Maintaining data communication through neighboring mobile units during handoff

• US 6,377,805 B1
• Filed: 08/04/1999
• Issued: 04/23/2002
• Est. Priority Date: 08/04/1999
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Prakash, Amol, Shorey, Rajeev, Anvekar, Dinesh Kashinath, Dang, Manpreet Singh
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): Vuong, Quochien B.
• Application Number:
  US09/368,120
• Time in Patent Office: 993 Days
• Field of Search: 455/436, 455/437, 455/438, 455/439, 455/11.1, 455/500, 455/507, 455/440, 370/331, 370/332, 370/335
• US Class Current: 455/436
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: H04W 88/04 adapted for relaying to or from another terminal or user

Abstract

A data communication for a handoff mobile unit is maintained by data forwarding through neighboring mobile units in indoor wireless cellular communication networks operates such that, when the master unit has no available channels, the mobile unit switches over to master status to create an ad hoc cell. The mobile unit then pages neighboring slave mobile units for data forwarding assistance. The mobile unit chooses one or more slave mobile units and establishes wireless links with the chosen slave mobile units. These chosen mobile units then have two masters; one the master unit of the cell and the other the handoff mobile unit which has created the ad hoc cell. A list of the slave mobile units in the ad hoc cell is sent to the network server, and data communication proceeds with data forwarding through the chosen mobile slave units. When a channel becomes available with the master unit for the cell, the handoff mobile unit becomes a slave mobile unit to the master unit and the ad hoc cell is dissolved.

Claims

1. A method of maintaining packet data communication for a handoff mobile unit in wireless cellular networks when the handoff mobile unit enters a new cell which is already busy and unable to provide immediate connection for the handoff mobile unit comprising the step of initiating a creation of an ad hoc handoff cell by the handoff mobile unit paging slave mobile units in the vicinity of the handoff mobile unit, the handoff mobile unit becoming the master of the handoff cell when it is created.

2. The method of maintaining packet data communication for a handoff mobile unit in wireless cellular networks recited in claim 1, wherein one or more neighboring mobile units are capable of forwarding data packets between a network server and the handoff mobile unit.

3. The method of maintaining packet data communication for a handoff mobile unit in wireless cellular networks recited in claim 2, wherein the network server is intimated by the handoff mobile to continue further communication through one or more of the mobile units in the ad hoc handoff cell.

4. The method of maintaining packet data communication for a handoff mobile unit in wireless cellular networks recited in claim 2, wherein one or more mobile units in the ad hoc handoff cell forward data packets to and from the handoff mobile unit acting as the master of the ad hoc handoff cell while the handoff mobile unit is waiting for data connection with the master of a busy cell.

5. The method of maintaining packet data communication for a handoff mobile unit in wireless cellular networks recited in claim 4, wherein data forwarding is distributed among mobile units in the ad hoc handoff cell.

6. The method of maintaining packet data communication for a handoff mobile unit in wireless cellular networks recited in claim 5, wherein distribution of data forwarding is based on relative activity/idleness of the mobile units.

7. The method of maintaining packet data communication for a handoff mobile unit in wireless cellular networks recited in claim 5, wherein allocation of data forwarding load for mobile units is carried out in a processor present in the network server.

8. The method of maintaining packet data communication for a handoff mobile unit in wireless cellular networks recited in claim 5, wherein allocation of data forwarding load for mobile units is carried out in a processor present in the handoff mobile unit.

9. The method of maintaining packet data communication for a handoff mobile unit in wireless cellular networks recited in claim 5, wherein mobile units are chosen based on predetermined criteria.

10. The method of maintaining packet data communication for a handoff mobile unit in wireless networks recited in claim 9, wherein the predetermined criteria includes RSSI (Received Signal Strength Indicator), battery power level, relative mobility, or idleness of mobile units.

11. The method of maintaining packet data communication for a handoff mobile unit in wireless cellular networks recited in claim 4, wherein the mobile units within the ad hoc handoff cell communicate with their regular masters and the master of the handoff cell in a time division multiplexed manner.

12. The method of maintaining packet data communication for a handoff mobile unit in wireless cellular networks recited in claim 11, wherein mobile units have the capability to become masters for other slave units.

13. The method of maintaining packet data communication for a handoff mobile unit in wireless cellular networks recited in claim 12, wherein mobile units have the capability to be slaves to multiple master units.

14. The method of maintaining packet data communication for a handoff mobile unit in wireless cellular networks recited in claim 1, wherein the ad hoc handoff cell is dissolved by the handoff mobile unit after a communication link with the master of the target cell into which the mobile unit had moved is established.

15. The method of maintaining packet data communication for a handoff mobile unit in wireless cellular networks recited in claim 1, further comprising the function of extending a coverage range of an edge cell by utilizing mobile units, if any, in the edge cell to forward data packets to the handoff mobile unit which has moved out of the edge cell into a region which is not covered by any other master units.

16. A system for maintaining packet data communication for a handoff mobile unit in wireless cellular networks when the handoff mobile unit enters a new cell which is already busy and unable to provide immediate connection for the handoff mobile unit comprising:

a wireless cellular network including a plurality of base stations functioning as a master within a cell of the cellular network for a predetermined number of channels; and

a plurality of mobile units functioning as slave units to a respective one of said base stations within a cell of the cellular network, said mobile units being capable of moving between cells of the cellular network and, when entering a cell as a handoff mobile unit for which cell all channels are currently occupied, of initiating creation of an ad hoc handoff cell by the handoff mobile unit paging slave mobile units in the vicinity of the handoff mobile unit, the handoff mobile unit becoming the master of the handoff cell when it is created.

17. The system for maintaining packet data communication for a handoff mobile unit in wireless cellular networks recited in claim 16, further comprising a network server connected to each of said base stations and wherein one or more neighboring mobile units are capable of forwarding data packets between the network server and the handoff mobile unit.

18. The system for maintaining packet data communication for a handoff mobile unit in wireless cellular networks recited in claim 17, wherein the network server is intimated by the handoff mobile to continue further communication through one or more of the mobile units in the ad hoc handoff cell.

19. The system for maintaining packet data communication for a handoff mobile unit in wireless cellular networks recited in claim 17, wherein one or more mobile units in the ad hoc handoff cell forward data packets to and from the handoff mobile unit acting as the master of the ad hoc handoff cell while the handoff mobile unit is waiting for data connection with the base station of a cell entered by the handoff mobile unit for which all channels are currently busy.

20. The system for maintaining packet data communication for a handoff mobile unit in wireless cellular networks recited in claim 19, wherein data forwarding is distributed among mobile units in the ad hoc handoff cell.