back off for OQPSK modulation ?

I have to design a PA/LNA for a Zigbee application, which uses OQPSK modulation.

I heard that we have to handle a back off value to avoid using a linear PA into saturation but I did not succeed in finding the back off value for OQPSK modulation.

Thanks

The offset-QPSK with half-sine pulse
shaping modulation selected for the 2.4 GHz
PHY is equivalent to minimum shift keying
(MSK), which is a constant envelope modulation
scheme. This allows the use of simple,
low-cost and relatively non-linear power
amplifier designs.

I hope it can help.

Mazz

So, if I well understood, I do not need to handle any back off value without risks to use a non-linear PA into saturation ?

And do we need to handle a back off value anyway, if we want to design a linear PA ?