182 research outputs found
Adaptive minimum symbol-error-rate decision feedback equalization for multilevel pulse-amplitude modulation
No full textThe design of decision feedback equalizers (DFEs) is typically based on the minimum mean square error (MMSE) principle, as this leads to effective adaptive implementation in the form of the least mean square algorithm. It is well-known, however, that in certain situations the MMSE solution can be distinctly inferior to the optimal minimum symbol error rate (MSER) solution. We consider the MSER design for multi-level pulse-amplitude modulation. Block-data adaptive implementation of the theoretical MSER DFE solution is developed based on the Parzen window estimate of probability density function. Furthermore, a sample-by-sample adaptive MSER algorithm, called the least symbol error rate (LSER), is derived for adaptive equalization application. The proposed LSER algorithm has a complexity that increases linearly with the equalizer length. Computer simulation is employed to evaluate the proposed alternative MSER design for equalization application with multi-level signalling schemes
Asymptotic Bayesian Decision Feedback Equalizer Using a Set of Hyperplanes
No full textWe present a signal space partitioning technique for realizing the optimal Bayesian decision feedback equalizer (DFE). It is known that, when the signal to noise ratio (SNR) tends to infinity, the decision boundary of the Bayesian DFE is asymptotically piecewise linear and consists of several hyperplanes. The proposed technique determines these hyperplanes explicitly and uses them to partition the observation signal space. The resulting equalizer is made up of a set of parallel linear discriminant functions and a Boolean mapper. Unlike the existing signal space partitioning technique of Kim and Moon, which involves complex combinatorial search and optimization in design, our design procedure is simple and straightforward, and guarantees to achieve the asymptotic Bayesian DFE
The social construction of meaning : Reading Animal Farm in the classroom
No full textThe novel, it has generally been assumed, was from its very beginnings a literary form designed to be read by solitary, silent individuals. One consequence of this assumption is that the class novel, read amid all the noise and sociality of the classroom, tends to be treated as a preparation formore authentic, private reading, or even as poor substitute for it. This essay argues that the history of novel-reading is more complicated and more varied than has been assumed; it goes on to explore, through the story of a single lesson, the possibilities for meaning-making that are the product of particular pedagogic practices as well as of the irreducibly social process of reading the class novel
Analysis and Design of Decision Feedback Equalizers for Bitrates of 10 Gbps and Beyond in Submicron CMOS
No full textA guideline on how to design and specify a Decision Feedback Equalizer (DFE) for bitrates of 10 Gbps and Beyond. First, this work provides a classification of the state of the art for Decision Feedback Equalizers. Second, this work provides insight about the behaviour of a DFE with increasing number of taps and channel length with measurements done with a state of the art Digital Spectrum Analyser. It also includes a Two-Tap adaptive DFE behavioural model developed by the author of this report. A comparison within the impulse response, the Digital Spectrum Analyzer and the taps obtained with the behavioural model is also developed on this report. Third, on a circuit level perspective, this work exposes the pros and cons of implementing the DFE with different kind of summers and it proposes two unexplored alternative summers to achieve Decision Feedback Equalizer. At the end of this report, a final implementation for the target Clock Data Recovery is done with state of the art performance for a Tenth-Rate DFE. The recommendations on implementing the DFE, how to make it adaptive and all the relevant conclusions are exposed in the last chapter of this report.MicroelectronicsElectrical Engineering, Mathematics and Computer Scienc
A New Noise Variance Based Layered Pruning ML-DFE Algorithm
No full textA new noise variance based reduced maximum likelihood decision feedback equalization (ML-DFE) algorithm has been developed. This algorithm reduces the calculation complexity by exploring the intrinsic statistical properties layer by layer. Through setting layered thresholds, part of the nodes in the searching process will be cut by comparing with the thresholds. Simulation results show that the complexity drops lots while the performance drops small.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000309338500262&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701TelecommunicationsTransportation Science & TechnologyEICPCI-S(ISTP)
K-axis dissolved iron (dFe) data from the Kerguelen-Axis region of the Southern Ocean
No full textProgress Code: completedStatement: No problems with analysis, but there were a lot of problems with GO-FLO bottles during sampling, i.e. bottles either not closing or leaking on arrival on deck. As a result, there is a large number of missing samples (NaN), and we also took some salinity samples for additional data quality control as follows:
A subset of salinity samples (n=124) was taken from GO-FLO bottles to check whether bottles had closed at the expected depths and/or whether there were problems with leaking. Salinity samples were compared to CTD salinities, and samples where measured salinity did not match the respective CTD salinity (n=9) were flagged as suspect and are not included in the data sheet. Note that salinity checks were predominantly performed on GO-FLO bottles that were suspicious (e.g. leaking), so they do not represent a random set of samples.<b>Purpose</b><br/>Supply dissolved iron data for the K-axis region. Complimentary to other K-axis data.Sampling was conducted according to GEOTRACES protocols. Samples for trace element analyses, including dissolved iron (dFe), were filtered through acid-cleaned 0.2 um cartridge filters (Pall Acropak) under constant airflow from several ISO class 5 HEPA units. All plastic ware was acid-cleaned prior to use, following GEOTRACES protocols. Samples were collected into low-density polyethylene (LDPE) bottles, acidified immediately to pH 1.7 with Seastar Baseline hydrochloric acid (HCl), double-bagged and stored at room temperature until analysis on shore. <br/><br/>Samples for dFe analysis were pre-concentrated offline (factor 40) on a SeaFAST S2 pico (ESI, Elemental Scientific, USA) flow injection system with a Nobias Chelate-PA1 column. Samples were eluted from the column in 10% distilled nitric acid (HNO3), with calibration based on the method of standard additions in seawater (made using multi-element standards in a 10% HNO3 matrix, rather than an HCl matrix). Pre-concentrated samples were analysed using Sector Field Inductively Coupled Plasma Mass Spectrometry (SF-ICP-MS, Thermo Fisher Scientific, Inc.). Data were blank-corrected by subtracting an average acidified milli-Q blank that was treated similarly to the samples. <br/><br/>The dFe detection limit for a given analysis run on the SeaFAST/SF-ICP-MS was calculated as 3 x standard deviation of the milli-Q blank on that run. Detection limits ranged from 0.016 to 0.067 nmol kg-1, with a median of 0.026 nmol kg-1 (n=12). GEOTRACES reference materials were analyzed along with samples and results were in good agreement with consensus values: SAFe D1 was measured at 0.69 +/- 0.05 nmol kg-1 (n=7; consensus value = 0.67 +/- 0.04 nmol kg-1) and GD was measured at 1.02 +/- 0.01 nmol kg-1 (n=6; consensus value = 1.00 +/- 0.1 nmol kg-1). <br/><br/>Comments regarding the data spreadsheet:<br/>NaN = no sample<br/>dFe QC flags: 1 = high confidence in data quality<br/> 2 = detection limit<br/> 3 = low confidence in data quality<br/>detection limits: dFe data that were below the daily detection limit were replaced with the respective detection limit. They are flagged with the number 2 in the dFe QC flag column
Frequency-domain precoding for single carrier frequency-division multiple access
No full textAt present there is considerable interest in the use of single carrier frequency-division multiple access. This interest is justified by the inherent single carrier structure of the SC-FDMA scheme, which is more robust against phase noise and has a lower peak-to-average power ratio than orthogonal frequency-division multiple access. This consequently makes it more attractive for uplink transmission from low-cost devices with limited transmit power. SC-FDMA commonly makes use of frequency domain linear equalization in order to combat the frequency selectivity of the transmission channel. Frequency domain decision feedback equalization, composed of a frequency domain feed forward filter and a time domain feedback filter, outperforms LE due to its ability to cancel precursor echoes. Although these solutions suffer from error propagation, results show that DFE still offers a significant performance gain over conventional LE for uncoded SC-FDMA. In this article we show how precoding can be used on the uplink of the LTE standard to overcome the frequency selective nature of the radio channel. We propose a frequency domain implementation of Tomlinson- Harashima precoding and investigate the bit error rate and the PAPR performance for SCFDMA using ZF and MMSE THP.At present there is considerable interest in the use of single carrier frequency-division multiple access. This interest is justified by the inherent single carrier structure of the SC-FDMA scheme, which is more robust against phase noise and has a lower peak-to-average power ratio than orthogonal frequency-division multiple access. This consequently makes it more attractive for uplink transmission from low-cost devices with limited transmit power. SC-FDMA commonly makes use of frequency domain linear equalization in order to combat the frequency selectivity of the transmission channel. Frequency domain decision feedback equalization, composed of a frequency domain feed forward filter and a time domain feedback filter, outperforms LE due to its ability to cancel precursor echoes. Although these solutions suffer from error propagation, results show that DFE still offers a significant performance gain over conventional LE for uncoded SC-FDMA. In this article we show how precoding can be used on the uplink of the LTE standard to overcome the frequency selective nature of the radio channel. We propose a frequency domain implementation of Tomlinson-Harashima precoding and investigate the bit error rate and the PAPR performance for SCFDMA using ZF and MMSE TH
A Phenomenological Approach to Care Leavers’ Transition to Higher Education
No full textPrevious research conducted in the UK has highlighted issues with the educational experiences of care leavers in general and has suggested that life transitions affect care leavers’ later experiences. However, the participation and achievement of care leavers in education particularly care leavers’ experiences of transitions in education, remains under-researched. This research investigated the educational experiences of nine care leavers studying in their first or second year, at universities across the Greater Manchester and Yorkshire areas of Northern England. Each participant took part in a semi-structured interview relating to their transition to university. Adopting a phenomenological approach, interview transcripts were analysed through Interpretative Phenomenological Analysis (IPA). Three main themes emerged; ‘care leaver identity’, ‘lack of positive care leaver role models’, and ‘corporate versus normal parenting’. The first theme ‘care leaver identity’, investigates what impact being a care leaver has on the participant personally and within their education. The second theme ‘lack of positive care leaver role models’ explores, what effect role models have on care leavers within their educational pursuits, and the final theme ‘corporate versus normal parenting’, investigates care leavers’ perception of what ‘parenting’ means and the nature of the parenting they receive
‘A School Under Scrutiny: A Personal Account of The Impact of Inclusion on a Small Primary School in England’
No full textThis paper presents a personal account of a teacher who has
responsibility for the coordination of pupils with special educational
needs. In this paper she has been referred to as Sally. Sally teaches in a
school in England with a significantly high proportion of pupils with
special educational needs. The account demonstrates how current
measures of school effectiveness in England have disadvantaged a small
school which has an outstanding local reputation for inclusion. This has
led to increased levels of surveillance for the teachers who have chosen
to work in this school, whilst other local schools enjoy the benefits of
having good reputations. The paper raises questions about whether
inclusion is too much of a risk for schools given that they operate within
a climate of performativity. Additionally, it raises questions about
whether current measures of school effectiveness are fair on those
schools with more diverse populations
Recent Results From the EU POF-PLUS Project: Multi-Gigabit Transmission Over 1 mm Core Diameter Plastic Optical Fibers
No full textRecent activity to achieve multi-gigabit transmission over 1 mm core diameter graded-index and step-index plastic optical fibers for distances up to 50 meters is reported in this paper. By employing a simple intensity-modulated direct-detection system with pulse amplitude or digital multi-tone modulation techniques, low-cost transceivers and easy to install large-core POFs, it is demonstrated that multi-gigabit transmission up to 10 Gbit/s over 1-mm core diameter POF infrastructure is feasible. The results presented in this paper were obtained in the EU FP7 POF-PLUS project, which focused on applications in different scenarios, such as in next-generation in-building residential networks and in datacom applications
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