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The shallow underwater acoustic channel offers a challenging environment. Besides long delay spreads caused by multiple surface-bottom reflections, the channel is time variant as well. In tropical waters, the problem is compounded further by impulsive noise created by snapping shrimp. Conventionally, the noise process is modeled by white impulsive noise. However, in reality, snapping shrimp noise...
A comparison is made on high-frequency SiGe imagers to investigate the performance enhancement with circuit-level approaches: employing a front-end low noise amplifier (LNA) and employing heterodyne topology. Two imagers operating near 130 GHz, one with and the other without an LNA, were compared for the responsivity and the noise equivalent power (NEP). Also, two imagers operating near 300 GHz, one...
A 290-GHz heterodyne integrated imager has been developed in a 65-nm CMOS technology. The imager consists of a mixer, an LO (local oscillator), an IF amplifier, and an IF detector. A responsivity of 20 kV/W and a noise equivalent power (NEP) of 29 pW/Hz1/2 were measured. Images were successfully acquired with an image acquisition setup that employs the fabricated imager circuit.
The recent advancing in click analyser technology aims at reducing costs and time required to perform a full CISPR 14-1 compliant click measurement. The two relevant approaches to achieve costs and time reductions are, respectively, the use of Fast Fourier Transform (FFT) EMI receivers and performing the threshold calculation and actual measurement in a single run (single-run systems). However, there...
Full frequency reuse in multi-beam satellite communication systems allows to achieve a high capacity, provided that the inter-beam co-channel interference (CCI) can be properly dealt with. Tomlinson-Harashima precoding (THP) is a popular technique applied at the basestation transmitter to cancel the interference in the forward link. However, the conventional detection of THP, involving a modulo operation...
A collaborative spectrum sensing system with a fusion center, which utilizes the eigenvalues of the sample covariance matrix for detection, is investigated. On the example of two widely known detectors, we show that imperfect calibration with respect to the noise powers of the receivers leads to a so-called SNR wall in eigenvalue-based detectors. The SNR wall manifests itself as an SNR threshold below...
Multiple input multiple output(MIMO) system has been widely researched in recent years. To match high-speed data stream, detector in receiver becomes especially important. Exiting detectors, such as zero-forcing(ZF), minimum mean square error(MMSE) and maximum likelihood(ML) can not meet the demand. So lattice reduction aided detection(LRAD) has been introduced as a new type of MIMO detector. The...
In this paper, a common framework for maximum likelihood (ML) detection of spatial multiplexed (SM) and space time coded multiple-input multiple-output (MIMO) signals is proposed. It facilitates a common field programmable gate array (FPGA) based hardware design for the detection of both SM and space time block coded (STBC) MIMO signals with reduced computational complexity. We reduce the number of...
Single modulated signal is apt to be captured by passive detector in radar system. In this study, we put forward the structure of LFM/Barker which is a hybrid modulated signal based on linear frequency modulation (LFM)signal and Barker code, discuss ambiguity function and intercept factor and power spectrum density (PSD). Simulation results show that the designed signal has a lower peak-to-sidelobe...
This paper proposes a novel orthogonal spreading matrix (OSM) for the iterative detection (ID) with the minimum mean square error-soft interference cancellation soft-in soft-out (MMSE-SIC SISO) detector. The novel OSM concatenates block diagonal orthogonal matrices and random permutation matrices. Simulation results show that the novel OSM using ID significantly improves the BER of the conventional...
This paper considers a selective detect-and-forward two-way relay network employing differential MPSK modulation with Weighted Decision-Feedback Differential Coherent (W-DFDC) receivers. The system employs a three-phase relaying protocol with direct transmissions, where two terminals transmit separately in the first two phases. In the third phase, the relay forwards the network coded message to both...
Use of multiple light emitting diodes (LED) is an attractive way to increase spectral efficiency in visible light communications (VLC). A non-DC-biased OFDM (NDC OFDM) scheme that uses two LEDs has been proposed in the literature recently. NDC OFDM has been shown to perform better than other OFDM schemes for VLC like DC-biased OFDM (DCO OFDM) and asymmetrically clipped OFDM (ACO OFDM) in multiple...
This paper investigates the evaluation of a spectrum sensing techniques from the point of view of detection degradation caused by the transceiver front-end imperfections. Two spectrum sensing detectors (an energy detector and a goodness of fit detector) have been evaluated with the selected single carrier modulation formats for four different types of front-ends — two of them designed for the currently...
This paper proposes two techniques to improve the communication coverage of an indoor space division multiplexing visible light communication (SDM-VLC) system. One technique is a non-Hermitian symmetry orthogonal frequency division multiplexing (NHS-OFDM) scheme which can be achieved by parallelly transmitting the real (Re) and imaginary (Im) parts of a complex-valued OFDM signal via a pair of white...
A significant problem in a phase locked loop (PLL) is the initial acquisition. High resolution is a major requirement in phase modulation (PM) receivers; however, such accuracy is hindered by side band locking in the existing PM detectors. A Fast Fourier Transform (FFT) based anti-sideband locking scheme is proposed for wide band acquisition in PM receivers. It takes into purview the problems encountered...
Turbo equalization has demonstrated to be a powerful approach for wireless transmission over frequency-selective channels introducing intersymbol interferences (ISI). Regarding multiple-input multiple-output (MIMO) systems, tree-search based MIMO detection techniques (e.g., sphere detection) are well suited for significantly reducing multi-antenna interferences. However, direct application of these...
In this paper, a low-complexity turbo detection scheme based on a weighted factor graph (FG) serial-schedule (SS) belief propagation (BP) equalization method is proposed for Faster-than-Nyquist (FTN) signaling. The iterative equalization method is applied to mitigate the severe intersymbol interference (ISI) introduced by FTN signaling. In order to reduce the complexity of the equalization method,...
Next-generation (Next-G) wireless terminals need to sense their ambient and adapt to the diverse deployment scenario requirements on the fly while leveraging technology scaling. Several key circuit and system innovations are required to make the realization of this vision possible. We discuss how compressed sampling can be exploited to design a rapid, GHz-wide and energy-efficient interferer detector...
In this paper, we introduce a power recycling method for multiport receivers. A general formulation for multi-port structures as a demodulator is presented. This is followed by proposing the recycling method based on harmonic separation at the outputs. Then, the method is tested on an implemented six-port receiver at 2.4 GHz. The results shows about 17% power recovery without any degradation in the...
In this paper, we deal with the problem of detecting the signal of interest in the presence of Gaussian disturbance with symmetric spectrum and assuming that the cell under test (primary data) and the training samples (secondary data) share the same covariance matrix up to an unknown power scaling factor. Moreover, we exploit the symmetric spectral property of the disturbance to transfer the binary...
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