A 
cellular radio system in which a 
base station receiver can receive, on the reverse link, data from a mobile terminal in one of four control 
modes. In the first mode, the mobile terminal sends an independent user 
pilot, not synchronized with the 
base station, on the reverse link and the user 
data channel is synchronized to this independent user 
pilot. In the second mode, the mobile terminal slaves its user 
pilot to the pilot it receives from the 
base station and the user 
data channel is synchronized with this slaved user pilot. This second mode allows the user terminal to receive round trip 
delay information for purposes of 
geolocation and rapid reacquisition. In the third mode, the mobile terminal slaves its user pilot to the incoming base 
station pilot, as in the case of mode two, but the user 
data channel operates in the orthogonal mode using the 
ranging information received from the base 
station. The 
phase relationship between the user 
pilot channel and the user data channel is calibrated. The user pilot carrier is also the carrier for the user data channel and can be used as the carrier reference for detecting the user data channel. In the fourth mode, the slaved pilot implementation of mode three is used for acquisition but, after acquisition, the user pilot code is 
phase shifted to be synchronous with the user data channel, thus also making it an orthogonal channel. In this mode, the pilots no longer contribute interference to the user data channels, within the 
cell, and can be transmitted at 
higher power levels.