Results 221 to 230 of about 47,365 (251)

Fundamentals of Quadrature Amplitude Modulation

1995
Quadrature amplitude modulation (QAM) is a widely used method for transmitting digital data over bandpass channels. It can be viewed as a generalization of PAM to bandpass channels. All current telephone line modems based on the ITU-T V series recommendations for transmission at rates of 2400 bps or more use QAM or include it as an option.
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Constellation Design for Odd-Bit Quadrature Amplitude Modulation

2010 IEEE Wireless Communication and Networking Conference Workshops, 2010
In this paper, we study the constellation design of quadrature amplitude modulations (QAMs) with odd number of bits per symbol. A square constellation, which adopts symmetrical Gray labeling, is proposed. Simplified mapping and demapping methods are also designed for it.
Yiling Wu, Yuping Zhao, Hongbin Li
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Performance of Quadrature Amplitude Modulation for Indoor Radio Communications

IEEE Transactions on Communications, 1987
The performance of M -QAM for indoor radio communications is evaluated via a realistic model for indoor multipath propagation [1]. It is found that the outage (BER < 10-4) is about 0.3 percent at 1 Mbit/s and 20 percent at 4 Mbits/s. Two-antenna predetection diversity reduces the outage from 1.2 to 0.04 percent at 2 Mbits/s.
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An Automatically Controlled Predistorter for Multilevel Quadrature Amplitude Modulation

IEEE Transactions on Communications, 1983
In digital microwave transmission, the nonlinear characteristics in a high power amplifier, such as a TWT (traveling-wave tube) inhibit efficient output use. This note introduces a new predistorter control technique, and assesses the nonlinear compensation capability of a third-order predistorter incorporating this technique.
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Costas Loop for Quadrature Amplitude Modulation

2017
A Costas loop for the reception of Quadrature Amplitude Modulation (QAM) signals is presented in this chapter. The generation of the QAM signal is described first. When the data signals (I and Q in this case) are unfiltered, the modulated QAM signal would occupy a large frequency range. To reduce bandwidth, the I and Q signals are usually filtered.
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Bitwise Log-Likelihood Ratios for Quadrature Amplitude Modulations

IEEE Communications Letters, 2015
For an increase in spectral efficiency and improvement of error performance, a high-order modulation and an advanced channel coding scheme are jointly used for many digital communication systems. In this paper, a new and simple method for calculating bitwise log-likelihood ratios which are required for soft decision decoding is proposed for $M ...
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Transmission System with Quadrature Amplitude Modulation

2018
This chapter presents an overview on the principles of digital communications. We focus on a system with one transmitter and one receiver, i.e., for a channel with a single input single output (SISO). This will also provide the necessary basics for multiple input multiple output (MIMO) systems investigated in Part III.
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Third-Order Quadrature Oscillator With Arbitrary Phase Shift Generation and Amplitude Modulation Using MDXCCCTA

IEEE Transactions on Instrumentation and Measurement, 2023
Garima Shukla, Sajal K Paul
exaly  

A new hexagonal quadrature amplitude modulation aided media‐based modulation

International Journal of Communication Systems, 2021
Erdogan Aydin
exaly  

Quadrature Amplitude Modulation Theory

2022
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