what is the difference between QPSK and 4QAM?

Question

i need to know the main difference between QPSK and 4QAM, i have searched over the internet and still i have not found a good explenation.

I vote to close this questions on the grounds that it is a duplicate of I and Q components and the difference between QPSK and 4QAM. — Dilip Sarwate, Dec 28 '16 at 02:40

score 2 · Accepted Answer · answered Dec 27 '16 at 10:16

2

There are different types of QPSK: Offset (staggerd) QPSK, $\pi/4$-QPSK, etc.

In its most known form, QPSK is identical to $4$-QAM or $4$-PSK. That is, the same constellation can be referred to by different names. So there is no difference.

This constellation can be seen in the picture bellow (from Wikipedia)

Similarly, $2$-QAM is actually the same as BPSK, as is also pointed out here.

answered Dec 27 '16 at 10:16

msm

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you mean that there is no difference between them? – user24907 Dec 27 '16 at 16:00
but when applied both of them for AWGN channel QPSK gives better BER values than 4QAM – user24907 Dec 27 '16 at 16:03
If one is a subset of the other, the can be an optional difference. – hotpaw2 Dec 27 '16 at 20:44
@user24907 With equal parameters, their BER is also exactly the same. – msm Dec 27 '16 at 21:51

what is the difference between QPSK and 4QAM?

1 Answers1