Method and apparatus for stabilizing communication in mobile communication system

• US 6,760,588 B2
• Filed: 12/27/2000
• Issued: 07/06/2004
• Est. Priority Date: 12/28/1999
• Status: Expired due to Term

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Okajima, Ichiro, Yamao, Yasushi, Umeda, Narumi, Suzuki, Yoshifumi
• Primary Examiner(s): Gary, Erika
• Assistant Examiner(s): BEAMER, TEMICA M
• Application Number:
  US09/748,260
• Publication Number:
  US 20010018346A1
• Time in Patent Office: 1,287 Days
• Field of Search: 455/463, 455/437, 455/438, 455/439, 455/442, 455/449, 455/426.1, 455/226.1, 455/226.2, 455/226.3, 455/67.11, 370/331, 370/332, 370/338, 370/349, 370/394, 370/352, 370/353, 370/354, 370/355, 370/356
• US Class Current: 455/437
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/026 Co-operative diversity, e.g. using fixed or mobile stations as relays
• CPC Class Codes: H04W 92/20 between access points

Abstract

A mobile communication system includes a plurality of base stations in a communication service area connected to a packet communications network. A mobile station communicates with a second station through the plurality of base stations and the network. The mobile communication system determines a virtual base station group as an aggregation of the plurality of base stations communicating with the mobile station, based on a condition of a radio transmission path between the mobile station and each base station, and combines information received by the plurality of base stations that belong to the virtual base station group at a base station included in the virtual base station group. The network connects the plurality of base stations non-hierarchically and the base station transmits combined information to the second station through the network relative to combined packets having the second station as a destination.

Claims

1. A mobile communication system including a plurality of base stations placed in a communication service area and connected to a packet communication network, wherein a mobile station communicates with a second station through the plurality of base stations and the packet communication network, said mobile communication system comprising:

a first means for determining a virtual base station group as an aggregation of the plurality of base stations communicating with said mobile station based on a condition of a radio transmission path between said mobile station and each base station;

a second means for combining packets received by the plurality of base stations that belong to the virtual base station group at a base station included in said virtual base station group, and

means for incrementing and transmitting a sequence number that distinguishes signals including an identical mobile station identification (ID) each time said base station transmits combined packets whose destination is the second station to the packet communication network

wherein said packet communication network connects the plurality of base stations non-hierarchically.

2. The mobile communication system as claimed in claim 1, wherein said first means determines the base station whose radio transmission path to said mobile station is in a better condition than a predetermined condition as a component of said virtual base station group.

3. The mobile communication system as claimed in claim 2, wherein the base station whose radio transmission path is in the best condition among the plurality of base stations that belong to said virtual base station group determined by said first means is selected to be a parent base station, wherein said second means combines the information transmitted from said mobile station and then received by the plurality of base stations belonging to said virtual base station group at said parent base station.

4. The mobile communication system as claimed in claim 2, further comprising a third means for measuring a received-signal strength of a radio channel used by each base station as the condition of the radio transmission path at said mobile station, wherein said first means determines the base station whose radio channel'"'"'s received-signal strength is higher than a predetermined received-signal strength as the part of said virtual base station group.

5. The mobile communication system as claimed in claim 4, wherein the base station whose radio channel'"'"'s received-signal strength is the highest among the plurality of base stations belonging to said virtual base station group is selected as a parent base station, wherein said second means combines the packets transmitted from said mobile station and then received by the plurality of base stations belonging to said virtual base station group at said parent base station.

6. The mobile communication system as claimed in claim 1, wherein the plurality of base stations belonging to said virtual base station group communicate with said mobile station through identical radio channels.

7. The mobile communication system as claimed in claim 1, further comprising a fourth means for canceling a relation of each base station being the part of said virtual base station group after a fixed period.

8. The mobile communication system as claimed in claim 7 wherein said fourth means comprising:

a first management means executed by a base station belonging to said virtual base station group for managing other base stations in said virtual base station group;

a second management means executed by each of said other base stations for managing said base station,

wherein said mobile communication system cancels the relation of each base station being the part of said virtual base station group by terminating management of the plurality of base stations belonging to said virtual base station group by use of said first management means and said second management means when the fixed period passes after determination of said virtual base station group.

9. The mobile communication system as claimed in claim 1, further comprising a fifth means for copying original packets transmitted from the second station to said mobile station at the base station included in the virtual base station group, and forwarding copied packets from said base station to other base stations included in said virtual base station group through the packet communication network when said base station receives the original packets, wherein said base station and said other base stations respectively transmit the original packets and the copied packets to said mobile station.

10. A method of controlling a mobile communication system including a plurality of base stations placed in a communication service area and connected to a packet communication network, wherein a mobile station communicates with a second station through the plurality of base stations and the packet communication network, said method comprising the steps of:

connecting the plurality of base stations non-hierarchically to the packet communication network;

determining a virtual base station group as an aggregation of the plurality of base stations communicating with said mobile station based on a condition of a radio transmission path between said mobile station and each base station;

combining information received by the plurality of base stations that belong to the virtual base station group at a base station included in said virtual base station group into combined packets; and

incrementing and transmitting a sequence number that distinguishes signals including an identical mobile station identification (ID) each time said base station transmits combined packets whose destination is the second station from said base station to said packet communication network.

11. The method as claimed in claim 10, further comprising the steps of:

copying original packets transmitted from the second station to said mobile station at the base station included in the virtual base station group when said base station receives the original packets;

forwarding copied packets from said base station to other base stations included in said virtual base station group through the packet communication network; and

transmitting the original packets from said base station and the copied packets from said other base stations to said mobile station.