81 research outputs found

    Concatenation of space-time block codes and turbo trellis coded modulation (ST-TTCM) over Rician fading channels with imperfect phase

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    In this paper, the performance of space time-turbo trellis coded modulation (ST-TTCM) is evaluated over Rician and Rayleigh fading channels with imperfect phase. We modify Baum-Welch (BW) algorithm to estimate the fading and phase jitter parameters for multi-antenna configurations. Thus, we assume that the channel parameters change slower than carrier frequency. We know that, at high data rate transmissions over wireless fading channels, space-time block codes (STBC) provide the maximal possible diversity advantage. Here, the combined effects of the amplitude and the phase of the received signal are considered, each one modelled by Rician and Tikhonov distributions, respectively. We investigate space time-turbo trellis coded modulation (ST-TTCM) for 8-PSK for several Rician factor K and phase distortion factor eta. Thus. our results reflect the degradations both due to the effects of the fading on the amplitude and phase noise of the received signal while the channel parameters are estimated by BW algorithm. Copyright (C) 2004 John Wiley Sons, Ltd

    Clustering Internet Usage Behaviours with SOM Neural Networks

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    According to different needs of users, there are different consumption habits. Consumption habits of people, which have the same age group or the same professions, are similar. A type of internet usage habits of people in this way is one of these habits. In recent years, developments in technology, GSM, and especially with 4G mobile internet usage have found applications in many areas of daily life. Enter to internet, wherever users need to, creates freedom. Messaging, media, finance and many different needs can be met through this connection. Users' occupation, age, gender, location, usage patterns according to different characteristics such as income level and the relevant properties are similar to each other according to the amount of internet usage (in Mb Download) connected to internet and internet usage frequency and duration of exposure can be clustered. SOM type of study, personal internet usage by artificial neural networks (data of the CDR) process and their profession, age, gender, location is to cluster usage patterns according to the values

    Blind equalization of turbo trellis-coded partial-response continuous-phase modulation signaling over narrow-band Rician fading channels

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    In this paper, a blind maximum-likelihood channel estimation algorithm is developed for turbo trellis-coded/continuous-phase modulation (TTC/CPM) signals propagating through additive white Gaussian noise (AWGN) and Rician fading environments. We present CPM for TTC signals, since it provides low spectral occupancy and is suitable for power- and bandwidth-limited channels. Here, the Baum-Welch (BW) algorithm is modified to estimate the channel parameters. We investigate the performance of TTC/CPM for 16-CPFSK over AWGN and Rician channels for different frame sizes, in the case of ideal channel state information (CSI), no CSI, and BW estimated CSI

    Blind equalization of space-time-turbo trellis coded/contilluous phase modulation over Rician fading channels

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    In this paper. to improve bit error performance and bandwidth efficiency. we combine space-time blockcodes (STBC), turbo trellis codes and continuous phase modulation and denote space-time-turbo trellis coded/continuous phase modulation (ST-TTC/CPM). For high data transmission over wireless fading! channels, STBC provide the maximal possible diversity advantage for multiple decoding algorithm. We present continuous phase modulation (CPM) for ST-TTC signal. mince CPM provided low-Spectral occupancy and is suitable for power and bandwidth-limited channels. In our model. to utilize STBC efficiently. we need to estimate the channel parameters. which influence the signals having continuity property. Therefore, we develop a blind maximum likelihood channel estimation algorithm for signal propagating through a Rician fading channel. Here. Baum-Welch (BW) algorithm based on hidden Markov model (HMM) is modified to provide computationally efficient channel parameter estimation. We also investigate the performance of ST-TTC/CPM in the case of no channel state information (CSI) for various Rician parameters K and Doppler frequency. Copyright (C) 2004 AEI

    Energy consumption and economic growth nexus: Evidence from developed countries in Europe

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    This paper analyzes the relationship between renewable and non-renewable energy consumption and economic growth for a panel of fifteen European Union countries over the period 1990-2011 within a multivariate framework. The heterogeneous panel cointegration tests present a long-run equilibrium relationship between real GDP, renewable and non-renewable energy consumption, greenhouse gas emissions and research and development. The Granger-causality results demonstrate unidirectional causality between non-renewable energy consumption and economic growth

    A new approach for residual gravity anomaly profile interpretations: Forced Neural Network (FNN)

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    This paper presents a new approach for interpretation of residual gravity anomaly profiles, assuming horizontal cylinders as source. The new method, called Forced Neural Network (FNN), is introduced to determine the underground structure parameters which cause the anomalies. New technologies are improved to detect the borders of geological bodies in a reliable way. In a first phase one neuron is used to model the system and a back propagation algorithm is applied to find the density difference. In a second phase, density differences are quantified and a mean square error is computed. This process is iterated until the mean square error is small enough. After obtaining reliable results in the case of synthetic data, to simulate real data, the real case of the Gulf of Mexico gravity anomaly map, which has the form of anticline structure, is examined. Gravity anomaly values from a cross section of this real case, result to be very close to those obtained with the proposed method

    Performance of turbo coded signals over partial response fading channels with imperfect phase reference

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    In this paper, the performance of turbo coded signals are investigated over a new channel model, denoted as 1 +/- D-n / Partial Response Fading Channels (PRFC) with imperfect phase reference. The combined effects of the 1 +/- D-n /PRFC and nonideal coherent receiver on the phase of the received amplitude and of a noisy carrier reference are considered. The numerical results demonstrate the error performance degradation due to both amplitude fading and phase noise process
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