Upsampling QPSK Symbols

In short yes an RRC filter can handle mapping, shaping and upsampling. The mixer is then applied at high sample rate.

The RRC filter will imply scaling as well.

start with say 80 coefficients (depends on baseband width), split up into 8 polyphases e.g. polyohase1 = coeffs(1:8:end)

polyphase 2 = coeffs(2:8:end)

since you will multiply these by +1 and -1 then you just store coeffs and add up the sum of coeffs (inverting if input stage = -1)

You run a counter 0~7 as polyphase pointer. and input delay line of 10 stages

at count0 you add up sum of coeffs for polyphase1 => first output

count1 add up those of polyphase2 => second output and so on

...

at count7 end advance the input stage once and repeat sums

That is all !the output will come out 8 samples for every input advance, nice and smooth ready for mixining