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1

Improved Two-Dimensional Double Successive Projection Algorithm for Massive MIMO Detection

Chakraborty Sourav, Sinha Nirmalendu Bika, Mitra Monojit

International Journal of Electronics and Telecommunications

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2023

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Vol. 69, No. 1

139--146

EN

In a massive multiple-input multiple-output (MIMO) system, a large number of receiving antennas at the base station can simultaneously serve multiple users. Linear detectors can achieve optimal performance but require large dimensional matrix inversion, which requires a large number of arithmetic operations. Several low complexity solutions are reported in the literature. In this work, we have presented an improved two-dimensional double successive projection (I2D-DSP) algorithm for massive MIMO detection. Simulation results show that the proposed detector performs better than the conventional 2D-DSP algorithm at a lower complexity. The performance under channel correlation also improves with the I2D-DSP scheme. We further developed a soft information generation algorithm to reduce the number of magnitude comparisons. The proposed soft symbol generation method uses real domain operation and can reduce almost 90% flops and magnitude comparisons.

2

Use of serious games for the assessment of mild cognitive impairment in the elderly

Choi Moon-gee

Applied Computer Science

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2022

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Vol. 18, no 2

5--15

EN

This study investigated the use of computer games to detect the symptoms of mild cognitive impairment (MCI), an early stage of dementia, in the elderly. To this end, three serious games were used to measure the visio-perception coordination and psycho-motor abilities, spatial memory, and short-term digit span memory. Subsequently, the correlations between the results of the games and the results of the Korean Mini-Mental State Examination (K-MMSE), a dementia screening test, were analyzed. In addition, the game results of normal elderly persons were compared with those of elderly patients who exhibited MCI symptoms. The results indicated that the game play time and the frequency of errors had significant correlations with K-MMSE. Significant differences were also found in several factors between the control group and the group with MCI. Based on these findings, the advantages and disadvantages of using serious games as tools for screening mild cognitive impairment were discussed.

3

QoS-based Joint User Selection and Scheduling for MU-MIMO WLANs

Rao D. S., Hency V. D. B.

Journal of Telecommunications and Information Technology

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2017

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nr 4

17--24

EN

The shift in Multi-User Multiple Input Multiple Output (MU-MIMO) has gained attention due to its wide support in very high throughput Wireless Local Area Networks (WLANs) such as the 802.11ac. However, the full advantage of MU-MIMO can be utilized only with proper user selection and scheduling. Also, providing Quality of Service (QoS) support is a major challenge for these wireless networks. Generally, user scheduling is done with the acquisition of Channel State Information (CSI) from all the users. In MU-MIMO based WLANs, the number of CSI request increases with the number of users. This results in an increased CSI overhead and in degradation of the overall throughput. Most of the proposals in the literature have not addressed the contention in the CSI feedback clearly. Hence, in this paper a Joint User Selection and Scheduling (JUSS) scheme is discussed and its performance is evaluated in terms of throughput, delay, packet loss and fairness. In the performance comparison some wellknown Medium Access Control (MAC) protocols are considered. The proposed scheme not only enhances throughput, but also avoids contention during CSI feedback period.

4

Reduced Complexity by Combining Norm Based Ordering MMSE-BSIDE Detection in MIMO Systems

Jothikumar R., Rangaswamy N.

International Journal of Electronics and Telecommunications

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2017

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Vol. 63, No. 3

305--308

EN

The breadth first signal decoder (BSIDE) is well known for its optimal maximum likelihood (ML) performance with lesser complexity. In this paper, we analyze a multiple-input multiple-output (MIMO) detection scheme that combines; column norm based ordering minimum mean square error (MMSE) and BSIDE detection methods. The investigation is carried out with a breadth first tree traversal technique, where the computational complexity encountered at the lower layers of the tree is high. This can be eliminated by carrying detection in the lower half of the tree structure using MMSE and upper half using BSIDE, after rearranging the column of the channel using norm calculation. The simulation results show that this approach achieves 22% of complexity reduction for 2x2 and 50% for 4x4 MIMO systems without any degradation in the performance.

5

Comparative Analysis of Channel Estimation Techniques in SISO, MISO and MIMO Systems

Obinna O., Kennedy O., Osemwegie O., Nsikan N.

International Journal of Electronics and Telecommunications

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2017

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Vol. 63, No. 3

299--304

EN

The ever-growing need for high data rate, bandwidth efficiency, reliability, less complexity and less power consumption in our communication systems is on the increase. Modern techniques have to be developed and put in place to meet these requirements. Research has shown, that compared to conventional Single Input Single Output (SISO) systems, Multiple-Input Single Output (MISO), and Multiple-Input Multiple-Output (MIMO) can actually increase the data rate of a communication system, without actually requiring more transmit power or bandwidth. This paper aims at the investigation of the existing channel estimation techniques. Based on the pilot arrangement, the block type and comb type are compared, employing the Least Square estimation (L.S) and Minimum Mean Squared Error (MMSE) estimators. Pilots occupy bandwidth, minimizing the number of pilots used to estimate the channel, in order to allow for more bandwidth utilization for data transmission, without compromising the accuracy of the estimates is taken into consideration. Various channel interpolation techniques and pilot-data insertion ratio are investigated, simulated and compared, to determine the best performance technique with less complexity and minimum power consumption. As performance measures, the Mean Squared Error (MSE) and Bit Error Rate (BER) as a function of Signal to Noise power Ratio (SNR) of the different channel estimation techniques are plotted, in order to identify the technique with the most optimal performance. The complexity and energy efficiency of the techniques are also investigated. The system modelling and simulations are carried out using Matlab simulation package. The MIMO gives the optimum performance, followed by the MISO and SISO. This is as a result of the diversity and multiplexing gain experienced in the multiple antenna techniques using the STBC.

6

Novel Ideas for Lossless Audio Coding

Ulacha G., Stasiński R.

International Journal of Electronics and Telecommunications

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2013

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Vol. 59, No. 1

17-23

EN

Novel ideas for lossless audio coding analyzed in the paper are linked with forward predictor adaptation, and concern optimization of predictors on the basis of zero-order entropy and MMAE criterions, and context sound coding. Direct use of the former criterion is linked with exponential growth of optimization procedure, hence, a suboptimal algorithm having polynomial complexity is proposed. It is shown that on average the new types of predictors are better than those obtained by MMSE technique, while two- and three context systems are on average better than a single predictor one. It also appears that 7-bit PARCOR coefficients in the MPEG-4 ALS standard have insufficient precision for some predictor length, and that for very long frames coding results improve with the predictor rank practically in unlimited way.

7

Signal detection methods for MIMO systems

Nadolna D.

Poznan University of Technology Academic Journals. Electrical Engineering

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2007

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No 54

157-164

EN

Multiple-input multiple-output, wireless systems are able to realize high spectral efficiency and high performance communication links. The benefits from using multiple antennas at the transmitter and receiver are associated with some costs. The most essential difficulty for this kind of systems is the increased complexity of recovering the transmitted signal. When the capacity rises linearly, the detection complexity increases exponentially. This paper presents an overview of the signal detection methods known in theory and particularly describes the main design approaches to MIMO systems: spatial multiplexing and transmit diversity. The article shows classes of receivers, which are used in these strategies. The most important algorithms with their assumptions and computational complexity are also discussed. The introduced receivers are briefly characterized and compared.