Browsing by Author "Duan, Ruifeng"
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- Ambient Backscatter Communications for Future Ultra-Low-Power Machine Type Communications: Challenges, Solutions, Opportunities, and Future Research Trends
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2020-02-14) Duan, Ruifeng; Wang, Xiyu; Yigitler, Huseyin; Sheikh, Muhammad; Jäntti, Riku; Han, ZhuThe widespread applications of massive MTC are limited by energy availability, spectrum congestion, and device costs. The emerging AmBC not only addresses these bottlenecks but also opens opportunities for new applications. This article aims to explore AmBC-enhanced future ultra-low-power MTC. In this context, we present the development trends in AmBC prototype designs and discuss potential applications, highlight the specific features of the AmBC technology, and review AmBC receiver designs. Finally, we investigate and outline the future research challenges and trends from the practical aspects of AmBC systems. - Asymmetric ACK/NACK Detection for Ultra-Reliable Low-Latency Communications
A4 Artikkeli konferenssijulkaisussa(2018-08-20) Shariatmadari, Hamidreza; Duan, Ruifeng; Iraji, Sassan; Jantti, Riku; Li, Zexian; Uusitalo, Mikko A.The fifth generation wireless systems are expected to encounter new services in order to provide connectivity for a wide range of applications. One of the considered services is ultra-reliable low-latency communications (URLLC), which has stringent requirements on availability, reliability, and latency. The communication efficiency of URLLC can be improved by employing error control protocols, such as automatic repeat request (ARQ) and hybrid ARQ (HARQ). However, this requires a reliable feedback channel to carry acknowledgement (ACK) and negative ACK (NACK) signals. Improving the detection reliability of ACK and NACK signals simultaneously entails allocating more resources for the feedback channel. Instead, we propose employing an asymmetric signal detection to provide a better protection for NACK signals compared to the ACK signals, without assigning more resources to the feedback channel. The simulation results show that the asymmetric signal detection can achieve a better resource utilization for URLLC. - Asymptotic Analysis for Spectrum-sharing Systems with TAS/MRC Using Extreme Value Theory
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2019-09-23) Duan, Ruifeng; Zheng, Zhong; Jäntti, Riku; Hämäläinen, Jyri; Haas, Zygmunt. J.We investigate the asymptotic behavior for an overlooked aspect of spectrum-sharing systems when the number of transmit antennas nt at the secondary transmitter (ST) grows to infinity. Considering imperfect channel state information (CSI), we apply the transmit antenna selection and the maximal-ratio combining techniques at the ST and the secondary receiver (SR), respectively. First, we obtain the signalto-noise ratio (SNR) distributions received by the SR under perfect and imperfect CSI conditions. Then we show that the SNR distributions are tail-equivalent in the sense that the right tails of the two distributions decay in the same rate as the number of transmit antennas nt grows to infinity. Based on the extreme value theory, when the transmit power of the ST is solely limited by the interference constraint, we show that the limiting SNR at the SR is Fréchet-distributed and the limiting rate scales as log(nt). When the transmit power of ST is determined by both the maximal transmit power and the interference power constraints, the limiting SNR is Gumbel-distributed and the limiting rate scales as log(log(nt)). We further show that the average rate can be estimated by the corresponding easier-to-obtain outage rate. Numerical results indicate that the derived asymptotic rate expressions represent accurate approximations even when nt is “not-solarge”. Finally, we study the robustness of the secondary transmissions by analyzing the corresponding average symbol error rates (SER) under general modulation and coding schemes. The findings indicate that the SER is Weibull distributed, when the maximal transmit power and interference power constraints are comparable. - Coherent Multi-antenna Receiver for BPSK-modulated Ambient Backscatter Tags
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2022-01-15) Wang, Xiyu; Yiğitler, Hüseyin; Duan, Ruifeng; Menta, Estifanos Yohannes; Jäntti, RikuAmbient backscatter communication (AmBC) is an emerging communication technology enabling green Internet of Things deployments. The widespread acceptance of this paradigm is limited by the low signal-to-interference-plus-noise ratio (SINR) of the signal impinging on the receiver antenna due to the strong direct path interference and unknown ambient signal. The adverse impact of these two factors can be mitigated by using noncoherent multiantenna receivers, which are known to require a higher SINR to reach the bit-error-rate (BER) performance of coherent receivers. However, considering the unknown ambient signal, unknown location of AmBC tags, and varying channel conditions, coherent receivers for AmBC systems are rarely studied in the literature. In this article, a coherent multiantenna receiver, which requires no prior information of the ambient signal for decoding the binary-phase-shift-keying (BPSK) modulated signal, is presented. The performance of the proposed receiver is compared with an ideal coherent receiver that has perfect phase information, and also with the performance of a noncoherent receiver, which assumes distributions for ambient signal and phase offset caused by the excess length of the backscatter path. Comparative simulation results show the designed receiver can achieve the same BER performance of the ideal coherent receiver with 1-dB more SINR, which corresponds to 5-dB or more gain with respect to noncoherent reception of on-off-keying modulated signals. Variation in the detection performance with the tag location shows that the coverage area is in the close vicinity of the transmitter and a larger region around the receiver, which is consistent with the theoretical results. - Does Ambient Backscatter Need Additional Regulations?
A4 Artikkeli konferenssijulkaisussa(2018) Ruttik, Kalle; Duan, Ruifeng; Jäntti, Riku; Han, ZhuAmbient Backscatter Communication (AmBC) is an emerging ultra-low power communication scheme which enables smart devices to communicate by modulating ambient radio frequency (RF) signals without requiring active RF transmission. AmBC can be interpreted as a spectrum sharing system that AmBC devices share the spectrum with the incumbent wireless broadcast systems. In this paper, we study the impact of AmBC from the incumbent receiver perspective since AmBC introduces a new situation for regulators. In the analysis, we consider a generic Orthogonal Frequency Division Multiplexing based broadcast broadcast system that corresponds to digital audio or video broadcasting or downlink of a mobile communication system. Broadcasting spectrum can be used by unlicensed transmitters in television white space framework. Contrary to the television white space transmitters that always cause interference to the incumbent system, the impact of AmBC depends on the equalization interval of the receiver. The incumbent receiver sees an AmBC device as an additional fast fading multi-path component. AmBC can sometimes even contribute positively to the received signal quality. Our results suggest that in many practical scenarios AmBC systems can co-exist with digital broadcast systems without causing harmful interference. - Machine Learning-Assisted Detection for BPSK-modulated Ambient Backscatter Communication Systems
A4 Artikkeli konferenssijulkaisussa(2019) Wang, Xiyu; Duan, Ruifeng; Yigitler, Yusein; Menta, Estifanos; Jäntti, RikuAmbient backscatter communication (AmBC), a green communication technology, is hampered by the continuously and extremely fast varying, strong and unknown ambient radio frequency (RF) signals. This paper presents a machine learning-assisted method for extracting the information of the AmBC device. The information is modulated on top of the unknown Gaussian-distributed ambient RF signals. The proposed approach can decode the binary phase shift keying backscatter signals encoded using Hadamard codes. This method extracts the learnable features for the tag signal by first eliminating the direct path signal and then correlating the residual signal with the coarse estimate of ambient signal. Thereafter, the tag signals are recovered by using the k-nearest neighbors classification algorithm. The recovered signals are decoded by a Hadamard decoder to retrieve the original information bits. We validate the performance using simulations to corroborate the proposed approach. - Multi-Antenna Receiver for Ambient Backscatter Communication Systems
A4 Artikkeli konferenssijulkaisussa(2018-08-24) Duan, Ruifeng; Jantti, Riku; Elmossallamy, Mohamed; Han, Zhu; Pan, MiaoConsider an ambient modulated backscatter communication (AmBCC) system adopting binary phase shift keying modulation that the receiver is to decode the backscatter device induced message without knowledge of the channel state information, the statistical channel covariance matrices, and the noise variance at the receiver antennas. In this paper, we apply the fact that the ambient orthogonal frequency-division multiplexing (OFDM) signals with a large number of subcarriers contain repetitive elements inducing time correlation. We propose a simple sample covariance matrix distance based rule that does not need to invert the estimated covariance matrices. The results show that the developed method enables the receiver to detect the backscatter symbol over one ambient OFDM symbol period applying the time correlation induced by the wideband ambient OFDM transmission which contains repetitive elements. - Multi-bounce Effect in Multi-Tag Monostatic Backscatter Communications
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2022-01-01) Al-nahari, Azzam; Jäntti, Riku; Duan, Ruifeng; Mishra, Deepak; Yigitler, HuseyinIn this letter, we investigate the multi-bounce effect on the performance of multi-tag monostatic backscatter communication systems with multi-antenna reader. We derive a channel model for the considered system setup and propose a minimum mean square error receiver followed by a sequential demodulation to decode the backscattered information from the tags. A tight lower bound on the achievable sum rate is derived and the asymptotic analysis demonstrates the effect the different system parameters on the performance. It is shown that with proper receiver design, the multi-bounce effect can play an important role in improving the sum-rate performance especially at low signal to noise ratio regime. - Multi-bounce Effect: an Overlooked Aspect in Analysis of Ambient Backscatter Networks
A4 Artikkeli konferenssijulkaisussa(2018-02) Duan, Ruifeng; Ruttik, Kalle; Jäntti, Riku - Multiantenna Quantum Backscatter Communications
A4 Artikkeli konferenssijulkaisussa(2017-12) Jäntti, Riku; Di Candia, Roberto; Duan, Ruifeng; Ruttik, KalleQuantum illumination (QI) is a revolutionary photonic quantum sensing paradigm that enhances the sensitivity of photodetection in noisy and lossy environments. In this paper, we propose to use QI in a quantum backscatter communication (QBC), with the aim of increasing the receiver sensitivity beyond the limits of its classical counterpart. One of the practical challenges in microwave QI is the slow rate at which the entangled microwave modes can be generated. Here, we propose to mitigate this problem by using a multiple-input multiple-output antenna system to synthetically increase the number of efficiently- distinguishable modes in the QBC context. - Quantum Backscatter Communication: A New Paradigm
A4 Artikkeli konferenssijulkaisussa(2018) Di Candia, Roberto; Jäntti, Riku; Duan, Ruifeng; Lietzén, Jari; Khalifa, Hany; Ruttik, KalleIn this paper, we propose a novel quantum backscatter communications (QBC) protocol, inspired by the quantum illumination (QI) concept. In the QBC paradigm, the transmitter generates entangled photon pairs. The signal photon is transmitted and the idler photon is kept at the receiver. The tag antenna communicates by performing the pulse amplitude modulation (PAM), binary phase shift keying (BPSK) or quadratic phase shift keying (QPSK) on the signal impinging at the antenna. Using the sum-frequency-generation receiver, our QBC protocol achieves a 6 dB error exponent gain for PAM and BPSK, and 3 dB gain for QPSK over its classical counterpart. Finally, we discuss the QI-enhanced secure backscatter communication. - Quantum-Enhanced Microwave Backscattering Communications
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2020-01-01) Jantti, Riku; Duan, Ruifeng; Lietzen, Jari; Khalifa, Hany; Hanzo, LajosThe recent advances in the field of microwave superconducting circuits open the way for a multitude of engineering applications that revolutionize the field of classical communications. To exploit this new technology, we propose a novel microwave quantum-enhanced backscattering system based on the laws of quantum physics. Both the transmitter and the receiver are quantum mechanical in nature and are accommodated at the infrastructure side, while the backscattering device is classical. The advocated system breaks the performance barrier of the classical backscattering systems and approaches the ultimate attainable receiver sensitivity. Finally, our quantum solution outperforms the classical solutions in terms of its level of security. - Towards Smart Networking through Context Aware Traffic Identification Kit (TriCK) in 5G
A4 Artikkeli konferenssijulkaisussa(2018-11-12) Xu, Lina; Duan, RuifengIn order to distribute diverse traffic flow into proper network interfaces, Access Network Discovery and Selection Function (ANDSF) is proposed by 3GPP, which can distribute every traffic flow to a preferred network interface according to several observed features from that flow. However, the static policies in ANDSF can neither understand the context nor adapt to real time changes. In order to address that problem, in our previous work, we have proposed a server-client based Context aware Traffic identification Kit (TriCK) to dynamically identify traffic, which can extend the functionalities of 3GPP ANDSF. It can classify traffic data not only based on its own characteristics, but also the real time network conditions and the current context. In this paper, we provide an implementation for the network selection component in TriCK based on clustering techniques, with a complexity of O(n) . A static version and a dynamic version of the implementation are analysed. The static approach is easy to implement and comprehend. The static solution can distribute the traffic flow according to the traffic characteristics and the network context. The dynamic approach can further balance the traffic load between different network interfaces and therefore provide an overall better transmission quality.