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 clipping or reducing the... [11 Apr 2007]
Development of an OFDM Based High Speed Wireless LAN Platform Using the TI C6x DSP
White Paper Each standard operates using adaptive sub-band Quadrate Amplitude Modulation (QAM) and offers a maximum data rate of 54 Mbits/s over a 20 MHz channel. Coded Orthogonal Frequency Division Multiplexing (COFDM) is currently specified in all three of... [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]
Wideband: Delivering the Connected Life
White Paper In addition to enabling higher bandwidth through channel bonding, Cisco Wideband also makes use of low-cost, field-proven edge QAM modulators to dramatically lower costs and also to increase density. Subscribers are increasingly demanding "Many... [06 Oct 2006]
A Pragmatic Adaptive OFDM/FDD Cellular System in Frequency-Selective Fading Channels
White Paper This paper talks about an adaptive transmission scheme using QAM and LDPC code proposed for an OFDM cellular system employing FDD. By approximating the LLR distribution to a Gaussian distribution, only two parameters, the mean and the normalized... [26 Jul 2005]
Low-Complexity Blind Carrier Frequency Recovery for OFDM Signals Over Frequency-Selective Radio Channels
White Paper Due to this feature, a carrier frequency offset has a similar impact on OFDM as a clock timing offset has in a quadrature amplitude modulation (QAM) system. This paper introduces a blind (i.e.data independent) algorithm for carrier frequency offset... [26 Jul 2005]
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 exploiting the non-circularity... [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 to be a competitive one. [21 Jul 2005]
A Recursive Least Square Channel Estimator for Digital Terrestrial Broadcasting System
White Paper However, channel estimation is one of the problems pertinent to high order QAM modulations in OFDM systems. OFDM modulation is essentially the simultaneous transmission of a large number of narrow band carriers, each modulated with a low data rate... [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 being developed and tested... [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 cyclostationarity induced by the... [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 case of critical time... [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 Inter-carrier Interference (ICI... [28 Mar 2005]
The Benefits of Discrete Multi-Tone (DMT) Modulation for VDSL Systems
White Paper This paper discusses DMT's advantages over QAM from the perspectives of performance, flexibility, compatibility, and operational issues, all of which are extremely important to a service provider. Multi-Carrier Modulation has features that make it... [21 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 amplitude... [13 Feb 2005]
