Spread spectrum communication system and handover method therein

A spread spectrum communication system comprising at least one mobile station and a plurality of base stations arranged in a plurality of sites to communicate with said at least one mobile station by a spread spectrum scheme,

• said at least one mobile station notifying a base station of reception timing differences between a main perch channel and a plurality of perch channels in the plurality of sites;
• and
• searching for a reception timing of one of the plurality of perch channels in the plurality of sites based on the reception timing differences, and
• said base station including transmission means for totalizing the reception timing differences notified from said mobile station, and sending a difference in reception timing between the main perch channel and the one perch channel to said mobile station by including the difference in reception timing in a perch channel in said base station transmitted to said mobile station.

A handover method in a spread spectrum communication system, comprising the steps of:

• causing each of a plurality of base stations located in respective sites to communicate with at least one mobile station located in one of the respective sites by a spread spectrum scheme;
• causing each of said plurality of base stations to accumulate a reception timing difference indicating a difference between reception timing of a transmission signal from a mobile station to a base station in an adjacent site and a transmission signal from said mobile station to a self-station;
• and
• causing each of said base stations to obtain a reception timing of the transmission signal from said mobile station to the self-station by using an accumulated reception timing difference between the self-station and a handover source base station in an adjacent site when the self-station becomes a handover destination base station upon handover of said mobile station between adjacent sites.

A handover method in a spread spectrum communication system, comprising the steps of:

• causing each of a plurality of base stations located in respective sites to communicate with at least one mobile station located in one of the respective sites by a spread spectrum scheme;
• causing said at least one mobile station to notify a base station of reception timing differences between a main perch channel having a highest reception level in the respective sites and a plurality of perch channels in the respective sites;
• causing said base station to totalize the reception timing differences notified from said at least one mobile station and send a difference in reception timing between the main perch channel and one of the plurality of perch channels to said mobile station by including the difference in reception timing in a perch channel in said base station transmitted to said mobile station;
• and
• causing said at least one mobile station to search for a reception timing of the one perch channel based on the reception timing differences.