If you are using the m-file editor, try making a block of the source code of your QPSK, then in the toolbox of simulink, look for a block with a name like "from file" or something like that, I don't use matlab a long time ago, but i'm sure I used that sometime.
variable1 is the matrix you have in workspace, but if you want to use data from a file than you can use second icon. Initially shows as untitled.mat for filename.
Picture is from Matlab 6.1 Simulink.
Now if you want to implement the receiver without simulink than use load filename data.