WiMax, Metro-Fi More Energy Efficient Than 3G > why?

why?

I suspect this is on the base station end...
Sure a WiMAX base station will cover a large area, and doesn't use a whole lot of power. Standard cells are 1-3 miles apart. The power consumption comes from having multiple sites.
Also, do WiMAX phones/data cards use more power than cell phones ?

eg. AMPS uses a lot of power
iDEN uses a lot of power (short battery life)
CDMA (1x/EVDO) is more efficient (power control)
GSM (TDMA) is more efficient yet (less cpu power usage than CDMA)