The future wireless communication systems require of improvement spectral efficiency. We propose in this paper a solution of the faster at emission-reception of data in a MC-CDMA system. The interest of this technique is able to reduce the time of data processing by using of the fixed point at emissionreception to increase the flows of processing.
Keywords-(MC-CDMA)-FFT-IFFT-fixed point-floatint pointtime of processing
In recent years, there is an increased requirement including transfers rapidity of information, due to the widespread use of multimedia applications on wireless communication system. The MIMO technology offers a promising solution for increasing spectral efficiency and transmitting data across a multi-antenna transmission and reception network. The goal of this study is to improve the data processing time, which poses a big problem of digital communication. In this article, a solution is proposed to improve this problem. The adopted approach shows that the use of the CORDIC algorithm to calculate the cosine and sine of the DFT / IDFT is very efficient and that the use of the fixed point gives a remarkable speed while maintaining a better accuracy. In addition, the use of a powerful fixed-point processor dedicated to signal processing could also have given better results than other results obtained in the literature. The results obtained conclude that the use of the CORDIC algorithm on a fixed point is faster compared to receiver without the CORDIC algorithm.
<span lang="EN-US">A sub-1V opamp based β-multiplier CMOS bandgap voltage reference (BGVR) with high power supply rejection ratio (PSRR) and low temperature coefficient (TC) is proposed in this paper. A current mode regulator scheme is inserted to isolate the supply voltage of the operational amplifier (opamp) and the supply voltage of the BGVR core from the supply voltage source in order to reduce ripple sensitivity and to achieve a high PSRR. The proposed circuit is designed and simulated in 0.18-μm standard CMOS technology. The proposed voltage reference delivers an output voltage of 634.6mV at 27°C. Tthe measurement temperature coefficient is 22,3ppm/°C over temperature range -40°C to 140°C, power supply rejection ratio is -93dB at 10kHz and -71dB at 1MHz and a line regulation of 104μV/V is achieved over supply voltage range 1.2V to 1.8V. The layout area of the proposed circuit is 0.0337mm<sup>2</sup>. The proposed sub-1V bandgap voltage reference can be used as an internal voltage reference in low power LDO regulators and switching regulators.</span>
Fourier transform is a tool enabling the understanding and implementation of a large number of numerical methods for signal and image processing. This tool has many applications in domains such as vocal recognition, image quality improvement, digital transmission, the biomedical sector and astronomy. This paper proposes to focus on the design methodology and experimental implementation of Discrete Fourier Transform (DFT). The interest of this work is an improvement which makes it possible to reduce the processing time of calculates the DFT while preserving the best performances by using the operator CORDIC and the fixed point, so this work is compared with the results found in the literatures.
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