Patent ID: 6038250
Filing Date: 2000-03-14
Classification: H04B

Abstract:
An initial synchronization method for a DS-CDMA inter base station asynchronous cellular system, which uses a plurality of synthesized spread code sequences, each synthesized spread code sequence being synthesized from a long code corresponding to a cell and one of a plurality of short codes corresponding to communication channels, wherein a specific short code of the plurality of the short codes is assigned to a control channel of the cells, comprising the steps of:(1) receiving a control signal in the control channel of a base station, a part of the control signal in every long code period being spread only by the specific short code, and other parts of the control signal being spread by one of the synthesized spread code sequence;(2) correlating the control signal with the specific short code to produce a correlation signal;(3) determining a long code synchronization timing of the control signal based on the correlation signal;(4) detecting correlation between the control signal and segments of the synthesized spread code sequences, the synthesized spread code sequences being synthesized from the different long codes and the specific short code, each segment being taken from a portion of a respective one of the synthesized spread code sequences, starting from a first position in a first of the synthesized spread code sequences from where a first segment is taken, and in successive synthesized spread code sequences, starting from a position in each successive synthesized spread code sequence which is shifted by a predetermined shifting amount from where a preceding segment was taken from a preceding one of the synthesized spread code sequences, the predetermined shifting amount being less than a length of each segment, and the control signal and each segment being synchronized by the long code synchronization timing; and(5) identifying which of the different long codes synthesizes said one of the synthesized spread code sequences, which corresponds to the control signal, based on the electric power level of the correlation signal.