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EN
The performance of the multi-input multi-output (MIMO) systems can be improved by spatial modulation. By using spatial modulation, the transmitter can select the best transmit antenna based on the channel variations using channel state information (CSI). Also, the modulation helps the transmitter to select the best modulation level such that the system has the best performance in all situations. Hence, in this paper, two issues are considered including spatial modulation and information modulation selection. For the spatial modulation, an optimal solution for obtaining the probability of selecting antenna is calculated and then Huffman coding is used such that the transmitter can select the best transmit antenna to maximize the channel capacity. For the information modulation, a multi quadrature amplitude modulation (MQAM) strategy is used. In this modulation, the modulation size is changed based on the channel state variations; therefore, the best modulation index is used for transmitting data in all channel situations. In simulation results, the optimal method is compared with Huffman mapping. In addition, the effect of modulation on channel capacity and a bit error rate (BER) is shown.
EN
This paper presents the design of digital controller for longitudinal aircraft model basedon the Dynamic Contraction Method. The control task is formulated as a tracking problem of velocity and flight path angle, where decoupled output transients are accomplished in spite of incomplete information about varying parameters of the system and external disturbances. The design of digital controller based on the pseudo-continuous approach is presented, where the digital controller is the result of continuous-time controller discretization. A resulting output feedback controller has a simple form of a combination of low-order linear dynamical systems and a matrix whose entries depend nonlinearly on certain known process variables. Simulation results for an aircraft model confirm theoretical expectations.
3
Content available Design of transmultiplexer integer filters
EN
The designing of transmultiplexer systems relies on determining filters for the transmitter and receiver sides of multicarrier communication system. The perfect reconstruction conditions lead to the bilinear equations for FIR filter coefficients. Generally there is no way of finding all possible solutions. This paper describes methods of finding a large family of solutions. Particular attention is devoted to obtaining algorithms useful in fixed-point arithmetic needed to design the integer filters. As a result, the systems perform perfect reconstruction of signals. Additionally, a simple method is presented to transform any transmultiplexer into an unlimited number of different transmultiplexers. Finally, two examples of integer filters that meet perfect reconstruction conditions are shown. The first illustrates a FIR filter which does not require multiplications. The frequency properties of filters and signals are discussed for the second example.
PL
Przedstawiono kilka nowoczesnych technik antenowych, które mogą być wykorzystane tylko w terahercowym zakresie częstotliwości. Zwrócono uwagę na możliwość zastosowania szyków antenowych wielkiej skali, w tym dla technik MIMO, inteligentne kształtowanie wiązki zapewniające rozmaite scenariusze, zastosowanie nowych materiałów, w tym grafenu oraz możliwości ich wykonania wterahercowej komunikacji bezprzewodowej. Wyniki ostatnich badań wskazują, że bezprzewodowa komunikacja terahercowa będzie miata duży wpływ na rozwój przyszłych systemów bezprzewodowych, a systemy antenowe będą odgrywały w tym wiodącą rolę.
EN
The article is devoted to the presentation of several modern techniques of antennas applying, which can be used only in the terahertz frequency range. Attention was drawn to the possibility of large-scale antenna arrays, icluding MIMO techniques, smart beamforming providing a variety of scenarios, the use of new materials, including graphene and the possibility of their use in terahertz wireless communications. The results of recent studies indicate that terahertz wireless communication will have a big impact on the developmentotfi wireless systems and antenna systems will play a leading role in this.
Logistyka
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2015
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nr 4
4272--4278, CD2
PL
W referacie omawiane jest zagadnienie ograniczenia adaptacji technologi ICT w komunikacji mobilnej. Omówione zostało radiowe środowisko propagacyjne wraz z możliwością adaptacji nowych technologii. Dotyczy to w głównej mierze zaawansowanej technologii MIMO w zakresie systemów MISO oraz MIMO2x2 i 3x3. Przytacza się wyniki badań symulacyjnych przeprowadzonych dla zaników Raileigh’a oraz typu Nakagami. Prezentowane są wyniki badań symulacyjnych dotyczących kanałów skorelowanych. Dokonana jest ocena wpływu korelacji międzykanałowej na niezawodność adaptowanego systemu. Dokonany został też krótki przegląd strategii odbioru sygnału.
EN
The article analyses problems of adaptation technology ICT (wireless communication, mainly-Multiple Input - Multiple Output (MIMO) in radio communication environment. The models of channels under Rayleigh and Nakagami fading conditions is studied in detail. It are compared BER in MIMO systems 2x2, 3x3 over not and correlated channels with supposed depth of faiding.. The results of the analysis are encouraging.
PL
Zaproponowano zastosowanie kodowania, przeplotu i iteracyjnego dekodowania dla wielostrumieniowej transmisji OFDM, oddzielnie dla sygnału w każdym odstępie modulacji. Opisany schemat transmisji może być zastosowany w sieciach i systemach MIMO następnej generacji. Własności zaproponowanego sposobu transmisji w kanale Rayleigha i kanałach WLAN-owskich zbadano w drodze symulacji. Zaprezentowano i omówiono wybrane wyniki BER(SNR).
EN
This paper investigates the MIMO communication system in which encoding, interleaving and iterative decoding of multi-stream OFDM signal is done separately in each signaling interval. The proposed transmission scheme may be used in the next generation MIMO systems. Properties of the proposed method of transmission over the Rayleigh and WLAN channels have been tested by a simulation. The article presents and discusses selected results of BER(SNR).
7
Content available remote The OSA-MIMO Technologies for Future Communication and Information Systems
EN
The article analyses the role of Multiple Input – Multiple Output (MIMO) and Opportunity Spectrum Access (OSA) technologies in future Cognitive Radio (CR). The model of two networks operating in the same frequency band under Rayleigh fading conditions is studied in detail. The network of licensed users called the primary operates in SISO mode, while the secondary one – in MIMO mode. The results of the analysis are encouraging. For the future it is proposed that the networks should be equipped with a dense grid of spectrum sensing detectors and OSA-routers.
PL
W artykule analizuje się rolę technologii MIMO (multiple input – multiple output) oraz OSA (Opportunity Spectrum Access) w perspektywicznych inteligentnych systemach komunikacyjnych typu Cognitive Radio. W szczególności rozpatrywany jest model współoperacyjności dwóch sieci w tym samym paśmie częstotliwości w warunkach typowych zaników Rayleigha. Sieć licencjonowanego użytkownika pracuje w systemie SISO (single input – single output), natomiast sieć użytkownika drugorzędnego – w systemie MIMO. Uzyskane rezultaty są zachęcające. Przewiduje się, że przyszłe sieci będą wyposażone w gęstą siatkę detektorów-routerów umożliwiających kontrolę i sterowanie całością systemu.
PL
Przedstawiono ideę bezprzewodowych sieci kognitywnych (inteligentnych). Omówiono przykład kompatybilnego systemu złożonego z sieci podstawowej (licencjonowanej) i dodatkowej (drugorzędnej). Podano podstawowe równania i przykładowe wyniki symulacji koegzystencji obu sieci.
EN
The idea and motivation of the cognitive wireless networks has been presented. An example of two networks, one primary (licensed) and one secondary has been considered in detail. The main equations and some results of simulation are provided as an illustration of the process of compatibility.
EN
MIMO (multiple in multiple out) antenna system draw attention in the recent years due to its potential for achieving high data rates. In this work novel DSP algorithm and FPGA implementation will be presented that allows transmitting M data streams to M receiving antennas from N transmitting antennas (M ≤ N) into the same frequency with total interference suppression while maximizing channel gain for each data stream at the same time.
PL
W artykule zaprezentowano nowy algorytm DSP z implementacja w FPGA umożliwiający transmisję strumienia M danych do M anteny odbiornika z anteny przesyłowej N (M ≤ N) z tą sama częstotliwością z tłumieniem zakłóceń – przy maksymalizacji wzmocnienia dla każdego strumienia danych w kanale.
10
Content available remote Multiuser cpm transmission for mimo systems
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.
11
Content available remote Outage Analysis and Power Allocation for Space-time Block Coded Two-way Relaying
EN
In this paper, we consider the two-way relay channel (TWRC) over which communication is performed using spacetime block codes (STBC) with physical-layer network coding (PNC) protocol. The three-node two-way relaying (TWR) model consists of two end nodes (sources) simultaneously communicating with each other over a relay node where each node is equipped with two antennas and uses Alamouti’s STBC to provide diversity. We consider non-reciprocal channels where fading channel coefficients are independent for opposite directions of the same link. We first derive closed form expressions for the outage probability of the STBC-TWR system and uncoded TWRC assuming equal transmit power at each node and decode-and-forward (DF) strategy at the relay. We show that the STBC-TWR system significantly improves the uncoded TWRC outage performance. Then, to further improve the performance, we propose an optimal ower allocation in TWR scheme employing Alamouti’s STBC and PNC protocol. The optimal power allocation is obtained by maximizing the sum-rate under the total power constraint. We show that the optimal power allocation considerably improves the outage performance as well as the sum-rate compared to the equal-power case.
12
Content available remote Minimum mean-squared error multi-user MIMO receive filtering
EN
In this paper we use two modifications of the minimum mean-squared-error (MMSE) cost function to derive new multi-user (MU) MIMO receive algorithms. We derive algorithms that have lower complexity than the lattice reduction techniques and are able to extract full diversity inherent in the system. The resulting algorithms work in the overloaded systems, i.e. can process signals at the user terminals (UTs) equipped with the arbitrary number of antennas, and have no bit error floor.
PL
W pracy wykorzystano dwie modyfikacje funkcji MMSE do otrzymania nowego algorytmu otrzymywania danych przez wielu użytkowników. Zaproponowany algorytm jest mniej złożony niż technika redukcji siatki i jest w stanie wydobyć różnorodność właściwą dla systemu. Możliwe jest przetwarzanie sygnału w terminalu użytkownika wyposażonego w dowolną liczbę anten.
PL
Artykuł dotyczy nowej techniki transmisji informacji w sieciach bezprzewodowych. Polega ona na tworzeniu wielu kanałów (ścieżek) przestrzennych między nadawcą i odbiorcą, co pozwala znacznie zwiększyć sumaryczną przepustowość łącza i/lub niezawodność. Autor wprowadza prosty model takiej transmisji, w którym uwzględnia istotne czynniki środowiskowe, w tym nie-selektywne (płaskie) zaniki sygnału. W efekcie otrzymuje się w drodze symulacji Monte Carlo krzywe elementowej stopy błędów w funkcji stosunku mocy sygnał/szum dla parametrycznej zmiany znormalizowanego pasma zaników BT, gdzie B- pasmo koherencji (niestałości) zaników, 1/T -szybkość transmisji sygnału. We wnioskach autor potwierdza efektywność nowej technologii z jednoczesnym zastrzeżeniem, że faktyczne zyski są znacząco mniejsze od przewidywań teorii dla typowych warunków eksploatacji i że konieczne są duże nakłady środków finansowych w toku opracowania i wdrażania nowej technologii do praktyki.
EN
The paper deals with a new technique of signal transmission in wireless networks. It consists in creation the many space channels between transmitter and receiver, which facilitates in significant growth of aggregate link capacity and/or reliability. In the paper the simple model of such transmission is given, which takes into account the essential environment factors, including non-selective fading. In a result the BER curves are obtained via Monte Carlo simulation for different normalized fading bandwidth BT, where B is a Doppler shift and T - duration of a signal symbol. In conclusion a high efficiency of new technology is emphasized, and some limitations specified such as high complexity and cost. The real gain is, however, quite well, thou lower than predictions of the pure theory.
EN
This paper presents a new simple approach to Alamouti MIMO system performance in channel cross-correlation and dynamic fading environment. The complete BER curves obtained via Monte Carlo and Exact Doppler Shift methods are given and their degradation due to both mentioned factors is assessed. The obtained results are compared with the data of other authors.
PL
W artykule przedstawiono nowe proste podejście do Alamouti MIMO wydajność systemu w kanale korelacji wzajemnej i dynamiczne środowisko blaknięcie. Kompletny BER krzywe otrzymane przez Monte Carlo i dokładne metody Dopplera Shift podane i ich degradacji zarówno ze względu na wymienione czynniki ocenia się. Uzyskane wyniki porównano z danymi innych autorów.
15
Content available remote Diversity and Multiplexing Techniques of 802.11n WLAN
EN
This paper is devoted to analyze an improvement in the performance of WLAN (Wireless Local Area Network) systems introduced by space and space-time diversity, as well as spatial multiplexing. These MIMO (Multiple-Input Multiple-Output) techniques are approved in the latest 802.11n specification. In order to perform the experiment, a Matlab application that simulates WLAN physical layer has been developed.
16
Content available remote Windup prevention for MIMO systems in the frequency domain
EN
Input saturation can have an undesired influence on the transients of the closed loop system and it can even lead to an unstable behavior. Controller windup is caused by badly damped or unstable modes in the compensator and controller windup is due to fast dynamics of the closed loop system. In a two-step approach one can first prevent controller windup by the so-called observer technique and if, in addition, there exists the danger of plant windup one adds an additional dynamic element to prevent it. There also exists a one-step approach that prevents controller and plant windup at the same time. This paper shows how both approaches to windup prevention can be designed directly in the frequency domain without recourse to time domain arguments. A simple example demonstrates the windup effects and their prevention.
17
Content available remote Signal detection methods for MIMO systems
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.
EN
In MIMO LTI continuous-time systems S(A, B, C) the classical notion of the Smith zeros does not characterize fully the output-zeroing problem. In order to analyze the question we extend this notion by treating multivariable zeros (called further the invariant zeros) as the triples (complex number, nonzero state-zero direction, input-zero direction). Nothing is assumed about the relationship of the number of inputs to the number of outputs nor about the normal rank of the underlying system matrix. The treatment is strictly connected with the output zeroing problem and in that spirit the zeros can be easily interpreted even in the degenerate case (i.e., when any complex number is such zero). A simple sufficient and necessary condition of nondegeneracy is presented. The condition decomposes the class of all systems S(A, B, C) such that and into two disjoint subclasses: of nondegenerate and degenerate systems. In nondegenerate systems, the Smith zeros and the invariant zeros are exactly the same objects which are determined as the roots of the so-called zero polynomial. The degree of this polynomial equals the dimension of the maximal (A, B)-invariant subspace contained in KerC, while the zero dynamics are independent of control vector. In degenerate systems the zero polynomial determines merely the Smith zeros, while the set of the invariant zeros equals the whole complex plane. The dimension of the maximal (A, B)-invariant subspace contained in KerC is strictly larger than the degree of the zero polynomial, whereas the zero dynamics essentially depend upon control vector.
19
Content available remote Beta Fuzzy Logic Systems: Approximation Properties in the mimo Case
EN
Many researches have been interested in the approximation properties of Fuzzy Logic Systems (FLS), which, like neural networks, can be seen as approximation schemes. Almost all of them tackled the Mamdani fuzzy model, which was shown to have many interesting approximation features. However, only in few cases the Sugeno fuzzy model was considered. In this paper, we are interested in the zero-order Multi-Input-Multi-Output (MIMO) Sugeno fuzzy model with Beta membership functions. This leads to Beta Fuzzy Logic Systems (BFLS). We show that BFLSs are universal approximators. We also prove that they possess the best approximation property and the interpolation characteristic.
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