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Cooperation diversity schemes employing distributed spacetime block coding (STBC) techniques have been proposed for wireless networks to increase system capacity and coverage even when each node is only equipped with a single antenna. Capitalizing on randomized STBC, a decentralized coding method that has been developed for decode-and-forward relaying, a cooperative communication protocol is proposed...
Noncoherent UWB receivers promise low power consumption and low processing complexity but their peak data rate is limited by the delay spread of the multipath radio channel. A recently proposed multichannel autocorrelation receiver (AcR) can break this rate limit because it can demodulate multicarrier signals. The hardware implementation of this receiver architecture is addressed in this paper. We...
Manufacturing process variations (PV) of transistors in the deep-submicron regime present the single biggest design challenge for large die size VLSI circuits such as processor arrays, GPUs, and FPGAs. However, there are a few applications in signal processing, such as image processing, and speech processing, where errors in computation by the underlying hardware could be tolerated or corrected off-line...
This paper looks at the Signal Transfer Function (STF) behaviour of cascaded Continuous-Time Delta-Sigma Modulators (CTDSMs) and how the flattening technique proposed by De Maeyer et al. can be used to reduce the effect of interfering signals and performance degradation for a subset of Excess Loop Delays (ELDs). Furthermore it will be shown that the noise-shaping performance of a CTDSM can be improved...
This paper presents a flash-type Time to Digital Converter (TDC) based on parallel delay elements in 65-nm CMOS process technology. By using parallel delay elements the conversion resolution of the TDC becomes equal to the difference of delay elements rather than the delay time of each element. A Sensed Amplifier Flip Flop (SAFF) ensures narrow sampling window. Operating at 1.2-V supply, this TDC...
This work presents a simple approach to the correction of absolute gain errors in a tunable continuous-time bandpass Delta-Sigma modulator based on a Leslie-Singh architecture. The calibration is performed in the digital domain using the employed hardware. Thus, no additional analog circuitry overhead is added to the system. By tuning the center frequency of the analog resonator for correction, matching...
In this paper, a design of the first-order Frequency-based Delta-Sigma Modulator (FDSM) utilizing multi-phase quantizer is presented. The VCO (Voltage-Controlled Oscillator) which behaves as a voltage-to-phase integrator will be proposed to generate multiple output phases. Each phase output from the VCO drives a counter using the proposed CMSA-FF (Current-Mirror Sense-Amplifier Flip-Flop), producing...
TLB misses have been considered an important source of system overhead and one of the causes that limit scalability on large supercomputers. This assumption lead to HPC lightweight kernel designs that usually statically map page table entries to TLB entries and do not take TLB misses. While this approach worked for petascale clusters, programming and debugging exascale applications composed of billions...
In this paper, a simple topology to reduce delay variations in domino logic gates is discussed. According to a previous analysis by the same authors, the feedback loop implemented by the keeper transistor and the output inverter gate is responsible for a delay variability increase, compared to static CMOS logic. The proposed strategy reduces the loop gain associated with this feedback loop, and hence...
In this paper, an output-dependent delay cancellation (ODDC) technique is proposed. For a high-accuracy digital-to-analog converter (DAC), the delay differences caused by output voltage is one of the major nonlinearities that deteriorate the dynamic performance. The ODDC technique has the advantages of significant improvement on the dynamic performance in a wide frequency range without increasing...
In the 3rd generation partnership project (3GPP) long term evolution (LTE) time division duplex (TDD) systems, base stations use uplink sounding reference signals (SRSs) to estimate downlink channel state information (CSI) for downlink beamforming transmissions. Because SRSs sent by up to 8 users are multiplexed on the same time-frequency resources, there exist mutual interferences among these SRSs...
One of the today challenges for the mesh networks researches is reliable transmission of multimedia traffic. This traffic demands high quality of service (QoS), to provide which it is suitable to use Mesh Coordinated Channel Access (MCCA) — the novel medium access method described in IEEE 802.11s. According to MCCA, mesh stations (STAs) set up periodic reservations; if all STAs in the network support...
In this paper, some codes are designed for a binary chip-asynchronous CDMA system which guarantee errorless communication in the absence of noise. These codes also show good performance for noisy channels. In addition, lower and upper bounds for the sum channel capacity are derived for finite and asymptotic cases with the assumption of both noiseless and noisy channels. The results are derived assuming...
This paper investigates the impact of noise dependence and signal delay on the capacities of networks. It is shown that statistical dependence between the noise in a network's component channels is helpful for communication. In particular, the capacity region of a network whose component channels exhibit dependent noise is a superset of the capacity region of a network built from the same component...
eLoran has the potential to act as a cross-platform backup radio-navigation system to GPS to provide Position Navigation and Timing. As service providers of differential-eLoran for maritime navigation, the General Lighthouse Authorities of the UK and Ireland (the GLAs) must ensure that the system meets the internationally agreed standards for Accuracy, Availability, Continuity and Integrity.
Recently, Delay-Tolerant Space-Time Codes (DT-STCs) have been designed for cooperative communications. They are optimal in synchronous transmission and preserve their full-diversity order for arbitrary delays in asynchronous case. In this paper, we investigate these DT-STCs in femtocell networks where Femtocell Access Points can assist Macrocell Base Stations to transmit data information to users...
Orthogonal Frequency Division Multiplexing (OFDM) is considered as an effective method for overcoming problems such as noise, multi-path propagation and frequency selective fading in low voltage power-line communication (PLC). However, OFDM system is sensitive to the error of synchronization. Accurate symbol timing and carrier frequency offset estimation are crucial to the PLC system based on OFDM...
Abstract-Temperature variation of some important nodes in the substation can reflect the danger operation of substation equipment. By predicting the temperature we can discover the potential hidden fault in the substation. An improved algorithm for predicting the temperature of the substation in this article is presented in this paper, which combines Echo State Network (ESN) and Local Average Denoising...
This paper details one of the front-end components of the system used at the PASCAL-CHiME multi-source robust automatic speech recognition (ASR) challenge 2011. The presented approach uses uncertainty propagation techniques to integrate conventional beamforming with automatic speech recognition. The paper addresses the derivation of a complex Gaussian posterior for the multi-channel Wiener and the...
In this paper, we describe a distributed delay and sum beamformer (DDSB) for speech enhancement based on a randomized gossip algorithm. The proposed algorithm operates in a randomly connected wireless sensor network. Without any network topology constraint, the DDSB estimates the desired signal at each node by only exchanging information with its neighbors. Since the DDSB performs only local signal...
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