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Future and emerging radar systems are experiencing growing reliance on MIMO functionality in order to support demand for finer resolution and greater data collection under increasingly stringent spectral requirements. In order to support MIMO functionality while preserving spectral usage requirements, pseudo-orthogonal waveform sets are desired. In order to balance the complicated and often contradicting...
Cloud computing has been proposed as a new paradigm to deliver services over the internet. The proliferation of cloud services and increasing users' demands for computing resources have led to the appearance of geo-distributed data centers (DCs). These DCs host heterogeneous applications with changing characteristics, like the CPU-load correlation, that provides significant potential for energy savings...
This paper investigates the time-domain characteristics of an ultrawideband (UWB) dielectric resonator antenna (DRA) for two UWB input pulses. The computed spectrum amplitude of a fifth-order Gaussian pulse has better compliance, as per FCC mask, compared to a first-order Rayleigh pulse. The correlation between the input pulses and the radiated pulses in many directions were found to be less when...
The exponential growth and proliferation of the MOOC platform in recent years has facilitated easy access to advanced learning materials in the form of video lectures across almost all major specializations. The ever expanding outreach of internet has further boosted the utility and attraction of this medium of learning across the globe. Handheld devices like i-pad and e-notebooks can be used to access...
Improving antenna arrays characteristics such as power consumption, cost and complexity has gained wide attention in the context of cognitive radio networks. One antenna array configuration that offers great potential is the electronically-steerable parasitic array radiator (ESPAR) antenna. In this paper, we propose a transmitter patch ESPAR antenna system for underlay spectrum sharing in cognitive...
Precise understanding of the sea bottom characteristics and accurate identification of objects on the seabed are critical in many underwater applications. The severe multi-path along with the time varying and random reflections from the surface and the bottom of shallow waters, present an interesting and complex signal processing problem. A thin line hydrophone array, deployed from small Autonomous...
The use of orthogonal waveform can offer many advantages in covert underwater acoustic communication, including improved symbol detection ability. In this paper, we derive a new orthogonal code design. The proposed code has a good autocorrelation property compared to other codes. We present some results of a lake trial to evaluate the performance of the proposed method.
A novel approach based on digital linear frequency modulation (LFM) with anti-aliasing system for adjustable compensation of the active filter frequency response has been proposed to implement high speed pulse compression on Field Programmable Gate Array (FPGA) chip. The main objectives are high speed pulse compression for high range resolution in target detection using modified Fast Fourier Transformation...
A multi-service (MS) code based Spectral Amplitude Coding-Optical Code Division Multiple Access (SAC-OCDMA) system at different number of basic user, typically suitable for video, audio and data transmission is experimentally investigated. The work is carried out to show the feasibility of the previous work that has been demonstrated using mathematical computation. The obtained results indicate that...
This paper introduces a novel image error concealment technique, wherein the correlation among the correctly received pixels is implicitly exploited to recover the missing areas. This correlation is modeled as sparse representations of the correctly received surrounding areas of a lost regions, hence as a linear combination of very few atoms chosen from an over-complete dictionary. Under mild conditions,...
Antennas can couple if they are placed near each other, such as on portable wireless devices. Such coupling is often viewed as a nuisance that is a detriment to system performance. We show how coupling, if exploited properly, can lead to higher achievable data rates than an equivalent uncoupled system. Our conclusions build on some recent results on the bandwidth of coupled radiofrequency systems.
We report the design of a new application-specific integrated circuit (ASIC) for use in radio telescope correlators. It supports the construction of correlators for an arbitrarily large number of signals. The ASIC uses an intrinsically low-power architecture along with design techniques and a process that together result in unprecedentedly low power consumption. The design is flexible in that it can...
The dynamic spectrum allocation is important to improve spectrum efficiency usage of available radio spectrum. Cognitive radio has emerged as a solution to dynamic spectrum access, due to its adaptability and re-configurability. The main problem of cognitive radio is how the secondary users can detect the holes in the frequency band of the primary users. Spectrum sensing is the main feature of cognitive...
Lag windowing has long been used for the autocorrelation method of linear predictive (LP) analysis to prevent possible instability of the synthesis filter with the obtained coefficients. We have investigated the lag-window shape in terms of the trade-offs between stability and the coding efficiency. On the basis of these investigations, we have devised an adaptive selection scheme in which the window...
This paper proposes a distributed compressive sensing (CS) scheme for robust image transmission over unknown or time-varying channels with highly correlated images at the decoder. A compressed thumbnail is first transmitted after digital forward error correction (FEC) and modulation to retrieve highly correlated images and generate a side information (SI) at the decoder. The current residual image...
In this paper, we propose a frequency coding waveform with a nonlinear frequency modulation (NLFM) signal for the multiple-input multiple-output (MIMO) radar. The transmitted signal of each transmitting antenna is a pulse train, of which, the sub-pulses are NLFM signals with different carrier frequencies. The frequency sequence and the parameter of the nonlinear frequency function are optimized to...
The time-varying landscape of spectral congestion is driving the investigation into new forms of “spectrally aware” radar emissions based on passive sensing of the environment. The recent Pseudo-Random Optimized FMCW (PRO-FMCW) framework, which can be viewed as an instantiation of FM noise radar, generates a nonlinear FMCW waveform that does not repeat and is designed using spectrally shaped optimization...
We propose and experimentally demonstrate a microwave photonic system that iteratively performs principal component analysis on partially correlated, 8-channel, 13 Gbaud signals. The system that is presented is able to adapt to oscillations in interchannel correlations and follow changing principal components. The system provides advantages in bandwidth performance and fan-in scalability that are...
Modern communication systems demand proper utilization of power as well as bandwidth. To satisfy the requirements of bandwidth and power, various multiple access technologies are used successfully in communication systems. Code Division Multiple Access (CDMA) is the most popular among these schemes which uses total available channel bandwidth to serve all users simultaneously. In CDMA system, individual...
A hybrid direct sequence and frequency hopping (DSFH) spread spectrum signal can greatly improve ranging precision and jamming resisting capability in spacecraft TT and C (Tracking, Telemetry and Command). The frequency hopping adds another searching dimension to acquisition and increases the acquisition complexity. Therefore, this paper designs a phase-compensating-based acquisition algorithm. First,...
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