- Singapore, Singapore
Yonghong Zeng
Peking University, MATH, Department Member
We proposed two methods for the localization of drone controllers based on received signal strength indicator (RSSI) ratios: the RSSI ratio fingerprint method and the model-based RSSI ratio algorithm. To evaluate the performance of our... more
We proposed two methods for the localization of drone controllers based on received signal strength indicator (RSSI) ratios: the RSSI ratio fingerprint method and the model-based RSSI ratio algorithm. To evaluate the performance of our proposed algorithms, we conducted both simulations and field trials. The simulation results show that our two proposed RSSI-ratio-based localization methods outperformed the distance mapping algorithm proposed in literature when tested in a WLAN channel. Moreover, increasing the number of sensors improved the localization performance. Averaging a number of RSSI ratio samples also improved the performance in propagation channels that did not exhibit location-dependent fading effects. However, in channels with location-dependent fading effects, averaging a number of RSSI ratio samples did not significantly improve the localization performance. Additionally, reducing the grid size improved the performance in channels with small shadowing factor values, b...
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Since atomically thin two-dimensional (2D) graphene was successfully synthesized in 2004, it has garnered considerable interest due to its advanced properties. However, the weak optical absorption and zero bandgap strictly limit its... more
Since atomically thin two-dimensional (2D) graphene was successfully synthesized in 2004, it has garnered considerable interest due to its advanced properties. However, the weak optical absorption and zero bandgap strictly limit its further development in optoelectronic applications. In this regard, other 2D materials, including black phosphorus (BP), transition metal dichalcogenides (TMDCs), 2D Te nanoflakes, and so forth, possess advantage properties, such as tunable bandgap, high carrier mobility, ultra-broadband optical absorption, and response, enable 2D materials to hold great potential for next-generation optoelectronic devices, in particular, mid-infrared (MIR) band, which has attracted much attention due to its intensive applications, such as target acquisition, remote sensing, optical communication, and night vision. Motivated by this, this article will focus on the recent progress of semiconducting 2D materials in MIR optoelectronic devices that present a suitable categor...
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Prime factor fast algorithms are computationally efficient for various discrete transforms. However, they generally need an index mapping process to convert one-dimensional input sequence into a two-dimensional array, which results in a... more
Prime factor fast algorithms are computationally efficient for various discrete transforms. However, they generally need an index mapping process to convert one-dimensional input sequence into a two-dimensional array, which results in a substantially computational overhead and an irregular computational structure. This letter attempts to minimize the computation overhead by a simple and general mapping procedure.
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Research Interests: Computer Science and MIMO
A phosphorescent probe based on a long-lived iridium(iii) complex has been developed for time-resolved CO2gas identification with high selectivity and photostability.
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We consider a distributed opportunistic spectrum access (D-OSA) scenario in which multiple cognitive radio (CR) users attempt to access a channel licensed to some primary network. CR users operate on a frame-by-frame basis and need to... more
We consider a distributed opportunistic spectrum access (D-OSA) scenario in which multiple cognitive radio (CR) users attempt to access a channel licensed to some primary network. CR users operate on a frame-by-frame basis and need to carry out spectrum sensing at the beginning of each frame to determine whether the primary network is active or idle. Upon detecting the primary
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Research Interests: Mathematics, Computer Science, Distributed Computing, Statistical Analysis, Cognitive Radio Networks, and 13 moreCognitive radio, Probability, Spectrum Sensing, Detectors, Throughput, Signal Detection, SNR, Signal to Noise Ratio, Electrical And Electronic Engineering, Probability of Detection, Energy Detector, Bayesian approach, and Phase shift keying
Research Interests: Computer Science, Distributed Computing, Cognitive Radio Networks, Cognitive radio, Probability, and 15 moreComputer Network, Computer Simulation, Software Radio, Radio Frequency, Primary User, Energy Detection, Detection Probability, Radio Wave, Information Rate, Signal to Noise Ratio, Electrical And Electronic Engineering, Frequency Bands, Cognitive Radio Network, Probability of Detection, and Receivers
Research Interests: Engineering, Mathematics, Computer Science, Technology, Signal Processing, and 15 moreAlgorithm, Cognitive radio, Spectrum Sensing, Cooperative Spectrum Sensing, Digital television, Primary User, Spectrum Sensing in Cognitive Radio, Communication Channels, Spectrum, Signal Detection, Covariance Matrix, Detection Probability, MIMO Spectrum Sensing, Covariance Matrices, and Multiple Antennas
Research Interests: Engineering, Mathematics, Computer Science, Signal Processing, Algorithm, and 15 moreCognitive radio, Simulation, Software Radio, Key words, Random Matrix Theory, Frequency, Eigenvalues, Signal Detection, Energy Detection, Covariance Matrix, Signal to Noise Ratio, Electrical And Electronic Engineering, Probability of Detection, arXiv, and Eigenvalue
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Research Interests: Approximation Theory, Computer Science, Distributed Computing, Statistics, Cognitive radio, and 11 moreOFDM, Sensors, Estimation, Frequency offset, Time Frequency Analysis, Signal Detection, Signal to Noise Ratio, Electrical And Electronic Engineering, Covariance, Cyclostationary, and OFDM modulation
Research Interests: Computer Science, Radio, Cognitive radio, Big Bang, Spectrum Sensing, and 15 moreSensors, Cooperative Spectrum Sensing, Wireless, Software Radio, Space Time, Matched Filter, Joint, Energy Detection, Eigenvalue Problems, Statistical tests, Articulation, Electrical And Electronic Engineering, Eigenvalues and Eigenfunctions, Research areas, and Cyclostationary
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A semi-blind method is proposed for simultaneously estimating the carrier frequency offsets (CFOs) and channels of an uplink multi-user MIMO-OFDM system. By incorporating the CFOs into the transmitted symbols and channels, the MIMO-OFDM... more
A semi-blind method is proposed for simultaneously estimating the carrier frequency offsets (CFOs) and channels of an uplink multi-user MIMO-OFDM system. By incorporating the CFOs into the transmitted symbols and channels, the MIMO-OFDM with CFO is re-modeled into a MIMO-OFDM without CFO. The known blind method for channel estimation (Y.H. Zeng and T.S. Ng, 2004) is then directly used for the re-modeled system to obtain the shaped channels with an ambiguity matrix. A dedicated pilot OFDM block for each user is then designed to resolve the CFOs and the ambiguity matrix. As a result, based on the second-order statistics (SOS) of the received signal and one pilot OFDM block, the CFOs and channels are found simultaneously
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ABSTRACT Since a cognitive radio does not have fixed spectra, it may need to sense a very large frequency range to find an available band. The sensed aggregate bandwidth could be as large as several GHz. This is especially challenging if... more
ABSTRACT Since a cognitive radio does not have fixed spectra, it may need to sense a very large frequency range to find an available band. The sensed aggregate bandwidth could be as large as several GHz. This is especially challenging if the center frequencies and bandwidths of the sensed signals are unknown and need to be detected. In this paper, an edge based wideband sensing is proposed. The method first uses the product of wavelet transforms at different scales to detect the edges (sharp changing points) of the power spectral density (PSD) of the received signal. It then forms the possible bands based on the detected edges. Thereafter, it applies a multi-band detection scheme to classify the bands as occupied or vacant. Finally, the signal to noise ratio (SNR) of each occupied band is estimated. Performance evaluation is also a complicated issue for wideband sensing. Other than the conventional metrics as probability of detection and probability of false alarm, three new criteria are proposed to evaluate the performance of a wideband sensing. Simulations are provided to verify the methods.
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This paper presents the application of cyclic delay diversity (CDD) to block-based single carrier cyclic prefix (SC-CP) systems. It is shown that diversity advantage is achieved even without additional coding due to the inherent... more
This paper presents the application of cyclic delay diversity (CDD) to block-based single carrier cyclic prefix (SC-CP) systems. It is shown that diversity advantage is achieved even without additional coding due to the inherent cross-tone pre-coding present in SC-CP. We also present a CDD SC-CP transmission system for correlated channels. By using beamforming techniques, virtual uncorrelated channels are created for
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In this paper, we consider the performance enhancement of signal detection for single carrier-cyclic prefix (SC-CP) transmissions over correlated multiple inputs single outputs (MISO) channels. The block-iterative generalized decision... more
In this paper, we consider the performance enhancement of signal detection for single carrier-cyclic prefix (SC-CP) transmissions over correlated multiple inputs single outputs (MISO) channels. The block-iterative generalized decision feedback equalizer (BI-GDFE) receiver is used to combat the effect of intersymbol interference (ISI). While BI-GDFE outperforms linear equalizers, the improvement could be limited if the channel does not contain a
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Measurements performed at several locations clearly show that frequency spectrum is under-utilized. Cognitive radio is a strong candidate to ensure better spectrum utilization by providing access in an opportunistic manner. Simulations... more
Measurements performed at several locations clearly show that frequency spectrum is under-utilized. Cognitive radio is a strong candidate to ensure better spectrum utilization by providing access in an opportunistic manner. Simulations performed on the algorithm that we proposed show promising results in sensing vacant channels in TV bands. Here we present the work, which implements the algorithm on a real-time
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Cyclostationary detection is regarded as a major method for spectrum sensing in cognitive radio and other applications as well. The rationale behind the detection is that the second order statistic of the interested signal is periodical.... more
Cyclostationary detection is regarded as a major method for spectrum sensing in cognitive radio and other applications as well. The rationale behind the detection is that the second order statistic of the interested signal is periodical. The period is therefore used as the critical feature for detection. In practice, due to clock error or oscillator error or other errors, the detector is hardly able to know the exact period of the signal. This causes a cyclic frequency mismatch in the detection. In this paper, the origin of the mismatch and the impact of it are analyzed. Theoretic analysis and simulations are presented to show that the cyclostationary detection is actually very sensitive to the mismatch. The theoretic analysis on the test statistics matches very well with simulations and can be used for predicting the detection performances and designing the detection parameters.
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In this paper, we consider the problem of blind channel estimation for multi-input, multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems via second order statistics (SOS) only. By an appropriate re-modulation on... more
In this paper, we consider the problem of blind channel estimation for multi-input, multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems via second order statistics (SOS) only. By an appropriate re-modulation on the received signal blocks, we find an effective way to apply the subspace based channel estimation for the cyclic prefix (CP) based MIMO-OFDM system when the number of
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Sensing (signal detection) is a fundamental problem in cognitive radio. In this paper, a new method is proposed based on the eigenvalues of the covariance matrix of the received signal. It is shown that the ratio of the maximum eigenvalue... more
Sensing (signal detection) is a fundamental problem in cognitive radio. In this paper, a new method is proposed based on the eigenvalues of the covariance matrix of the received signal. It is shown that the ratio of the maximum eigenvalue to the minimum eigenvalue can be used to detect the signal existence. Based on some latest random matrix theories (RMT),
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In this paper, a class of unitary transform based optimal pilots is found for time domain channel estimation in multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. Also, a frequency domain... more
In this paper, a class of unitary transform based optimal pilots is found for time domain channel estimation in multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. Also, a frequency domain channel estimation which does not need interpolation is obtained. It is shown that the frequency domain method achieves the same performance as the time domain method and is better than interpolation methods. Furthermore, fast algorithms are proposed to implement the methods. Simulations demonstrate that the methods are effective
Research Interests: Computer Science, Algorithm, OFDM, Antenna arrays, MIMO, and 11 moreChannel Estimation, Frequency-domain analysis, MIMO OFDM, Time Domain, Orthogonal Frequency Division Multiplexing, Frequency Domain, Fast Algorithm, Multiple Input Multiple Output, Interpolation Method, OFDM modulation, and FREQUENCY DIVISION MULTIPLEXING
ABSTRACT In recent years, filter bank multicarrier (FBMC) has recaptured widespread interests for its possible applications in cognitive radio and dynamic spectrum access. A distinctive feature for cognitive radio is its adaptivity to... more
ABSTRACT In recent years, filter bank multicarrier (FBMC) has recaptured widespread interests for its possible applications in cognitive radio and dynamic spectrum access. A distinctive feature for cognitive radio is its adaptivity to environment. When environment changes, a cognitive radio will change its parameters to optimize the transmission and receiving. Thus it is desirable to design a unified structure and algorithm for FBMC that needs little change for different parameters. In this paper, we propose a unified structure and parallel algorithms to implement the FBMC. The FBMC system and parallel algorithms are constructed based on the normalized prototype filter. The coefficients of the normalized prototype filter can be pre-computed and stored. The proposed parallel algorithms have the same structure for various choices of time duration, subcarrier spacing and bandwidth. Combined with known parallel algorithms for the fast Fourier transform (FFT), the proposed algorithms fully parallelize the computations for the transmitter and receiver, which can run much faster than conventional serial algorithms as modern processors usually have massive parallel capability.
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ABSTRACT In a cognitive radio network, the secondary user (SU) will cause the primary user (PU) to be in outage when the SU miss-detects the PU and transmits with a power that prevents the PU receiver from decoding its data. Hence, the... more
ABSTRACT In a cognitive radio network, the secondary user (SU) will cause the primary user (PU) to be in outage when the SU miss-detects the PU and transmits with a power that prevents the PU receiver from decoding its data. Hence, the outage of the PU caused by the SU depends on the SU's transmission power and its probability of detection. For a given outage probability, it is possible for the SU to lower its transmission power in exchange for a lower probability of detection. The SU may not even require spectrum sensing to protect the PU if the SU's transmission power is low enough or when it is very far from the PU. In this paper, we first determine the distance of the SU from the PU such that the SU could use the channels without spectrum sensing. Then, at locations where the SU requires spectrum sensing, we determine the sensing parameters and the transmission power that will maximize the SU's throughput subject to an outage constraint for the PU.
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Efficient estimations of the carrier frequency offset (CFO) and channel are vital to orthogonal frequency division multiplexing (OFDM). In this paper, a new method based on limited channel length and null subspace is proposed to estimate... more
Efficient estimations of the carrier frequency offset (CFO) and channel are vital to orthogonal frequency division multiplexing (OFDM). In this paper, a new method based on limited channel length and null subspace is proposed to estimate the CFO in OFDM. The method needs only one OFDM block (symbol) as pilot. The identifiability of the method is analyzed and requirements for