Wyniki 1-4 spośród 4 dla zapytania: authorDesc:"Mihajlo STEFANOVIC"

Switch and stay combining diversity receiver in microcellular mobile radio system

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In this paper, the performance of switch and stay combining (SSC) receiver operating over correlated Rician fading channels in the presence of multiple Nakagami-m cochannel interferences (CCIs) is studied. This investigation is important since such environment seems to be the most realistic in microcellular radio communications systems. Analytical expressions for the probability density function (PDF) and cumulative distribution function (CDF) of SSC output signal-to-interference ratio (SIR) are derived and used to study important system performance measures. Abstract. W artykule analizowano właściwości odbiornika “switch and stay combining - SSC) pracującego w skorelowanych kanałach Rician w obecności interferencji kanałów Nakagami-m. Ta analiza jest ważna, ponieważ podobne okoliczności mogą wystąpić w większości mikrokomórkowych systemów komunikacyjnych. Podano analityczną zależność krzywej gęstości prawdopodobieństwa oraz dystrybuantę stosunku sygnału wyjściowego do interferencji. (Odbiornik typu "switch and stay" w mikrokomórkowych mobilnych systemach komunikacyjnych) Keywords: switch and stay combining, correlated Rician fading channels, cochannel interferences. Słowa kluczowe: mikrokomórkowe systemy komunikacyjne, inteferencje. Introduction In cellular mobile radio systems, the main causes for the performance degradation are fading due to multipath propagation and cochannel interference (CCI) due to frequency reuse [1]. Space diversity techniques [2], which combine input signals from multiple receive antennas, are the well known techniques that can be used to alleviate the effects of these degradations. Diversity improvement is achieved without increasing transmission power and bandwidth but at the expense of increased system complexity and moderate increase in receive power consumption. The most popular space diversity techniques are maximal-ratio combining (MRC), equal-gain combining (EGC) and selection combining (SC) [[...]

Cooperative MRC diversity over Hoyt fading channels

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Performance analysis of cooperative non-regenerative transmission system operating over Nakagami-q (Hoyt) fading channels will be presented in this paper. Usage of Maximal Ratio Combining (MRC) space diversity technique at the reception will be considered. Closed form expression will be provided for the moment generating function (MGF) of the received signal-to-noise ratio (SNR). Capitalizing on this, standard performance measure, average symbol error probability (ASEP) over various modulation formats will be efficiently evaluated. Obtained numerical results will be graphically presented in order to show the influence of system parameters, like fading severity and reception diversity order on overall system performances. Streszczenie. Przeanalizowano kooperacyjny system transmisji wykorzystuj ¸acy kanałNagakami-q (Hoyt). Rozwa˙zono u˙zycie techniki Maximal Ratio Combining (MRC). Przedstawiono przykład ilustruj ¸acy wpływ parametrów transmisji, takich jak zró˙znicowanie zaniku (fading severity) czy ró˙znorodno´s´c porz¸adku odczytu (reception diversity order) na mo˙zliwo´sci systemu. (Transmisja kooperacyjna MRC w kanałach Hoyt). Keywords: Non-regenerative cooperative transmission, Amplify-and-Forward, Maximal Ratio Combining, Hoyt fading channels Słowa kluczowe: transmisja kooperacyjna, kanały z zanikami Introduction Wireless systems in the future will be envisaged to offer ubiquitous high data-rate coverage in large areas [1]. A promising solution for providing broader and more efficient coverage in both modern (ad-hoc, WLAN) and traditional (bent pipe satellites) communications networks, are multihop relaying technology communications. Multihop transmission is a communication technique that arises in many applications: to attain broader coverage without the need to use large power at the transmitter; to communicate via ad hoc networks where nodes are communicating without the aid of central control/infrastructure; to combat the impa[...]

Multiple co-channel interferers influence on the selection diversity system over Rayleigh fading channels

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Selection combining (SC) diversity receiver experiencing an arbitrary number of multiple, independent, equal power co-channel interferers, in the presence of Rayleigh fading channels was analyzed. Closed form expressions are obtained for the output SIR’s probability density function (PDF) and cumulative distribution function (CDF). In order to show the effects of the number of multiple interferers, diversity order and input SIR unbalance to the system performances, an outage probability (OP) analysis is derived. Another important measure of the system’s performances, an average bit error probability (ABER) is efficiently evaluated for non-coherent modulation schemes such as binary frequency-shift keying (BFSK) and binary differentially phase-shift keying (BDPSK). Streszczenie. Przeanalizowano wpływ interferencji mi¸edzy wieloma niezale˙znymi kanałami(w obecno´sci kanału Rayleigha z zanikami) na wybór najlepszego sygnału. Przedstawiono wyra˙zenie na prawdopodobie´nstwo parametru SIR (signal to interference ratio) oraz ´srednie prawdopodobie´nstwo bitu bł ¸edu (ABER).(Wpływ interferencji mi¸edzy wieloma niezale´znymi kanałami(w obecno´sci kanału Rayleigha z zanikami) na wybór najlepszego sygnału) Keywords: co-channel interference, correlated fading channels, probability distribution, Rayleigh fading, selection diversity combining Słowa kluczowe: interferencja mi¸edzy kanałami, korelacja kanałów z zanikami. Introduction In cellular communication systems, usually a large number of low-power transmitters broadcast a signal in relatively small geographic areas - cells. Commercial and military cellular systems tend to conserve the available spectrum by reusing allocated frequency channels in areas that are geographically located as close to each other as possible. Unfortunately, due to frequency reuse, signals from two or more channels operating at the same frequency, but from different locations, interfere. Amount of co-channel i[...]

Average BER of SSC receiver over correlated Rayleigh fading channels in the presence of interference

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In this paper switch-and stay combining (SSC) receivers over Rayleigh fading channels are observed. The case of interference-limited system in the environment with multiple co-channel interferers is considered. The proposed analysis gives the brand new expression for evaluating the probability density function (pdf) of signal-to-interference (SIR) at the output of combiner. Based on this, the average bit error probability (ABER) of the system, as one of the most important performance measure, is discussed. Streszczenie. W artykule przedstawiono wyniki obserwacji odbiornika SSC w kanale Rayleigha z zanikami. Rozważono system z ograniczonymi zakłóceniami i interferencją wielokanałową. Wyniki umożliwiają określenie funkcji gęstości prawdopodobieństwa i na ich podstawie określenia średniego błędu przypadkowego bitu. (Średni błąd bitu odbiornika z kanałem Rayleigha z zanikami w obecności zakłóceń) Keywords: average bit error rate, diversity combining, fading channel. Słowa kluczowe: średni błąd bitu, kanał z zanikami.. Introduction Fading phenomena is a major obstacle in a mobile wireless environment, introduced as random amplitude and phase distortion to the transmitted signal [1]. In addition to fading, interference is also present in communication systems. In the cellular mobile terrestrial and satellite communication systems, increasing of spectral efficiency is the main design goal. In such systems, signals from two or more channels and different locations operate at the same frequency and interfere for each other due to frequency reuse. This often result in co-channel interference as a general distortion in the performance of wireless communication systems [1], [2]. So, it is important to analyse how the interference affects well-accepted performance criteria of wireless systems, such as the outage probability, average output signal-to-interference ratio (SIR) and average bit-error probability (ABER) in order to implement practic[...]

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