![International Journal of Electrical and Computer Engineering (IJECE)
Vol. 13, No. 4, August 2023, pp. 4432~4440
ISSN: 2088-8708, DOI: 10.11591/ijece.v13i4.pp4432-4440 4432
Journal homepage: http://ijece.iaescore.com
An efficient ultra-wideband digital transceiver for wireless
applications on the field-programmable gate array platform
Santhosh Kumar Ramachandragowda1
, Devaraju Ramakrishna2
, Rajashree Narendra3
1
Department of Electronics and Communication Engineering, Dayananda Sagar University, Bangalore, India
2
Department of Electronics and Telecommunication Engineering, Dayananda Sagar College of Engineering, Bangalore, India
3
Department of Electronics and Communication Engineering, Dayananda Sagar University, Bangalore, India
Article Info ABSTRACT
Article history:
Received Aug 31, 2022
Revised Dec 15, 2022
Accepted Dec 17, 2022
The ultra-wideband (UWB) technology is a promising short-range
communication technology for most wireless applications. The UWB
works at higher frequencies and is affected by interferences with the same
frequency standards. This manuscript has designed an efficient and low-
cost implementation of IEEE 802.15.4a-based UWB-digital transceiver
(DTR). The design module contains UWB transmitter (TX), channel, and
UWB-receiver (RX) units. Convolutional encoding and modulation units
like burst position modulation and binary phase-shift keying modulation
are used to construct the UWB-TX. The synchronization and Viterbi
decoder units are used to recover the original data bits and are affected by
noise in UWB-RX. The UWB-DTR is synthesized using Xilinx ISE®
environment with Verilog hardware description language (HDL) and
implemented on Artix-7 field-programmable gate array (FPGA). The
UWB-DTR utilizes less than 2% (slices and look-up table/LUTs),
operates at 268 MHz, and consumes 91 mW of total power on FPGA. The
transceiver achieves a 6.86 Mbps data rate, which meets the IEEE
802.15.4a standard. The UWB-DTR module obtains the bit error rate
(BER) of 2×10-4
by transmitting 105 data bits. The UWB-DTR module is
compared with similar physical layer (PHY) transceivers with
improvements in chip area (slices), power, data rate, and BER.
Keywords:
802.15.4a
Binary phase-shift keying
Burst position modulation
Digital transceiver
Field-programmable gate array
Ultra-wideband
This is an open access article under the CC BY-SA license.
Corresponding Author:
Santhosh Kumar Ramachandragowda
Department of Electronics and Communication Engineering, Dayananda Sagar University
Bangalore 562112, India
Email: rsanthoshkumar15ec@gmail.com
1. INTRODUCTION
In recent years, ultra-wideband (UWB) technology has been used in most short-range wireless
communication applications. UWB system uses the IEEE 802.15.4a standard as one of the efficient interface
mechanisms for low-data-rate transmission with precision-ranging features in wireless personal area
networks (WPANs). The IEEE introduced the first 802.15.4a 2006 for low-data-rate WPANs and later
updated it as IEEE 802.15.4-2015 [1]. The IEEE used another UWB standard IEEE 802.15.6-2012, for
wireless body area networks (WBANs). The UWB standards are commonly used in impulse radio (IR) UWB
physical layer (PHY) and frequency modulation (FM) UWB PHY's. Using UWB and other technology,
short-range communication with a specific data rate and frequency band range is established. With a
frequency band of 10.6 GHz, the IR-UWB (IEEE 802.15.4-2015) enables a data rate of 0.11-27 Mbps, and
the IR-UWB (IEEE 802.15.6-2015) may provide data rates of 0.49 to 15 Mbps. The FM-UWB (IEEE
802.15.6-2012) enables a 0.25 Mbps data rate, and multiband (MB)-UWB enables a data rate of up to](https://image.slidesharecdn.com/v8129914emn-230621070111-29931a05/85/An-efficient-ultra-wideband-digital-transceiver-for-wireless-applications-on-the-field-programmable-gate-array-platform-1-320.jpg)
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An efficient ultra-wideband digital transceiver for wireless … (Santhosh Kumar Ramachandragowda)
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480 Mbps. The Zigbee (IEEE 802.15.4) supports 0.02 to 0.25 Mbps data rates with a frequency of 868 MHz
to 2.5 GHz. The Bluetooth technology (IEEE 802.15.1) supports data rates up to 1-24 Mbps and operates at
2.4 and 5 GHz bands [2].
The UWB system is standardized and compatible with the PHY, medium access control (MAC), and
other upper layers. The IEEE 802.15.4z is enhanced from IEEE 802.15.4 to improve measurements' security
and accuracy range. The IEEE UWB PHY is operated in two modes: high-rate pulse (HRP) and low-rate
pulses (LPR). Most of the system is utilized in HPR mode rather than LPR because LPR-based UWB PHY is
incompatible with other IEEE standards [3]. The IR-UWB is a single-band carrier system that transmits input
streams directly into waveforms, covering the entire spectrum. The IR-UWB has many advantages: low-cost,
multiple access, low power spectral density, lower-power consumption, high data rate, fading removal
feature, channel capacity improvements, higher multi-path resolution, and availability in the form of wide
unlicensed bands [4]. The frequency-shifted reference (FSR) based UWB transceiver (TR) is introduced to
remove the delay elements in UWB TR. However, the complexity of the FSR TR is high and offers moderate
performance. So, the code shifted reference (CSR) based UWB TR is introduced to separate the data pulses
sequence from reference sequences through time-shift features or Walsh codes sequences [5], [6]. The
security enhancement [7] and advanced error correction codes (ECC) mechanism [8] for bit error rate (BER)
improvements have been incorporated in recent times to improve the performance of the UWB system. UWB
system is mainly used in most of the wireless personal area network (PAN) and body area network (BAN)
applications apart from that, the healthcare system, high-speed chip-to-chip communications, Internet of
things (IoT) applications, network bio-sensors applications, radio-frequency identification (RFID) system,
and industrial and scientific applications [6]–[10]. The UWB-based monopole antenna [11] with super
compact features is designed for small IoT devices. This monopole antenna operates up to 12.56 GHz at a
return loss of -10 dB. The modified circular printed monopole (MCPM) antenna [12] is designed with ultra-
miniaturized features for UWB applications. The MCPM antenna operates up to 11 GHz and achieves a peak
gain of 3.2 dB.
In this manuscript, the IEEE 802.15.4a-based efficient UWB digital transceiver (DTR) system
architecture on the field-programmable gate array (FPGA) platform using burst position modulation (BPM)
with binary phase-shift keying (BPSK) and Viterbi decoding techniques. The contribution of the proposed
work is listed as follows.
The transmitter and receiver units use the digital frequency synthesizer (DFS) module generation for in-
phase and quadrature phase (Q) generation. The DFS offers less area and improves the system
performance than the oscillator-based signal generation.
The UWB transceiver supports the range of 3 to 10 GHz frequency bands by configuring the data bits in
the physical service data unit (PSDU).
The obtained data rate met the IEEE 802.15.4a standards and was used further in wireless PAN
applications.
The proposed UWB-TR offers low-cost FPGA implementation, with less chip area resources (slices),
utilization of, and less power consumed, and also works at a moderate data rate with better BER.
The manuscript's organization is as follows: the recent works of the UWB architectures are
discussed in section 1. The proposed UWB-DTR hardware architecture with a detailed explanation of
architectures is in section 2. Section 3 discusses the proposed work simulation, synthesis results, and
comparative discussion. Lastly, it concludes the overall work with improvements and highlights its future
scope in section 4.
The existing PHY TR architectures and their performance metrics for various applications with
different platforms are explained as follows. Santhi et al. [13] presented the multi-band (MB)-based
orthogonal frequency division multiplexing (OFDM) UWB TR with asynchronous pipelined architecture on
the FPGA platform. The transceiver module used fast Fourier transformation and Viterbi decoding
architecture to speed up the system. The architecture consumed more chip resources, including 48 digital
signal processor (DSP) elements. A pulse position modulation (PPM) based UWB baseband TR on both
software (MATLAB) and hardware (FPGA) platforms [14] could achieve up to 10-3
BER on the hardware
platform. An application-specific integrated circuit (ASIC) implementation of the IR-UWB-based band TR
[15] was interfaced with the analog front-end (AFE) module via a serial peripheral interface (SPI). The work
investigated an ASIC device's chip resources and power consumption to know the performance realization.
The system consumed 120 mW dynamic power with a 2,264 mm2
area on-chip. Olonbayar et al. [16]
presented 802.15.4a-based multi-rate IR-UWB baseband TR designed and implemented on the FPGA
platform. The design used a PPM-BPSK modulation scheme and analyzed the baseband's different data rates.
The data detection was achieved using hamming codes. The transmitted and received burst signals were
varied with 160 kHz. The same architecture was implemented on the ASIC environment using 250 nm
technology [17].](https://image.slidesharecdn.com/v8129914emn-230621070111-29931a05/85/An-efficient-ultra-wideband-digital-transceiver-for-wireless-applications-on-the-field-programmable-gate-array-platform-2-320.jpg)
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Int J Elec & Comp Eng, Vol. 13, No. 4, August 2023: 4432-4440
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Shanthi and Krishnamurthi [18] presented a 14-band frequency synthesizer for the MB-OFDM
UWB TR system. The delay-locked loop (DLL) based frequency synthesizer reduced the interference issues
and provides an efficient signal to improve the BER. Costa [19] presented the UWB system designed using
the continuous-time binary value (CTBV) approach in an FPGA environment. The work demonstrated the
pulse generation and detection of FPGA and analyzed the propagation delay and line distance estimation. The
UWB TR worked at 5.5 Mbps with a minimum load distance of 26 m. The IR-UWB TR with ultra-low-
power features for wireless sensor networks (WSN) designed on the ASIC platform [20] used the on-off
keying (OOK) technique for modulation and demodulation. The system achieved 3.86 mW of total power on
65 nm technology and is used further for WSN-based health monitoring applications. Gimeno et al. [21]
presented the IR-UWB TR for high-speed chip-to-chip communications in ASIC environments. The system
used OOK, PPM, and PPM2 modulation techniques and analyzed the BER versus signal to noise ratio
(SNR). The system used a radio-frequency (RF) front-end and analog baseband for data transmission and
reception. The work achieved 15 mW of power with an energy efficiency of 6 pJ/bit at 2.5 Gbps.
An adaptive beaming method was adopted for the IR-UWB TR system by Qiu et al. [22]. The
transmitter (TX) mainly contained injected locked voltage-controlled oscillator (IL-VCO) and delta-sigma
delay locked-loop (DLL) for TX signal generation. The adaptive receiver (RX) unit used beamforming with a
self-tuning mechanism for detecting correct bits. The TX and RX units consumed 67 and 151 mW of total
power using 18 nm complementary metal-oxide-semiconductor (CMOS) technology. A differential code
shifted reference (DCSR) encoding and decoding mechanism was designed by Jayaprakash and
Samundiswary [23] for UWB-TR. The DCSR module utilized less area and power than the CSR-based
FPGA system. Kopta and Enz [24] presented the frequency modulation-based UWB TR for IoT applications.
The TX consumed 575 µW of power, while RX consumed 267 µW while transmitting and receiving
100 Kbps signals. Tantiparimongkol and Phasukkit [25] presented the IR-UWB pulse generation unit for
obstacle human detection on the FPGA platform. The design used a digital clock manager, delay tree, and
edge combiner for pulse generation. The system achieved a bandwidth of 2.07 GHz with a pulse duration of
540 ps. Wang et al. [26] presented a detailed review of the recent UWB TR system architectures and their
applications. The IR-UWB and FM-UWB discussed in detail concludes that the IR-UWB TR is promising
for secured IoT mobile applications in the future.
2. PROPOSED UWB DIGITAL TRANSCEIVER
The UWB PHY transceiver is designed per IEEE 802.15.4a [27]. The UWB PHY operates in sub
gigahertz (250 to 750 MHz) and 3 to 10 GHz bands. The low-band high-rate pulse (HRP) UWB works with a
frequency band of 3.244 to 4.742 GHz, and the high-band HRP UWB performs with a frequency band of
5.944 to 10.234 GHz. The HRP UWB system-based physical protocol data unit (PPDU) mainly contains the
preamble and data unit parts). The representation of the UWB PPDU format [25] is shown in Figure 1. The
preamble contains the preamble and the start of the frame delimiter (SFD) as a synchronization header
(SHR). The data unit includes the physical layer header (PHR) and PSDU. The UWB digital transceiver
architecture is represented in Figure 2 as part of PSDU. It contains TX, additive white Gaussian noise
(AWGN) as a channel, and RX units.
Preamble SFD PHR PSDU
32-bit 8-bit 19-bit 14-bits
73-bits
Figure 1. UWB PPDU format
Convolutional
Encoder
BPM + BPSK
Modulation
Preamble + PHY
Header Module
Channel
Synchronization
BPDM + BPSK
Demodulation
Viterbi Decoder
Input
Bits
Output
Bits
BER Calculation
Figure 2. Hardware architecture of the UWB DTR module](https://image.slidesharecdn.com/v8129914emn-230621070111-29931a05/85/An-efficient-ultra-wideband-digital-transceiver-for-wireless-applications-on-the-field-programmable-gate-array-platform-3-320.jpg)
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2.1. UWB transmitter unit
The UWB transmitter mainly includes a convolutional encoder (CE), BPM, BPSK modulation,
preamble, and PHR data units. The CE is mainly performing the encoding operation with generator
polynomials C0 = [101]2 and C1 = [111]2. The code rate of CE is ½ with constraint length (K) three. Initially,
all the states in CE are set to zero. Based on PPDU data transmission, The C0 and C1 bits will be generated.
The CE hardware architecture contains a 3-bit shift register and two XOR operations. The input data bits are
fed as the stream of data bits in CE. These bits are convolved to output bits based on encoding logic. The two
output bits are depending previous input bits stored in the shift register and the present input bit. These two
C0 and C1 bits are parity and systematic, respectively. The BPM unit receives the parity bit, and the BPSK
unit receives the systematic bit for further modulation.
The hardware architecture of the BPM and BPSK modulation is represented in Figure 3. The BPM
unit mainly contains a DFS unit, sawtooth wave generation unit, and multiplexor unit shown in Figure 3(a).
The DFS produces the sinusoidal signal, and a 10-bit counter generates the sawtooth signal. The sawtooth
signal is subtracted from the DFS signal to produce the burst position signal. The parity bit from the CE is
used in the multiplexor, which acts as a select line. If the parity bit is one, the subtracted output is considered
the final BPM signal; otherwise, the inverted output (subtracted) is regarded as a 1-bit BPM signal. The
BPSK modulation hardware architecture is illustrated in Figure 3(b). It mainly contains DFS, data flip-flop,
multiplexor, and adder units. The DFS unit produces a sinusoidal signal, considered the in-phase (I), and an
inverted sinusoidal signal, which is viewed as a Q signal. The systematic bit from CE is used as a select line
in the multiplexor. If the systematic bit is one, then the in-phase (I) is considered; otherwise, the Q signal is
considered with delay. The I and Q signals are added to generate the 12-bit BPSK modulated signal.
DFS
Sawtooth
Module
-
in
BPM
signal D-FF
Adder
I
Q
DFS
1
0
in
BPSK
signal
(a) (b)
Figure 3. The architecture of (a) BPM and (b) BPSK modulation units used in UWB-TX
The preamble and SFD are generated based on the IEEE 802.15.4a standard [25]. The preamble is
generated using 31-bit ternary codes as code sequences. The code index is one, and the supported UWB
channel number (0, 1, 8, 12) is used to select the code sequence. The 8-bit SFD bits are generated based on
spread codes and set as "48" in hexadecimal format. The PHR format is illustrated in Figure 4. The 19-bit
PHR contains a 2-bit data rate, 7-bit frame length, 1-bit ranging packet, 1-bit header extension, 2-bit
preamble time, and 6-bit check bits. The data rate is set with "01" for UWB-compliant PHY implementation.
The 7-bit frame length indicates the number of octants used in PSDU, which requests the system to transmit.
The ranging packet is set with 0. The header extension bit is set to 0 for future extensions. The preamble
length in SHR is represented by preamble duration bits and default set with '01". The 6-bit check bits are
used to detect the errors caused by noise. After the calculation, the 19-bit PHR obtains the value of "40C56" in
hexadecimal format. Finally, the UWB Transmitter contains the concatenation of the 32-bit Preamble, 8-bit
SFD, 19-bit PHR, 1-bit BPM, 12-bit BPSK modulated signal, and 1-bit unused bit to form the 73-bit transmitted
signal.
Data
rate
Frame
Length
RP
Preamble
Time
HE Check Bits
2-bits 7-bits 1-bit 1-bit 2-bit 6-bit
Figure 4. PHR format [25]
2.2. UWB receiver unit
The UWB receiver unit has a synchronization unit, burst position demodulation (BPDM), BPSK
demodulation unit, and Viterbi decoder (VD) units. The UWB receiver receives the 73-bit corrupted data and](https://image.slidesharecdn.com/v8129914emn-230621070111-29931a05/85/An-efficient-ultra-wideband-digital-transceiver-for-wireless-applications-on-the-field-programmable-gate-array-platform-4-320.jpg)
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The comparison of the different PHY transceivers with the proposed UWB-DTR on hardware
platforms is tabulated in Table 3. The PHY TR module selected IEEE standards, modulation, or technique
adopted and obtained performance metrics like slice, frequency, power, data rate, and BER parameters on
selected FPGAs that are considered for comparative analysis. The proposed module combines BPM with
BPSK modulation for improved performance metrics than the different PHY TR techniques. The model drive
architecture [28] is incorporated into the UWB-DTR module to improve the reliability features.
Figure 8. Resource utilization of the UWB-DTR (submodules) on Artix-7
Table 3. Comparative results for different PHY Transceivers on the FPGA platform
Reference
Designs
PHY TR IEEE Std. Techniques FPGA Slices
Freq.
(MHz)
Power
(mW)
Data rate
(Mbps)
BER
[29] IR-UWB 802.15.4a PPM Virtex-4 1012 100 NA NA NA
[30] IR-UWB 802.15.4a PPM Spartan-3 1821 134 NA 3 Up to 10-3
[31] IR-UWB 802.15.4 2015 MPPM Virtex-6 2711 120 NA 2 Up to 10-3
[32] NB-PHY 802.15.6 BCH Virtex-6 2668 100 117 0.971 Up to 10-3
[33] IR-UWB 802.15.4a DWPT Virtex-7 557 99 514 NA NA
[34] HB-PHY 802.15.6 Walsh Artix-7 1084 32 114 6 Up to 10-3
[35] PHY 802.15.4 O-QPSK Artix-7 224 270 171 4.3 <10-4
Proposed UWB- DTR 802.15.4a BPM + BPSK Artix-7 209 268 91 6.86 2x10-4
4. CONCLUSION AND FUTURE WORK
In this manuscript, the IEEE 802.15.4a-based UWB-DTR hardware architecture is designed and
implemented on Artix-7 FPGA for WPANs applications. The UWB-DTR mainly offers low-cost
implementation, consumes low power, and operates at a better data rate with less BER. The UWB-DTR used
BPM-BPSK modulation techniques with a Viterbi decoding mechanism to transmit and receive data streams
in sequence. The timing synchronization mechanism is introduced on the UWB-RX side to recover the
corrupted data using the Viterbi decoding method. The simulation results prove that the designed architecture
receives the original data sequence within 39 clock cycles with minimal error. The UWB-DTR system
utilizes <2% chip resources at 268 MHz by consuming 91 mW of total power on Artix-7 FPGA. The UWB-
DTR system achieves a data rate of 6.86 Mbps, matching the IEEE 802.15.4a standard. The UWB-DTR
system achieves the BER of 2×10-4
by transmitting 105
input data bits. Compared with similar physical layer
transceivers, the UWB-DTR module outperforms them in chip area (slices), power, data rate, and BER. The
UWB-DTR module will be incorporated with a security algorithm to improve the system's security and
performance metrics.
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pp. 2085–2089, Jan. 2020, doi: 10.35940/ijitee.C8926.019320.](https://image.slidesharecdn.com/v8129914emn-230621070111-29931a05/85/An-efficient-ultra-wideband-digital-transceiver-for-wireless-applications-on-the-field-programmable-gate-array-platform-8-320.jpg)
An efficient ultra-wideband digital transceiver for wireless applications on the field-programmable gate array platform
- 1. International Journal of Electrical and Computer Engineering (IJECE) Vol. 13, No. 4, August 2023, pp. 4432~4440 ISSN: 2088-8708, DOI: 10.11591/ijece.v13i4.pp4432-4440 4432 Journal homepage: http://ijece.iaescore.com An efficient ultra-wideband digital transceiver for wireless applications on the field-programmable gate array platform Santhosh Kumar Ramachandragowda1 , Devaraju Ramakrishna2 , Rajashree Narendra3 1 Department of Electronics and Communication Engineering, Dayananda Sagar University, Bangalore, India 2 Department of Electronics and Telecommunication Engineering, Dayananda Sagar College of Engineering, Bangalore, India 3 Department of Electronics and Communication Engineering, Dayananda Sagar University, Bangalore, India Article Info ABSTRACT Article history: Received Aug 31, 2022 Revised Dec 15, 2022 Accepted Dec 17, 2022 The ultra-wideband (UWB) technology is a promising short-range communication technology for most wireless applications. The UWB works at higher frequencies and is affected by interferences with the same frequency standards. This manuscript has designed an efficient and low- cost implementation of IEEE 802.15.4a-based UWB-digital transceiver (DTR). The design module contains UWB transmitter (TX), channel, and UWB-receiver (RX) units. Convolutional encoding and modulation units like burst position modulation and binary phase-shift keying modulation are used to construct the UWB-TX. The synchronization and Viterbi decoder units are used to recover the original data bits and are affected by noise in UWB-RX. The UWB-DTR is synthesized using Xilinx ISE® environment with Verilog hardware description language (HDL) and implemented on Artix-7 field-programmable gate array (FPGA). The UWB-DTR utilizes less than 2% (slices and look-up table/LUTs), operates at 268 MHz, and consumes 91 mW of total power on FPGA. The transceiver achieves a 6.86 Mbps data rate, which meets the IEEE 802.15.4a standard. The UWB-DTR module obtains the bit error rate (BER) of 2×10-4 by transmitting 105 data bits. The UWB-DTR module is compared with similar physical layer (PHY) transceivers with improvements in chip area (slices), power, data rate, and BER. Keywords: 802.15.4a Binary phase-shift keying Burst position modulation Digital transceiver Field-programmable gate array Ultra-wideband This is an open access article under the CC BY-SA license. Corresponding Author: Santhosh Kumar Ramachandragowda Department of Electronics and Communication Engineering, Dayananda Sagar University Bangalore 562112, India Email: [email protected] 1. INTRODUCTION In recent years, ultra-wideband (UWB) technology has been used in most short-range wireless communication applications. UWB system uses the IEEE 802.15.4a standard as one of the efficient interface mechanisms for low-data-rate transmission with precision-ranging features in wireless personal area networks (WPANs). The IEEE introduced the first 802.15.4a 2006 for low-data-rate WPANs and later updated it as IEEE 802.15.4-2015 [1]. The IEEE used another UWB standard IEEE 802.15.6-2012, for wireless body area networks (WBANs). The UWB standards are commonly used in impulse radio (IR) UWB physical layer (PHY) and frequency modulation (FM) UWB PHY's. Using UWB and other technology, short-range communication with a specific data rate and frequency band range is established. With a frequency band of 10.6 GHz, the IR-UWB (IEEE 802.15.4-2015) enables a data rate of 0.11-27 Mbps, and the IR-UWB (IEEE 802.15.6-2015) may provide data rates of 0.49 to 15 Mbps. The FM-UWB (IEEE 802.15.6-2012) enables a 0.25 Mbps data rate, and multiband (MB)-UWB enables a data rate of up to
- 2. Int J Elec & Comp Eng ISSN: 2088-8708 An efficient ultra-wideband digital transceiver for wireless … (Santhosh Kumar Ramachandragowda) 4433 480 Mbps. The Zigbee (IEEE 802.15.4) supports 0.02 to 0.25 Mbps data rates with a frequency of 868 MHz to 2.5 GHz. The Bluetooth technology (IEEE 802.15.1) supports data rates up to 1-24 Mbps and operates at 2.4 and 5 GHz bands [2]. The UWB system is standardized and compatible with the PHY, medium access control (MAC), and other upper layers. The IEEE 802.15.4z is enhanced from IEEE 802.15.4 to improve measurements' security and accuracy range. The IEEE UWB PHY is operated in two modes: high-rate pulse (HRP) and low-rate pulses (LPR). Most of the system is utilized in HPR mode rather than LPR because LPR-based UWB PHY is incompatible with other IEEE standards [3]. The IR-UWB is a single-band carrier system that transmits input streams directly into waveforms, covering the entire spectrum. The IR-UWB has many advantages: low-cost, multiple access, low power spectral density, lower-power consumption, high data rate, fading removal feature, channel capacity improvements, higher multi-path resolution, and availability in the form of wide unlicensed bands [4]. The frequency-shifted reference (FSR) based UWB transceiver (TR) is introduced to remove the delay elements in UWB TR. However, the complexity of the FSR TR is high and offers moderate performance. So, the code shifted reference (CSR) based UWB TR is introduced to separate the data pulses sequence from reference sequences through time-shift features or Walsh codes sequences [5], [6]. The security enhancement [7] and advanced error correction codes (ECC) mechanism [8] for bit error rate (BER) improvements have been incorporated in recent times to improve the performance of the UWB system. UWB system is mainly used in most of the wireless personal area network (PAN) and body area network (BAN) applications apart from that, the healthcare system, high-speed chip-to-chip communications, Internet of things (IoT) applications, network bio-sensors applications, radio-frequency identification (RFID) system, and industrial and scientific applications [6]–[10]. The UWB-based monopole antenna [11] with super compact features is designed for small IoT devices. This monopole antenna operates up to 12.56 GHz at a return loss of -10 dB. The modified circular printed monopole (MCPM) antenna [12] is designed with ultra- miniaturized features for UWB applications. The MCPM antenna operates up to 11 GHz and achieves a peak gain of 3.2 dB. In this manuscript, the IEEE 802.15.4a-based efficient UWB digital transceiver (DTR) system architecture on the field-programmable gate array (FPGA) platform using burst position modulation (BPM) with binary phase-shift keying (BPSK) and Viterbi decoding techniques. The contribution of the proposed work is listed as follows. The transmitter and receiver units use the digital frequency synthesizer (DFS) module generation for in- phase and quadrature phase (Q) generation. The DFS offers less area and improves the system performance than the oscillator-based signal generation. The UWB transceiver supports the range of 3 to 10 GHz frequency bands by configuring the data bits in the physical service data unit (PSDU). The obtained data rate met the IEEE 802.15.4a standards and was used further in wireless PAN applications. The proposed UWB-TR offers low-cost FPGA implementation, with less chip area resources (slices), utilization of, and less power consumed, and also works at a moderate data rate with better BER. The manuscript's organization is as follows: the recent works of the UWB architectures are discussed in section 1. The proposed UWB-DTR hardware architecture with a detailed explanation of architectures is in section 2. Section 3 discusses the proposed work simulation, synthesis results, and comparative discussion. Lastly, it concludes the overall work with improvements and highlights its future scope in section 4. The existing PHY TR architectures and their performance metrics for various applications with different platforms are explained as follows. Santhi et al. [13] presented the multi-band (MB)-based orthogonal frequency division multiplexing (OFDM) UWB TR with asynchronous pipelined architecture on the FPGA platform. The transceiver module used fast Fourier transformation and Viterbi decoding architecture to speed up the system. The architecture consumed more chip resources, including 48 digital signal processor (DSP) elements. A pulse position modulation (PPM) based UWB baseband TR on both software (MATLAB) and hardware (FPGA) platforms [14] could achieve up to 10-3 BER on the hardware platform. An application-specific integrated circuit (ASIC) implementation of the IR-UWB-based band TR [15] was interfaced with the analog front-end (AFE) module via a serial peripheral interface (SPI). The work investigated an ASIC device's chip resources and power consumption to know the performance realization. The system consumed 120 mW dynamic power with a 2,264 mm2 area on-chip. Olonbayar et al. [16] presented 802.15.4a-based multi-rate IR-UWB baseband TR designed and implemented on the FPGA platform. The design used a PPM-BPSK modulation scheme and analyzed the baseband's different data rates. The data detection was achieved using hamming codes. The transmitted and received burst signals were varied with 160 kHz. The same architecture was implemented on the ASIC environment using 250 nm technology [17].
- 3. ISSN: 2088-8708 Int J Elec & Comp Eng, Vol. 13, No. 4, August 2023: 4432-4440 4434 Shanthi and Krishnamurthi [18] presented a 14-band frequency synthesizer for the MB-OFDM UWB TR system. The delay-locked loop (DLL) based frequency synthesizer reduced the interference issues and provides an efficient signal to improve the BER. Costa [19] presented the UWB system designed using the continuous-time binary value (CTBV) approach in an FPGA environment. The work demonstrated the pulse generation and detection of FPGA and analyzed the propagation delay and line distance estimation. The UWB TR worked at 5.5 Mbps with a minimum load distance of 26 m. The IR-UWB TR with ultra-low- power features for wireless sensor networks (WSN) designed on the ASIC platform [20] used the on-off keying (OOK) technique for modulation and demodulation. The system achieved 3.86 mW of total power on 65 nm technology and is used further for WSN-based health monitoring applications. Gimeno et al. [21] presented the IR-UWB TR for high-speed chip-to-chip communications in ASIC environments. The system used OOK, PPM, and PPM2 modulation techniques and analyzed the BER versus signal to noise ratio (SNR). The system used a radio-frequency (RF) front-end and analog baseband for data transmission and reception. The work achieved 15 mW of power with an energy efficiency of 6 pJ/bit at 2.5 Gbps. An adaptive beaming method was adopted for the IR-UWB TR system by Qiu et al. [22]. The transmitter (TX) mainly contained injected locked voltage-controlled oscillator (IL-VCO) and delta-sigma delay locked-loop (DLL) for TX signal generation. The adaptive receiver (RX) unit used beamforming with a self-tuning mechanism for detecting correct bits. The TX and RX units consumed 67 and 151 mW of total power using 18 nm complementary metal-oxide-semiconductor (CMOS) technology. A differential code shifted reference (DCSR) encoding and decoding mechanism was designed by Jayaprakash and Samundiswary [23] for UWB-TR. The DCSR module utilized less area and power than the CSR-based FPGA system. Kopta and Enz [24] presented the frequency modulation-based UWB TR for IoT applications. The TX consumed 575 µW of power, while RX consumed 267 µW while transmitting and receiving 100 Kbps signals. Tantiparimongkol and Phasukkit [25] presented the IR-UWB pulse generation unit for obstacle human detection on the FPGA platform. The design used a digital clock manager, delay tree, and edge combiner for pulse generation. The system achieved a bandwidth of 2.07 GHz with a pulse duration of 540 ps. Wang et al. [26] presented a detailed review of the recent UWB TR system architectures and their applications. The IR-UWB and FM-UWB discussed in detail concludes that the IR-UWB TR is promising for secured IoT mobile applications in the future. 2. PROPOSED UWB DIGITAL TRANSCEIVER The UWB PHY transceiver is designed per IEEE 802.15.4a [27]. The UWB PHY operates in sub gigahertz (250 to 750 MHz) and 3 to 10 GHz bands. The low-band high-rate pulse (HRP) UWB works with a frequency band of 3.244 to 4.742 GHz, and the high-band HRP UWB performs with a frequency band of 5.944 to 10.234 GHz. The HRP UWB system-based physical protocol data unit (PPDU) mainly contains the preamble and data unit parts). The representation of the UWB PPDU format [25] is shown in Figure 1. The preamble contains the preamble and the start of the frame delimiter (SFD) as a synchronization header (SHR). The data unit includes the physical layer header (PHR) and PSDU. The UWB digital transceiver architecture is represented in Figure 2 as part of PSDU. It contains TX, additive white Gaussian noise (AWGN) as a channel, and RX units. Preamble SFD PHR PSDU 32-bit 8-bit 19-bit 14-bits 73-bits Figure 1. UWB PPDU format Convolutional Encoder BPM + BPSK Modulation Preamble + PHY Header Module Channel Synchronization BPDM + BPSK Demodulation Viterbi Decoder Input Bits Output Bits BER Calculation Figure 2. Hardware architecture of the UWB DTR module
- 4. Int J Elec & Comp Eng ISSN: 2088-8708 An efficient ultra-wideband digital transceiver for wireless … (Santhosh Kumar Ramachandragowda) 4435 2.1. UWB transmitter unit The UWB transmitter mainly includes a convolutional encoder (CE), BPM, BPSK modulation, preamble, and PHR data units. The CE is mainly performing the encoding operation with generator polynomials C0 = [101]2 and C1 = [111]2. The code rate of CE is ½ with constraint length (K) three. Initially, all the states in CE are set to zero. Based on PPDU data transmission, The C0 and C1 bits will be generated. The CE hardware architecture contains a 3-bit shift register and two XOR operations. The input data bits are fed as the stream of data bits in CE. These bits are convolved to output bits based on encoding logic. The two output bits are depending previous input bits stored in the shift register and the present input bit. These two C0 and C1 bits are parity and systematic, respectively. The BPM unit receives the parity bit, and the BPSK unit receives the systematic bit for further modulation. The hardware architecture of the BPM and BPSK modulation is represented in Figure 3. The BPM unit mainly contains a DFS unit, sawtooth wave generation unit, and multiplexor unit shown in Figure 3(a). The DFS produces the sinusoidal signal, and a 10-bit counter generates the sawtooth signal. The sawtooth signal is subtracted from the DFS signal to produce the burst position signal. The parity bit from the CE is used in the multiplexor, which acts as a select line. If the parity bit is one, the subtracted output is considered the final BPM signal; otherwise, the inverted output (subtracted) is regarded as a 1-bit BPM signal. The BPSK modulation hardware architecture is illustrated in Figure 3(b). It mainly contains DFS, data flip-flop, multiplexor, and adder units. The DFS unit produces a sinusoidal signal, considered the in-phase (I), and an inverted sinusoidal signal, which is viewed as a Q signal. The systematic bit from CE is used as a select line in the multiplexor. If the systematic bit is one, then the in-phase (I) is considered; otherwise, the Q signal is considered with delay. The I and Q signals are added to generate the 12-bit BPSK modulated signal. DFS Sawtooth Module - in BPM signal D-FF Adder I Q DFS 1 0 in BPSK signal (a) (b) Figure 3. The architecture of (a) BPM and (b) BPSK modulation units used in UWB-TX The preamble and SFD are generated based on the IEEE 802.15.4a standard [25]. The preamble is generated using 31-bit ternary codes as code sequences. The code index is one, and the supported UWB channel number (0, 1, 8, 12) is used to select the code sequence. The 8-bit SFD bits are generated based on spread codes and set as "48" in hexadecimal format. The PHR format is illustrated in Figure 4. The 19-bit PHR contains a 2-bit data rate, 7-bit frame length, 1-bit ranging packet, 1-bit header extension, 2-bit preamble time, and 6-bit check bits. The data rate is set with "01" for UWB-compliant PHY implementation. The 7-bit frame length indicates the number of octants used in PSDU, which requests the system to transmit. The ranging packet is set with 0. The header extension bit is set to 0 for future extensions. The preamble length in SHR is represented by preamble duration bits and default set with '01". The 6-bit check bits are used to detect the errors caused by noise. After the calculation, the 19-bit PHR obtains the value of "40C56" in hexadecimal format. Finally, the UWB Transmitter contains the concatenation of the 32-bit Preamble, 8-bit SFD, 19-bit PHR, 1-bit BPM, 12-bit BPSK modulated signal, and 1-bit unused bit to form the 73-bit transmitted signal. Data rate Frame Length RP Preamble Time HE Check Bits 2-bits 7-bits 1-bit 1-bit 2-bit 6-bit Figure 4. PHR format [25] 2.2. UWB receiver unit The UWB receiver unit has a synchronization unit, burst position demodulation (BPDM), BPSK demodulation unit, and Viterbi decoder (VD) units. The UWB receiver receives the 73-bit corrupted data and
- 5. ISSN: 2088-8708 Int J Elec & Comp Eng, Vol. 13, No. 4, August 2023: 4432-4440 4436 performs the synchronization, de-mapping, and decoding operations to return the original data bit sequences. The received 73-bits are decomposed. Instead, the least significant bit (LSB) 13 bits (data part) is used for de- mapping with synchronization. The hardware architecture of the BPSK demodulation and BPDM units is illustrated in Figure 5. The synchronization mechanism is incorporated in both BPDM and BPSK demodulation to recover original bits from corrupted data. The BPSK demodulation contains the DFS, two delay units, and a comparator. The generated DFS (Q) signal is inverted first and later delayed with two flip- flops to maintain synchronization between the received data and the global clock. The comparator compares the 12-bit data with the delayed Q signal to obtain the BPSK demodulated signal (out) shown in Figure 5(a). The burst position signal is generated from DFS and sawtooth signal. The burst position signal and received 1-bit data are delayed one clock cycle to maintain synchronization with the global clock. The BPDM signal is generated by comparing the delayed received bit with the delayed burst position signal, represented in Figure 5(b). These de-mapped signals (1-bit BPSK demodulated signal and 1-bit BPDM signal) are used further in the VD to recover the final data bits with a decoding mechanism. DFS D-FF D-FF Compare Q I rx_in out DFS Sawtooth Module - in D-FF BPDM signal Compare (a) (b) Figure 5. The architecture of (a) BPSK demodulation and (b) BPDM units used in UWB-RX The hardware architecture of the VD is illustrated in Figure 6. The VD unit mainly contains the counter, branch metric unit (BMU), add-compare-select unit (ACSU), traceback unit (TBU), and shift register. The BMU received the 2-bit and was used to calculate the branch metrics. The hard decision-based VD is used for branch metric (BM) calculation. The BMU performs the essential XOR operation using received and expected data bits and counts the differed bits to calculate the Hamming distance. The ACSU is also called a path metric unit (PMU). The ACSU receives the BM data and performs the path metric calculation using add, compare, and select operations. Counter ACS Unit Track back Unit Shift register In Out BMU Unit Figure 6. Viterbi decoder hardware architecture In the VD design, 8 ACSU's are used to find the decision bits. The received 2-bit BM data are added with new path metric data to find the lower and upper data. The lower data bits are compared with the upper bits to see the new path metric data and find the decision. Each ACSU produces the 2-bit decision bits. So, 16 decision bits are used further in the TBU of the trellis state. The TBU receives the 16-bit decision values with a counter to trace the best possible path. The TBU contains the memory unit to store the decision bit's history from the ACSU. The decision bits are stored in a memory unit based on the counter values. The 16 stored memory values act as decision vectors for each trellis state at each time (clock cycle). The decision vector is used further to reconstruct the best possible trellis path. Lastly, the shift register received the TBU data and shifted right to produce the correct 1-bit output. The received 1-bit data from VD and 1-bit input data are compared to realize the BER. The input data is delayed based on latency compared with the received data. If both the data bits are equal, there is no error; else error bit will be produced. 3. RESULTS AND DISCUSSION The UWB digital transceiver architecture results are discussed in this section. The UWB-DTR module is designed using Verilog hardware description language on Xilinx ISE® 14.7 environment and
- 6. Int J Elec & Comp Eng ISSN: 2088-8708 An efficient ultra-wideband digital transceiver for wireless … (Santhosh Kumar Ramachandragowda) 4437 implemented on Artix-7 (XC7A100T-3CSG324) FPGA. The simulation results are carried out using ModelSim 10.5 simulator. The UWB TX, AWGN channel, and UWB RX units are integrated to form the UWB DTR module. The simulation results of the UWB-DTR module are illustrated in Figure 7. The global clock (clk) is activated with an active-low reset (rst). The 1-bit data input (din) stream is feeding in a sequence. Based on UWB-DTR module operations, The 1-bit data output (dout) is obtained with a delay of 39 clock cycles. To estimate the BER, the delayed input (delayed_din) is introduced to match the received 1-bit dout. If the delayed input and received output (dout) are equal, the error signal will be low; otherwise, the error signal will be high. The error counter (error_count) is introduced to estimate the unmatched bits. The main counter forecasts the number of input bits to be transmitted. The 8-bit noise is added in every clock cycle with transmitted output. Figure 7. Simulation results of the UWB-DTR module The UWB-DTR module resource utilization results after synthesis on Artix-7 FPGA, tabulated in Table 1. The UWB-TX unit has 74 slices and 155 look-up tables (LUTs), operates at 268.17 MHz, and uses 87 mW of total power. Similarly, The UWB-RX unit has 166 slices and 562 LUTs, operates at 268.18 MHz, and uses 87 mW of total power. The integrated UWB-TR module utilizes 209 slices and 876 LUTs, operates at 267.37 MHz, and consumes 91 mW of total power on Artix-7 FPGA. Using an XPower analyzer, the total power is estimated based on a frequency of 31.2 MHz. Table 1. Resource Utilization results for UWB-DTR module on Artix-7 Resources UWB TX UWB RX UWB TR Slices 74 166 209 LUTs 155 562 876 Max. Frequency (MHz) 268.17 268.182 267.376 Total power (mW) 87 87 91 The UWB-DTR module performance results include latency in terms of clock cycles (CC), throughput (Mbps), hardware efficiency (Kbps/Slice), BER, and percentage error efficiency are tabulated in Table 2. The latency of 39 clock cycles is obtained after receiving the first output bit using the UWB-RX unit and is analyzed using the ModelSim simulator. The throughput is estimated based on input bits, obtained maximum frequency, and latency. So, throughput (Mbps)=(input width*max. frequency)/latency. The UWB- DTR achieves a 6.86 Mbps throughput or data rate. The hardware efficiency of the UWB-DTR module achieves 31.5 Kbps/Slice. The BER is calculated based on the number of errors obtained by the number of bits transmitted. The total number of error bits is 20 for 100,000 bits. So UWB-DTR module achieves a BER of 2×10-4 with a system efficiency of 99.98 % for 105 bits. Table 2. Performance results for the UWB-DTR module Latency (CC) Throughput (Mbps) Efficiency (Kbps/Slice) BER System Efficiency 39 6.86 31.5 2 x 10-4 99.98 % The resource utilization of the UWB-DTR (submodules) on Artix-7 is represented in Figure 8. The BPSK modulator and VD unit consume more chip area resources (slices and LUTs) on the sides of the UWB- TX and UWB-RX units on the Artix-7 Chip. The CE and VD unit obtain better operating frequencies of 1519.5 and 350.128 MHz on the UWB-TX and UWB-RX units, respectively, on the Artix-7 chip.
- 7. ISSN: 2088-8708 Int J Elec & Comp Eng, Vol. 13, No. 4, August 2023: 4432-4440 4438 The comparison of the different PHY transceivers with the proposed UWB-DTR on hardware platforms is tabulated in Table 3. The PHY TR module selected IEEE standards, modulation, or technique adopted and obtained performance metrics like slice, frequency, power, data rate, and BER parameters on selected FPGAs that are considered for comparative analysis. The proposed module combines BPM with BPSK modulation for improved performance metrics than the different PHY TR techniques. The model drive architecture [28] is incorporated into the UWB-DTR module to improve the reliability features. Figure 8. Resource utilization of the UWB-DTR (submodules) on Artix-7 Table 3. Comparative results for different PHY Transceivers on the FPGA platform Reference Designs PHY TR IEEE Std. Techniques FPGA Slices Freq. (MHz) Power (mW) Data rate (Mbps) BER [29] IR-UWB 802.15.4a PPM Virtex-4 1012 100 NA NA NA [30] IR-UWB 802.15.4a PPM Spartan-3 1821 134 NA 3 Up to 10-3 [31] IR-UWB 802.15.4 2015 MPPM Virtex-6 2711 120 NA 2 Up to 10-3 [32] NB-PHY 802.15.6 BCH Virtex-6 2668 100 117 0.971 Up to 10-3 [33] IR-UWB 802.15.4a DWPT Virtex-7 557 99 514 NA NA [34] HB-PHY 802.15.6 Walsh Artix-7 1084 32 114 6 Up to 10-3 [35] PHY 802.15.4 O-QPSK Artix-7 224 270 171 4.3 <10-4 Proposed UWB- DTR 802.15.4a BPM + BPSK Artix-7 209 268 91 6.86 2x10-4 4. CONCLUSION AND FUTURE WORK In this manuscript, the IEEE 802.15.4a-based UWB-DTR hardware architecture is designed and implemented on Artix-7 FPGA for WPANs applications. The UWB-DTR mainly offers low-cost implementation, consumes low power, and operates at a better data rate with less BER. The UWB-DTR used BPM-BPSK modulation techniques with a Viterbi decoding mechanism to transmit and receive data streams in sequence. The timing synchronization mechanism is introduced on the UWB-RX side to recover the corrupted data using the Viterbi decoding method. The simulation results prove that the designed architecture receives the original data sequence within 39 clock cycles with minimal error. The UWB-DTR system utilizes <2% chip resources at 268 MHz by consuming 91 mW of total power on Artix-7 FPGA. The UWB- DTR system achieves a data rate of 6.86 Mbps, matching the IEEE 802.15.4a standard. The UWB-DTR system achieves the BER of 2×10-4 by transmitting 105 input data bits. Compared with similar physical layer transceivers, the UWB-DTR module outperforms them in chip area (slices), power, data rate, and BER. The UWB-DTR module will be incorporated with a security algorithm to improve the system's security and performance metrics. REFERENCES [1] R. Chávez-Santiago, I. Balasingham, and J. Bergsland, “4 ultrawideband technology in medicine: A survey,” Journal of Electrical and Computer Engineering, vol. 2012, pp. 1–9, 2012, doi: 10.1155/2012/716973. [2] V. Niemela, J. Haapola, M. Hamalainen, and J. Iinatti, “An ultra wideband survey: Global regulations and impulse radio research based on standards,” IEEE Communications Surveys & Tutorials, vol. 19, no. 2, pp. 874–890, 2017, doi: 10.1109/COMST.2016.2634593. 0 200 400 600 800 1000 1200 1400 1600 CE BPM-TX BPSK Mod. BPSK Demod. BPM-RX VD UWB TX UWB RX UWB TR Utilization UWB-DTR (submodules ) Slices LUTs Fmax (MHz)
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- 9. ISSN: 2088-8708 Int J Elec & Comp Eng, Vol. 13, No. 4, August 2023: 4432-4440 4440 BIOGRAPHIES OF AUTHORS Santhosh Kumar Ramachandragowda is currently pursuing a Ph.D. from Dayananda Sagar University, Bengaluru. His main research interests are wireless communication and VLSI design. He is presently working as an assistant professor in the Department of Electronics and Communication Engineering, Dayananda Sagar College of Engineering, Bengaluru, with six years of academic service. He has published research articles in reputed peer-reviewed journals and presented papers at six international conferences. He can be contacted at [email protected]. Devaraju Ramakrishna completed a Ph.D. degree in the year 2016 from Visvesvaraya Technological University in wireless networks. He is presently working as an associate professor in the Department of Electronics and Telecommunication Engineering, Dayananda Sagar College of Engineering, Kumaraswamy Layout, Bangalore. He has presented papers at national and international conferences. He guided many UG and PG projects and is having professional body membership MIEEE and is a member of BOS and BOE. He completed 14 years of academic service. He can be contacted at devaraju- [email protected]. Rajashree Narendra completed her bachelor’s degree in electronics and communication engineering from the University of Mysore, India, in 1988 and her master’s degree in electrical engineering in the area of optical fiber communication at the University of Alberta, Edmonton, Canada, in 1992. She completed her doctoral program in electronics and communication engineering in the susceptibility of electronics systems and devices by electrostatic discharge at UVCE, Bangalore University, India. Her major field of study is integrated optical devices, 5G wireless communication, wireless sensor networks, electrostatic discharge, and EMI/EMC. She has about 33 years of research, industrial, and teaching experience. She worked as a research engineer at TR Laboratories, Edmonton, Canada. She worked as a Scientist at CEERI, CSIR Labs, Pilani, India. She worked as a consulting engineer at FRIS Robotics Sdn. Bhd., Penang, Malaysia. She is currently a professor at the Department of Electronics and Communication, School of Engineering, Dayananda Sagar University, Bangalore. She worked as a professor and Head Department of Telecommunications at BNM Institute of Technology, Bangalore. She has worked at BITS, Pilani; PESIT, Bangalore; Amrita Viswa Vidyapeetham, Bangalore, and East Point College of Engineering and Technology, Bangalore. She has published and presented papers in IEEE Transactions, Photonics Technology Letters, Springer Lecture Series, SPIE, IEEE–LEOS International Conference, Saratov Fall Meet at Russia, Asia Pacific Symposium on EMC, Beijing, China, PIERS–KL, Malaysia, IEEE AEMC, Kolkata, and INCEMIC-Bangalore. She can be contacted at [email protected].