Human-centric Computing and Information Sciences volume 12, Article number: 19 (2022)
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https://doi.org/10.22967/HCIS.2022.12.019
Radio frequency radars have garnered considerable attention in contactless sensing. The congestion in frequency bands and ultra-wideband (UWB) sensing requirements pose challenges to the design of the radars. RF radars can be alternatively considered as channel sounders, which too are facing new channel characterization and modeling challenges owing to new frequency bands in 5th generation (5G) and 6th generation (6G) cellular networks. Various sounding systems were developed to meet the frequency and system bandwidth requirements. However, most offer limited system bandwidth and cannot be easily tuned for different applications. This work aims to address these challenges, by providing a new multiband multicarrier architecture and flexible signal design for channel sounding. Firstly, a channel sounder architecture is developed using commercial software-defined radios (SDRs). Secondly, a new phase-modulated multiband orthogonal frequency division multiplexing (MB-OFDM) waveform, which is designed to provide a flexible frame structure with a low peak-to-average power ratio (PAPR), is proposed to optimize the pulse repetition period for the sounding system by maintaining all the valuable properties of OFDM. The overall system is implemented in a simulated environment, and the results show an improved PAPR performance of the MB-OFDM signal design. In addition, the overall system is tested for different channel conditions and validated against theoretical data. The numerical experiments show that the proposed system is a viable option for UWB channel sounding for a wide range of applications.
Radars Sensing, Passive Sensing, Channel Sounder, PAPR, Channel Impulse Response, Channel Characteristics, 5G/6G, OFDM, MB-OFDM
Radar sensing has already proved its usefulness and significance in defense applications. Recently, radar sensing has been prominently showcased in various domains, such as passive sensing, healthcare, and autonomous vehicles [1, 2]. Contactless sensing of various parameters makes radars an alternative to direct sensing technologies [3]. Lately, transduction-based electromagnetic sensors have been introduced for remote sensing [4–6]. In the same way, the backscattering radar principle is used for passive radio frequency identification (RFID) localization and battery-free surface acoustic wave (SAW) based sensors [7, 8]. The emerging application of battery-free passive sensors is posing new challenges in combating frequency congestion problems. In addition, the demand for new frequency bands is increasing to meet future consumer and industry needs. The envisioned 5G and 6G of cellular networks are focused on enhanced mobile broadband, massive machine-type communication, and ultra-reliable and low latency communications. The 5G network utilizes new frequency spectrums below 60 GHz, while 6G targets to use frequency bands beyond 95 GHz [9, 10], with below 6 GHz having well-understood propagation conditions. However, the propagation behavior of radio waves in new frequency bands needs more study. Generally, each frequency band behaves very differently in a similar propagation environment. Especially in the millimeter wave (mm-Wave) domain, the attenuation factor is very dominant due to oxygen, humidity, and rain. An extensive channel measurement data is required to develop a channel model, and these channel models are then used to design robust modulation schemes for a reliable communication system.
Primarily, radio frequency radar interrogators for passive sensing and channel sounders are similar, and both of them output a channel impulse response (CIR) at the receiver. In brief, sounding the channel with radio signals, acquiring knowledge of propagation phenomenon in specific channels, extraction of model parameters from measurement data, and channel model development are a few of the main objectives of channel sounding. The developed channel models are then used to design and test reliable communication systems. In comparison, radar sensing must similarly first learn the channel characteristics, thus it can accurately decipher the sensing variable by eliminating the effects of the channel. In this work, a more flexible channel sounder design framework is proposed to support various applications.
Sliding correlation is a well-known time domain technique for wideband CIR measurements [11–15]. Various dedicated sliding correlator sounders were proposed to meet the needs for wideband channel measurements [16–20]. Generally, the sliding correlator sounding system transmits pseudo-random noise (PN) sequences and performs a correlation at the receiver with a slightly slower rate identical copy of the PN sequence. Due to the efficient correlation properties of PN, this system can achieve high processing gain, better dynamic range, and fine resolutions [13, 15, 21, 22]. Sliding correlator sounders also have the advantages of low peak-to-average power ratio (PAPR) and efficient data compression for real-time recording. However, this system requires a complex and dedicated hardware system, and the choice of parameters, such as PN sequence length and chip rate, are also critical to optimize this system’s performance.
Frequency sweep is another well-known technique among channel sounding techniques. A frequency swept system utilizes a vector network analyzer (VNA) to perform channel sounding [23–26]. The VNA sweeps a set of discrete frequencies within the required bandwidth, and a complex channel frequency transfer function or S-parameter S21 is then recorded in the acquisition systems. Afterward, inverse discrete Fourier transform (IDFT) is performed to compute the CIR. While straightforward, there are a few practical limitations of the VNA-based sounding system. Firstly, the system is only suitable for a static environment because of its long sweep time. Secondly, the transmitter and receiver must be co-located due to cable length limitations.
To mitigate the limitations of sliding correlation and VNA-based sounders, multicarrier or orthogonal frequency division multiplexing (OFDM)-based sounding systems are developed to perform frequency domain channel sounding [27–35]. In the OFDM sounding system, the probing signal is synthesized in the frequency domain, while IDFT is performed before transmitting into the air. At the receiver, the matched filter operation is performed in digital baseband processors. However, the major problem of multicarrier channel sounder is the high PAPR. In this regard, various sequences have been proposed to reduce the PAPR. OFDM systems are usually implemented on software-defined radio (SDR). Accordingly, simple hardware implementation and faster computation make this technique a strong candidate for channel sounding.
The time resolution of the channel sounder depends on the system’s bandwidth. As a result, custom hardware is required for larger instantaneous bandwidth systems, and the overall solution is usually not affordable for many institutes and organizations. Recently, inspired by a VNA, new multiband sweep techniques have been proposed to perform faster and wider bandwidth channel sounding using low-cost commercial off-the-shelf (COTS) equipment. In [36], the authors have proposed a 60-GHz PN sequence-based wideband channel sounder using a heterodyne transmitter and receiver based on an arbitrary waveform generator (AWG), digitizers, and data storage device. To increase the system bandwidth, ten sequential measurements are performed with a 500-MHz frequency step to cover the full 5 GHz. After calibration, the channel transfer function (CTF) of all sub-bands are concatenated in the frequency domain, and IDFT is used to obtain the CIR of the complete 5 GHz channel bandwidth. This system has the advantage of constant envelope (CE) transmission. However, this system can only be used for indoor channel measurements.Bas et al. [37] have proposed another multiband sounding technique based on direct up/down conversion transceivers using AWG, an in-phase and quadrature (IQ) mixer, digitizer, frequency synthesizer, and high-speed data recorder of a redundant array of independent disks (RAID) storage. This system has an instantaneous bandwidth of 1 GHz, and operates from 3 GHz to 18 GHz. A fast-switching system is used to sweep the complete 15 GHz with overlapping frequency sub-bands. The proposed configuration of the system has a maximum delay spread of 2 μs, which limits it to urban and outdoor measurement scenarios, and the overall solution is also not very cost-effective. In [38], the authors have proposed a similar technique to develop a multiband multitone channel sounder. The proposed system is based on low-cost SDR and an open-source software named GNU radio [39]. The SDR can be tuned from a 300 MHz to 3.8 GHz RF frequency range with a maximum of 28 MHz instantaneous bandwidth. Channel sounding is performed in multiple sub-bands, and in each sub-band, 8 multitone are transmitted with phase randomization to reduce PAPR. Due to the latency between PC and SDR communication, this system is only used for the static environment. Li et al. [40] have proposed a frequency domain technique using a multiband (MB) OFDM signal. This sounder is based on superheterodyne SDR with 20 MHz instantaneous bandwidth, and measures 10 continuous sub-bands to cover 200 MHz in 3 ms, while a guard time is used to handle the switching time of hardware. A shared global positioning system (GPS) reference clock is used to synchronize a transmitter (TX) and receiver (RX). This system uses the IEEE Standard 802.11, a frame structure for sounding purposes that consists of the training sequence and data sections. The training section is used for frame and symbol synchronization. Although this system is very cost-effective in terms of hardware implementation, this system uses a shared clock between TX and RX, limiting it to perform channel sounding in an indoor environment. This system also has an inherent problem of the OFDM system, namely poor dynamic range and PAPR. Recently, in [41], the authors have proposed a flexible SDR-based multiband sounder for real-time channel measurement. In their work, a standard OFDM waveform is used as a probing signal. However, the PAPR problem is not addressed for optimal OFDM sounding.
Based on the limitations of the previous MB system, this work has contributed to defining an improved and flexible MB-OFDM-sounding architecture based on COTS SDRs. Particularly, due to the fact that most hardware systems are not suitable for UWB signal, MB-OFDM allows for combining one narrowband hardware into time-interleaved narrowband hardware that mimics MB UWB hardware. OFDM provides a flexible digital implementation of the UWB signal waveform. Nevertheless, the major problem in MB-OFDM signal design is the high PAPR. CE OFDM waveforms are highly encouraged to optimize transmitter performance. In this regard, various techniques have been proposed to reduce PAPR in the OFDM system [42]. Based on the previous limitations, there is a need to design an optimum MB-OFDM signal design. Accordingly, it is hypothesized that the constant amplitude zero autocorrelation (CAZAC) family sequence can provide a low PAPR MB-OFDM spectrum constraint waveform. A new Chu phasing scheme has been introduced in this work to produce a low PAPR probing signal, and an MB-OFDM signal design is developed for channel sounding. In addition, flexible sounding architecture is developed to perform sounding in different environmental conditions.
In order to develop a new OFDM sounding system, a brief introduction to the overall system architecture is needed. Accordingly, Section 2 first introduces a general architecture of an MB-OFDM sounding system. Afterward, in Section 3, a detailed formulation and numerical implementation of the MB-OFDM signal design is presented, and the probing signal is shown to meet all design requirements. Section 4 provides a brief formulation for CIR estimation. In Section 5, a discussion on the procedure to evaluate the methods’ performance and its validation against those in the literature is presented.A conclusion of the study is presented in Section 6.
Conventionally, the hardware of radios is implemented on a component level, and most of the functionality is achieved using analog circuitry, while a fixed hardware platform limits the use of radios to a few specific applications. On the other hand, the SDR approach provides a versatile platform for re-programmable applications, and divides the radio functionality into two parts, a programmable digital platform and wideband analog frontend. The digital platform of SDR is built using a digital processor (DP) and field-programmable gate array (FPGA). The analog front is designed for a wide range of tunable RF frequencies, so that this makes SDR a highly desirable tool for R&D and implementation of new communication systems. This architecture also offers another advantage of using high-level programming languages for faster prototyping.
Given the hardware specification of SDRs, it is noted that almost all COTS SDRs offer only a few MHz of baseband signal bandwidth. Due to limited signal bandwidth, the available SDR systems cannot perform UWB channel sounding for finer time resolution. In this work, a multiband approach has been adapted for UWB communication making use of the IEEE 802.15.3a standard [43]. However, the proposed multiband sounder approach is different in several aspects (e.g. the signal bandwidth for the channel sounder is not fixed). Similarly, the physical layer is highly flexible to meet the sounding requirements.
$x_m(n)= \displaystyle\sum_{k=0}^{N-1} s_m(k) exp(j2πnk/N),$(1)
where $s_m(k)$ represents a complex modulated symbol to be transmitted in subcarrier k. The frequency spacing between adjacent subcarriers is $∆f=BW⁄N$. The resulting time-domain waveform has a duration of $T_b=1⁄∆f$. Let $T_c$ be the duration of a cyclic prefix, which is created by copying the last $N_c$ samples of IFFT and concatenating them to the front of the symbol. This gives a continuous waveform where the symbol and cyclic prefix are joined together to provide sufficient time for the longest significant path of the CIR. A guard time, $T_g$ is also added at the end of the symbol to prevent a windowing effect from attenuating the sample within $T_b$ period. It can also be used to cater to the switching time between carrier frequencies. Thus, the total duration of an individual OFDM symbol is$T_{sym}=T_b+T_c+T_g.$(2)
$f_c= f_o+BW×s,$(3)
where $f_o$ is the center frequency for first sub-band and $s=1,2,…,S$.$N_u=N_d+N_p-1, where N_u<N-N_g$(4)
For sounding mode, N_d=0 and N_p=N-N_g-1. The pilot tones q_(k_p ) for mth symbol are assigned from a complex-valued p_u sequence expressed as:$q_{m,k_p}=p_{m,u},$(5)
where, $k_p=N_{gl}+1,N_{gl}+2,…,N_{gl}+N/2,N_{gl}+N/2+2,…,N_{gl}+N_p,m=0,1,2,…,M_{sym}-1, u=0,1,2,…,N_p-1,$ and $M_{sym}$ is the $M^{th}$ symbol. In (5), $p_u$ is either BPSK or polyphase modulated sequence. The guard subcarriers $g_{m,k}$ takes the location expressed as:$g_(m,k_g )=0,$(6)
where $k_g=1,2,3,… N_{gl},N_{gl}+N_p+1,N_{gl}+N_p+2,N$.$c_{m,k_d}=d_{u_d+N_d m},$(7)
where,$u_d=0,1,2,…,N_d-1, m=0,1,2,…,M_{sym}-1,$ and $k_d$ indexes are computed as follows:$A_u=A_{sub}\(B_g∪B_{dc})={N_{gl}+1,…,N⁄2,N⁄2+2 ,…,N-N_{gu} }.$(8)
If the OFDM symbol contains no pilot tones then $k_d⊆A_u$, otherwise $k_d⊂A_u$ and the number of elements of $k_d$ is equal to $N_d$. The pilot tones $q_{m,k_p}$ for mth symbol are assigned from a complex-valued, $p_{u_p}$, sequence as,$q_{m,k_p}=p_{m,u_p},$(9)
where $k_p=A_u\k_d, u_p=0,1,2,…,N_p-1$ and $m=0,1,2,…,M_{sym}-1$.$T_{subframe}=N_{sym}^{sub}×T_{sym}.$(10)
In a communication system, the preamble-sounding symbols are constructed in time-domain using CAZAC sequences. A CAZAC sequence provides constant envelope properties. However, it limits the use of symbols to only sounding, and no data can be transmitted during that time.
In this work, the sounding scheme is developed to provide flexibility for simultaneous sounding and data transmission. Although the data transmission is not a primary objective of a sounder, there are cases where TX and RX are not co-located, and there may be a need to exchange data between TX and RX. Hence, the proposed system has different challenges to meet the MB-OFDM sounding system requirement, and it has more similarities to OFDM data symbols where symbols are constructed in frequency-domain for better flexibility and control over data pilot subcarriers and spectrum shaping.
$x_m(n)= \displaystyle\sum_{k=0}^{N-1} [c_m(k)+q_m(k)]exp(j2πnk/N).$ (11)
The crest factor of $x_m(n)$ is a critical parameter to optimize the PA performance. Multicarrier techniques are prone to the high PAPR because the phase of tones is dependent on the constellation of a random input data stream and pilot sequence. The instantaneous power can be written as,$P(n)= |x(n) |^2.$(12)
The average power is given by,$P_{avg} (n)=avg {|x(n) |^2 },$(13)
and PAPR is the ratio of maximum envelope power to average power. Thus,$PAPR= \frac{max{P(n)}}{P_avg (n)}.$(14)
The data tones, $c_m(k)$, are assigned from the QPSK or QAM constellations, whereas pilot tones, $q_m(k)$, are unity-gain phase-modulated tones that take values from sequences $p_m(u)$ as described below,$p_m(u)=a_m(u) expj(θ_m(u)).$(15)
Here, $a_m(u)$ and $θ_m(u)$ are amplitude and phase associated with uth element of sequence for $m^{th}$ symbol, and $j=sqrt{-1}$ is an imaginary number. The crest factor of $x_m(n)$ caused by pilot sequence is dependent on the phase angle $θ_m(u)$. Each element of the pilot sequence $p_m(u)$ is assigned to dedicated tones in the frequency domain using (9). The choice of phase angle is very critical to the PAPR of the transmit signal. Having the same phase for all tones is the worst choice. Conventionally, pilot subcarriers are BPSK modulated with pseudo-random binary sequence (PRBS). PRBS is generated using linear feedback shift registers (LFSR). Though this is better than the same-phase case, the PAPR still grows as the number of tones increases. In[45], the author used PRBS sequence-based phase randomization with a recursive algorithm to reduce the PAPR. However, these recursive algorithms require very high computational effort, especially for a large number of carriers. On the other hand, there is another approach where researchers look for sequences that can provide a phasing scheme that achieves the desired low PAPR waveform without the need for recursive algorithms, precoding, or clipping methods [46].$p_m^{Chu}(u)=a_m^{Chu}(u) exp(θ_m^{Chu}(u)).$(16)
In (16), $a_m^{Chu}$ is the amplitude of sequence and $θ_m^{Chu}$ is the phase, described as$θ_m^{Chu}(u)=-jπγu(u+c_"f" +2κ)/N_p ,$(17)
where, 0≤u<N_p, 0<u<N_p "and" gcd〖(N_p,γ)=1〗, c_"f" =N_p "mod" 2, κ∈Z, N_p= length of the sequence.The impulse response of the multipath channel for an ideal Dirac pulse, δ(n), can be given from the equation:
$h(n)=\displaystyle\sum_{l=0}^{L-1}α_l e^{jθ_l} δ{n-τ_l},=\displaystyle\sum_{l=0}^{L-1}h_lδ(n-τ_l),$(18)
where L is the total number of multipath, $α_l$ is the amplitude, $τ_l$ is an additional time delay and $θ_l=2πf_c τ_l$ is the phase associated with the $l^th$ path. The transmitted signal, $x_m(n)$, goes through the multipath channel and a received baseband signal, $y_m(n)$, for mth symbol can be written as:
$y_m (n)=\displaystyle\sum_{l=0}^{L-1}h_{m,l} x_m (n-τ_l)+w_m(n),or$
$y_m (n)=h_m (n)*x_m (n)+w_m (n),$
(19)
$y_m (n)=h_m (n)x_m (n)+w_m (n),$(20)
where operator ⊛ represents periodic convolution.Extensive numerical experiments are performed to extend the validation of the proposed multiband channel sounders, and the proposed channel sounder is implemented in MATLAB. In this work, known CSI is used as a benchmark, and conventional techniques are also implemented such as LS, DFT-based LS, and FPTC in a similar MATLAB environment to evaluate the proposed sounder. The testing is performed to show that the particular implementation of the proposed CIR estimation techniques is valid and suitable for its intended purpose, respectively, within a reasonable bound of accuracy. For a detailed performance evaluation, mean-square error (MSE) is computed for each case with known CIR as a reference. The channel transfer function (CTF) is computed using FFT of CIR, with the formula used to calculate MSE given by [53]:
$MSE=E{|H(k)-H ̃(k)|^2 },$(21)
where $H(k)$ is the known CTF and $\tilde H(k)$ is the estimated CTF using proposed and conventionalSystem parameter | Value |
---|---|
Data transmission mode | |
Number of pilot subcarriers | 27 |
Number of data subcarriers | 26 |
QAM order | 4 |
Number of guard subcarriers | 10 |
$∆f$ : subcarrier spacing (kHz) | 312.5 |
$T_b$ : OFDM Symbol duration of sub-band (μs) | 3.2 |
$T_c$ : Cyclic Prefix duration of sub-band (μs) | 1.6 |
$T_g$ : Guard Interval duration (μs) | 0.25 |
$T_{sym}$ : Symbol duration (μs) | 5.05 |
Number of sub-bands | 10 |
Number of transmitters | 2 |
Path No. | Delay (μs) | Power (dB) |
---|---|---|
1 | 0 | -3 |
2 | 0.002 | -9 |
3 | 0.01 | -3 |
4 | 0.05 | -6 |
5 | 0.2 | -9 |
6 | 0.3 | -12 |
In this work, a detailed design methodology of a flexible multiband OFDM sounding system has been presented. We have so far discussed the general architecture of a multiband OFDM sounding system. Subsequently, a detailed formulation and numerical implementation of the MB-OFDM signal design has been presented, while a low PAPR transmitter waveform was designed for MB-OFDM sounding, whose PAPR results were validated. Using the proposed sounding architecture and probing signal, a high-resolution CIR performance has been validated by comparing results from known CIR, LS, LS-DFT, and FPTC, the results of which in turn validate that a high-resolution impulse response can indeed be obtained through the broadband sounding technique proposed herein. Accordingly, the proposed flexible architecture has the capability to allow a vast range of use cases beyond channel sounding, such as those in radar sensing. Nevertheless, there are still gaps in the channel estimation techniques for a sounding application that will be further explored in a future work.
Conceptualization, AI, VJ. Funding acquisition, GS, MS. Investigation and methodology, AI, VJ, NZ. Supervision, MD, AAA, VJ. Writing of the original draft, AI. Writing of the review and editing, VJ, MD, AAA, NZ, GS, MS. Formal analysis, AI.
This study has received funding for publication from the European Union’s Horizon 2020 research & innovation programme under grant agreement No. 854194.
The authors declare that they have no competing interests.
Asif Iqbal, received his M.Sc. degree in Electrical & ElectronicsEngineering from Universiti Teknologi PETRONAS,Malaysia in 2012. Currently, he is Ph.D. student atthe Department of Electrical and Electronics Engineering, UniversitiTeknologi PETRONAS, Malaysia. His research interestincludes fast and efficient numerical algorithms, radiopropagation, wireless channel characterization, and modeling.He is currently working on the channel sounder andemulators.
Micheal Drieberg (Member, IEEE) received the B.Eng. degree in electrical and electronics engineering from UniversitiSains Malaysia, Penang, Malaysia, in 2001, the M.Sc. degree in electrical and electronics engineering from Universiti Teknologi PETRONAS, Seri Iskandar, Malaysia, in 2005, and the Ph.D. degree in electrical and electronics engineering from Victoria University, Melbourne, Australia, in 2011. He is currently a Senior Lecturer with the Department of Electrical and Electronics Engineering, Universiti Teknologi PETRONAS. He has made several contributions to the Wireless Broadband Standards Group. He has published and served as a reviewer for several high impact journals and flagship conferences. His research interests include radio resource management, medium access control protocols, energy harvesting communications, and performance analysis for wireless and sensor networks.
Varun Jeoti, (SM’13) received his Ph.D. degree from Indian Institute of Technology, Delhi, India in 1992. He has over 29 years of teaching experience in leading Indian and Malaysian universities teaching students from various social and cultural backgrounds. He has been conducting frontier research for over 38 years in the area of surface acoustic wave (SAW) devices, signal processing and wireless communication. Starting in 1980 from IIT Delhi soon after his graduation, he worked on government sponsored projects developing SAW Pulse Compression filters, and underwater optical receivers in IIT Madras. He was a Visiting Faculty in Electronics department in Madras Institute of Technology, Anna University for about a year during 1989 to 1990 and joined Delhi Institute of Technology for next 5 years till 1995. He moved to School of Electrical & Electronic Engineering (E. & E. Engg.) in Universiti Sains Malaysia in 1995 and later moved to Dept. of E. & E. Eng. in Universiti Teknologi PETRONAS in 2001. He is presently working in Faculty of Technical Sciences, University of Novi Sad, Serbia as ERA Chair leading research efforts in Stretchable and Textile Electronics. His research interests include, among others, signal processing, SAW sensor-tags, SAW microfluidics and wireless communication for various applications.
Azrina Abd Aziz (Senior Member, IEEE) is currently a senior lecturer at the Department of Electrical and Electronic Engineering of UniversitiTeknologi PETRONAS (UTP), Malaysia. Prior to her academic appointment, she worked briefly in industry handling the final visual inspection process of IC packaging. She received herbachelor’s degree in Electrical and Electronic Engineering (Hons) from The University of Queensland, Australia in 1997 and MSc. in System Level Integration from the Institute for System Level Integration (ISLI), Scotland in 2003. She then completed her Ph.D. degree in Computer Systems Engineering at Monash University, Melbourne, Australia in 2013. Her recent research interests focus on energy-efficient techniques for topology control in wireless sensor networks (WSNs), wireless body area networks (WBANs) for biomedical applications and medical imaging, and machine learning techniques. Azrina is currently leading the SMART assistive and rehabilitation technology research group in UTP. She is a senior member of IEEE, a member of Board of Engineers Malaysia. She is holding the positions of the treasurer of IEEE Robotics and Automation Society and Chair-Elect of IEEE Women in Engineering Malaysia. Azrina is the journal reviewer of Ad Hoc Networks under the ScienceDirect publisher.
Prof. Dr. Goran Stojanović (M’04) is a full professor at Faculty of Technical Sciences (FTS), University of Novi Sad (UNS), Serbia. He received a BSc, MSc and a PhD degree in 1996, 2003 and 2005, respectively, from FTS-UNS, all in electrical engineering.
He has 25 years of experience in R&D. His research interests include sensors, flexible electronics, textile electronics and microfluidics. He is an author/coauthor of 260 articles, including 96 in leading peer-reviewed journals with impact factors, 5 books, 3 patents, 1 chapter in monograph. Keynote speaker for 12 international conferences. Stojanović has been a supervisor of 11 PhD students, 40 MSc students and 60 diploma students at the FTS-UNS. He has more than 14 years’ experience in coordination of EU funded projects (H2020, FP7, EUREKA, ERASMUS, CEI), with total budget exceeding 14.86 MEUR. Currently, he coordinates 4 Horizon2020 projects in the field of green electronics and textile electronics.
Dr. Mitar Simić (S’16, M’18) was born in Ljubovija, Republic of Serbia in 1987. He received the B.Sc. and M.Sc. degrees in electrical engineering from the University of East Sarajevo, Bosnia and Herzegovina, in 2010 and 2012, respectively. He received the Ph.D. degree in electrical engineering from the University of Novi Sad, Serbia in 2017.
He is a Postdoctoral Researcher within the STRENTEX project at the Faculty of Technical Sciences, University of Novi Sad, Serbia.
He is an author/coauthor of one monograph and more than 40 scientific papers. His research interests include sensors, flexible electronics, impedance spectroscopy analysis, equivalent circuit modeling, and development of devices for impedance measurement and data acquisition.
Nazabat Hussain Nazabat Hussain completed his M.Sc. ad Ph.D. in Electrical & Electronics Engineering from UniversitiTeknologi PETRONAS, Malaysia. He is specialized in computational algorithms, image processing, signal processing, AI, embedded system, Wireless Communication, and applied electromagnetics. He has published his research work indexed Journal/Conferences. Currently, he is working as R&D Engineer GE Vingmed Ultrasound AS.
Asif Iqbal1,*, Micheal Drieberg1, Varun Jeoti2, Azrina Binti Abd Aziz1, Goran M. Stojanović2, Mitar Simić2, and Nazabat Hussain3, A Flexible Multiband Multicarrier Signal Design for Broadband Channel Sounding Applications, Article number: 12:19 (2022) Cite this article 1 Accesses
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