What is Constellation in QAM?

A constellation diagram is a representation of a signal modulated by a digital modulation scheme such as quadrature amplitude modulation or phase-shift keying. It displays the signal as a two-dimensional xy-plane scatter diagram in the complex plane at symbol sampling instants.

What is the symbol rate of 16-QAM?

Tabular difference between 16-QAM, 64-QAM and 256-QAM

Specifications	16-QAM modulation	64-QAM modulation
Number of bits per symbol	4	6
Symbol rate	(1/4) of bit rate	(1/6) of bit rate
KMOD	1/SQRT(10)	1/SQRT(42)

What is the difference between 16 PSK and 16 QAM?

More the distance between the constellation, lesser is the chance of a constellation point getting decoded incorrectly. This implies that for the same symbol error rate, 16QAM modulation requires only 4.19dB lesser signal to noise ratio , when compared with 16PSK modulation.

What is the difference between 16 QAM and 64 QAM?

The 16 qam bits per symbol are 4 (four). This means in 16-QAM each symbol represents 4 bits as mentioned in the 16-QAM constellation diagram above. The 64 qam bits per symbol are 6 (six). In 64-QAM, each symbol is represented by 6 bits as shown in the 64-QAM constellation diagram above.

What are advantages of 16QAM?

The advantages of QAM are higher data rates, high noise immunity, low probability of error values, and increased bandwidth.

How many different symbols are possible at the output of a 16QAM modulator?

Each dot in Figure 1.8 is a symbol, as it represents a unique combination of amplitude and phase of the I and Q waves. So, in each symbol period, only one of the ‘dots’ is transmitted. As there are 16 symbols, this version of QAM is called 16-QAM. Figure 1.8 Constellation diagram for 16-QAM.