designing bpsk transmitter circuit

Hi
I want to design a low power bpsk transmitter circuit, which should be in a few mW of power consumption.
- how should i choose the oscillator? i think using RC should be better?
- what is the relationship between carrier frequency and bit rate? i c some papers with 400MHz and 20 MHz have pretty similar bit rates of few Mbps.
- is the bpsk modulator can be implemented with simply an XOR?

thank you~

you need to post in digital forum than RF

http://www.vmsk.org/Modulation.pdf