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This paper presents the simulation of a variable gain amplifier from three perspectives: functional, using LTspice circuit simulator; signal-to-noise-ratio, computed with Excel and power consumption, estimated with ACEplorer power simulator. The architectural decisions are taken based on these simulations to meet the following requirements: a dynamic range greater than 60 dB, the frequency domain...
We consider a single cell wireless uplink in which randomly arriving devices transmit their payload to a receiver. Given SNR per user, payload size per device, a fixed latency constraint T, total available bandwidth W, i.e., total symbol resources is given by N = TW. The total bandwidth W is evenly partitioned into B bins. Each time slot of duration T is split into a maximum number of retransmission...
A particular problem in satellite communications is the estimation of the current operating point of a bent-pipe transponder. Various special effects aggravate this estimation problem, among which the capture effect, gain compression, unknown attenuation in the transmission channel, or noisy received signals are the most prominent. In most practical cases, operators desire a fully blind estimator...
Multiscale systems are characterized by dynamics that evolve over different times scales and are encountered frequently in process industries. Conventional identification techniques yield poor results when applied directly to MS systems because of their inherent assumption that the system evolves at a single scale. In this paper, we discuss the key challenges in the discrete-time (DT) identification...
Usually energy-detection based spectrum sensing techniques for Cognitive Radios need, as preliminary operation, the spectrum segmentation in smaller sub-bands, in order to apply test statistic over each sub-band rather than over the entire span, resulting in a sensitivity and selectivity improvement of the output. Despite uniform subdivision is the easiest way, the problem resides on the optimal sub-band...
Genetic Algorithms (GAs) have been shown to be a very effective optimisation tool on a wide variety of problems. However, they are not without their drawbacks. GAs require time to run, and evolve a bespoke solution to the desired problem in real time. This requirement can prove to be prohibitive in a high-frequency dynamic environment where on-line training time is limited. Neural Networks (NNs) on...
A heterogeneous system is based on an integration of different types of networks. In this paper, a system based on LTE and WIMAX for the Virtual University of Senegal is presented. It aims to study and optimize the system performance considering the Signal to Interference plus Noise Ratio (SINR), the blocking probability, user communications, and mobility loss. A Markov chain was used to assess and...
Robust indoor positioning and location awareness at a sub-meter accuracy typically require highly accurate radio channel measurements to extract precise time-of-flight measurements. Emerging UWB transponders like the DecaWave DW1000 chip offer to estimate channel impulse responses with reasonably high bandwidth and excellent clock stability, yielding a ranging precision below 10 cm. The competitive...
Massive MIMO is a promising technology for 5G due to its huge extended multi-user spatial multiplexing and beamforming capability, but its high complexity makes the associated MAC scheduling suffer from long processing time in practice. To solve such problem, this paper designs a low-latency uplink MAC scheduling scheme for Massive MIMO-OFDM systems. Specifically, first, a framework enabling processing...
A novel distributed fiber-optic vibration sensor (DVS) is proposed based on multi-pulse time-gated digital optical frequency domain reflectometry (TGD-OFDR), which can solve both the trade-off between the maximum measurable distance and the spatial resolution, and the one between the measurement distance and the vibration response bandwidth. A 21-kHz vibration is detected experimentally over 10-kilometer-long...
WiFi networks play a significant role in providing today's wireless connectivity, therefore, understanding and improving WiFi network performance is important for today's mobile applications and services. Previous studies conducted to investigate WiFi network performance have generally been performed using specific types of WiFi networks in relatively small areas and have been limited by either the...
Time reversal (TR) have been widely used in underwater acoustic signal recovery. When compared with active TR, passive TR can achieve spatial-temporal compression with one-way propagation, which is more convenient to apply and can reduce the system requirement. Chirp signal, which has unique pulse compression, can effectively be combined with conventional phase, frequency, amplitude modulation with...
A cognitive radar adapts the transmit waveform in response to changes in the radar and target environment. In this work, we analyze the recently proposed sub-Nyquist cognitive radar wherein the total transmit power in a multi-band cognitive waveform remains the same as its full-band conventional counterpart. For such a system, we derive lower bounds on the mean-squared-error (MSE) of a single-target...
Cognitive Radio requires both efficient and reliable spectrum sensing of wideband signals. In order to cope with the sampling rate bottleneck when dealing with such signals, sub-Nyquist methods have been proposed. However, these techniques decrease the signal to noise ratio (SNR) due to aliasing effects. Cyclostationary detection, which exploits the periodic property of communication signal statistics,...
This paper investigates the impact of phase errors of beamforming networks on the performance of distributed transmit beamforming systems. Through multi-tone signal, wider band, models and the defined phase error percentage (PEP) of the beamforming networks, the distorted signal waveforms for different wider band occupying beamforming systems are presented. Furthermore, simulated bit error rates (BERs)...
The rapid advancement in the era of wireless applications and services has made huge demand of spectrum resources. The cognitive radio is a new concept that can utilize radio spectrum resources efficiently and sufficiently. The spectrum sensing is a function of cognitive radio. This paper develops an energy detection algorithm based on wavelet packet transform for spectrum sensing. The performance...
Software defined radios and wideband instrumentation demand the ability to digitize wide BW RF signals with moderately high dynamic range. A 12b 10GS/s ADC with an input analog bandwidth of 7.4GHz is developed for such applications in 28nm CMOS. The ADC achieves an SNR of 56dB, SNDR of 55dB and SFDR of 64dB with a 4GHz input at 10GS/s, and realizes an NSD of −157dBFS/Hz (i.e. DR = 60dB) while dissipating...
This paper presents the design procedure for a 2nd_order two-path Discrete-Time Time-Interleaved (DTTI) ΔΣ modulator from a conventional single-loop 2nd-order Discrete-Time (DT) ΔΣ modulator through the use of time domain equations and time-interleaving concepts [1]. The resulting modulator is free from the delayless feedback path and has only one set of integrators. The delayless feedback path issue...
Approximate computing aims to expose and exploit quality vs. efficiency tradeoffs to enable ever-more demanding applications on energy-constrained devices such as smartphones, or IoT devices. This paper makes the case for arbitrary quantization as a compelling approximation technique that exposes quality vs. energy tradeoffs and provides practical error guarantees. We present QAPPA (Quality Autotuner...
Scheduling process is a tedious task in heterogeneous networks because of the large number of users and the reduced radio resource facilities. Scheduling is nothing but granting certain number of sources to the users in a frequency and timing fashion. Resources define the symbols and subcarriers for transmitting the bits in scheduling. There are many ways to assign these things to the subscribers...
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