Patent ID: 7019691

Claim:
An apparatus for discovering beacon signals communicated from base stations to mobile units in a spread spectrum radio communication system, wherein the beacon signals comprise a common code sequence that is transmitted at predetermined phase delays relative to one another, each predetermined phase delay having an index value associated therewith, and wherein the beacon signals are part of corresponding channels between the base stations and the mobile units, the apparatus comprising: a radio subsystem that downconverts a received RF signal to a baseband signal and samples the baseband signal to derive baseband samples in digital form that represent at least one received beacon signal; buffer means, operably coupled to said radio subsystem, for storing said baseband samples; means for generating a local reference timing signal; and beacon discovery means, operably coupled to said buffer means and said means for generating a local reference timing signal, for i) correlating said baseband samples with said common code sequence over different phase delays to identify a set of correlation peaks that correspond to a plurality of detected beacon signals, ii) for each correlation peak in the set of i), deriving and storing a time offset based upon said local reference timing signal, iii) for each correlation peak in the set of i), deriving and storing a time delay relative to said time offset, said time delay based upon said time offset for the correlation peak in ii) and said predetermined phase delays, wherein said time delay is indicative of a distance between said apparatus and a base station that transmits a detected beacon signal corresponding to the correlation peak, iv) identifying a particular detected beacon signal within said plurality of detected beacon signals, said particular detected beacon signal satisfying a constraint based upon said time delay of each correlation peak derived in iii), v) recovering the index value for said particular detected beacon signal from a channel corresponding to said particular detected beacon signal, and vi) for each given detected beacon signal within a subset of said plurality of detected beacon signals that does not include said particular detected beacon signal, assigning and storing an index value to said given detected beacon signal based upon the recovered index value for said particular detected beacon signal and relative timing between said particular detected beacon signal and said given detected beacon signal.