I believe that to save battery life and reduce your brains exposure to RF radiation, the handset transmits with the minimum power possible to reach the base station. If that is transmitting on reduced power then the handset will increase it's own power as the base station appears futher away. Would be interesting to see measurements of the change in battery usage between a phone 50m from a mast and say 1500m from that mast.
Demon Internet > O2 BB > BT Unlimited ADSL > BT Infinity 2
Connection speed (U/D) [kbps/kbps]: 20000 / 79999
'Max attainable' rate : 19999 / 99212