Patent ID: 6195343
Filing Date: 2001-02-27
Classification: H04B,H04L,H04W

Abstract:
A spectrum spread communication system comprising:a plurality of base stations and a plurality of mobile stations having communication means using a direct spread CDMA (Code Division Multiple Access) method as a multi-dimensional access method, each of said plurality of base stations having synchronizing code transmission means for periodically transmitting a synchronizing code together with a specific spread code, said specific spread code having a length which is integer times as great as a transmission symbol length of the synchronizing code, each of said plurality of mobile stations having means for acquiring symbol synchronization of the base stations by detecting correlation of the synchronizing code;wherein each of said plurality of base stations employs a combination of a short code, whose symbol length is equal to said synchronizing code length, and a long code, whose period is longer than that of the short code, as a spread code for use in a channel for transmitting information and as a control signal to the mobile stations, the synchronizing code transmission period being equal to the long code period, the synchronizing code conforming to the leading end of the long code;wherein each of said plurality of mobile stations uses the synchronizing code transmission period and timing obtained by detecting the correlation of the synchronizing code to acquire long code synchronization;wherein kinds of synchronizing codes and transmission frequencies of all said plurality of base stations are equalized, different long codes are allocated to adjacent base stations; andfurther wherein each of said plurality of mobile stations detects the correlation of the synchronizing code over the whole phase of the synchronizing code transmission period to determine a closest base station which transmitting the synchronizing code whose correlation value is the highest, uses the synchronizing code transmission period and timing obtained by detecting the correlation of the synchronizing code to detect the correlation of the whole long code allocated to the closest base station, and acquires long code synchronization by deciding a long code with the greatest correlation value to be the long code of the closest base station.