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The paper evaluates the performance of a CDMA based wireless sensor networks (WSN) in terms of packet error rate (PER) and energy consumption, considering correlation among interferers in shadowed environment. An appropriate model for the interference power, PER and average number of retransmission for successful delivery in a single hop communication are presented. An energy model is considered for...
In this paper we apply approximate and multiscale entropy metrics to spectrum occupancy data gathered during an extensive measurement campaign. We show that the presented methods can be successfully applied to search for and quantify structures of highly varying complexities and time scales. Although structures can be found they are unfortunately relatively complex and it does not appear to be easy...
This paper introduces an on-line unsupervised LEArning neural network (NN) for adaptive feature extraction via Principal component analysis (LEAP) of lower signal to noise ratios (SNR) direct sequence code-division multiple-access (DS-CDMA) signals. The proposed method is based on eigen-analysis of DS-CDMA signals, and exploits the cyclo-stationarity of communication signals adequately. The received...
In this paper, we propose a robust STBC transmission scheme to combat the timing synchronization errors over frequency-selective multiple-access channels. First, the equivalent channel model in the presence of timing synchronization errors is derived and we find that the synchronization errors result in an equivalent channel model with larger number of correlated channel taps. Based on this correlated...
This work studies the performance of a data-driven reduced rank scheme for rapid timing acquisition in multiple access communications. Our results show that when only a limited amount of preamble bits are available, instead of the true second-order statistics (SOS), the reduced rank scheme provides reliable timing information. Exploiting the structure of the multiple access interference, the data...
While two-dimensional (2-D) orthogonal variable spreading factor (OVSF) codes were proposed for multicarrier direct-sequence code-division multiple-access (MC/DS-CDMA) systems in order to eliminate multiple-access interference, the number of orthogonal sequences (or code cardinality) was restricted by the number of carrier frequencies. Non-orthogonal 2-D frequency-time-spreading (FTS) codes were then...
In this paper we present a new method of compensating for complex multipath channel fading in blind multiuser detection for DS-CDMA communication. This compensation allows for the use of different chip pulse shapes. The compensation is based on the incorporation of priors derived from the FFT of the pulse shape. The system employs detectors that incorporate methods of independent component analysis...
Due to the increasing interest in mobile/wireless communication, there has been a continuous research in antenna diversity to combat fading. And the model of correlated and unbalanced diversity branches reflects the real-world scenario. The diagonalizer is introduced here before the diversity branches are combined, which can transform the correlated and balanced branches to the uncorrelated and unbalanced...
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