Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
THE EFFECT OF DOPPLER FREQUENCY SHIFT, FREQUENCY OFFSET OF THE LOCAL OSCILLATORS, AND PHASE NOISE ON THE P... NASA/TM-2001-210595... JUN. 20
Author: Digital Modulation Techniques
Author: Fuqin XiongPublisher: Artech House Publishers
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 1056
Book Description
This newly revised and expanded edition of an Artech House classic builds on its success as far and away the most comprehensive guide to digital modulation techniques used in communications today. The second edition adds a wealth of up-to-date, critical material, including: Five new chapters devoted to orthogonal frequency division multiplexing (OFDM) covering its basics and practical implementation issues: peak-to-average power ratio (PAPR) reduction, synchronization, fading channel performance, and mitigation methods, as well as the newest developments such as wavelet OFDM schemes; New modulations for optical communications; Enhanced coverage of M-ary amplitude shift keying (ASK); More accurate bit error rate (BER) equations for quaternary phase shift keying (QPSK) and quadrature amplitude modulation (QAM); Enhanced coverage of fading channel mitigation methods such as channel estimate and diversity techniques; Fast-access comparison of all modulation schemes; New appendixes covering trigonometry identities, Fourier transform pairs and properties, and Q-function and error function values.
The Effect of Doppler Frequency Shift, Frequency Offset of the Local Oscillators, and Phase Noise on the Performance of Coherent Ofdm Receivers
Author: National Aeronautics and Space Administration (NASA)Publisher: Createspace Independent Publishing Platform
ISBN: 9781721259878
Category :
Languages : en
Pages : 30
Book Description
This paper first shows that the Doppler frequency shift affects the frequencies of the RF carrier, subcarriers, envelope, and symbol timing by the same percentage in an Orthogonal Frequency Division Multiplexing (OFDM) signal or any other modulated signals. Then the SNR degradation of an OFDM system due to Doppler frequency shift, frequency offset of the local oscillators and phase noise is analyzed. Expressions are given and values for 4-, 16-, 64-, and 256-QAM OFDM systems are calculated and plotted. The calculations show that the Doppler shift of the D3 project is about 305 kHz, and the degradation due to it is about 0.01 to 0.04 dB, which is negligible. The degradation due to frequency offset and phase noise of local oscillators will be the main source of degradation. To keep the SNR degradation under 0.1 dB, the relative frequency offset due to local oscillators must be below 0.01 for the 16 QAM-OFDM. This translates to an offset of 1.55 MHz (0.01 x 155 MHz) or a stability of 77.5 ppm (0.01 x 155 MHz/20 GHz) for the DI project. To keep the SNR degradation under 0.1 dB, the relative linewidth (0) due to phase noise of the local oscillators must be below 0.0004 for the 16 QAM-OFDM. This translates to a linewidth of 0.062 MHz (0.0004 x 155 MHz) of the 20 GHz RIF carrier. For a degradation of 1 dB, beta = 0.04, and the linewidth can be relaxed to 6.2 MHz. Xiong, Fuqin and Andro, Monty Glenn Research Center NASA/TM-2001-210595, NAS 1.15:210595, E-12553