Advantages of QAM | Disadvantages of QAM | 16QAM,64QAM,256QAM

This page covers advantages and disadvantages of QAM modulation technique. It mentions QAM advantages or benefits and QAM disadvantages or drawbacks. QAM are of many types viz. 16QAM, 64QAM, 256QAM, 512QAM, 1024QAM, 2048QAM, 4096QAM etc.

What is QAM?

The QAM term stands for Quadrature amplitude modulation. This modulation technique utilizes both amplitude and phase variations to represent binary data. For 16QAM type, 4 bits are represented by one complex symbol as shown in the figure-1. For 64QAM modulation type, 6 bits are represented by one complex symbol and so on. As the modulation order in QAM increases, it maps more number of bits per carrier but phase transition between the symbols decreases. This makes receiver more complex in order to recover the original information bits.


Refer QAM basics>> and 512QAM vs 1024QAM vs 2048QAM vs 4096QAM>> for more information.

Benefits or advantages of QAM

Following are the benefits or advantages of QAM:
➨The major benefit of QAM modulation variants is efficient usage of bandwidth. This is due to the fact that QAM represent more number of bits per carrier. For example, 16QAM maps 4 bits per carrier, 64QAM maps 6 bits per carrier, 256QAM maps 8 bits per carrier and so on.

Drawbacks or disadvantages of QAM

Following are the disadvantages of QAM:
➨As states are more closer as shown in the figure, QAM modulation is more susceptible to the noise. Due to this QAM receiver is more complex compare to receivers of other modulation types.
➨As QAM uses amplitude component of signal to represent binary data, linearity need to be maintained and hence linear amplifier is needed which consumes more power.

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