how to use Matlab to add an pi/2 phase shift to a complex signal

I have a GSM signal and in my derivation, I got an derivation like this

In the original term of GSM signal, the signal that I actually received is looked like this

There exist pi/2 phase shift between the signal I need to process and the signal I received. Can you give me some advise how to solve this problem in any way? Thank you very much Shixian Wen Email:[e-mail]