Performance evaluation and implementation complexity analysis framework for ZF based linear massive MIMO detection

Wireless Networks - This paper discusses a framework for algorithm-architecture synergy for (1) performance evaluation and (2) FPGA implementation complexity analysis of linear massive MIMO...     

Novel transmit antenna selection strategy for massive MIMO downlink channel

In this paper, we deal with the problem of acquiring the channel state information (CSI) at the transmitter in large-scale multiple input multiple output (MIMO) systems, so-called massive MIMO systems. Clearly, obtaining CSI plays a central role to provide high system performance. Even though, in frequency-division duplexed systems, acquiring this information requires a prohibitive amount of feedback, since it increases with the number of transmit antenna. In this work, we design an efficient transmit antenna selection strategy aware of the amount of required CSI for a point-to-multipoint transmission in massive MIMO systems. The proposed strategy provides high sum-rate with limited CSI feedback and limited computational complexity. Innovatively, the antenna selection in our strategy is performed in a decentralized fashion successively at the receiving users. Two schemes are proposed in this work to perform the antenna selection at each user. Next, taking into consideration that the large-scale MIMO transmitter suffers from imperfect knowledge of CSI, we design a new performance criterion. Computer simulations validate that, when the CSI is perfectly known, the proposed strategy is able to achieve high performance in terms of system sum-rate while a significant reduction in both CSI feedback overhead and computational complexity is observed. Moreover, assuming imperfect CSI, the new proposed criterion achieves higher performance when the estimation accuracy is low and at high SNR regime.     

Determination of cadmium in Arctic air filters by epithermal neutron activation analysis and Compton suppression

Arctic pollution is a problem of great concern, because its characteristics (transportation, assimilation into the environment, etc.) are complex and not fully understood. Detection of elemental constituents has been undertaken through the use of neutron activation analysis and Compton suppression (to lower the detection limits for radionuclides characteristic of mainly single gamma-ray emission) to discover possible pollutant sources. The goal of this project was to perform a feasibility study to determine the suitability of neutron activation analysis (NAA) to evaluate cadmium concentrations on air filters collected in the Arctic.     

Reconstruction method for jitter tolerant data acquisition system

A waveform digitizing system tolerant to deterministic jitter can be obtained by isolating the deterministic part of the jitter and calibrating the system to eliminate its effects. Calibration of the system can be made from measured nonuniform sampling times. It will be shown that this information allows reconstructing the signal at uniformly spaced sampling times. To reconstruct a signal from its nonuniform samples, we use the Shannon expansion combined with a time stretching/compressing method. Moreover, the reconstruction of a signal from a finite number of samples introduces a truncation error. We propose, using a windowing technique, to reduce the truncation error, which improves considerably the resolution, or the number of effective bits of an analog to digital conversion system.     

On MSE Exit Chart Analysis and Real Time DSP Implementation for Iterative (Turbo) Detection

We investigate the use of the mean square error (MSE) transfer characteristics to examine the convergence behaviour of the iterative (turbo) multiuser detector for coded code-division multiple-access (CDMA) systems. Both MSE and mutual information (MI) based extrinsic information transfer (MSE-EXIT and MI-EXIT) chart techniques reveal the same asymptotic and convergence behaviours. An improved low complexity version of the soft interference cancellation MMSE (SIC-MMSE) detection scheme is also proposed for CDMA systems utilizing BPSK modulation. Herein, under fixed-point data representation and computation constraint a real time DSP implementation (using TMS320C6416) is suggested. EXIT charts reveal that fixed-point implementation is feasible at possibly no performance degradation. Based on the measured number of cycles of different constituent sub-functions of the proposed receiver, a data transmission rate of up to 186 Kb/s can be reached for a 5-users load and a processing gain of 7 in an AWGN channel.     

Low-voltage, high-speed CMOS analog latched voltage comparator using the “flipped voltage follower” as input stage

The design and characterization of a low-voltage, high-speed CMOS analog latched voltage comparator based on the flipped voltage follower (FVF) cell and input signal regeneration is presented. The proposed circuit consists of a differential input stage with a common-mode signal detector, followed by a regenerative latch and a Set-Reset (S-R) latch. It is suitable for successive-approximation type’s analog-to-digital converters (ADC), but can also be adapted for use in flash-type ADCs. The circuit was fabricated using 0.18 μm CMOS technology, and its measured performance shows 12-bit resolution at 20 MHz comparison rate and 1 V single supply voltage, with a total power consumption of 63.5 μW.     

Model-aided distributed shallow learning for OFDM receiver in IEEE 802.11 channel model

Wireless Networks - Deep learning (DL) has been recognized as an instrumental tool for the design of future communication systems. Since it is still not clear whether a fully data-driven end-to-end...     

VLSI Implementation of an Adaptive Multiuser Detector for Multirate WCDMA Systems

A multirate receiver for WCDMA systems based on the adaptive signature method was designed and implemented. We employed an adaptive signature algorithm to consider two well-known multirate schemes, namely, the low rate and the high rate detector for variable spreading factor systems. In monorate scenarios, numerical experimentations showed that the adaptive signature method outperforms the Rake receiver and reaches the performances of the soft 4-stage multistage parallel interference cancellation receiver. In multirate scenarios, the performance comparison of two multirate schemes in floating-point and fixed-point was analyzed. Reusing the existing hardware architecture previously developed for monorate systems, we targeted the hardware implementation of these two multirate schemes on FPGA components.     

Low-voltage lab-on-chip for micro and nanoparticles manipulation and detection: experimental results

In this paper, a low voltage fully integrated Laboratory-on-Chip (LoC) for dielectrophoretic manipulation and capacitive sensing of nano and micro particles is presented. The proposed system is intended to design an implantable LoC. The lowest static power consumption of the implemented Integrated circuit is 650???A with a voltage supply of ?1.10 and +1.8?V. Three different sizes of carboxyl-modified polystyrene particles (diameters of 0.22, 0.97 and 2.04???m) where tested experimentally with three different electrode architectures to achieve dielectrophoretic mixing and separation. U-shaped, L-shaped and octagonal electrodes are used to perform the separation and mixing operations. The biosensing part is designed with a charge based capacitive sensor with an integrated sigma-delta modulator at its output stage. It was tested experimentally with algae and ethanol. The chip size is 1.2 by 1.2?mm and it is connected to a 15?×?30?cm microfluidic design. An efficient particle manipulation was achieved by applying a voltage of 1.7 V peak to peak in the microchannel with 90 and 180° dephased signals.