Hala Mansour Abdel-Kader

Performance analysis of Multi Stream Single Code SCM-OFDM in mobile communication system

This paper is concerned with the performance analysis of a Multi Stream Single Code Superposition Coded Modulation Orthogonal Frequency Division Multiplexing (MS-SC-SCM-OFDM) communication system. A simple Chip-By-Chip (CBC) iterative Multi User Detection (MUD) strategy is used in MS-SC-SCM-OFDM system. Saleh model is used as a High Power Amplifier (HPA), the system performance has been studied over AWGN, Jack fading and Rician channels. The goal of this paper is to reduce the number of the encoders and decoders for low design complexity and low bit error degradation. In case of double layer, the performance of Multi Code SCM-OFDM is better than the SC-SCM-OFDM system by only 0.5 dB. For complexity analysis, the multi code system uses two convolutional encoders and two viterbi decoders, while, for the single code system, only one encoder and one decoder are used. Finally, the single code SCM-OFDM is better than multi code SCM-OFDM by 50% complexity.

C4. Multi Rate Single Code Multi Carrier Superposition Coded Modulation (MR-SC-MC-SCM) for Multi User Communications

This paper introduces a Multi Rate Single Code Multi Carrier Superposition Coded Modulation (MR-SC-MC-SCM) for Multi User Communication System, achieving Un-equal Error Protection (UEP) for each user using the multi rate coding concept to provide different levels of data protection based on the user application requirement with some complexity reduction. Saleh model is used as a High Power Amplifier (HPA) and the system performance has been studied over Additive White Gaussian Noise (AWGN), fading channel Jack model and Rician channel. A simple Chip-By-Chip (CBC) iterative Multi User Detection (MUD) strategy is used. The main contribution of this paper is to reduce the transceiver complexity in terms of number of encoders and decoders with minor performance degradation in-terms of Bit Error Rate (BER).

Implementation of a smart and power efficient Turbo Decoder using SDR algorithm

Turbo coding is one of the great achievement in the field of communication systems and signal processing. It is embedded in most of the European standardizations for the radio access networks of start-of-art cellular radio technologies. A Turbo-Decoder consists of two soft-in soft-out component decoders, which exchange information (soft-values) in an iterative process. Turbo-Decoder can be implemented using different algorithm, but Maximum A Posteriori decoding algorithm (MAP) is high Bit Error Rate (BER) performance, nearer to Shannon limit. However, decoding with a fixed number of iterations may lead to excessive processing, penalizing battery operated terminals while fewer iterations are sometimes sufficient. It is necessary to stop the decoding process at an appropriate moment to reduce the computational time, latency and power dissipation. Sign difference ratio (SDR) presents a simple and efficient criterion for stopping the iteration process in turbo-decoding with a negligible degradation of the error performance. In this paper MATLAB simulated results of turbo decoder are implemented using MAP decoder and its performance are presented.