O-QPSK demodulation

Dear all,

I am struggling with O-QPSK receiver that I hope I can utilize GnuRadio
radio for it. However, after doing quite a lot of search, I am still
stuck,
making no headway. Some results I could find are:

  1. The mpsk_receiver states he can do OQPSK demodulation (based on the
    comments in the source code and in some documents e.g., Simple GNU Radio
    User manual); however, I can not figure it out how he could do it

  2. The second approach used in UCLA Zigbee (
    https://www.cgran.org/wiki/UCLAZigBee) with the links among O-QPSK ↔
    MSK
    <->FSK then FSK Demod is used to accomplish O-QPSK demodulation. The
    problem here is with this direction, we can only handle the case O-QPSK
    with half-sine pulse shaping - then OQPSK becomes MSK, a special case
    while
    I wish could do general OQPSK. One question also strikes my mind is with
    this approach, where is the parameters for the root raised cosine (rrc)
    filter?

Can anyone kindly show me the way to solve my problem: OQPSK
demodulation
using GnuRadio, or just tell me if I missed or misunderstood something?

I would like to thank you very much in advance,

Nguyen Anh Duc