Cooperative relaying is gaining a significant attention in that, intermediate relay nodes assist the source nodes to enhance the overall network efficiency. In network coded cooperative communications, the relay node ...
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ISBN:
(纸本)9781479905430
Cooperative relaying is gaining a significant attention in that, intermediate relay nodes assist the source nodes to enhance the overall network efficiency. In network coded cooperative communications, the relay node linearly combines the data received from the sources and forward the linear combination to the destination. In this paper, we present the maximum likelihood decoding scheme for a network composed of two sources, single relay, and single destination. We derive a closed form expression for upper bound on the word error probability. The simulation results show that the analytical upper bound is very tight especially at higher values of the SNR. The results also show that there exists an error floor in the error probability. Therefore, the closed form expression of the upper bound is used to study the reasons of this error floor and how to mitigate it.
The originality of this paper consists of combining Code Division Multiple Access (CDMA) technique with Multi Input Multi Output (MIMO) antenna system. The main objective of our contribution is to improve the capacity...
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ISBN:
(纸本)9781424417513
The originality of this paper consists of combining Code Division Multiple Access (CDMA) technique with Multi Input Multi Output (MIMO) antenna system. The main objective of our contribution is to improve the capacity of the existing DS-CDMA systems by supporting an increased number of users and to achieve good performance in terms of bit error rate. This new communication scheme combining the two techniques benefit from perfect codes by employing a spectrally efficient Algebraic Space Time Coding (ASTC) and spreading spectrum by using CDMA technique equipped with Multi User Detector (MUD) that is near far resistant. In our system each user is distinguished by its spreading code signature and its unique channel impulse response (CIR) transfer function. The MIMO-CDMA system, associated by multi user detector, improves the spectral efficiency of wireless system, combat channel fading and reduce narrowband interference. The resulting is a multi-user CDMA-ASTC solution promising high speed communication for 4G cellular wireless networks. Our study and numerical results show the utility of this new wireless communication;a significant BER versus Signal to Noise Ratio (SNR) was achieved thus Multiple access interference (MAI) is suppressed and so supporting a large number of users.
In this paper, a joint adaptive interference canceller (AIC) and maximum likelihood (ml) decoder scheme is proposed for a space-time coded DS-CDMA system with the difference between arrival times from transmit antenna...
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In this paper, a joint adaptive interference canceller (AIC) and maximum likelihood (ml) decoder scheme is proposed for a space-time coded DS-CDMA system with the difference between arrival times from transmit antennas. As the arrival time difference causes not only ISI and MAT, but also inter-antenna interference, performance degradation in the space-time coded DS-CDMA system is more severe than that of a regular DS-CDMA system with single transmit antenna. To mitigate the effect of the interference during space-time decoding, a joint algorithm for the proposed scheme merges adaptation process of the AIC into a ml decoding algorithm. Performance of the proposed scheme is evaluated for QPSK space-time trellis codes with two transmit antennas. It is shown that the proposed scheme achieves better performance than the conventional ml decoding scheme.
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