Rach ramp-up acknowledgement

Abstract

A disclosed code-division-multiple-access (CDMA) system has a base station (BS) and remote stations (RSs). A BS-spread-spectrum transmitter broadcasts a common-synchronization channel having a chip-sequence signal common to the remote stations served by the BS, and a frame-timing signal. A RS-spread-spectrum receiver receives the broadcast common-synchronization channel, and determines frame timing from the frame-timing signal. A first RS-spread-spectrum transmitter transmits an access-burst signal, which has a plurality of segments. Each access burst signal segment has a plurality of power levels. A BS-spread-spectrum receiver receives the access-burst signal at a detected-power level. In response to receiving the access-burst signal, a BS-spread-spectrum transmitter transmits an acknowledgment signal to the RS-spread-spectrum receiver. The RS-spread-spectrum receiver receives the acknowledgment signal, and in, the RS-spread-spectrum transmitter transmits a spread-spectrum signal having data to the BS-spread-spectrum receiver.

1 . An improvement to a code-division-multiple-access (CDMA) system employing spread-spectrum modulation, with the CDMA system having a base station (BS) with a BS-spread-spectrum transmitter and a BS-spread-spectrum receiver, and a plurality of remote stations, with each remote station (RS) having an RS-spread-spectrum transmitter and an RS-spread-spectrum receiver, the method comprising the steps of:
 transmitting from said BS-spread-spectrum transmitter located at said base station, a broadcast common-synchronization channel having a common chip-sequence signal common to the plurality of remote stations, the broadcast common-synchronization channel having a frame-timing signal;   receiving at a first RS-spread-spectrum receiver the broadcast common-synchronization channel, and determining frame timing at said first RS-spread-spectrum receiver from the frame-timing signal;   transmitting from a first RS-spread-spectrum transmitter an access-burst signal, the access-burst signal having a collision-detection portion;   receiving at said BS spread-spectrum receiver the access-burst signal, including the collision-detection portion;   transmitting from said BS-spread-spectrum transmitter to said first RS-spread-spectrum receiver, responsive to receiving the access-burst signal with the collision-detection portion, a collision-detection signal, the collision-detection signal including the collision-detection portion from the access-burst signal;   receiving at said first RS-spread-spectrum receiver the collision-detection signal with the collision detection portion; and   transmitting from said first RS-spread-spectrum transmitter, responsive to receiving the collision-detection signal, to said BS-spread-spectrum receiver, a spread-spectrum signal having data.