QAM

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Symbol Error rate for QAM (16, 64, 256,.., M-QAM)

by Krishna Sankar on January 1, 2012

plot_symbol_error_rate_16qam_64qam_256qam_ofdm_awgn

In May 2008, we derived the theoretical symbol error rate for a general M-QAM modulation (in  Embedded.com, DSPDesignLine.com and dsplog.com) under Additive White Gaussian Noise. While re-reading that post, felt that the article is nice and warrants a [...]

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Softbit for 16QAM

by Krishna Sankar on July 5, 2009

Gray coded 16QAM bit mapping for bit b1

In the post on Soft Input Viterbi decoder, we had discussed BPSK modulation with convolutional coding and soft input Viterbi decoding in AWGN channel. Let us know discuss the derivation of soft bits for 16QAM [...]

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Download free e-book on error probability in AWGN

by Krishna Sankar on October 1, 2008

We have quite a few articles discussing bit and symbol error rates for popular digital modulation schemes in Additive White Gaussian Noise (AWGN) channel. This post summarizes the articles discussing the theoretical and simulated error [...]

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Comparing BPSK, QPSK, 4PAM, 16QAM, 16PSK, 64QAM and 32PSK

by Krishna Sankar on July 8, 2008

I have written another article in DSPDesginLine.com. This article can be treated as the third post in the series aimed at understanding Shannon’s capacity equation. For the first two posts in the series are: 1. [...]

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16QAM Bit Error Rate (BER) with Gray mapping

by Krishna Sankar on June 5, 2008

Bit Error Rate plot for 16QAM with Gray mapping

Let us derive the theoretical 16QAM bit error rate (BER) with Gray coded constellation mapping in additive white Gaussian noise conditions. Further, the Matlab/Octave simulation script can be used to confirm that the simulation is [...]

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Binary to Gray code for 16QAM

by Krishna Sankar on June 1, 2008

16QAM modulation with Gray coded mapping

In the previous post on Binary to Gray code conversion for PSK, I had claimed that “for a general M-QAM modulation the binary to Gray code conversion is bit more complicated“. However following a closer [...]

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Article in DSPDesignLine.com: M-QAM symbol error

by Krishna Sankar on May 24, 2008

Its been a nice week for me, wherein I guest posted an article in DSPDesignLine.com. The article derives the theoretical symbol error rate for M-QAM modulation. The theoretical results are further supplemented by Matlab/Octave simulation [...]

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Need for I-Q modulator and demodulator

by Krishna Sankar on April 5, 2008

spectrum of passband PAM

Post describes about the need for I-Q modulation by comparing the spectral efficiency of passband PAM and passband QAM.

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Comparing 16PSK vs 16QAM for symbol error rate

by Krishna Sankar on March 29, 2008

Comparing 16PSK and 16QAM symbol error rate

In two previous posts, we have derived theoretical symbol error rate for 16-QAM and 16-PSK modulation schemes. The links are: (a) Symbol error rate for 16-PSK (b) Symbol error rate for 16-QAM Given that we [...]

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Symbol Error Rate (SER) for 16-QAM

by Krishna Sankar on December 9, 2007

16QAM constellation plot

Given that we have went over the symbol error probability for 4-PAM and symbol error rate for 4-QAM , let us extend the understanding to find the symbol error probability for 16-QAM (16 Quadrature Amplitude [...]

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Symbol Error Rate (SER) for QPSK (4-QAM) modulation

by Krishna Sankar on November 6, 2007

probability density function of 4QAM

Given that we have discussed symbol error rate probability for a 4-PAM modulation, let us know focus on finding the symbol error probability for a QPSK (4-QAM) modulation scheme. Background Consider that the alphabets used [...]

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Scaling factor in QAM

by Krishna Sankar on September 23, 2007

When QAM (Quadrature Amplitude Modulation) is used, typically one may find a scaling factor associated with the constellation mapping operation. It may be reasonably obvious that this scaling factor is for normalizing the average energy [...]

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