Patent ID: 6480525
Filing Date: 2002-11-12
Classification: H04B,H04L,H04W

Abstract:
In a code-division-multiple-access (CDMA) system employing spread-spectrum modulation comprising a radio network controller, a plurality of base stations, each base station (BS) comprising a BS-spread-spectrum transmitter and a BS-spread-spectrum receiver, and a plurality of mobile stations, each mobile station (MS) comprising an MS-spread-spectrum transmitter and an MS-spread-spectrum receiver, a method comprising the steps of:transmitting from an MS-spread-spectrum transmitter of a first mobile station at least one access preamble comprising an access preamble signature corresponding to a group of common packet channel (CPCH) channels selected from a plurality of groups of CPCH channels; transmitting from an MS-spread-spectrum transmitter of a second mobile station at least one access preamble comprising said access preamble signature; receiving at the BS spread-spectrum receiver of one of the base stations at least one of the access preambles at a detectable-power level; responsive to receipt of the at least one access preamble at the detectable power level, transmitting an acknowledgment signal corresponding to the access preamble signature from the BS-spread-spectrum transmitter of the one base station; receiving the acknowledgment signal at the MS-spread-spectrum receiver of each of the first and second mobile stations; transmitting from the MS-spread-spectrum transmitter of the first mobile station a first collision detection preamble comprising a first collision detection signature; transmitting from the MS-spread-spectrum transmitter of the second mobile station a second collision detection preamble comprising a second collision detection signature; substantially concurrently receiving the first and second collision detection preambles at the BS spread-spectrum receiver of the one base station; identifying a first available CPCH channel among the selected group of CPCH channels; selecting the first mobile station for assignment of the identified CPCH channel; transmitting from the BS-spread-spectrum transmitter of the one base station a base station collision detection preamble, the base station collision detection preamble corresponding to the first collision detection preamble signature and to the identified CPCH channel; receiving the base station collision detection preamble at the MS-spread-spectrum receiver of the first mobile station; and transmitting from the MS-spread-spectrum transmitter. of the first mobile station a spread-spectrum signal comprising any of data and power control information, over the identified CPCH channel, responsive to the receipt of the base station collision detection preamble.