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We have conducted the basic research on long horizontal communication using time reversal in the deep ocean, which will be applied for communicating with an autonomous underwater vehicle (AUV) in the future. To achieve such communication, time reversal is an attractive solution. Because intersymbol interferences (ISI) are removed and signal noise ratio is improved. In our previous studies, a method...
The use of infrared radiation as a medium for high speed and short-range application is proposed for communication in the aircraft passenger cabin since it does not cause any interference to aircraft navigation systems. In this paper: first of all, using Lambert's model, the power received at the receiver via single reflection propagation inside the cabin was modeled. Then, the free space loss which...
Digital beamforming (DBF) technology is progressed with the development of adaptive algorithms and architectures Modern beam forming systems have been aided by advancements in VLSI design, adaptive algorithms, RF up/down conversion systems and high sampling rate ADCs. Digital beamforming enables full utilization of the maximum number of degrees of freedom in the array. In conventional N-element array...
Analog shortwave radio on bands up to 30 MHz has typically been limited in applicability for long-distance broadcast applications requiring high signal fidelity. This is because of the vulnerability of analog modulation schemes to atmospheric dispersion; however, the Digital Radio Mondiale (DRM) standard, introduced in 2001, is a promising solution for shortwave radio. DRM provides various audio and...
This paper reports a research testbed of real-time ultra-wideband (UWB) multiple-input multiple-output (MIMO) radio. In the receiver design, the UWB MIMO receiver supports up to eight channels, where each channel is equipped with an analog-to-digital converter (ADC) with 8-bit resolution and sampling rate up to 3 Giga samples per second (Gsps). The transmitter is able to transmit two independent arbitrary...
In any communication system, the emphasis is on estimating the channel response so as to retrieve the transmitted input signal accurately at the receiver's end. Channel Equalisation at the transmitter refers to pre-distorting the input signal so that the effect of the channel is nullified during transmission. This approach works out for slow fading channels where the channel response remains almost...
In wireless applications, power consumption has been, and will be, one of the important characteristics when designing any wireless device. This is the case especially in sensor networks where a single sensor may be functioning, hopefully for very long time, without external power source. Generally, the architecture complexity reduces the battery life, but the performance increases with complexity...
GPS common-view is the main method for the time and frequency remote transfer originally, of which the uncertainty can reach several nanoseconds. This paper presents a procedure to simplify the original common-view time transfer system constructed using a powerful dual-frequency multi-channel EURO-160 GPS receiver and a high precision time interval counter SR-620. The relevant data-processing software...
This paper presents the results and methodology of recent system-level proton testing which was performed on a COTS-based GPS receiver to be used in a launch vehicle application. Susceptibility to ionizing radiation was a concern due to a high part count and component sophistication. Testing was conducted using 50 MeV protons at the Lawrence Berkeley National Laboratory (LBNL). An approach for the...
Communications in the aerospace environment is often very challenging. These challenges increase with the demand for higher data rates. This paper focuses on design and implementation of synchronization circuits for Direct Sequence Spread Spectrum (DSSS) receivers using Field Programmable Gate Arrays (FPGAs). In aerospace communications, it is the wireless digital communications receiver which bears...
We study the definition of exclusion region through handshake control bursts. The RTS/CTS (request to send/clear to send) bursts that typically take part in the handshake between the radio transmitter and receiver are a perfect medium for sounding their surroundings. Therefore, they can be utilized for setting exclusion regions - geographical areas protecting the active receivers from interference...
In this paper, the exact symbol error probability expression for a decode-and-forward cooperative relaying scheme using quadrature amplitude modulation (QAM) in the presence of Rayleigh fading and Bernoulli-Gaussian impulsive noise is derived. Different from, we only consider the practical receiver structure at the destination without requiring any knowledge of impulsive noise. Also, the source retransmission...
TCP does not perform well in networks with stochastic channels, with links that randomly drop packets or have long outages. Diversity routing has been proposed to improve TCP's performance in these networks. In diversity routing, a sublayer between TCP and the network replicates each transmitted packet and sends the multiple copies along parallel paths. As long as at least one of the copies reaches...
Non-coherent UWB receivers are often implemented using energy detection architectures which are very sensitive to noise in the channel and interference. Therefore, the receiver bandwidth plays an important role since the total noise and interference energy is proportional to this bandwidth. This work provides analytical expressions to find the optimal receiver bandwidth and quantifying the effect...
Wake-up radio technology is a means to improve energy efficiency in low-power wireless sensor networks. In such radios, low-power low-complexity designs are considered, often based on narrow-band transmission, simple modulation techniques, noncoherent detection and matched filter receivers. In order to improve the performance of wake-up radios in interference limited scenarios, while keeping the power...
Spectrally Efficient Frequency Division Multiplexing (SEFDM) systems aim to reduce the utilized spectrum by multiplexing non-orthogonal overlapped carriers. Since the per carrier transmission rate is maintained, SEFDM yields higher spectral efficiency relative to an equivalent Orthogonal Frequency Division Multiplexing (OFDM) system. Yet, due to the loss of the orthogonality, detection of the SEFDM...
A co-simulation result of a Zero crossing BFSK demodulator with a frequency-hopped spread-spectrum receiver for wireless sensor applications in the 863-870-MHz ISM band is presented. The structure is suitable for Zigbee (IEEE 802.15.4) receiver. The zero crossing demodulator uses a digital one-shot circuit as a differentiator and a pulse width equalization circuit. The proposed demodulator is able...
New method for equalization and symbol detection for 8-PSK EDGE system is investigated in this study. The exact solution to this problem, Maximum Likelihood Sequence Estimation (MLSE) turns out to be too complex for practical purposes, but this method introduce a new version of Delayed Decision Feedback Sequence Estimation (DDFSE) equalizer that has less complexity and totally comparable performance...
This article addresses the signal distortion caused by receiver phase noise (PN) on OFDM waveforms in direct-conversion radio receivers. A closed-form solution for the observed signal-to-interference-plus-noise ratio (SINR) is derived, describing the level of intercarrier interference (ICI) stemming from PN. Compared to existing literature, the analysis is valid for arbitrary oscillator spectral shape,...
This paper considers the problem of uplink scheduling in wireless networks supporting successive interference cancellation (SIC) at the physical layer. By allowing concurrent interfering transmissions, SIC enables multi-packet reception at the receiver resulting in increased network throughput. Specifically, we consider maximum throughput scheduling and proportional fair scheduling problems and study...
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