SNRs after themultipath fading equalizationThe equalization is carried outin the WCDMA UE Rx Antenna subsystem of the MATLABmodel Figure 5 shows a plot of the BER characteristics ofthe communication system The receiver calibration and 119868119876

demodulation was done at a nonlinearity order of 2 memorydepth of 4

From these results it can be concluded that in the caseof a WCDMA communication system including a multipathfading channel both calibration techniques (in the third andfourth cases) are able to provide similar BER performance toan ideal receiver with a multipath channel Therefore boththese calibrations are able to compensate for the receiverimperfections to acceptable levels It is worth mentioningthat the calibration technique based onmemory polynomialshas more coefficients and therefore is more complex toimplement


00001

0001

001

01

1

0 5 10

Bit error rate profile

BER

10minus5

10minus6minus20 minus15 minus10 minus5

Matlab wo multipathSPRc w multipath

SPRc w multipath

SPRmp w multipathMatlab w multipath

EsNo (dB)

Figure 5 BER plot of the communication system



DSP platform


Six-portwave

correlatorDiode power

detectors

GPI

Bin

terfa

ce

Hawking techHAI7SIP

omnidirectionalantenna

Figure 6 Test bench setup for the SPR Front-End using transmit-ting and receiving antennas

41 Supplementary Result Further hardware test was carriedout using the schematic setup in Figure 6 to verify the suitabil-ity of the SPR for real communication signals with high datathroughput An LTE signal with 3MHz bandwidth was sentand received at 24GHz using two commercially availableomnidirectional antennas (Hawking Tech HAI7SIP) Theresulting EVM of the received 119868119876 data as compared to thetransmitted data was 2This further shows the suitability ofthe SPR for high data rate communication systems coupledwith being multistandard and highly reconfigurable

5 Conclusion

This paper investigates the viability of an SPR front end ina WCDMA communication system with a multipath fadingchannel The BER profile for the communication system isplotted for four different cases In the first case the system

is without a multipath channel effect and assumes a perfectreceiver FE In the second case the system has a multipathchannel effect and also assumes a perfect receiver FE In thethird and fourth cases a multipath channel is consideredalong with an implemented SPR FE In the third casemodified memory polynomial calibration technique is usedwhile in the fourth case a less complex calibration techniqueusing linear estimation is adopted A comparison between thefour BER plots concludes that both calibration techniques arecapable of providing very good BER performances similar tothe BER of an ideal receiver with multipath channel fadingTherefore this work concludes that it is sufficient to use theleast complex calibration technique in the case of aWCDMAcommunication system in a multipath fading environment

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] G Hueber R Stuhlberger and A Springer ldquoAn adaptive digitalfront-end for multimode wireless receiversrdquo IEEE Transactionson Circuits and Systems II vol 55 no 4 pp 349ndash353 2008

[2] H Xie O Oliaei P Rakers et al ldquoSingle-Chip MultibandEGPRS and SAW-less LTE WCDMA CMOS receiver withdiversityrdquo IEEE Transactions on Microwave Theory and Tech-niques vol 60 no 5 pp 1390ndash1396 2012

[3] R Barrak A Ghazel and F Ghannouchi ldquoOptimized multi-standard rf subsampling receiver architecturerdquo IEEE Transac-tions on Wireless Communications vol 8 no 6 pp 2901ndash29092009

[4] J Perez-Duenas J G Wanguemert-Perez and I Molina-Fernandez ldquoNovel modulation scheme and six-port basedRAKE receiver for DSUWBrdquo IEEE Transactions on WirelessCommunications vol 8 no 7 pp 3628ndash3633 2009

[5] A O Olopade A Hasan and M Helaoui ldquoConcurrent dualband six port receiver for multi-standard and software definedradio applicationsrdquo IEEETransactions onMicrowaveTheory andTechniques vol 61 no 12 pp 4252ndash4261 2013

[6] J Li R G Bosisio and K Wu ldquoDual-tone calibration of six-port junction and its application to the six-port direct digitalmillimetric receiverrdquo IEEE Transactions on Microwave Theoryand Techniques vol 44 no 1 pp 93ndash99 1996

[7] T Hentschel ldquoA simple IQ-regeneration technique for six-portcommunication receiversrdquo in Proceedings of the 1st InternationalSymposium on Control Communications and Signal Processing(ISCCSP rsquo04) pp 311ndash314 March 2004

[8] A Hasan and M Helaoui ldquoNovel modeling and calibrationapproach for multiport receivers mitigating system imper-fections and hardware impairmentsrdquo IEEE Transactions onMicrowaveTheory and Techniques vol 60 no 8 pp 2644ndash26532012

[9] B Laemmle G Vinci L Maurer R Weigel and A KoelpinldquoAn integrated 77-GHz six-port receiver front-end for angle-of-arrival detectionrdquo in Proceedings of the 25th IEEE Bipo-larBiCMOS Technology and Circuits Meeting (BCTM rsquo11) pp219ndash222 October 2011

[10] A Khy and B Huyart ldquoA 94GHz radar using a six-port reflec-tometer as a phasefrequency discriminatorrdquo in Proceedings of


the 2nd European Radar Conference (EURAD rsquo05) pp 233ndash236October 2005

[11] P Hakansson and S Gong ldquoUltra-wideband six-port transmit-ter and receiver pair 31ndash48 GHzrdquo in Proceedings of the AsiaPacific Microwave Conference (APMC rsquo08) pp 1ndash4 December2008

[12] T Bugo B KlippensteinM SaizewMWoods andMHelaouildquoDual-band receiver using passive six-port down-conversiontechnique suitable for multi-standards and SDR applicationsrdquoin Proceedings of the Asia Pacific Microwave Conference (APMCrsquo10) pp 1312ndash1315 December 2010

[13] G Colef P R Karmel and M Ettenberg ldquoNew in-situ cali-bration of diode detectors used in six-port network analyzersrdquoIEEE Transactions on Instrumentation and Measurement vol39 no 1 pp 201ndash204 1990

[14] S Lindner F Barbon G Vinci R Weigel and A KoelpinldquoInitial calibration procedure of a six-port receiver system forcomplex data receptionrdquo in Proceedings of the 2nd EuropeanRadar Conference (EURAD rsquo12) pp 570ndash573 2012

[15] X Z Xiong and C Iiao ldquoCalibration methods of microwavediode detectorsrdquo in Proceedings of the Asia-Pacific MicrowaveConference (APMC rsquo05) vol 5 December 2005

[16] WCDMA End-to-End Physical Layer httpwwwmathworkscomhelpcommexampleswcdma-end-to-end-physical-layerhtml

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Antenna

ADC DSP

BasebandIQ data

Figure 1 Ideal Software Defined Radio Configuration

low-cost SAW-less single chip multiband receivers posessignificant challenges The required thresholds on the noisefigure (NF) second-order intermodulation intercept point(IIP2) third-order intermodulation intercept point (IIP3)and local oscillator (LO) phase noise are quite challenging toattain Also the voltage-control oscillator (VCO) frequencytuning range and analog-to-digital converter (ADC) signal-to-noise ratio (SNR) and dynamic-range requirements toenable a multiband and multimode operation are quitechallenging to achieve [2] DC offset 119868119876 mismatch and LOleakage are some of the drawbacks when these requirementsare not met The subsampling receiver on the other handhas a highly reconfigurable structure because bulk of thedemodulation process is done in the digital domain It how-ever has limitation on bandwidth Typical design challengesassociated with the RF subsampling receiver include the trackand hold thermal noise folding effects aliasing and aperturejitter noise generated from the sampling clock phase noise [3]

Perez-Duenas et al [4] proposed a six-port based rakereceiver for direct sequence ultrawideband systems (DS-UWB) which has been considered a type of physical layer(PHY) suitable for high-speed wireless personal area net-works (WPANs) in IEEE 802153a The six-port receiver(SPR) is an alternative direct conversion receiver whosestructure is composed of a passive six-port wave correlatorand four diode power detectors While the SPR is typicallybroadband and highly reconfigurable its performance isdegraded due to the nonidealities in the wave correlatorcircuit and the limited dynamic range of the diode powerdetectors This necessitates driving the detectors outside oftheir square law region and a suitable calibration techniqueto mitigate these structural drawbacks to achieve goodperformance across a broad frequency band at the cost ofincreasing the computation complexity The SPR is evenmore appealing in concurrent dual band receiver operationwhich uses the same architecture as in the single band casethus avoiding hardware component duplication which istypical in state-of-the-art concurrent dual band receivers [5]While previous work investigated some SPR configurationsrequiring low power consumption and no calibration for lowpower applications such as millimeter-wave (especially inthe 60GHz band) this work proposes the use of a six-portreceiver (SPR) FE for a WCDMA communication systemThe SPR is implemented as the receiver FE and the bit errorrate of the received signal is used as an index to measurethe fidelity of the communication system The remainder ofthis paper is structured as follows Section 2 introduces thesix-port receiver theory and discusses its implementation in

the WCDMA communication system Section 3 describesthe measurement setup Section 4 details the results of thereceiver and Section 5 concludes the paper

2 Six-Port Receiver (SPR) Technique

21 Six-Port Receiver Theory Among the first use of the six-port technique for a receiver application is the work of Liet al in [6] Due to its simplicity and broad bandwidth alot of work has been done to improve its performance andextend its usage [4ndash12] A six-port receiver comprises of asix-port wave correlator and four envelope power detectorsAs shown in Figure 2 the wave correlator is configured usingthree quadrature hybrid couplers and a power divider Diodepower detectors (D3 to D6) are typically used as the envelopedetectors of the output at ports P3 to P6 The LO signaland the RF have the same center frequency for homodyneoperation and are fed through ports P1 and P2 respectivelyThe SPR operates using an addictive mixing of the RF andLO signal in the SPR wave correlator and then a square lawprocessing by the diode power detectorsThe wave correlatorhas predefined phase-shifts and attenuations for the LO andthe RF signals such that these two input signals generatedifferent amplitudes and phases at the four output ports [7]

The 119868119876 information can be recovered from the four diodemeasurement at the output ports Equation (1) gives the diodeoutput power (119875

119894) expression in terms of the 119878-parameters of

the six-port wave correlator as follows

119875119894=

10038161003816100381610038161198781198941 (119886LO) + 1198781198942

(119886RF)1003816100381610038161003816

2 for 119894 = 3 4 6 (1)

where 119886LO = (1radic2)|119886LO|119890119895(120596119905+0LO) is the LO signal and

119886RF = (1radic2)|119886RF|119890119895(120596119905+0RF) is the RF signal

Expanding (1) the difference equation between two diodeoutputs is given by

119875119894minus 119875119895= (

100381610038161003816100381611987811989411003816100381610038161003816

2minus

100381610038161003816100381610038161198781198951

10038161003816100381610038161003816

2

)1003816100381610038161003816119886LO

1003816100381610038161003816

2

+ (10038161003816100381610038161198781198942

1003816100381610038161003816

2minus

100381610038161003816100381610038161198781198952

10038161003816100381610038161003816

2

) (119868RF2minus 119876RF

2)

+ 2119868RF1003816100381610038161003816119886LO

1003816100381610038161003816 10038161003816100381610038161198781198941

1003816100381610038161003816

100381610038161003816100381611987811989421003816100381610038161003816 cos (ang119878

1198942minus ang1198781198941

minus 0LO)

minus cos (ang1198781198952

minus ang1198781198951

minus 0LO)

minus 2119876RF1003816100381610038161003816119886LO

1003816100381610038161003816 10038161003816100381610038161198781198941

1003816100381610038161003816

100381610038161003816100381611987811989421003816100381610038161003816 sin (ang119878

1198942minus ang1198781198941

minus 0LO)

minus sin (ang1198781198952

minus ang1198781198951

minus 0LO)

(2)

As mentioned earlier the ideal six-port wave correlatorhas specific predefined phase and amplitude relationshipfor optimum performance in the demodulation processThese conditions must be constant and valid over the entirebandwidth of operation of the SPR [8]


BPF RF

Port2

Six-port correlator

Port1 LO

minus

minus

+

+

QC1

QC2

QC3

D4

D3

D

Vcc

Vcc

LNA

D6

D5

IEST

QEST

(a)

DSP

LO

RFBPF

Port1Port 2

Six-port correlator

QC1

QC2

QC3

D4

D3

D

ADC

ADC

ADC

ADC

LNA

D6

D5

IEST + jQEST

(b)



(1) |11987841| = |11987831| and |119878

51| = |11987861|

(2) |11987842| = |11987832| and |119878

52| = |11987862|

(3) ang11987841

= ang11987831

+ 90∘ and ang119878

32= ang11987842

+ 90∘

(4) ang11987851

= ang11987861

+ 90∘ and ang119878

62= ang11987852

+ 90∘

(5) ang11987842

minus ang11987831

minus 0LO = 2119899120587 119899 = 0 1 2 (6) ang119878

52minus ang11987861

minus 0LO = (2119899 + 12)120587 119899 = 0 1 2







3and 119881



6 Equations


119868EST =1198611198681198702(1198814minus 1198813)

4100381610038161003816100381611987831

1003816100381610038161003816

1003816100381610038161003816119878321003816100381610038161003816

1003816100381610038161003816119886LO1003816100381610038161003816

(3a)

119876EST =1198611198761198701(1198815minus 1198816)

4100381610038161003816100381611987851

1003816100381610038161003816

1003816100381610038161003816119878521003816100381610038161003816

1003816100381610038161003816119886LO1003816100381610038161003816

(3b)

119861119868and 119861





119868EST =

6

sum

119894=3

120572119894119875119894 (4a)

119876EST =

6

sum

119894=3

120573119894119875119894 (4b)


(119868 + 119895119876)EST (119899) =

6

sum

119889=3

119872

sum

119902=0

119873

sum

119901=1

119860119901119902119889

V119901119889[119899 minus 119902] (5)

where 119860119901119902119889




DTCH

DCCH



BLER


UE (user equipment)

Channel

blocks

Simulation time


Wcdma UE Rxantenna

Wcdma UE Rxantenna









Wcdma channel model

Wcdma BS Txantenna

Wcdma BS Txantenna

Receiver FE

Modelparameters

synd2

synd1

synd2synd1


TxRx


TxRx

Bernoullibinary

Bernoullibinary

BLERcalculation

dtchdtch

dtch

dcchcctrch dpch

synd1

synd2

cctrch Tx signal

dtch

dpch

Rx signal

dtch Txdtch Rx

dcch Txdcch Rx

1234


dtch Rx

dcch Rx

dtch Tx

dcch Tx

Homodyne receiver















BER ()

SPRc w multipath(119873 = 1 119872 = 0)





DSP platform


Six-portwave


GPI

Bin

terfa

ce














00001

0001

001

01

1

0 5 10


BER

10minus5



SPRc w multipath


EsNo (dB)




DSP platform


Six-portwave


detectors

GPI

Bin

terfa

ce

Hawking techHAI7SIP




5 Conclusion





References





















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










BPF RF

Port2

Six-port correlator

Port1 LO

minus

minus

+

+

QC1

QC2

QC3

D4

D3

D

Vcc

Vcc

LNA

D6

D5

IEST

QEST

(a)

DSP

LO

RFBPF

Port1Port 2

Six-port correlator

QC1

QC2

QC3

D4

D3

D

ADC

ADC

ADC

ADC

LNA

D6

D5

IEST + jQEST

(b)



(1) |11987841| = |11987831| and |119878

51| = |11987861|

(2) |11987842| = |11987832| and |119878

52| = |11987862|

(3) ang11987841

= ang11987831

+ 90∘ and ang119878

32= ang11987842

+ 90∘

(4) ang11987851

= ang11987861

+ 90∘ and ang119878

62= ang11987852

+ 90∘

(5) ang11987842

minus ang11987831

minus 0LO = 2119899120587 119899 = 0 1 2 (6) ang119878

52minus ang11987861

minus 0LO = (2119899 + 12)120587 119899 = 0 1 2







3and 119881



6 Equations


119868EST =1198611198681198702(1198814minus 1198813)

4100381610038161003816100381611987831

1003816100381610038161003816

1003816100381610038161003816119878321003816100381610038161003816

1003816100381610038161003816119886LO1003816100381610038161003816

(3a)

119876EST =1198611198761198701(1198815minus 1198816)

4100381610038161003816100381611987851

1003816100381610038161003816

1003816100381610038161003816119878521003816100381610038161003816

1003816100381610038161003816119886LO1003816100381610038161003816

(3b)

119861119868and 119861





119868EST =

6

sum

119894=3

120572119894119875119894 (4a)

119876EST =

6

sum

119894=3

120573119894119875119894 (4b)


(119868 + 119895119876)EST (119899) =

6

sum

119889=3

119872

sum

119902=0

119873

sum

119901=1

119860119901119902119889

V119901119889[119899 minus 119902] (5)

where 119860119901119902119889




DTCH

DCCH



BLER


UE (user equipment)

Channel

blocks

Simulation time


Wcdma UE Rxantenna

Wcdma UE Rxantenna









Wcdma channel model

Wcdma BS Txantenna

Wcdma BS Txantenna

Receiver FE

Modelparameters

synd2

synd1

synd2synd1


TxRx


TxRx

Bernoullibinary

Bernoullibinary

BLERcalculation

dtchdtch

dtch

dcchcctrch dpch

synd1

synd2

cctrch Tx signal

dtch

dpch

Rx signal

dtch Txdtch Rx

dcch Txdcch Rx

1234


dtch Rx

dcch Rx

dtch Tx

dcch Tx

Homodyne receiver















BER ()

SPRc w multipath(119873 = 1 119872 = 0)





DSP platform


Six-portwave


GPI

Bin

terfa

ce














00001

0001

001

01

1

0 5 10


BER

10minus5



SPRc w multipath


EsNo (dB)




DSP platform


Six-portwave


detectors

GPI

Bin

terfa

ce

Hawking techHAI7SIP




5 Conclusion





References





















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










DTCH

DCCH



BLER


UE (user equipment)

Channel

blocks

Simulation time


Wcdma UE Rxantenna

Wcdma UE Rxantenna









Wcdma channel model

Wcdma BS Txantenna

Wcdma BS Txantenna

Receiver FE

Modelparameters

synd2

synd1

synd2synd1


TxRx


TxRx

Bernoullibinary

Bernoullibinary

BLERcalculation

dtchdtch

dtch

dcchcctrch dpch

synd1

synd2

cctrch Tx signal

dtch

dpch

Rx signal

dtch Txdtch Rx

dcch Txdcch Rx

1234


dtch Rx

dcch Rx

dtch Tx

dcch Tx

Homodyne receiver















BER ()

SPRc w multipath(119873 = 1 119872 = 0)





DSP platform


Six-portwave


GPI

Bin

terfa

ce














00001

0001

001

01

1

0 5 10


BER

10minus5



SPRc w multipath


EsNo (dB)




DSP platform


Six-portwave


detectors

GPI

Bin

terfa

ce

Hawking techHAI7SIP




5 Conclusion





References





















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation














BER ()

SPRc w multipath(119873 = 1 119872 = 0)





DSP platform


Six-portwave


GPI

Bin

terfa

ce














00001

0001

001

01

1

0 5 10


BER

10minus5



SPRc w multipath


EsNo (dB)




DSP platform


Six-portwave


detectors

GPI

Bin

terfa

ce

Hawking techHAI7SIP




5 Conclusion





References





















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










00001

0001

001

01

1

0 5 10


BER

10minus5



SPRc w multipath


EsNo (dB)




DSP platform


Six-portwave


detectors

GPI

Bin

terfa

ce

Hawking techHAI7SIP




5 Conclusion





References





















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation



















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









research article performance analysis of a six-port...

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