IRJET - Modeling of Swipt System using QPSK Modulation

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 07 Issue: 03 | Mar 2020 www.irjet.net p-ISSN: 2395-0072
© 2020, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 2679
MODELING OF SWIPT SYSTEM USING QPSK MODULATION
S. Sudhesi dhevi1, S. Nandhinisri2, S.Anusuya3, AJIN R NAIR4
1,2,3Student & Bannari Amman Institute of Technology, Tamilnadu, India
4Professor, Dept. of Electronics and communication Engineering, Bannari Amman Institute of Technology,
Tamilnadu, India
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Abstract - This paper presents a simultaneous wireless
information and power transfer system modeling in
LabVIEW. Since SWIPT system is very active research topic, a
complete system level modeling is indispensable. The
LabVIEW based modeling of SWIPT system facilitate the
research by providing the system level simulation in an
efficient and comprehensive way. Both the SWIPT
transmitter and receiver are modeled in LabVIEW
environment. The SWIPT transmitter modulates digital data
and up- convert to RF carrier frequency at 1 GHz. At SWPIT
receiver, RF energy is harvestedthroughRFrectifierinenergy
harvesting (EH) path. Simultaneously, digital information is
recovered through information decoding(ID)path. TheQPSK
modulation is used for data transfer in SWIPT system.
Presented modeling utilizes powerful system design
capabilities of LabVIEW which assistsinthedevelopmentand
testing of SWIPT system.
Key Words: SWIPT, LabVIEW, QPSK.
1. INTRODUCTION
SWIPT system simultaneously transmits the
power and information .In the emerging technology of
wireless SWIPT system draws a major attention for the
simultaneous power and information transfer.The
harvesting of energy from the RF signals which is
transmitted forms the basis for SWIPT transmission
system.Apart from the energy harvesting path,these is one
more path for information decoding.
In swipt system, there is mainly two types of
architecture a)Time-swifting, b)power-spliting.Time
switching system gives access to RF signal to the paths in
attenuate manner.power splitting architecture is equally
splits the signal for the path in the given power splitting
ratio.The swipt transmitter and receiversystemisdesigned
using QPSK modulation.The power splitting architecture is
employed here.
A labview based SWIPT system is designed using qpsk
modulation which is obtains the following result;
• A comprehensive system level model of SWIPT
transmitter and receiver.
• A flexible and variable input output scheme for
checking different results inteutively.
• Employnment of QPSK transmitter and receiver
system for power and information receving.
2. LITERATURE SURVEY
Energy harvesting for wireless communication
networks is a new paradigm that allows terminals to
recharge their batteries from external energysourcesinthe
surrounding environment. A promising energy harvesting
technology is wireless power transfer where terminals
harvest energy from electromagnetic radiation. Thereby,
the energy may be harvested opportunistically from
ambient electromagnetic sources or from sources that
intentionally transmit electromagnetic energy for energy
harvesting purposes. A particularly interesting and
challenging scenario arises when sources perform
simultaneous wireless information and power transfer
(SWIPT), as strong signals not only increase powertransfer
but also interference. A CAD-oriented design methodology
is also proposed, which is aimed at maximizing the overall
power conversion efficiency of the harvester through an
optimum trade-off amongmatchinglosses,power reflection
and rectifier efficiency. According to the proposed
methodology, a 915-MHz harvester comprising an
integrated input matching network and a 17-stage self-
compensated rectifier has beendesignedandfabricatedina
90-nm CMOS technology. The rectifier exhibits a
remarkably low input power threshold, as it is able to
deliver a 1-V dc output voltage to a capacitive load with a
very small input power of 24 dBm (4 W). When driving a 1-
M load, the device can supply a 1.2-V output with an input
power of 18.8 dBm (13.1 W). The achieved results exceed
the performance of previously reported RF multi-stage
rectifiers in standard analog CMOS technology. Numerical
results show that the optimumlocationofthe relayterminal
is closer to the source than to the destination. Moreover, it
is demonstrated that the valueofthepowersplitting ratioat
the relay significantly impacts the systemperformance.The
results of Monte-Carlo simulations are provided to
corroborate the analysis. The parameters such as average
bit error rate and end to end signal to noise ratio of the
system is analyzed for system performance. Early
information theoretical studies on SWIPT have assumed
that the same signal can convey both energy and
information without losses, revealing a fundamental trade-
off between information and power transfer[10].However,
this simultaneous transfer is not possible in practice, as the
energy harvesting operation performed in the RF domain
destroys the information content. To practically achieve
SWIPT, the received signal has to be split in two distinct
parts, one for energy harvesting and one for information
decoding. SWIPT may provide a promising solution to
address this challenge by encouraging the cooperation

between the primary and secondary systems at both the
information and energy levels: Transmitters can increase
the energy of the information carrying signal to facilitate
energy harvesting at the receivers. On the other hand,
receivers requiring power transfer may take advantage of
the transmitter by falsifying their reported channel state
information. Therefore, new QoS concerns regarding
communication and energy security naturally arise in
SWIPT systems. SWIPT technology has promising
applications in several areas that can benefit from ultra-
low-power sensing devices. Potential applications include
structure monitoring by embedding sensors in buildings,
bridges, roads, and so on; healthcare monitoring using
implantable bio-medical sensors; and building automation
through smart sensors that monitor and control different
building processes. However, for successful realization of
such SWIPT applications, several challenges must be
overcome at various layers from hardware implementation
over protocol development to architectural design.
3. SWIPT system with QPSK modulation
3.1 TRANSMISSION OF BINARY DATA STREAMS
The SWIPT system which is designed for
transmitter block is shown in the figure 1. The QPSK
modulator which consists of odd and even bit
extraction,NRZ encoder,adder is designed for the
modulation process.The given input binary data stream is
modulated using QPSK modulator block.
Binary Data stream and random sequence generator:
Binary data is data whose unit can take on only
two possible states, traditionally labeled as 0 and 1 in
accordance with the binary numeral system and Boolean
algebra.A random sequence generator is a system used to
randomly order a range of numbersina mannerthatcannot
be reasonably predicted better than by randomchance.You
can use this tool to draw winning numbers for your raffle.
EVEN OR ODD BIT EXTRACTOR:
A parity bit, or check bit, is a bit added to a string
of binary code to ensure that the total number of 1-bits in
the string is even or odd. Parity bits are used asthesimplest
form of error detecting code.
NRZ ENCODER:
In telecommunication, a non-return-to-zero (NRZ)
line code is a binary code in which ones are represented by
one significant condition, usually a positive voltage, while
zeros are represented by some other significant condition,
usually a negative voltage, with no other neutral or rest
condition.The pulses in NRZ have more energy than a
return-to-zero (RZ) code, which also has an additional rest
state beside the conditions for ones and zeros.
NRZ is not inherently a self-clocking signal, so some
additional synchronization technique must be used for
avoiding bit slips; examples of such techniques are a run-
length-limited constraint and a parallel synchronization
signal.
Fig -1: SWIPT transmitter block diagram
QPSK MODULATOR:
The QPSK Modulator uses a bit-splitter, two
multipliers with local oscillator, a 2-bit serial to parallel
converter, and a summer circuit are separated by the bits
splitter and are multiplied withthesamecarriertogenerate
odd BPSK (called as PSKI) and even BPSK (called as PSKQ).
3.2 RECEPTION OF SIGNAL WITH CHANNEL NOISE
SWIPT receiver block diagram is presentedin
Figure 2. RF signal at the receiver is addedwithchannel and
circuit noise. After adding the noise, RF signal is forwarded
to power splitter. It splits RF signal power for each EH and
ID paths based on power splitting ratio. In EH path, RF
rectifier and filter block converts RF signal into DC voltage.
In parallel, the ID path down converts RF signal to the
baseband and recover binary data stream using QPSK
demodulation.The RF signal is obtained after applying the
adder is upconverted using RF upconverter at a specific
carrier frequency,for example 1GHZ at this case.
QPSK DEMODULATOR:
QPSK is a digital modulation format that
modulates data onto the carrier by changing the phase of
the carrier. The data is demodulated by comparing the
received signal to the carrier and sampling the phase at a
constant rate (symbol rate).

Fig -2: SWIPT receiver block diagram
4. SWIPT system modeling in LabVIEW
LabVIEW simulation model comprisesoffront
panel and block diagram. User input and results are
displayed on front panel in LabVIEW. While block diagram
in LabVIEW contains graphical code for the SWIPT system.
Binary data stream is QPSK modulated according to the
symbol rate specified at the front panel. Baseband
modulated signal is upconverted to specified carrier
frequency. RF signal output power is controlled by
specifying RF output power level. At the SWIPT receiver,
channel and circuit noise is added with RF signal. Power
splitter distributes RF signal power among the energy
harvesting path and information decoding path depending
on power splitting ratio specified at the front panel. In EH
path, RF rectifier and filter converts RF signal into DC
voltage. Parameters related to RF rectifier thresholdandits
efficiency along with filter cut-off frequency are specified
through the front panel.
Figure 3. Generated RF signal waveform
4. SIMULATION RESULT
Functionality of SWIPT system modeling is
authenticated by performing a simulationofSWIPTsystem.
A QPSK RF signal is generated at 1GHz carrier frequency
with an output power selected as 0dBm. Generated RF
signal waveform is shown in Figure 6. Power splitting ratio
is selected as 0.8 to harvest more energy from RF signal. RF
signals provided to both EH and ID paths after power
splitting.

Since RF signal power is very limited, RF rectifier
having near a zero-volt threshold is required for the SWIPT
system. Threshold value of0.01Valongwith efficiencyof 0.5
for RF rectifier is selected. DC voltage appears at the end of
EH path is shown. Binary data stream is successfully
demodulated at the receiver and comparison with
transmitted binary data stream is shown.The efficiencies of
signal with respect to before and after transmission is
analyzed.
5. CONCLUSION
In this paper, LabVIEW based SWIPT system
simulation model using QPSK modulation is presented. It
can generate RF signals with QPSK modulation for the
testing of SWIPT system. Energy harvesting path and
information decoding path operate in parallel at SWIPT
receiver. Presented simulation model utilizes powerful RF
system design capabilities offered by LabVIEW whichhelps
in the SWIPT system design process and testing.
REFERENCES
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IRJET - Modeling of Swipt System using QPSK Modulation

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