Wyniki wyszukiwania - BazTech

1

Analysis of an LSTM-based NOMA Detector Over Time Selective Nakagami-m Fading Channel Conditions

Shankar Ravi, Bangare Jyoti L., Kumar Ajay, Gupta Sandeep, Mehraj Haider, Kulkarni Shriram S.

Journal of Telecommunications and Information Technology

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2022

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nr 3

17--24

EN

This work examines the efficacy of deep learning (DL) based non-orthogonal multiple access (NOMA) receivers in vehicular communications (VC). Analytical formulations for the outage probability (OP), symbol error rate (SER), and ergodic sum rate for the researched vehicle networks are established Rusing i.i.d. Nakagami-m fading links. Standard receivers, such as least square (LS) and minimum mean square error (MMSE), are outperformed by the stacked long-short term memory (S-LSTM) based DL-NOMA receiver. Under real time propagation circumstances, including the cyclic prefix (CP) and clipping distortion, the simulation curves compare the performance of MMSE and LS receivers with that of the DL-NOMA receiver. According to numerical statistics, NOMA outperforms conventional orthogonal multiple access (OMA) by roughly 20% and has a high sum rate when considering i.i.d. fading links.

2

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.

3

Modulation-Mode and Power Assignment in SVD-Assisted Broadband MIMO Systems using Polynomial Matrix Factorization

Sandmann A., Ahrens A., Lochmann S.

Przegląd Elektrotechniczny

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2015

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R. 91, nr 4

10-13

EN

Singular-value decomposition (SVD)-based multiple-input multiple-output (MIMO) systems have attracted a lot of attention in the wireless community. However, applying SVD to frequency-selective MIMO channels results in unequally weighted single-input single-output (SISO) channels requiring complex resource allocation techniques for optimizing the channel performance. Therefore, a different approach utilizing polynomial matrix factorization for removing the MIMO interference is analyzed, outperforming conventional SVD-based MIMO systems in the analyzed channel scenario.

PL

Analizowano właściowści układu SVD (single value decomposition) w technologii MIMO w bezprzewodowym przesyłaniu informacji. Tego typu układy mają problemy z alokacją kanałów. Dlatego zaproponowano inny system wykorzystujący rozkład macierzy wielomianowej do usuwania interferencji kanałów.

4

Assessing Capabilities of Commercial WiMAX Networks for Deliverling Real-Time Surveillance Video Traffic in Uplink

Flizikowski A., Półcienniczak M., Rybicki M., Hołubowicz W., Podyma M.

Image Processing & Communications

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2015

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Vol. 20, no. 1

33--44

EN

Streaming video in uplink is an interesting opportunity for network operators for capitalizing unused part of bandwidth (due to Internet asymmetry). The uplink seems not optimized nowadays due to lack of business cases. The main challenge however is bursty and unpredictable nature of wireless channel observed especially as mobility comes into play in current broadband networks. That is why in this paper, we have approached the diagnosis of commercial mobile WiMAX network towards the capabilities of assuring real-time video in uplink direction. We present results of drive tests showing that delay in WiMAX networks for LOS-NLOS (Line of sight - No n line of sight) mobile conditions is largely contributed by uplink direction (60-90% of RTT (Round trip time)) whereas downlink directions hardly ever exceeds 40ms. We show that enabling MIMO-A(Multiple Input Multiple Output) can decrease delays by 100ms in NLOS conditions and decrease delay variation by up to 90%. For each of tests we have presented exact probabilities of particular modulations involved based on channel realizations.

5

Transmit Diversity in the Downlink for the TETRA-TEDS System

Rutkowski D. A., Możdżonek S.

Journal of Telecommunications and Information Technology

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2014

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nr 1

49--53

EN

In the paper a proposal for the improvement of performance for the TETRA Enhanced Data System (TEDS) employing transmit diversity based on two antennas in the downlink is described. The key idea of the considerations relies on using the space-frequency coding algorithm. The proposal described required some relatively simple changes to the existing TEDS’s Single Input Single Output (SISO) interface but the original number of payload and signaling symbols in the normal downlink burst is preserved. The simulation results obtained indicate a significant improvement in performance. The Eb/No parameter could be reduced from 5 to 8 dB with respect to Frame Error Rate (FER), compared to a single antenna transmission for the same FER = 10⁻³.

6

Multiuser cpm transmission for mimo systems

Remlein P.

Image Processing & Communications

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2013

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Vol. 18, no. 4

59--65

EN

Frequency-Division Multiplexed Continuous Phase Modulation (FDM-CPM) systems with Multiple Input Multiple Output (MIMO) transmission are investigated. In this paper, a multiuser reception scheme for CPM MIMO transmission is presented. The analyzed system is designed to achieve high spectral efficiency by exploiting the multiplexing gain of MIMO techniques. To take advantage of the multiplexing gain of MIMO systems, a Zero Forcing (ZF) MIMO detector and a low-complexity iterative algorithm for Inter- Carrier Interference (ICI) cancellation are considered. Numerical simulations have been performed to assess the performance improvement achieved with the proposed frequency-division multiplexed CPM multiuser MIMO system.

7

Throughput physical layer analysis of LTE

Reznikov M., Olszewski S., Al-Shuraifi Talib M., Al-Zayadi H., Komada P.

Elektronika : konstrukcje, technologie, zastosowania

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2013

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Vol. 54, nr 8

63-66

PL

Technologia Long Term Evolution (LTE) Wyd. 8 zapewnia wysoką szybkość transmisji danych szczytowych na poziomie 300 Mbps w dół strumienia (ang. Downlink) i 75 Mbps w górę strumienia (ang. Uplink) dla częstotliwości 20 MHz. Artykuł dotyczy badania, maksymalnej przepustowości łącza w dół oraz w górę strumienia, w zależności od scenariusza względem warstwy fizycznej. W pracy, obliczenia przepustowości zostały przeprowadzone wyłącznie kanałów danych PUSCH (Physical Kanał Share Uplink) i PDSCH (Physical Downlink Share Channel) z uwzględnieniem metody dostępu zarówno częstotliwościowej FDD (Frequency Division Duplex), jak i czasowej TDD (Time Division Duplex). Analiza przepustowości, różnych elementów zasobów, przypisanych do odpowiednich kanałów danych: downlink i uplink została przeprowadzonoa dla FDD i TDD przy różnych warunkach. Przy czym elementy w dół strumienia (downlink), w ramach FDD zostały obliczone dla wszystkich możliwych pasm systemowych (1,4 MHz do 20 MHz) oraz portów anteny. W artykule zamieszczono rezultaty przeprowadzonej analizy warstwy fizycznej technologii LTE.

EN

Long Term Evolution (LTE) Release 8 provides high peak data rates of 300 Mbps on the downlink and 75 Mbps on uplink for 20 MHz bandwidth. In this study, the maximum throughput of downlink and uplink transmission is investigated depending on scenario for the physical layer. In this paper the throughput calculation exclusively contains data channels (Physical Uplink Share Channel (PUSCH) and Physical Downlink Share Channel (PDSCH)) for both Frequency Division Duplex (FDD) and Time Division Duplex (TDD) operations. For throughput analysis, different resource elements that are assigned for data channels of downlink and uplink are calculated for FDD and TDD operations in different conditions. FDD downlink resource elements are calculated for all the possible system bandwidths (1.4 MHz to 20 MHz) and antenna ports. These results of throughput physical layer analysis of LTE are presented in this paper.

8

Fuzzy Fast Time Simulation Model of Ship's Manoeuvring

Zalewski P.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2010

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Vol. 4, no. 1

25--28

EN

The paper presents a concept of fuzzy FTS (fast time simulation) model of twin-screw ship manoeuvring autonomously (without tugs) in confined waters. The conceptual model has been based on the fuzzy logic controller with expert database formed by manoeuvres obtained from the real-time non-autonomous trials classified in relation to expert manoeuvre impact on ship’s advance, lateral and rotation speed and her position in reference to the present ship status. Exemplary pitch controller for vessels with two propellers at specified hydro-meteorological conditions has been presented.

9

Performance of Distributed Multi-Stage Virtual MIMO Systems with Random Position of Ancillary Nodes

Zanella A., Buratti C.

Electronics and Telecommunications Quarterly

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2009

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Vol. 55, No 3

471-483

EN

The performance of two-hop decode-and-forward virtual multiple-input-multiple-output systems with random location of nodes, is investigated. We suppose that source, relay and destination nodes create clusters with ancillary nodes which are spatially distributed according to a Poisson point process. Random fluctuations are accounted for in the channel model which considers both slow and fast fading. By assuming that the application requires a minimum amount of rate, we evaluate the system performance in terms of cumulative density function of the required signal-to-noise ratio. The use of orthogonal space-time-block codes is also considered and the role played by connectivity parameters is investigated.