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A power-efficient analog beamforming embedded SAR ADC for ultrasound imaging systems is presented. It is constructed from multiple sub-beamforming SAR ADCs, which sequentially perform analog beamforming and analog-to-digital conversion for an assigned focal point on a scan-line. Power is saved because these operations are carried out in the charge domain without a summing op-amp. This is realized...
This paper proposes an incremental redundancy hybrid ARQ (IR-HARQ) scheme for the wireless local area network (WLAN) system employing multiband simultaneous transmission. The proposed scheme adopt the rate compatible low-density parity-check (RC-LDPC) codes based on IEEE802.11n LDPC codes and ensure backward compatibility with WLAN devices by using the current WLAN control frame. Additionally, it...
This paper presents a ray tracing approach to optimise the position of a relay in a static environment such that the signal-to-noise ratio (SNR) is maximised at the receiver. The underlying principles behind the ray tracing wireless channel model are summarised. An implementation of a ray tracing algorithm is developed in MATLAB to calculate the channel state information (CSI) of a relay-assisted...
Security threats such as jamming and route manipulation can have significant consequences on the performance of modern wireless networks. To increase the efficacy and stealthiness of such threats, a number of extremely challenging, next-generation cross-layer attacks have been recently unveiled. Although existing research has thoroughly addressed many single-layer attacks, the problem of detecting...
Time Difference Of Arrival (TDOA) method is very often used inside electronic intelligence systems. TDOA method requires the high signal to noise ratio at the output of the intermediate frequency amplifier for target localization, usually around 12 dB or more. At low signal-to-noise ratio TDOA is inaccurate and especially in case of the active jamming it is nearly impossible. The multilateral TDOA...
A new technique to reduce the clock jitter effect on single-bit continuous-time delta-sigma modulators (CTDSM) is proposed. It utilizes a delay line to generate N highly correlated clock sources to reconstruct the feedback waveform. Theoretical analysis show that the jitter-induced random noise power is reduced by a factor of 1/N2. Simulation results confirming the analysis are reported.
Multi-channel speech enhancement algorithms rely on a synchronous sampling of the microphone signals. This, however, cannot always be guaranteed, especially if the sensors are distributed in an environment. To avoid performance degradation the sampling rate offset needs to be estimated and compensated for. In this contribution we extend the recently proposed coherence drift based method in two important...
In this paper, we propose a cross-layer design framework for transmitting Markov modulated Poisson process (MMPP) traffic over cognitive cooperative networks, which considers the energy efficient transmissions for different delay-aware packets. The adaptive modulation and coding (AMC) is used in the cooperative transmission system. The queueing process is considered in the buffer aided relay and source...
In this paper, a waveform design method utilizing the low maximum side-lobe in the synthetic range profile as the criterion for the random hopping frequency radar is proposed. Firstly, the center range ambiguity function which represents matched filtering output of transmitted signal is derived. And the output signal to noise ratios (SNR) of it and the synthetic range profile based on correlation...
Multichannel receivers are usually employed in high-rate underwater acoustic communication to achieve spatial diversity. Passive time reversal combined with a single-channel adaptive decision feedback equalization (PTR-DFE) is a low-complexity solution to achieve both spatial and temporal focusing. Block-based PTR-DFE (BB-PTR-DFE) extends PTR-DFE to time-varying channels. Multichannel DFE (M-DFE)...
Feature-based classification is a method used for automatic modulation classification of communication signals. This method requires extraction of various features from a signal. One of the approaches for feature extraction is the use of instantaneous amplitude, phase and frequency. The performance of these features under different SNR conditions is well described in literature [1]-[2], but the effect...
A dynamic bias pre-amplifier based latch type comparator is designed in a 65nm CMOS process. Its performance is compared with the double-tail latch-type comparator fabricated on the same chip in terms of energy consumption, input referred noise and speed. Measurements demonstrate that the proposed dynamic bias pre-amplifier based comparator consumes 2.8 times less energy per comparator operation with...
The development of ultrafast ultrasound imaging brings great opportunities to improve imaging technologies such as shear wave elastography and ultrafast Doppler imaging. In ultrafast imaging, there are trade-offs among image signal-to-noise ratio (SNR), resolution, and the high frame rate. Multiplane wave (MW) imaging is proposed to solve this tradeoff by encoding multiple plane waves with positive/negative...
Ultrafast ultrasound imaging offers great opportunities to new imaging technologies such as shear wave elastography and ultrafast Doppler. Multiplane wave (MW) imaging is a new technique in which multiple positively or negatively encoded plane waves are emitted successively with short interleaved time during one transmission event (i.e. pulse-echo event), aiming at increasing the signal-to-noise ratio...
The heaviest challenge in wireless is to provide seamless connectivity even during mobility. In our paper, we have proposed a scenario where we use a telemedicine vehicle which supports IEEE 802.11b and Long Term Evolution (LTE). The connection between heterogeneous networks is done through the support of the proposed Dynamic Media Selection algorithm (DMS). DMS comes into the scenario when the mobile...
The inherent nature of polar codes being channel specific makes it difficult to use them in a setting where the communication channel changes with time. In particular, to be able to use polar codes in a wireless scenario, varying attenuation due to fading needs to be mitigated. To the best of our knowledge, there has been no comprehensive work in this direction thus far. In this work, a practical...
Non-line-of-sight (NLOS) propagation is one of the major barriers to accurate ranging and positioning based on time of arrival (TOA) in the application of an ultra wideband (UWB) system. This paper proposes a new method for NLOS identification and mitigation based on signal characteristic analysis and fuzzy theory. This method neither requires to build a statistical model nor to create and update...
An electric network frequency (ENF) signal can be found in multimedia recordings due to propagation from the power grid. There a variety of applications based on ENF signal use, such as video and audio stream synchronization, and origin determination of multimedia recordings. In this paper, we propose the use of ENF to synchronize real-time audio streams from different, non-synchronized sound devices,...
Direction of Arrival estimation is a topic of paramount significance to both military and commercial applications in locating under water objects. Passive localization system, traditionally using acoustic pressure sensor array, estimates the geometrical coordinates of the acoustic sources by spatially sampling the propagating scalar pressure field radiated from the sources. The performance of spatial...
Effective Capacity (EC) indicates the maximum communication rate subject to a certain delay constraint while effective energy efficiency (EEE) denotes the ratio between EC and power consumption. In this paper, we analyze the EEE of ultra-reliable networks operating in the finite blocklength regime. We obtain a closed form approximation for the EEE in Rayleigh block fading channels as a function of...
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