Multicast communication method in a CDMA mobile communication system

• US 6,542,755 B1
• Filed: 12/07/1999
• Issued: 04/01/2003
• Est. Priority Date: 12/07/1998
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Tsukagoshi, Tsutomu
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): Iqbal, Khawar
• Application Number:
  US09/456,377
• Time in Patent Office: 1,211 Days
• Field of Search: 455/414, 455/503, 455/557, 455/556, 455/442, 455/65, 455/272, 455/502, 370/312, 370/335, 370/342, 370/329, 370/328, 375/347, 375/349, 375/144, 375/148
• US Class Current: 455/503
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers
• CPC Class Codes: H04B 2201/70702 Intercell-related aspects
• CPC Class Codes: H04L 12/1845 broadcast or multicast in a specific location, e.g. geocast protocols for adapting network applications to user terminal location H04L67/52; services specially adapted for wireless communication networks making use of the location of users or terminals H04W4/02
• CPC Class Codes: H04L 12/185 with management of multicast group membership
• CPC Class Codes: H04L 12/189 in combination with wireless systems selective distribution or broadcast in wireless communication networks H04W4/06
• CPC Class Codes: H04W 4/06 Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
• CPC Class Codes: H04W 4/08 User group management
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff
• CPC Class Codes: H04W 72/30 Resource management for broadcast services
• CPC Class Codes: H04W 76/40 for selective distribution or broadcast
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: H04W 88/08 Access point devices
• CPC Class Codes: H04W 88/184 Messaging devices, e.g. message centre
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A multicast communication method in a CDMA mobile communication system which is capable of reducing a transmission power in a base station system, and is capable of performing an efficient multicast operation for a large number of mobile subscribers is provided. The starting of information distribution by a multicast operation and identification information indicating a content of the information thereof are notified through a broadcast channel to a mobile subscriber. Further, through the broadcast channel, information such as a spread code or the like to be used at this time, which is necessary for actual reception of communication data, is notified. Then, in the mobile subscriber, a surround environment of the mobile subscriber is checked to determine the possibility of simultaneous receiving from a plurality of other base station systems. If possible, similar notified information is also received from other base station systems. Thus, all kinds of information regarding the spread code or the like to be used for receiving distributed information are obtained.

Claims

1. A multicast communication method in a CDMA mobile communication system, which comprises a plurality of mobile subscribers, a plurality of base station systems connected to the mobile subscribers by radio channels, a plurality of mobile switching centers connected to the base station systems and a multicast communication server connected to the mobile switching centers for providing information to be distributed to the mobile subscribers, said method comprising:

sending a multicast request to at least one anchor base station system together with area information for multicasting;

instructing a multicast request from said anchor base station system to at least one branch base station system necessary for covering multicasting area indicated by the area information;

transmitting multicast starting information and spread code to be used for multicasting information to mobile subscribers through respective broadcast channels of said anchor base station system and said branch base station system; and

transmitting multicasting information from said anchor base station system and said branch base station system after proper time interval, during which said mobile subscribers have been ready for receiving multicasting information, has been elapsed.

2. The multicast communication method in a CDMA mobile communication system according to claim 1, wherein said anchor base station system uses a diversity hand-over trunk for establishing links to said branch base station systems.

3. The multicast communication method in a CDMA mobile communication system according to claim 1, wherein said method further comprising:

receiving multicasting information, at said mobile subscriber, transmitted from a plurality of base station systems, and performing a RAKE combine process for respective received signals.

4. A multicast communication method in a CDMA mobile communication system, which comprises a plurality of mobile subscribers, a plurality of base station systems connected to the mobile subscribers by radio channels, a plurality of mobile switching centers connected to the base station systems and a multicast communication server connected to the mobile switching centers for providing information to be distributed to the mobile subscribers, said method comprising:

sending a multicast request to at least one anchor base station system together with area information for multicasting;

instructing a multicast request and link establishment request from said anchor base station system to at least one branch base station system necessary for covering multicasting area indicated by the area information;

sending back information of link establishment completion and information of decided spread code for multicasting information at each base station system to said anchor base station system from said branch base station system,

transmitting multicast starting information together with a list indicating base station systems transmitting identical multicasting information and spread code to be used for multicasting information to mobile subscribers through respective broadcast channels of said anchor base station system and said branch base station system; and

transmitting multicasting information from said anchor base station system and said branch base station system after proper time interval, during which said mobile subscribers have been ready for receiving multicasting information, has been elapsed.

5. The multicast communication method in a CDMA mobile communication system according to claim 4, wherein said anchor base station system uses a diversity hand-over trunk for establishing links to said branch base station systems.

6. The multicast communication method in a CDMA mobile communication system according to claim 4, wherein said method further comprising:

detecting, at said mobile subscriber, receivable base station systems listed in said list transmitted through the broadcast channel, and preparing reception of multicasting information by setting spread codes indicated in said list; and

receiving multicasting information, at said mobile subscriber, transmitted from a plurality of base station systems, and performing a RAKE combine process for respective received signals.