Eq. of line: R(b)=s(b)*P+c(b), [where, b=body position(i.e. walk, sit, stand etc), s(b) is slope of line, c(b) intercept of line, P is the desired power, R(b) is the sensitivity (i.e. RSSI) of the receiver.
Dear vit sipal, I have read all the doc files of IEEE 802.15.6 OF tg6 group, but really I am still not too much clear about my case, because I am going to control the power with body posture change using Linear channel model........, thanks for your kind response.