Caput medusae in alcoholic liver disease

Caput medusae and palmar erythema are cardinal signs in cirrhosis of liver with portal hypertension. Palmar erythema is described more often as a marker for alcoholic etiology of chronic liver disease. The peripheral stigmata of chronic liver disease are not routinely seen now a days due to early diagnosis and better therapy. We recently encountered an interesting patient of alcoholic liver disease with two classical signs of the disease and report the same for this unusual presentation

A MIMO-OFDM testbed, channel measurements, and system considerations for outdoor-indoor WiMAX

The design, implementation, and test of a real-time flexible 2×2 (Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing) MIMO-OFDM IEEE 802.16 prototype are presented. For the design, a channel measurement campaign on the 3.5GHz band has been carried out, focusing on outdoor-indoor scenarios. The analysis of measured channels showed that higher capacity can be achieved in case of obstructed scenarios and that (Channel Distribution Information at the Transmitter) CDIT capacity is close to (Channel State Information at the Transmitter) CSIT with much lower complexity and requirements in terms of channel estimation and feedback. The baseband prototype used an (Field Programmable Gate Array) FPGA where enhanced signal processing algorithms are implemented in order to improve system performance. We have shown that for MIMO-OFDM systems, extra signal processing such as enhanced joint channel and frequency offset estimation is needed to obtain a good performance and approach in practice the theoretical capacity improvements

Bounds and joint estimators for channel, phase noise, and timing error in communication systems using statistical framework

Bounds and joint estimators for channel and phase noise, together with timing error in the communication systems are described in this paper. We consider the wireless communication systems using Orthogonal Frequency Division Multiplexing (OFDM) with Multiple Input Multiple Output (MIMO) techniques. A MIMO-OFDM system having the influence from impairments of the channel, timing, and phase is modeled. Also, a modified signal model is developed, with the timing error embedded in the channel. Derivation of Bayesian bounds for the estimation error is done. We propose a joint Bayesian estimator for channel and phase noise with timing ambiguity in a MIMO-OFDM single-user communication system. A modified algorithm with low complexity is also developed. The analysis of the estimation performance variation due to change in the number of antennas is done. Further, the consequence of channel statistics and noise information inaccuracy on estimator performance is analyzed. (C) 2018 Elsevier Ltd. All rights reserved

A novel fractional sampling offset estimation in an OFDM system

The Orthogonal Frequency Division Multiplexing (OFDM) is a form of Multi-Carrier Modulation where the data stream is transmitted over a number of carriers which are orthogonal to each other i.e. the carrier spacing is selected such that each carrier is located at the zeroes of all other carriers in the spectral domain. This paper proposes a new novel sampling offset estimation algorithm for an OFDM system in order to receive the OFDM data symbols error-free over the noisy channel at the receiver and to achieve fine timing synchronization between the transmitter and the receiver. The performance of this algorithm has been studied in AWGN, ADSL and SUI channels successfully

Novel subspace methods for blind estimation of multiple CFOs in MIMO-OFDM systems

The problem of estimating multiple Carrier Frequency Offsets (CFOs) in the uplink of MIMO-OFDM systems with Co-Channel (CC) and OFDMA based carrier allocation is considered. The tri-linear data model for generalized, multiuser OFDM system is formulated. Novel blind subspace based estimation of multiple CFOs in the case of arbitrary carrier allocation scheme in OFDMA systems and CC users in OFDM systems based on the Khatri-Rao product is proposed. The method works where the conventional subspace method fails. The performance of the proposed methods is compared with pilot based Least-Squares method

Study Of Acoustic Source Localization Algorithm For Planar Arrays

The source localization algorithms in the earlier works, mostly used non-planar arrays. If we consider scenarios like human-computer communication, or human-television communication where the microphones need to be placed on the computer monitor or television front panel, i.e we need to use the planar arrays. The algorithm proposed in 1], is a Linear Closed Form source localization algorithm (LCF algorithm) which is based on Time Difference of Arrivals (TDOAs) that are obtained from the data collected using the microphones. It assumes non-planar arrays. The LCF algorithm is applied to planar arrays in the current work. The relationship between the error in the source location estimate and the perturbation in the TDOAs is derived using first order perturbation analysis and validated using simulations. If the TDOAs are erroneous, both the coefficient matrix and the data matrix used for obtaining source location will be perturbed. So, the Total least squares solution for source localization is proposed in the current work. The sensitivity analysis of the source localization algorithm for planar arrays and non-planar arrays is done by introducing perturbation in the TDOAs and the microphone locations. It is shown that the error in the source location estimate is less when we use planar array instead of the particular non-planar array considered for same perturbation in the TDOAs or microphone location. The location of the reference microphone is proved to be important for getting an accurate source location estimate if we are using the LCF algorithm

Vehicle Detection Tool - VDtect

The report talks about the implementation of Vehicle Detection tool using opensource software - WxPython. The main functionality of this tool includes collection of data, plotting of magnetometer data and the count of the vehicles detected. The report list about how installation process and various functionality of the tool

Block Sparse Estimator for Grid Matching in Single Snapshot DoA Estimation

In this work, the grid mismatch problem for a single snapshot direction of arrival estimation problem is studied. We derive a Bayesian Cramer-Rao bound for the grid mismatch problem with the errors in variables model and propose a block sparse estimator for grid matching and sparse recovery

Interleaved Orthogonal Frequency Division Multiplexing System

A new orthogonal frequency division multiplexing (OFDM) system for wireless communications over frequency selective fading channels is presented. The proposed interleaved orthogonal frequency division multiplexing (IOFDM) system promises higher code rate as compared to the conventional OFDM system without bandwidth expansion and with very slight increase in computational complexity. Simulation results verify that the performance, in terms of the bit error rate, of the proposed IOFDM system is very close to the conventional OFDM system