A new software defined radio platform with multiport-based direct conversion is proposed, named SOPRANO (Software Programmable and Hardware Reconfigurable Architecture for Network). The main features of SOPRANO are a high-level design methodology for digital circuits, a new mixer-less direct conversion method, and software algorithms for multi-band and multi-mode operation. We built the first prototype SOPRANO 1.0, which was able to receive PSK and QAM signals with two different carrier frequencies at 2.45 GHz and 5.25 GHz by changing signal processing software

Haruyama, Shinichiro

Morelos-Zaragoza, Robert H

English

SJSU ScholarWorks

San Jose State UniversitySJSU ScholarWorksFaculty Publications Electrical Engineering2001A Software Defined Radio Platform with DirectConversion: SOPRANOShinichiro HaruyamaSONY Computer Science Laboratories, IncRobert H. Morelos-ZaragozaSONY Computer Science Laboratories, Inc, robert.morelos-zaragoza@sjsu.eduFollow this and additional works at: https://scholarworks.sjsu.edu/ee_pubPart of the Electrical and Computer Engineering CommonsThis Article is brought to you for free and open access by the Electrical Engineering at SJSU ScholarWorks. It has been accepted for inclusion in FacultyPublications by an authorized administrator of SJSU ScholarWorks. For more information, please contact scholarworks@sjsu.edu.Recommended CitationShinichiro Haruyama and Robert H. Morelos-Zaragoza. "A Software Defined Radio Platform with Direct Conversion: SOPRANO"Faculty Publications (2001): 1558-1560. doi:10.1109/VTC.2001.956459A Software Defined Radio Platform with Direct Conversion: SOPRANO Shinichiro Haruyama, Robert Morelos-Zaragoza ilktract-In this paper, a new software defined radio plat- forim with multiport-based direct conversion is proposed, named SOPRANO (Software Programmable and Hardware Eeconfigurable Architecture for Eetwgrk). The main fea- tures of SOPRANO are a high-level design methodology for digital circuits, a new mixer-less direct conversion method, and software algorithms for multi-band and multi-mode op- eration. We built the first prototype SOPRANO 1.0, which wa13 able to receive PSK and QAM signals with two differ- ent carrier frequencies at 2.45GHz and 5.25GHz by changing signal processing software. Keywods- Software radio, direct conversion, multimode receiver, synchronization. I. INTRODUCTION Due to recent advancements in hardware and software technologies, implementing software defined radio concept is becoming more realistic than ever before. One of the key functions of software defined radio is its multi-band and multi-mode operation. To implement that function, we need to have not only new FtF circuits and high-speed digital circuits, but also a new design methodology and software algorithms. This paper describes a new design methodology and several algorithms for a new multi-port direct conversion technology. 11. HARDWARE PLATFORM ,h block diagram of the hardware platform is shown in Figure 1. The first prototype SOPRANO 1.0 has only re- ceiver functions. The hardware consists of analog RF cir- cuits and digital circuits. The analog RF circuits consist of antennaR, FtF LNAs, filters, and a multi-port junction MMIC, which is a mixer-less direct converter. The digital circuits consist of ADCs, DACs and digital signal process- ing circuits including FPGAs and a CPU. 111. DIRECT CONVERSION BASED ON MULTI-PORT TECHNOLOGY .A software defined radio receiver should be able to re- ceive a wide range of frequencies and bandwidths. It is very difficult to achieve this using a conventional super- heterodyne receiver, because of fixed analog circuits. In SOPRANO direct conversion is utilized, i.e., RF signals are downconverted to baseband signals in just one stage of mixing. The simpler structure of direct conversion re- ceivers make them more suitable for a flexible software de- fined radio implementation. Moreover, direct conversion is performed without a mixer [l] [2]. A photograph of The authors are with Advanced Telecommunication Laboratory, S O W  Computer Science Laboratories, Inc., Tokyo Japan. Email: haruyama & morelosOcsl.sony.co.jp. 0-7803-7005-8/01/$10.00  2001 IEEE 1558 Fig. 1. Block diagram of SOPRANO platform the proposed five-port junction MMIC is shown in Fig- ure 2. Advantages of this direct conversion method in- clude wide band reception capability and low power con- sumption. Some of the unique features of direct conversion using six-port technology include[3]: (i) Immunity to im- age frequency and adjacent. channel interferences, relaxing the requirements of the channel selection filter; (ii) Tol- erance to variations of the input power level, making the dynamic range to depend mainly on ADC resolution; (iii) Wideband operation. With proper calibration, I/Q imbal- ances, DC offset and adjacent channels interference have a smaller impact in performance in five-port direct con- verter, compared to a conventional mixer. One of the main contributions of this work is that digital calibration (and, subsequently, compensation of time-varying imperfections) is accomplished with the aid of adaptive digital algorithms. Nevertheless, the five-port direct converter shares the prob  lems associated with other forms of direct conversion, such as flicker noise and DC offset. These problems can be alle- viated through the use of a linear equalizer together with a spectrum shaping method by line coding, as proved re- cently in [5]. IV. DESIGN METHODOLOGY The methodology employed in SOPRANO has the goal of filling the gaps in the design process between communi- cation engineers, usually performing top-level design and simulations of wireless communication systems using sig- nal processing tools such as SPW, Matlab, or C, and hard- ware designers, typically designing circuits in RTL with languages such as VHDL or Verilog. A design starts with C/C++ programs to do simulation of the target device. The C/C++ language models are Fig. 2. Photograph of five-port junction MMIC then modified with hardware implementation information and fed into a RTL synthesis tool along with user’s design restrictions such as hardware resource requirement [SI. The synthesized RTL is sent to a logic synthesis tool to generate a netlist, which is then mapped, placed, and routed on an FPGA. V. ALGORITHMS A Matlab Simulink model of the multiport direct- conversion receiver was developed. The model allows for key issues associated with this technology, such as the ef- fects on the demodulated symbols of variations in compo- nents, to be identified. Novel algorithms were then de- veloped in Matlab and C/C++ to compensate for these variations in the characteristics of the multiport device. Besides the signal processing tasks usually required in a digital receiver, such as symbol and carrier recovery, the algorithms implemented in SOPRANO can be broadly cat- egorized as (1) multiport specific (IQ computation and dig- ital calibration) and (2) direct-conversion specific (DC off- set and IQ imbalance compensation). In the following, the digital signal processing algorithms implemented in SO- PRANO are briefly described. A .  Calculation of baseband in-phase and quadrature sam- Based on the five-port device power detector outputs, 5, j = 1,2,3, the in-phase (I) and quadrature (Q) channel samples are computed as follows. ples I = hro + hiiTr, + h r 2 6  + h13V3, (1) Q = h ~ o  4- h ~ 1 K - k  h~21/2 + h ~ 3 h ,  (2 )  Also, in order to give an optimum use to the ADC out- put quantization bits, or ADC dynamic range, a digital automatic-gain control (AGC) stage follows the IQ com- putation stage to ensure that the levels of the received I- channel and Q-channel samples are properly normalized with respect to the maximum range of the ADC. This is achieved by monitoring the average amplitudes of the sam- ples and multiplying the incoming samples by a factor such that the average amplitudes lie approximately at 3 dB be- low the full scale. Li photograph of the real-time constella- tion calculation of the QPSK signal is shown in Figure 3. Fig. 3. Real-time constellation of a demodulated QPSK signal B. DC Ofiset Compensation In direct-conversion receivers, DC offsets is caused, among others, by LO leakage and interfering signals and can be removed partially in the RF front end through proper design. Any residual dynamic DC offset is corrected in the digital domain by removing the average values of the I-channel and Q-channel samples. C. IQ Imbalance Compensation Due to mismatches in the characteristics of the power de- tectors used in the multiport device, an imbalance between the I-channel and Q-channel symbols may be present. To compensate for this imbalance, a novel digital calibration and compensation algorithm has been developed and im- plemented. The algorithm adaptively modifies the ADC inputs from two of the power detectors, those associated with the sum and difference of phase-shifted versions of the local signal and the incoming RF signal, in order to minimize the IQ imbalance. D. Multi-band and Multi-mode Capability The goal of the current version of SOPRANO is to im- plement a multiple-band and multiple-mode digital receiver for a narrow band system operating in two different carrier frequencies (2.45 GHz and 5.25 GHz) with different modu- lation modes (BPSK, QPSK, 8PSK, l6QAM and 64QAM). To this end, a blind carrier recovery technique aided by modulation identification was developed and implemented in the platform. The technique combines a conventional digital PLL structure with a modulation identification al- gorithm. This technique is a modulation identification (ID) method that is robust against phase and frequency offsets. The phase error detector characteristics of this multiple- mode digital PLL are reconfigured based on the information produced by a bank of phase-lock detectors (PLD) and a novel ID logic [7]. The proposed modulation ID technique 1559 allows to  implement a receiver architecture that first ac- quines the signal in blind mode and then tracks the signal in d’ecision-directed mode. Figures 4 to 7 show snapshots of experimental results of 100 recovered constellation sym- bols, after IQ computation, gain and DC adjustment, and timing recovery, at a carrier frequency of 5.25 GHz. la pior 100 0 0 -100 f I I I -100 0 100 I Fig. 4. Demodulated BPSK constellation after timing recovery 100 0 0  -1 00 -100 b. .L I 0I I 100 Fig. 5. Demodulated QPSK constellation after timing recovery VI. CONCLUSION In this paper, a new software defined radio platform was introduced. SOPRANO features a direct conversion method based on a five-port junction MMIC, a high-level design methodology, and novel algorithms for multi-band and multi-mode operation. Both multi-band operation and multi-mode capability have been verified experimentally. The proposed high-level design methodology makes the SO- PILANO platform very suitable for software defined radio prototyping. 100 0 0  -100 I I I -100 0 100 I Fig. 6. Demodulated 8PSK constellation after timing recovery 100 O D  -100 ia pi01 0 I 100 Fig. 7. Demodulated l6QAM constellation after timing recovery REFERENCES [l] R. Kohno et al., “Universal Platform for Software Defined Ra- dio”, Proc. ISPACS’2000, pp. 523-526, Honolulu, Hawaii, Nov. 5-8, 2000. [2] Masayoshi Abe, Noboru Sasho, Veselin Brankovic, Dragain Kru- pezevic, “Direct Conversion Receiver MMIC based on Six-port Technology”, European Conference on Wireless Technology, 2000 [3] J. Li, R.G. Bosisio and K. Wu, “Computer and Measurement Sim- ulation of a New Digital Receiver Operating Directly at Milimiter- Wave Frequencies,” IEEE Trans. M T T ,  vol. 43, no. 12, pp. 2766- 2772, Dec. 1995. [4] 3. Hyyrylainen, L. Bogod, S. Kangasmaa, H.-0 .  Scheck and T. Ylamurto, “Six-Port Direct Conversion Receiver,” Proc. 27th Eu- ropean Microwave Conference and Exhibition, pp. 341-346, Sept. 8-12, 1997 [5] W. Namgoong and T.H. Meng, “Direct-Conversion RF Receiver Design,” IEEE Trans. Comm., vol. 49, no. 3, pp. 518-529, March 2001. [6] AlRT Designer Pro User’s and Reference Manual, Version 2.1, Frontier Design, Inc., 2000. [7] R.H. Morelos-Zaragoza, “Joint Phase-Lock Detection and Identi- fication of M-PSK and M-QAM Modulation,” Proc. of 3GWire- Ieas’OO, San Francisco, CA, pp. 272-279, June 1416, 2000. 1560 

A Software Defined Radio Platform with Direct Conversion: SOPRANO

San Jose State University

San Jose State University
SJSU ScholarWorks
Faculty Publications Electrical Engineering
2001
A Software Defined Radio Platform with Direct
Conversion: SOPRANO
Shinichiro Haruyama
SONY Computer Science Laboratories, Inc
Robert H. Morelos-Zaragoza
SONY Computer Science Laboratories, Inc, robert.morelos-zaragoza@sjsu.edu
Follow this and additional works at: https://scholarworks.sjsu.edu/ee_pub
Part of the Electrical and Computer Engineering Commons
This Article is brought to you for free and open access by the Electrical Engineering at SJSU ScholarWorks. It has been accepted for inclusion in Faculty
Publications by an authorized administrator of SJSU ScholarWorks. For more information, please contact scholarworks@sjsu.edu.
Recommended Citation
Shinichiro Haruyama and Robert H. Morelos-Zaragoza. "A Software Defined Radio Platform with Direct Conversion: SOPRANO"
Faculty Publications (2001): 1558-1560. doi:10.1109/VTC.2001.956459
A Software Defined Radio Platform with Direct 
Conversion: SOPRANO 
Shinichiro Haruyama, Robert Morelos-Zaragoza 
ilktract-In this paper, a new software defined radio plat- 
forim with multiport-based direct conversion is proposed, 
named SOPRANO (Software Programmable and Hardware 
Eeconfigurable Architecture for Eetwgrk). The main fea- 
tures of SOPRANO are a high-level design methodology for 
digital circuits, a new mixer-less direct conversion method, 
and software algorithms for multi-band and multi-mode op- 
eration. We built the first prototype SOPRANO 1.0, which 
wa13 able to receive PSK and QAM signals with two differ- 
ent carrier frequencies at 2.45GHz and 5.25GHz by changing 
signal processing software. 
Keywods- Software radio, direct conversion, multimode 
receiver, synchronization. 
I. INTRODUCTION 
Due to recent advancements in hardware and software 
technologies, implementing software defined radio concept 
is becoming more realistic than ever before. One of the 
key functions of software defined radio is its multi-band 
and multi-mode operation. To implement that function, 
we need to have not only new FtF circuits and high-speed 
digital circuits, but also a new design methodology and 
software algorithms. This paper describes a new design 
methodology and several algorithms for a new multi-port 
direct conversion technology. 
11. HARDWARE PLATFORM 
,h block diagram of the hardware platform is shown in 
Figure 1. The first prototype SOPRANO 1.0 has only re- 
ceiver functions. The hardware consists of analog RF cir- 
cuits and digital circuits. The analog RF circuits consist 
of antennaR, FtF LNAs, filters, and a multi-port junction 
MMIC, which is a mixer-less direct converter. The digital 
circuits consist of ADCs, DACs and digital signal process- 
ing circuits including FPGAs and a CPU. 
111. DIRECT CONVERSION BASED ON MULTI-PORT 
TECHNOLOGY 
.A software defined radio receiver should be able to re- 
ceive a wide range of frequencies and bandwidths. It is 
very difficult to achieve this using a conventional super- 
heterodyne receiver, because of fixed analog circuits. In 
SOPRANO direct conversion is utilized, i.e., RF signals 
are downconverted to baseband signals in just one stage 
of mixing. The simpler structure of direct conversion re- 
ceivers make them more suitable for a flexible software de- 
fined radio implementation. Moreover, direct conversion 
is performed without a mixer [l] [2]. A photograph of 
The authors are with Advanced Telecommunication Laboratory, 
S O W  Computer Science Laboratories, Inc., Tokyo Japan. Email: 
haruyama & morelosOcsl.sony.co.jp. 
0-7803-7005-8/01/$10.00  2001 IEEE 1558 
Fig. 1. Block diagram of SOPRANO platform 
the proposed five-port junction MMIC is shown in Fig- 
ure 2. Advantages of this direct conversion method in- 
clude wide band reception capability and low power con- 
sumption. Some of the unique features of direct conversion 
using six-port technology include[3]: (i) Immunity to im- 
age frequency and adjacent. channel interferences, relaxing 
the requirements of the channel selection filter; (ii) Tol- 
erance to variations of the input power level, making the 
dynamic range to depend mainly on ADC resolution; (iii) 
Wideband operation. With proper calibration, I/Q imbal- 
ances, DC offset and adjacent channels interference have 
a smaller impact in performance in five-port direct con- 
verter, compared to a conventional mixer. One of the main 
contributions of this work is that digital calibration (and, 
subsequently, compensation of time-varying imperfections) 
is accomplished with the aid of adaptive digital algorithms. 
Nevertheless, the five-port direct converter shares the prob  
lems associated with other forms of direct conversion, such 
as flicker noise and DC offset. These problems can be alle- 
viated through the use of a linear equalizer together with 
a spectrum shaping method by line coding, as proved re- 
cently in [5]. 
IV. DESIGN METHODOLOGY 
The methodology employed in SOPRANO has the goal 
of filling the gaps in the design process between communi- 
cation engineers, usually performing top-level design and 
simulations of wireless communication systems using sig- 
nal processing tools such as SPW, Matlab, or C, and hard- 
ware designers, typically designing circuits in RTL with 
languages such as VHDL or Verilog. 
A design starts with C/C++ programs to do simulation 
of the target device. The C/C++ language models are 
Fig. 2. Photograph of five-port junction MMIC 
then modified with hardware implementation information 
and fed into a RTL synthesis tool along with user’s design 
restrictions such as hardware resource requirement [SI. The 
synthesized RTL is sent to a logic synthesis tool to generate 
a netlist, which is then mapped, placed, and routed on an 
FPGA. 
V. ALGORITHMS 
A Matlab Simulink model of the multiport direct- 
conversion receiver was developed. The model allows for 
key issues associated with this technology, such as the ef- 
fects on the demodulated symbols of variations in compo- 
nents, to be identified. Novel algorithms were then de- 
veloped in Matlab and C/C++ to compensate for these 
variations in the characteristics of the multiport device. 
Besides the signal processing tasks usually required in 
a digital receiver, such as symbol and carrier recovery, the 
algorithms implemented in SOPRANO can be broadly cat- 
egorized as (1) multiport specific (IQ computation and dig- 
ital calibration) and (2) direct-conversion specific (DC off- 
set and IQ imbalance compensation). In the following, the 
digital signal processing algorithms implemented in SO- 
PRANO are briefly described. 
A .  Calculation of baseband in-phase and quadrature sam- 
Based on the five-port device power detector outputs, 
5, j = 1,2,3, the in-phase (I) and quadrature (Q) channel 
samples are computed as follows. 
ples 
I = hro + hiiTr, + h r 2 6  + h13V3, (1) 
Q = h ~ o  4- h ~ 1 K - k  h~21/2 + h ~ 3 h ,  (2 )  
Also, in order to give an optimum use to the ADC out- 
put quantization bits, or ADC dynamic range, a digital 
automatic-gain control (AGC) stage follows the IQ com- 
putation stage to ensure that the levels of the received I- 
channel and Q-channel samples are properly normalized 
with respect to the maximum range of the ADC. This is 
achieved by monitoring the average amplitudes of the sam- 
ples and multiplying the incoming samples by a factor such 
that the average amplitudes lie approximately at 3 dB be- 
low the full scale. Li photograph of the real-time constella- 
tion calculation of the QPSK signal is shown in Figure 3. 
Fig. 3. Real-time constellation of a demodulated QPSK signal 
B. DC Ofiset Compensation 
In direct-conversion receivers, DC offsets is caused, 
among others, by LO leakage and interfering signals and 
can be removed partially in the RF front end through 
proper design. Any residual dynamic DC offset is corrected 
in the digital domain by removing the average values of the 
I-channel and Q-channel samples. 
C. IQ Imbalance Compensation 
Due to mismatches in the characteristics of the power de- 
tectors used in the multiport device, an imbalance between 
the I-channel and Q-channel symbols may be present. To 
compensate for this imbalance, a novel digital calibration 
and compensation algorithm has been developed and im- 
plemented. The algorithm adaptively modifies the ADC 
inputs from two of the power detectors, those associated 
with the sum and difference of phase-shifted versions of 
the local signal and the incoming RF signal, in order to 
minimize the IQ imbalance. 
D. Multi-band and Multi-mode Capability 
The goal of the current version of SOPRANO is to im- 
plement a multiple-band and multiple-mode digital receiver 
for a narrow band system operating in two different carrier 
frequencies (2.45 GHz and 5.25 GHz) with different modu- 
lation modes (BPSK, QPSK, 8PSK, l6QAM and 64QAM). 
To this end, a blind carrier recovery technique aided by 
modulation identification was developed and implemented 
in the platform. The technique combines a conventional 
digital PLL structure with a modulation identification al- 
gorithm. This technique is a modulation identification (ID) 
method that is robust against phase and frequency offsets. 
The phase error detector characteristics of this multiple- 
mode digital PLL are reconfigured based on the information 
produced by a bank of phase-lock detectors (PLD) and a 
novel ID logic [7]. The proposed modulation ID technique 
1559 
allows to  implement a receiver architecture that first ac- 
quines the signal in blind mode and then tracks the signal 
in d’ecision-directed mode. Figures 4 to 7 show snapshots 
of experimental results of 100 recovered constellation sym- 
bols, after IQ computation, gain and DC adjustment, and 
timing recovery, at a carrier frequency of 5.25 GHz. 
la pior 
100 
0 0 
-100 
f 
I I I 
-100 0 100 
I 
Fig. 4. Demodulated BPSK constellation after timing recovery 
100 
0 0  
-1 00 
-100 
b. .L 
I 0
I 
I 100 
Fig. 5. Demodulated QPSK constellation after timing recovery 
VI. CONCLUSION 
In this paper, a new software defined radio platform 
was introduced. SOPRANO features a direct conversion 
method based on a five-port junction MMIC, a high-level 
design methodology, and novel algorithms for multi-band 
and multi-mode operation. Both multi-band operation and 
multi-mode capability have been verified experimentally. 
The proposed high-level design methodology makes the SO- 
PILANO platform very suitable for software defined radio 
prototyping. 
100 
0 0  
-100 
I I I 
-100 0 100 
I 
Fig. 6. Demodulated 8PSK constellation after timing recovery 
100 
O D  
-100 
ia pi01 
0 
I 
100 
Fig. 7. Demodulated l6QAM constellation after timing recovery 
REFERENCES 
[l] R. Kohno et al., “Universal Platform for Software Defined Ra- 
dio”, Proc. ISPACS’2000, pp. 523-526, Honolulu, Hawaii, Nov. 
5-8, 2000. 
[2] Masayoshi Abe, Noboru Sasho, Veselin Brankovic, Dragain Kru- 
pezevic, “Direct Conversion Receiver MMIC based on Six-port 
Technology”, European Conference on Wireless Technology, 2000 
[3] J. Li, R.G. Bosisio and K. Wu, “Computer and Measurement Sim- 
ulation of a New Digital Receiver Operating Directly at Milimiter- 
Wave Frequencies,” IEEE Trans. M T T ,  vol. 43, no. 12, pp. 2766- 
2772, Dec. 1995. 
[4] 3. Hyyrylainen, L. Bogod, S. Kangasmaa, H.-0 .  Scheck and T. 
Ylamurto, “Six-Port Direct Conversion Receiver,” Proc. 27th Eu- 
ropean Microwave Conference and Exhibition, pp. 341-346, Sept. 
8-12, 1997 
[5] W. Namgoong and T.H. Meng, “Direct-Conversion RF Receiver 
Design,” IEEE Trans. Comm., vol. 49, no. 3, pp. 518-529, March 
2001. 
[6] AlRT Designer Pro User’s and Reference Manual, Version 2.1, 
Frontier Design, Inc., 2000. 
[7] R.H. Morelos-Zaragoza, “Joint Phase-Lock Detection and Identi- 
fication of M-PSK and M-QAM Modulation,” Proc. of 3GWire- 
Ieas’OO, San Francisco, CA, pp. 272-279, June 1416, 2000. 
1560 


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A Software Defined Radio Platform with Direct Conversion: SOPRANO

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