BPSK and QPSK have identical BER curve ?

Davy said the following on 05/03/2006 11:55:

QPSK can be regarded as a pair of orthogonal BPSK systems, i.e. the real component is one BPSK system, the imaginary component is the second BPSK system. Because they are orthogonal, they don't interfere (to a good approximation), hence the BER curves are largely equivalent.

Hi Oli Filth,

Oh, I see. Thanks!

Best regards, Davy

If you plot Eb/No vs probability of bit error.

But you expect to see same PeBit for QPSK when the SNR is 3.01 dB higher than for BPSK because, at the same symbol rate, they occupy the same bandwidth and the signal energy needs to be twice as big for QPSK to have the same energy per bit as BPSK.

Best of luck - Mike

Hi, The probability of bit error of both the systems are equal with channel coding and without channel coding. If you derive analytical expression for BER with channel coding, both have the same expression. Best Regards,

-SaiRamesh.