Mobile communication system for accomplishing handover with phase difference of frame sync signals corrected

• US 20010024430A1
• Filed: 05/15/2001
• Published: 09/27/2001
• Est. Priority Date: 11/28/1996
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: OKI Electric Industry Company Limited
• Inventors: Horiguchi, Kenji, Kawabe, Manabu, Sekine, Kiyoki
• Granted Patent: US 6,975,607 B2
• Time in Patent Office: Days
• US Class Current: 370/331
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/083 wherein at least one of the access points is a moving node
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection

Abstract

A method of switching a communication channel when a mobile station moves from one service area to another service area is disclosed. The mobile station determines a difference between the transmission phase of a frame synchronizing signal received from a first base station currently holding a communication channel with the mobile station and the transmission phase of a frame synchronizing signal received from a second base station expected to newly set up a communication channel with the mobile station. The mobile station sends phase difference information representative of the above difference to the first base station via the communication channel. The first base station having received the phase difference information transfers the information to the second base station, causing it to correct the phase of data thereof to be sent to the mobile station. This successfully implements soft handover while guaranteeing the phase synchronization of frames sent from the two base stations.

Claims

1. A mobile station for interchanging communication data via a communication channel with a base station controlling a service area in which said mobile station is located;

said mobile station comprising;

a phase difference detecting circuit for detecting a difference between a transmission phase of a frame synchronizing signal received from a first base station currently holding a communication channel with said mobile station and a transmission phase of a frame synchronizing signal received from a second base station expected to newly set up a communication channel with said mobile station; and

a phase difference reporting circuit for reporting said difference to said first base station as phase difference information.

2. A mobile station in accordance with

claim 1

, further comprising a demodulating circuit for combining and demodulating a signal received from said first base station and a signal received from said second base station.

3. A mobile station in accordance with

claim 1

, further comprising:

a receipt condition measuring circuit for measuring receipt conditions of a signal received from each of a plurality of base stations including a base station currently holding a communication channel; and

a receipt condition reporting circuit for reporting said receipt conditions to said base station currently holding a communication channel with said mobile station as receipt condition information.