qam
RSS qamUsing Constellation Shaping to Reduce the Peak and Average Power of OFDM Signals
White Paper This paper suggests applying constellation shaping to reduce the peak and average power of Orthogonal Frequency Division Multiplexing (OFDM) signals using Quadrature Amplitude Modulation (QAM) in all subcarriers without... [11 Apr 2007]
Performance Degradation of OFDM Systems Due to Doppler Spreading
White Paper For conventional modulation methods such as Phase-Shift Keying (PSK) and Quadrature-Amplitude Modulation (QAM), the bivariate probability density function (pdf) of the ICI is shown to be a weighted Gaussian mixture. [11 Apr 2007]
Adaptive Modulation Based MC-CDMA Systems for 4G Wireless Consumer Applications
White Paper The digital modulation schemes considered are M-ary QAM, M-ary PSK, M-ary CPM, M-ary MHPM, and GMSK with varying bit-duration-bandwidth product. In this paper, various adaptive modulation based coded MC-CDMA systems have... [16 Jun 2006]
A Fine Blind Frequency Offset Estimator for OFDM/OQAM Systems
White Paper Like other OFDM systems, OFDM systems based on offset QAM (OFDM/OQAM) are very sensitive to carrier frequency offset. In this paper, a new blind carrier frequency offset estimator is developed for OFDM/OQAM systems by... [21 Jul 2005]
The OFDM Advantage
White Paper The OFDMA/QAM-32 solution employed by the ADC Homeworx system delivers the most services in the least amount of bandwidth, providing unsurpassed spectral efficiency. The broadband service delivery marketplace is likely... [21 Jul 2005]
Success Story: Satellite Radio - Terrestrial Digital Radio Is Also on the Way
White Paper QAM) schemes. While Sirius and XM battle each other for subscribers, they're about to face another digital radio competitor, HD Radio. Formerly known as In Band On Channel (IBOC), this terrestrial digital radio system is... [21 Jul 2005]
A Subspace-Based Approach to Blind Channel Identification in Pulse Shaping OFDM/OQAM Systems
White Paper This paper introduces a subspace-based algorithm for the blind identification of time-dispersive channels in pulse shaping OFDM systems based on offset QAM (OFDM/OQAM). The approach presented in this paper exploits... [29 Mar 2005]
Orthogonal Frequency Division Multiplexing Based on Offset QAM
White Paper OFDM based on offset quadrature amplitude modulation (OFDM/OQAM) bypasses a major disadvantage of OFDM based on ordinary QAM, namely the fact that time-frequency well-localized pulse shaping filters are prohibited in the... [28 Mar 2005]
Simple Doppler Compensation for DVB-T
White Paper The effect of ICI is mitigated by cancelling the ICI to a sufficiently low level to obtain a reliable detection of 64-QAM modulated signal, using the estimated data and channel parameters. In the DVB-T system, the... [28 Mar 2005]
The Benefits of Discrete Multi-Tone Modulation for VDSL Systems, Part I
White Paper Currently the T1E1 and ITU-T committees have decided to adopt dual line-code standards for VDSL: Multi-carrier modulation (MCM) in the form of discrete multi-tone (DMT) modulation, and single-carrier modulation in the form of quadrature... [14 Feb 2005]
Performance Degradation of Coded-OFDM Due to Phase Noise
White Paper System performance is evaluated as a degradation of the effective SINR, using BER simulations and in terms of achievable cut-off rate for different M-QAM OFDM schemes in the presence of the phase noise. [02 Nov 2004]
M-QAM OFDM and PCC-OFDM Performance in the Presence of Phase Noise
White Paper Theoretical and simulations results for bit error rate (BER) are presented for M-QAM OFDM and PCC-OFDM systems over Rayleigh fading channels. This paper addresses the issue of OFDM and PCC-OFDM systems impaired by phase... [26 Oct 2004]
Totally Blind APP Channel Estimation for Mobile OFDM Systems
White Paper The phase ambiguity problem is solved by using a 4-QAM scheme with asymmetrical arrangement. A new two-dimensional blind channel estimation scheme for coherent detection of OFDM signals in a mobile environment is presented. [21 Oct 2004]
Key RF Upconverter Parameters for Optimizing Your Cable Modem System
White Paper Many cable modem system vendors have opted to provide a fixed intermediate frequency (IF) quadrature amplitude modulation (QAM) signal from their Cable Modem Termination System (CMTS) instead of a variable radio... [02 Mar 2004]
Method for Using Non-squared QAM Constellations
White Paper This paper proposes a method for using non-square QAM constellations with independent I&Q. This method is based in the creation of non-separable I and Q constellations by combining constituent separable I and Q... [25 Feb 2004]
