MMSE Research Papers - Academia.edu (original) (raw)

During the signal identification process, massive multiple-input multiple-output (MIMO) systems must manage a high quantity of matrix inversion operations. To prevent exact matrix inversion in huge MIMO systems, several strategies have been presented, which can be loosely classified into similarity measures and evolutionary computation. In the existing Neumann series expansion and Newton methods, the initial value will be taken as zero as a result wherein the closure speed will be slowed and the prediction of the channel state information is not done properly. In this paper, fish swarm optimization algorithm is proposed in which initial values are chosen optimally for ensuring the faster and accurate signal detection with reduced complexity. The optimal values are chosen between 0 to 1 value and the initial arbitrary values are chosen based on number of input signals. In the proposed work, Realistic condition based channel state information prediction is done by using machine learning algorithm. Simulation results demonstrate that the suggested receiver's bit error rate performance characteristics employing the Quadrature Amplitude Modulation (QAM) methodology outperform the existing Neumann series expansion and Newton methods.

- by
- •
- Complexity, Multiple-input Multiple-output (MIMO) Systems, BER, MMSE

In wireless communication system, the multipath channels introduce frequency selectivity and time varying properties in OFDM symbols which causes Inter-Carrier Interference (ICI) within symbols. For mitigation of such impairments caused by the fading channels, channel estimation is imperative. In present work, two main block-type pilot symbols assisted Least Square (LS) and Minimum Mean Square Error (MMSE) channel estimation techniques for two fading channel models, Rayleigh and Rician are implemented. The bit error rate characteristic performance for both estimators is compared for slow fading channel models with different symbol mapping techniques. The results show that the MMSE estimator has good performance for both Rayleigh and Rician channels as compared to LS estimator. However, MMSE estimator has higher complexity than that of LS.

- by Vikram Patil and +1
- •
- OFDM, Rayleigh fading, MMSE, Rician fading

Cognitive impairment cases referred to psychiatric clinic are very few especially those who have mild disease. Formal evaluation of cognitive impairment is time consuming and it involves consultation with an expert in psychological training. One clinically useful test for practitioners is the Mini Mental State Examination(MMSE). Although MMSE has shown good reliability and validity, using this instrument in a language and culture other than English may create problems. However the test has never been validated in Bahasa Malaysia even though it is a widely used screening test during patient’s clinical examination. This study was done to translate and validate MMSE into Bahasa Malaysia.

- by Zahiruddin Othman and +1
- •
- Validation, Malay, MMSE

This paper compares the performance of various channel estimation techniques for OFDM systems over quasi-static channels using MATLab. It compares the performance of five channel estimation techniques, these are: decision directed (DD), linear interpolation, second-order interpolation, discrete Fourier transform (DFT) interpolation, minimum mean square error (MMSE) interpolation. The performance is evaluated in terms of two widely-used performance measures, namely, bit-error rate (BER) and the mean square error (MSE) for different levels of signal-to-noise ratio (SNR). The OFDM model is explained and implemented using MATLab to run different simulations. The simulation results demonstrate that the DD channel estimation provides the lowest BER and MSE as compared to interpolation techniques, at the cost of extra processing delay and comparatively sensitive to channel variations between OFDM symbols. Also, the MMSE interpolation outperforms all other interpolation techniques.

Fifth generation cellular networks are the key systems which are being deployed in the near future. The enabling technology, Multiple-In Multiple-Out (MIMO) wireless technology makes use of varied number of antennas at the transmitter and multiple antennas at the receiver for transmission of the information in cellular communication systems. This MIMO technology acts as a foundation and aims to improve the spectral efficiency and throughput in fifth generation wireless communication systems. The most common parameters we come across in wireless communications are Bit error rate (BER), Inter Symbol Interference (ISI), Signal to Noise ratio (SNR), Signal to Interference plus Noise ratio (SINR), Successive interference cancellation (SIC), etc. The primary objective of this paper is to improve the BER performance by minimizing SIC using Zero Forcing-Successive Interference Cancellation (ZF-SIC) with optimal ordering and suppress the noise enhancement prevailing in the channel by an extended detection technique, Minimum Mean Square Error (MMSE). As a purpose to improve the channel capacity, MIMO systems are utilized for transmission purpose lately. Quadrature Phase Shift Keying (QPSK) modulation technique is utilized in the system model, which makes use of the same channel bandwidth and carries twice the information and alongside Binary Phase Shift Modulation Technique (BPSK) is also made use of in the system model to provide a comparative analysis among the detection techniques and modulation techniques discussed previously. MIMO fading distribution such as alpha(α)-mu (μ) fading channel distribution is taken into consideration to generate a channel model. The simulated results are analysed and compared with respect to their BER performance taking into account diverse values of alpha(α), mu(μ) parameters. The significance of this paper is to provide a channel efficient, minimized successive interference cancellation at the receiver end in order to make the system more reliable, less complex, interference negligent and simultaneously improve the BER performance. In the near future, these MIMO techniques form a foundation to produce more reliable systems with high terahertz bandwidth. This indeed will open to more seamless communication in various fields of technology.

- by IJRASET Publication
- •
- ISI, BER, MMSE, Multi-User MIMO Communication
- by Rakesh Tripathi
- •
- Geriatrics, Specificity, Geriatric Psychiatry, Sensitivity

Background: Executive functioning (EF) coordinates cognitive functioning (CF). According to some studies, EF declines with age. CF is relatively stable until 50-60 years of age, but it declines after that. Interaction between executive impairment (EI) and cognitive impairment (CI) has been confirmed. It is not known which specific cognitive functions are affected by EI.
Objective: We have carried out a transversal study to determine the severity of EF and CF; prevalence of EI and CI, relationship between EF and CF, relationship between EF, CF, sociodemographic and emotional variables, the impact of EF on CF, by controlling the variables which have shown correlations between EF and CF.
Methodology: We use a convenience sample of 483 old persons, being between 60 and 100 years of age, the sample is very aged (53.7% above 81 years-old), female (76.6%), single (80.3%) and non-qualified job (91.3%). Through Mini Mental State Examination (MMSE), the sample was divided in two subgroups: elderly people with CI (n = 347) and elderly people without CI (n = 136). EF was assessed with Frontal Assessment Battery (FAB); CF was assessed with MMSE and its subscales (memory, praxis, language, orientation, and attention functions) and with Rey Complex Figure Test (FCR-O) and the emotional ones with the Geriatric Depression Scale (GDS) and the Geriatric Anxiety Inventory (GAI).
Results: The elderly inquired present significantly lower averages in EF and CF measured by the MMSE and by the FCR-O. Prevalence of the EI was high (74.6%), as was the CI (71.8%), the immediate (75.9%) and the delayed mnesic impairment (61.0%). EF correlates significantly with CF, with FCR-O copy and immediate memory, with depressive symptomatology, with education, and with profession. Logistic regression analysis, after controlling the role of emotional and sociodemographic variables, has shown that the EI increases 0,86 times the chance of suffering from CI measured by MMSE and 0.77 times by the FCR-O copy. The regression model wasn’t valid for immediate and delayed memory.
Conclusion: EF has an impact on elderly people’s CF under social response. This result sustains the importance of assessing EF to prevent CI through cognitive rehabilitation programs.

This paper presents the bit error rate (BER) performance of the low density parity check (LDPC) based space-time trellis coded 2×2 multiple-input multiple-output orthogonal frequency-division multiplexing(STTC-MIMO-OFDM) system on text message transmission. The system under investigation incorporates 1/2-rated LDPC encoding scheme under various digital modulations (BPSK, QPSK and QAM) over an additative white gaussian noise (AWGN) and other fading (Raleigh and Rician) channels for two transmit
and two receive antennas. At the receiving section of the simulated system, Minimum Mean-Square-Error(MMSE) channel equalization technique has been implemented to extract transmitted symbols without enhancing noise power level. The effectiveness of the proposed system is analyzed in terms of BER with signal-to-noise ratio (SNR). It is observable from the Matlab based simulation study that the proposed
system outperforms with BPSK as compared to other digital modulation schemes at relatively low SNRs under AWGN, Rayleigh and Rician fading channels. The transmitted text message is found to have retrieved effectively at the receiver under implementation of iterative sum-product LDPC decoding algorithm. It has also been anticipated that the performance of the LDPC-based STTC-MIMO-OFDM
system degrades with the increase of noise power.

In this paper, we propose a new method of channel estimation for asynchronous additive white Gaussian noise channels in satellite communications. This method is based on signals correlation and multiuser interference cancellation which adopts a successive structure. Propagation delays and signals amplitudes are jointly estimated in order to be used for data detection at the receiver. As, a multiuser detector, a single stage successive interference cancellation (SIC) architecture is analyzed and integrated to the channel estimation technique and the whole system is evaluated. The satellite access method adopted is the direct sequence code division multiple access (DS CDMA) one. To evaluate the channel estimation and the detection technique, we have simulated a satellite uplink with an asynchronous multiuser access.

Ai m : The ai m of this study was standardization and validation of the Mini-Mental State Examination (MMSE) in the general Croatian aging population. Methods: Three-hundred and forty-four participants underwent the MMSE test, 217 cogni-tively healthy subjects without neurological and psychiatric disorders and 127 patients with mild cognitive impairment (MCI) or dementia. Results: The optimal cutoff point for screening of the general Croatian population (cognitively healthy vs. MCI and dementia) is 26/27; in the Croatian population aged ≥65 years, the cutoff point is 24/25, whereas for screening of highly educated persons (≥14 years of education) aged ≥65 years a higher cutoff point should be used (26/27). Conclusions: MMSE results when standardized and validated in a certain population might better contribute to recognition of the individuals at risk that should be directed to dementia outpatient clinics.

- by Ninoslav Mimica
- •
- Croatia, MMSE

In this work we consider the problem of recovering shaped offset quadrature-phase shift keying (SOQPSK)-TG modulated data, which has been transmitted over an unknown channel, using the iNET data packet structure. Previous work has shown the effectiveness of a block processing CMA equalizer which uses the known data bits contained in the iNET packet structure (i.e. the preamble and ASM bits) to provide an alternative method of initialization. In this research we apply a CMA equalizer, which has been initialized by the minimum mean square error (MMSE) equalizer to measure data that was transmitted using the iNET packet structure in a laboratory experiment. Since the CMA equalizer does not determine the correct phase shift for each data packet, the known data bits contained in each iNET packet will be used to determine the phase correction. The total number of bit errors will be used as a basis to evaluate the performance of our MMSE-initialized CMA equalizer for this experimental data.

- by Serge Dossongui
- •
- CMA, MMSE, Equalizers

The adaptive algorithm has been widely used in the digital signal processing like channel estimation,
channel equalization, echo cancellation, and so on. One of the most important adaptive algorithms is the
LMS algorithm. We present in this paper an multiple objective optimization approach to fast blind channel
equalization. By investigating first the performance (mean-square error) of the standard fractionally
spaced CMA (constant modulus algorithm) equalizer in the presence of noise, we show that CMA local
minima exist near the minimum mean-square error (MMSE) equalizers. Consequently, Fractional Spaced
CMA may converge to a local minimum corresponding to a poorly designed MMSE receiver with
considerable large mean-square error. The step size in the LMS algorithm decides both the convergence
speed and the residual error level, the highest speed of convergence and residual error level.

- by International Journal of Ad hoc, Sensor & Ubiquitous Computing Journal and +1
- •
- LMS, Blackboard LMS, CMA, MMSE

Background: The Mini-mental State Examination (MMSE) and the Alzheimer’s Disease Assessment Scale- cognitive subscale (ADAS -Cog) are two of the most widely used instruments globally in the screening of dementia and in testing treatment efficacy in clinical trials of anti-dementia drugs. Little is known of their use in Caribbean populations who like many developing countries are experiencing faster ageing and as such face an increasing burden due to Alzheimer’s disease and other dementias. Methods: Caribbean and British patients with probable Alzheimer’s disease were matched for age and gender and their performance on the MMSE and ADAS-Cog was compared to control groups consisting of healthy Caribbean and British adults. Results: Analysis revealed that MMSE and ADAS-Cog total scores were able to discriminate between control and AD groups. However overall scores for Caribbean AD and Caribbean controls were lower than their British counterparts. The MMSE and ADAS-Cog were also able to...

- by Katija Khan
- •
- Psychology, Culture, Clinical Sciences, MMSE

In this paper, we have evaluated various methods of time-frequency-selective fading channels estimation in OFDM system and some of them improved under time varying conditions. So, these different techniques will be studied through different algorithms and for different schemes of modulations (16 QAM, BPSK,QPSK,…). Channel estimation gathers different schemes and algorithms, some of them are dedicated for slowly time varying (such as block type arrangement insertion, Bayesian Cramer-Rao Bound, Kalman estimator,Subspace estimator,…) whereas the others concern highly time varying channels (comb type insertion,…) . There are others methods that are just suitable for stationary channels like blind or semi blind estimators.For this aim, diverse algorithms were used for these schemes such as Least Squares estimator LS, Least Minimum Squares LMS, Minimum Mean-Square-ErrorMMSE, Linear Minimum Mean-Square-Error LMMSE, Maximum Likelihood ML,…to refine estimators shown previously.

The consistent demand for higher data rates and need to send giant volumes of data while not compromising the quality of communication has led the development of a new generations of wireless systems. But range and data rate limitations are there in wireless devices. In an attempt to beat these limitations, Multi Input Multi Output (MIMO) systems will be used which also increase diversity and improve the bit error rate (BER) performance of wireless systems. They additionally increase the channel capacity, increase the transmitted data rate through spatial multiplexing, and/or reduce interference from other users. MIMO systems therefore create a promising communication system because of their high transmission rates without additional bandwidth or transmit power and robustness against multipath fading. This paper provides the overview of Multiuser MIMO system. A detailed review on how to increase performance of system and reduce the bit error rate (BER) in different fading environment e.g. Rayleigh fading, Rician fading, Nakagami fading, composite fading.

- by International Journal of Electrical and Computer Engineering (IJECE) and +1
- •
- Wireless Communications, STBC, Rayleigh fading, BER

Impulsivity, conceptualized as impulsive personality trait, poor inhibitory control and enhanced reward sensitivity , has been strongly linked to obesity. In particular, a disequilibrium between cognitive control and reward sensitivity has been observed in obese individuals in both behavioural and imaging studies. While this issue has been widely investigated in children and adults, it has received little attention in older adults. Here, obese and non-obese participants aged between 40 and 70 years completed the Barratt Impulsiveness scale (assessing motor, non-planning and attentional impulsiveness), a Go/no-go task with foods and non-foods (assessing in-hibitory control) and a reward sensitivity battery with high and low caloric foods (assessing liking, wanting, tastiness and frequency of consumption). We observed that participants with higher BMI reported increased wanting for high calorie foods, but did not show poorer inhibitory control. Interestingly, participants who scored lower on the MMSE reported to consume high calorie more than low calorie foods. Finally, those who presented low scores on non-planning and motor impulsiveness subscales reported higher tastiness ratings for low calorie foods. These results show that increased reward sensitivity but not reduced inhibitory control may characterize higher BMI during aging. Importantly, they also highlight new findings concerning food preferences among older adults.

- by Francesco Foroni
- •
- Aging, Liking, MMSE, Body Weight

The paper describes how to improve channel estimation in Single Carrier Frequency Division Multiple Access (SC-FDMA) system, using a Hybrid Artificial Neural Networks (HANN). The 3 rd Generation Partnership Project (3GPP) standards for uplink Long Term Evolution Advanced (LTE-A) uses pilot based channel estimation technique. This kind of channel estimation method suffers from a considerable loss ofbitrate due to pilot insertion; all data frame sent contains reference signal. The HANN converts data aided channel estimator to semi blind channel estimator. To increase convergence speed, HANN uses some channel propagation Fuzzy Rules to initialize Neural Network parameters before learning instead of a random initialization, so its learning phase ismore rapidly compared to classic ANN.HANN allows more bandwidth efficient and less complexity. Simulation results show that HANN has better computational efficiency than the Minimum Mean Square Error (MMSE) estimator and has faster convergence than classic Neural Networks estimators.

High data rates and error-rate performance approaching close to theoretical limits are key trends for evolving digital wireless communication applications. To address the¯rst requirement , multiple-input multiple-output (MIMO) techniques are adopted in emergent wireless communication standards and applications. On the other hand, turbo concept is used to alleviate the destructive e®ects of the channel and ensure error-rate performance close to theoretical limits. At the receiver side, the incorporation of MIMO techniques and turbo processing leads to increased complexity that has a severe impact on computation speed, power consumption and implementation area. Because of its increased complexity, the detector is considered critical among all receiver components. Low-complexity algorithms are developed at the cost of decreased performance. Minimum mean-squared error (MMSE) solution with iterative detection and decoding shows an acceptable tradeo®. In this paper, the complexity of the MMSE algorithm in turbo detection context is investigated thoroughly. Algorithmic computations are surveyed to extract the characteristics of all involved parameters. Consequently, several decompositions are applied leading to enhanced performance and to a signi¯cant reduction of utilized computations. The complexity of the algorithm is evaluated in terms of real-valued operations. The proposed decompositions save an average of 29% and 17% of required operations for 2 Â 2 and 4 Â 4 MIMO systems, respectively. In addition, the hardware implementation designed applying the devised simpli¯cations and decompositions outperforms available state-of-the-art implementations in terms of maximum operating frequency, execution time, and performance.

- by Mostafa Rizk and +1
- •
- Wireless Communications, Turbo equalization, MMSE, Multi-User MIMO Communication

Coordinated multi-point transmission and reception
(CoMP) is introduced in LTE-A to mitigate co-channe
l
interference and improve the cell-edge user experie
nce.
In this paper we propose a joint transmission
scheme for LTE-CoMP and we enhance the performance
of CoMP with two techniques: 1- dynamic MIMO
cell selection and 2- closed loop MIMO with global
precoding matrix selection. A cell-edge user select
s the
base stations that jointly transmit the desired sig
nal from the available ones (we assumed 3). The use
r also
selects the closed loop precoding matrices for MIMO
in a joint fashion to fit the independent MIMO
channels from two base stations (eNBs).
In addition, edge users are likely to be subject to
severe Co-
channel interference from eNBs outside the joint tr
ansmission set.To address co-channel interference f
rom
the base station(s) that are not included in CoMP j
oint transmission set, the user equipment employs
Minimum Mean Squared Error receiver with Interferen
ce Rejection Combining (MMSE-IRC). We illustrate
the effect of fading correlation between elements o
f the transmit and receive antennas.
Also, the effect of
the desired to interference eNB power ratio in case
of medium correlation for 3 and 4 layers using MMS
E-
IRC receiver is studied. Also we compare the BER pe
rformance for 3 and 4 layers in case of different
values of the desired to interference eNB power rat
io. Simulation results show that the performance of
CoMP with cell selection considerably improves the
performance. Also, global selection of the precodin
g
matrices outperforms local selection. In addition,
using MMSE-IRC gives much better performance than
the conventional minimum mean square error (MMSE) i
n the presence of co-channel interference.

- by GARPH Publication
- •
- Wireless Communications, OFDM, ICI, BER
- by Katija Khan
- •
- Psychology, Culture, Clinical Sciences, MMSE

In this paper, we propose a study of performance of the channel estimation using LS, MMSE, LMMSE and Lr-LMMSE algorithms in OFDM (Orthogonal Frequency Division Multiplexing) system which, as known suffers from the time variation of the... more

In this paper, we propose a study of performance of the channel estimation using LS, MMSE, LMMSE
and Lr-LMMSE algorithms in OFDM (Orthogonal Frequency Division Multiplexing) system which, as
known suffers from the time variation of the channel under high mobility conditions, using block pilot
insertion.

The paper deals with the development of two new schemes of space-time MMSE receivers implemented for the forward link of a WCDMA multi-satellite system and their performance evaluation under non-ideal conditions. They are compared with two existing space-time MMSE detectors. The so called space-time transmit diversity (STTD) technique is coupled with MMSE interference suppression. The idea comes from the realization that the diversity gain is limited by a medium-high level of MAI. The classical Alamouti STTD technique needs symbol synchronicity at the receiver. First, we drop this need, extending the STTD technique to the asynchronous signals case. The schemes are named ST-MMSE pre STTD (MMSE filtering performed before the space-time combining) and ST-MMSE post STTD (interference suppression and space-time combining processed jointly). The paper investigates what happens when the channel coefficients are not perfectly estimated. A realistic multi-satellite WCDMA environment has been simulated to compare the detectors. Bit error rates have been calculated assuming a time-varying satellite channel model. The results show that the proposed post-combining scheme gives the best results, when estimation errors are not present, but it is more sensitive to estimation errors than other receivers in the pedestrian channel. Both of the proposed receivers outperform the other schemes in the vehicular channel, i.e., when the receiver has high mobility, although a channel phase coefficients estimation error of 30° is present.

- by Lorenzo Mucchi
- •
- Satellite Communications, CDMA, MMSE, Space-Time Codes

- by shital Raut
- •
- Computer Science, Wireless Communications, MIMO, STBC

The turbo detection of turbo coded symbols over correlated Rayleigh flat fading channels generated according to Jakes' model is considered in this paper. We propose a method to estimate the channel signal-to-noise ratio (SNR) and the maximum Doppler frequency. These statistics are required by the linear minimum mean squared error (LMMSE) channel estimator. To improve the system convergence , we redefine the channel reliability factor by taking into account the channel estimation error statistics. Simulation results for rate 1/3 turbo code and two different normalized fading rates show that the use of the new reliability factor greatly improves the performance. The improvement is more substantial when channel statistics are unknown. K EYWORDS MAP-BCJR decoder, SNR, maximum Doppler frequency, turbo processing, channel reliability.

This paper deals with the performance analysis of both linear (LE) and widely linear (WLE) equalization processes studied in the symbol spaced mode (SSE) as well as in the fractionally spaced one (FSE). This analysis is evaluated - using Matlab software- in terms of bit error rate (BER) and mean square error (MSE) in a system using a rectilinear modulation of type Pulse Amplitude Modulation (PAM) over a frequency selective channel and corrupted by multiple interferences. Moreover, the impact of the number of external interferers on the behavior of the different equalizers is studied. Thus, simulation results show the outstanding performance of the fractionally spaced mode when compared to the symbol spaced one besides the out-performance of the widely linear processing in both modes. Furthermore, results show the performance degradation for the different studied equalizers when the number of interferences increases

This paper analyzes the impact of fading correlation, cross polarization coupling and channel degeneracy
alias keyhole condition on the error performance of V-BLAST MIMO system that employs detector
algorithms like ZF, MMSE and ML with ordering and successive cancellation. Deleterious impact of above
mentioned channel impairments on MIMO system capacity is studied. Simulation results show the BER
performance of these detectors for different modulation schemes. It is observed that lesser the channel
fading correlation and cross polarization coupling values better is the performance of these detectors.
Study is extended to see the effect of transmit and receive antenna correlation on Ergodic MIMO capacity.

- by iaeme iaeme
- •
- Wireless Communications, OFDM, ML, Pso

Abstract This paper deals with the performance analysis of channel estimation methods for LTE downlink system over time varying mobile environments. The analysis of channel estimation in the presence of interference is also done. Least... more

- by Rajeswari Ramanthan
- •
- Engineering, Wireless Communications, Performance Analysis, ML

Objective: To determine whether the Mini-Mental State Examination (MMSE) could be used to predict short-term impairments in memory functions during a course of Electroconvulsive Therapy (ECT). Method: Patients with severe depression (n=32) were followed up while they were receiving ECTs, and up to a month after that. They were rated independently and blindly on the MMSE for global cognitive dysfunction, the PGI Mem- ory Scale (PGIMS) for memory loss, and the Montgomery-Asberg Depression Rating Scale (MADRS) for severity of depression. Results: MMSE scores dipped during the course of ECT, but picked up in the week and month following cessation of treatment. The PGIMS scores mimicked this pattern, whereas the MADRS scores continued to decline slowly as the patients improved. MMSE scores were highly correlated with memory impairment (PGIMS scores) prior to, during, and up to one month after treatment with ECT. MMSE scores were the strongest predictor of the PGIMS scores at virtually al...

- by subho chakrabarti
- •
- Electroconvulsive therapy, ECT, Clinical Sciences, Rating Scale

The sparse synthesis model for signals has become very popular in the last decade, leading to improved performance in many signal processing applica-tions. This model assumes that a signal may be described as a linear combi-nation of few columns (atoms) of a given synthesis matrix (dictionary). The Co-Sparse Analysis model is a recently introduced counterpart, whereby signals are assumed to be orthogonal to many rows of a given analysis dictionary. These rows are called the co-support. The Analysis model has already led to a series of contributions that address the pursuit problem: identifying the co-support of a corrupted signal in order to restore it. While all the existing work adopts a deterministic point of view towards the design of such pursuit algorithms, this paper introduces a Bayesian estimation point of view, starting with a random generative model for the co-sparse analysis signals. This is followed by a derivation of Oracle, Minimum-Mean-Squared-Error (MMSE), and Maxim...

- by Javier Turek
- •
- Mechanical Engineering, Digital Signal Processing, Bayesian estimation, Map
- by lokesh panchal
- •
- Wireless Communications, OFDM, MMSE, Engineering Technology

Background: Alzheimer's disease (AD) is the main cause of the neurodegenerative disorder, which is not detected unless the cognitive deficits are manifested. An early prediagnostic specific biomarker preferably detectable in plasma and hence non-invasive is highly sought-after. Various hypotheses refer to AD, with amyloid-beta (Aβ) being the most studied hypothesis and inflammation being the most recent theory wherein pro-and anti-inflammatory cytokines are the main culprits. Materials and Methods: In this study, the cognitive performance of AD patients (n=39) was assessed using mini-mental state examination (MMSE), AD assessment scale-cognitive subscale (ADAS-cog), and clinical dementia rating (CDR). Their neuropsychiatric symptoms were evaluated through neuropsychiatric inventory-questionnaire (NPI-Q). Moreover, plasma levels of routine biochemical markers, pro-/anti-inflammatory cytokines such as tumor necrosis factor α (TNF-α), interleukin-1 α (IL-1α), IL-1β, IL-2, IL-4, IL-6, IL-8, IL-12p70, IL-10, Interferon-gamma, chemokines, including prostaglandin E2 (PGE-2), monocyte chemoattractant protein-1, interferon gamma-induced protein 10, Aβ peptide species (42, 40) and Transthyretin (TTR) were measured. Results: Our results revealed that Aβ 42/40 ratio and TTR were correlated (r=0.367, P=0.037). IL-1α was directly correlated with ADAS-cog (r=0.386, P=0.017) and Aβ 40 (r=0.379, P=0.019), but was inversely correlated with IL-4 (r=-0.406, P=0.011). Negative correlations were found between MMSE and PGE2 (r=-0.405, P=0.012) and TNF-α/ IL-10 ratio (r=-0.35, P=0.037). CDR was positively correlated with both PGE2 (r=0.358, P=0.027) and TNF-α (r=0.416, P=0.013). There was a positive correlation between NPI-caregiver distress with CDR (r=0.363, P=0.045) and ADAS-cog (r=0.449, P=0.019). Conclusion: Based on the observed correlation between IL-1α, as a clinical moiety, and ADAS-cog, as a clinical manifestation of AD, anti-IL-1α therapy in AD could be suggested.

- by Galen Medical Journal
- •
- Neuroscience, Immunology, MMSE, ADAS-cog

Main objectives of this paper is to design the PSK and QAM system for Symbol Error Rate (SER) performance analysis and to estimate the channels in OFDM. PSK & QAM syatems are designed for 64 Sbcarriers. In this paper we will compare the SER for both techniques for same modulation rate and same number of subcarrier. In this paper we will show how Symbol error rate is reduced as modulation rate increases for PSK & QAM. We will use three algotihms LS, LMMSE & Modified MMSE to compare the result parameters. Modified MMSE gives better results than LS & LMSE but computational complexity will be increased that is its major drawback.

- by IAEME Publication
- •
- Service Learning, optical OFDM, Qam, MMSE

In Today’s World, the Wireless Community is in great demand of Increasing
capacity and to provide high data rate services due to increase in the number of users
and traffic due to a paradigm shift in the existing technology to support Internet
Application domain due to the increased popularity of Broadband Wireless
Access(BWA). The 2.4 GHz licensed band caters to a variety of applications and
5850-5925 MHz for Automotive Radar Applications. Smart Antenna Arrays here are
finding wide popularity in the EM community because they have a potential to
provide both high capacity by dynamically tuning Interference in real time
Environment (automotive motion, aerodynamics) by adjusting the weights, separations
as well as appropriate phases and have potential applications in Spacial Signal
processing such as DOA estimation, adaptive beamforming and other DSP
applications. A Novel Hybrid GA technique Hybrid Lamarckian-Baldwinian Model
has been tested and found to be successful in solving Real Life problems. A Novel
Equalization technique for mitigating the Multipath effects for Rayleigh Fading
Schenario has also been studied here which has advantages over the MMSE and the
Zero Forcing Equalization Techniques. The ability to adapt the radiation pattern
(sidelobe, main beam direction, nulls, beam width) has always been a field of study
from the past few decades.

- by IAEME Publication
- •
- Beamforming, Equalization, Adaptive, Traffic

Among all the available multiple access techniques, CDMA has the unique feature that it allows sharing of the same channel by all active users. CDMA performance is degraded up to some extent by two phenomenon i.e. Multiple-access interference (MAI) and multipath distortion. In the multiuser adaptive receiver for direct sequence code division multiple access (DS_CDMA) system the performance of least mean square (LMS) adaptive algorithm in three channels viz. flat, multipath Rayleigh and flat Nakagami channels is studied in this paper. For improving the performance of CDMA system by reducing interference among users, maximum ratio combining (MRC); a diversity scheme is used as a preprocessor to the adaptive MMSE detector of DS-CDMA system. Simulation result shows the bit error rate (BER) performance in above different channels.

- by RSIS International
- •
- Bit Error Rate, DS-CDMA, CDMA, Nakagami-m channels
- by Rajeswari Ramanthan
- •
- Wireless Communications, ML, Channel Estimation, MMSE

Background: Black ethnic minorities in the UK have been found to have a disproportionately higher incidence of dementia, are more likely to be rated as demented and have lower scores on the Mini Mental State Examination (MMSE) when compared to whites. Since these populations are poorly represented in the research literature, explanations for these disparities are largely speculative and inconclusive. Methods: A sample of 74 healthy, community adults of UK white, black ethnic minority migrants and native Caribbeans, ranging from 18 to 75 years (m=34.93, sd=12.95) with years of education ranging from 3 to 30 years (m=16.20, sd=4.21) were administered the MMSE. 210 students of White, Asian, African and Caribbean ethnicity, matched for age and years of education and educated either within or outside the UK were also administered the MMSE and the Arithmetic subtest of the WRAT (Wide Range Achievement Test). Results: A stepwise regression analysis found that years of education significant...

- by Katija Khan
- •
- Psychology, Education, Ethnicity, Clinical Sciences

An adaptive beam former is a device, which is able
to steer and modifies an array's beam pattern in or
der
to enhance the reception of a desired signal, while
simultaneously suppressing interfering signals thr
ough
complex weight selection. However, the weight selec
tion is a critical task to get the low Side Lobe Le
vel
(SLL) and Low Beam Width. One needs to have a low S
LL and low beam width to reduce the antenna's
energy radiation/reception ability in unintended di
rections. The weights can be chosen to minimize the
SLL and to place nulls at certain angles. The conve
rgence of the array output towards desired signal i
s
also very important for a good signal processing to
ol of an adaptive beam former. A vast number of
possible window functions are available to calculat
e the weights for Smart Antennas. From the analysis
of many of these algorithms, it is observed that th
ere is a compromise between HPBW and SLL. But in
case of smart antennas, both of these parameters mu
st have low values to get good performance. In our
earlier work it is proposed that Complex Least Mean
Square (CLMS) and Augmented Complex Least
Mean Square ( ACLMS) algorithms gives low beam widt
h and side lobe level in noisy environment.
Another neural algorithm Adaptive Amplitude Non Lin
ear Gradient Decent algorithm (AANGD) has the
advantage of more number of control parameters over
CLMS and ACLMS algorithms. In this paper the
hybrid of CLMS and AANGD is presented and this nove
l hybrid algorithm has outperformed the hybrid
algorithm of CLMS and ACLMS in the aspect of conver
gence towards the desired signal.

- by Reza Parsaee
- •
- Wireless Communications, OFDM, MMSE, FEC

The authors examined associations between exposure to aluminum or silica from drinking water and risk of cognitive decline, dementia, and Alzheimer’s disease among elderly subjects followed for 15 years (1988–2003). They actively searched for incident cases of dementia among persons aged 65 years or over living in 91 civil drinking-water areas in southern France. Two measures of exposure to aluminum were assessed: geographic exposure and individual exposure, taking into account daily consumption of tap water and bottled water. A total of 1,925 subjects who were free of dementia at baseline and had reliable water assessment data were analyzed. Using random-effects models, the authors found that cognitive decline with time was greater in subjects with a higher daily intake of aluminum from drinking water ( 0.1 mg/day, P 0.005) or higher geographic exposure to aluminum. Using a Cox model, a high daily intake of aluminum was significantly associated with increased risk of dementia. Conv...

- by virginie rondeau
- •
- Mini Mental State Examination, MMSE, Abbreviations

For high data rate ultra wideband communication system, performance comparison of Rake, MMSE and Rake-MMSE receivers is attempted in this paper. Further a detail study on Rake-MMSE time domain equalizers is carried out taking into account... more

- by Bikramaditya Das
- •
- Performance Analysis, Le, Bit Error Rate Evaluation, Internet Architecture

In recent studied we found that there are many optimization methods presented for optimal multiuser detection in SDMA-OFDM system, however each method is suffered from limitations. Hence in this paper we are presenting new method which is combination of two recent methods such as Genetic Algorithm and Partial Swarm Optimization (PSO). This approach is presented to overcome this limitations associated with existing methods of detecting multiuser in SDMA-OFDM systems. This two methods GA and PSO are easy to simulate as well as less complexity. These techniques are shown to provide a high performance as compared to the other detectors especially in a rank-deficient scenario where numbers of users are high as compared to the base station (BS) antennas. The proposed hybrid multiuser detection system (MUD) is simulated and its performance is compared against two MUDs such as MMSE (minimum mean square error) and ML (Maximum Likelihood). From the practical results it is cleared that proposed approach for MUD is performing better as compared to existing methods.

- by IAEME Publication
- •
- Game Theory, MIMO-OFDM systems, Berber, Multiuser Detection

In Today’s World, the Wireless Community is in great demand of Increasing capacity and to provide high data rate services due to increase in the number of users and traffic due to a paradigm shift in the existing technology to support Internet Application domain due to the increased popularity of Broadband Wireless Access (BWA). The 2.4 GHz licensed band caters to a variety of applications and 5850-5925 MHz for Automotive Radar Applications. Smart Antenna Arrays here are finding wide popularity in the EM community because they have a potential to provide both high capacity by dynamically tuning Interference in real time Environment (automotive motion, aerodynamics) by adjusting the weights, separations as well as appropriate phases and have potential applications in Spacial Signal processing such as DOA estimation, adaptive beamforming and other DSP applications. A Novel Hybrid GA technique Hybrid Lamarckian-Baldwinian Model has been tested and found to be successful in solving Real Life problems. A Novel Equalization technique for mitigating the Multipath effects for Rayleigh Fading Schenario has also been studied here which has advantages over the MMSE and the Zero Forcing Equalization Techniques. The ability to adapt the radiation pattern (sidelobe, main beam direction, nulls, beam width) has always been a field of study from the past few decades.

- by IAEME Publication
- •
- Web Applications, Domain Names, Beamforming, Equalization

Interference alignment (IA) is a recently proposed transmission technique for the K-user interference channel (IFC), which is proven to achieve a sum-rate multiplexing gain of K/2 at the high interference regime. Motivated by our recent work [1] that showed how the sum-rate scaling can range between K/2 and K for low-to-moderate interference conditions, in this paper we present a novel iterative algorithm for the K-user multiple-input multiple-output (MIMO) IFC with arbitrary number of transceiver antennas. The proposed algorithm automatically adjusts itself to the interference regime at hand, in the above sense, as well as to the channel conditions in order to achieve the appropriate sum-rate scaling. Our reconfigurable algorithm combines the system-wide mean squared error minimization criterion with the single-user waterfilling solution to maximize each user's transmission rate accordingly to the interference levels and channel conditions. Extensive computer simulation results for the sum-rate performance of the proposed reconfigurable algorithm over various Ricean fading channels are presented. It is shown that, in the interference-limited regime, the proposed algorithm reconfigures itself so as to achieve the IA scaling whereas, in the low-to-moderate interference regime, it chooses interference-myopic MIMO transmissions for all K communication pairs.

- by George Alexandropoulos
- •
- Interference management, MIMO Systems, Interference Alignment, MMSE

This paper analyzes the impact of fading correlation, cross polarization coupling and channel degeneracy alias keyhole condition on the error performance of V-BLAST MIMO system that employs detector algorithms like ZF, MMSE and ML with ordering and successive cancellation. Deleterious impact of above mentioned channel impairments on MIMO system capacity is studied. Simulation results show the BER performance of these detectors for different modulation schemes. It is observed that lesser the channel fading correlation and cross polarization coupling values better is the performance of these detectors. Study is extended to see the effect of transmit and receive antenna correlation on Ergodic MIMO capacity.

- by Gareth Hagger-Johnson
- •
- Aging, Fluency, Executive Function, Memory