3.6 Coded Performance of BPSK with SQRC

In BPSK & QPSK coded performance is better than the uncoded performance.The coding gain at 10^-5 is 0.2dB.The coding gain can be increased if we increase the number of coefficients of the FIR filter. Also notice that the difference between the simulation and theoretical curve for coded performance is due to the fact that the formulae used to evaluate the theoretical coded performance is actually an approximation value. \ 

Fig 3.7: Coded BPSK with SQRC

3.7 Coded Performance of QPSK with SQRC

The coded performance of the QPSK system is same as the BPSK system with coding gain of 0.2dB at BER of 10^-5. 

Fig 3.8: Coded QPSK with SQRC

3.8   8 QAM with Code

In QAM the coding gain at 10^-5  is 0dB. We obtained this small value of coding gain because due to the SQRC filter there is loss of 1.5dB on uncoded performance. Hence if we increase the number of coefficient in the FIR filter we can increase the coding gain. The following figure shows the BER performance of 8 QAM when applied with Hamming coding.

Fig 3.9: Coded 8-QAM with SQRC