Method for determining optimal parent terminal and ad hoc network system for the same

• US 6,026,303 A
• Filed: 11/06/1997
• Issued: 02/15/2000
• Est. Priority Date: 11/07/1996
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Minamisawa, Takeaki
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): Tran, Congvan
• Application Number:
  US08/965,297
• Time in Patent Office: 831 Days
• Field of Search: 455/446, 455/455, 455/500, 455/501, 455/502, 455/503, 455/507, 455/524, 455/525, 455/31.1, 455/31.2, 455/32.1, 370/335, 370/344, 370/445, 370/329, 370/331
• US Class Current: 455/446
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: H04W 84/20 Master-slave selection or change arrangements

Abstract

In a method of configuring an ad hoc network system including a plurality of wireless terminals, at least one of a plurality of wireless terminals of a network is selected as a current temporary parent wireless terminal, all of the plurality of wireless terminals other than the current temporary parent wireless terminal being set as child wireless terminals. Subsequently, a set of state determination data are collected from each of the child wireless terminals by the current temporary parent wireless terminal. The state determination data includes at least one of a wireless terminal state data of each of the child wireless terminals and a communication state data with each of the child wireless terminals. Then, it is determined whether the collecting operation is executed K cycles (K is a positive integer).

Claims

1. A method of configuring an ad hoc network system including a plurality of wireless terminals, comprising the steps of:

(a) selecting at least one of a plurality of wireless terminals of a network as a current temporary parent wireless terminal, all of the plurality of wireless terminals other than said current temporary parent wireless terminal being set as child wireless terminals;

(b) collecting a set of state determination data from each of said child wireless terminals by said current temporary parent wireless terminal, said state determination data including at least one of a wireless terminal state data of each of said child wireless terminals and a communication state data with each of said child wireless terminals;

(c) determining whether said step (b) is executed K cycles (K is a positive integer);

(d) when it is determined in said step (c) that said step (b) is not yet executed K cycles, setting said current temporary parent wireless terminal as a previous temporary parent wireless terminal, and newly selecting at least one of said child wireless terminals as said current temporary parent wireless terminal based on said sets of state determination data for said child wireless terminals during the executed cycles of said step (b) such that said current temporary parent wireless terminal executes said step (b), said previous temporary parent wireless terminal and said child wireless terminals other than said current temporary parent wireless terminal being set as said child wireless terminals; and

(e) when it is determined in said step (c) that said step (b) is executed K cycles, determining one of said child wireless terminals as a true parent wireless terminal by said current temporary parent wireless terminal based on said state determination data for said child wireless terminals for the K cycles.

2. A method according to claim 1, wherein said step (a) includes:

designating at least one of said plurality of wireless terminals as current temporary parent wireless terminal;

setting said plurality of wireless terminals other than said current temporary parent wireless terminal to said child wireless terminals; and

broadcasting an identifier of said current temporary parent wireless terminal to said child wireless terminals.

3. A method according to claim 2, wherein said step (a) further includes:

after said current temporary parent wireless terminal and said child wireless terminals are set, establishing synchronization between said current temporary parent wireless terminal and each of said child wireless terminals; and

after the synchronization is established, transmitting an identifier of each of said child wireless terminals to said current temporary parent wireless terminal as a connection request.

4. A method according to claim 1, wherein said step (b) includes:

collecting at least one of a remaining battery power quantity data as the wireless terminal state data and a transmission rate data, an error rate data and an electric field strength data as the communication state data to produce said state determination data.

5. A method according to claim 1, wherein said step (b) includes:

broadcasting a state determination data notifying request from said current temporary parent wireless terminal to said child wireless terminals;

detecting a remaining battery power quantity in each of said child wireless terminals to produce a remaining battery power quantity data;

transmitting said remaining battery power quantity data as said wireless terminal state data from each of said child wireless terminals to said current temporary parent wireless terminal; and

storing said set of remaining battery power quantity data collected from said child wireless terminal in a data base.

6. A method according to claim 1, wherein said step (b) includes:

broadcasting a test data to said child wireless terminals;

returning the test data from each of said child wireless terminals to said current temporary parent wireless terminal;

detecting a transmission rate of communication with each of said child wireless terminals by said current temporary parent wireless terminal to produce a transmission rate data as said communication state data; and

storing said set of transmission rate data collected from said child wireless terminals in a data base.

7. A method according to claim 1, wherein said step (b) includes:

broadcasting a test data to said child wireless terminals;

returning the test data from each of said child wireless terminals to said current temporary parent wireless terminal;

detecting an error rate of communication with each of said child wireless terminals to produce an error rate data as said communication state data; and

storing said set of error rate data collected from said child wireless terminals in a data base.

8. A method according to claim 1, wherein said step (b) includes:

broadcasting a test data from each of said current temporary parent wireless terminals to said child wireless terminals;

detecting electric field strength when the test data is received, in each of said child wireless terminals to produce an electric field strength data as said communication state data;

transmitting said electric field strength data from each of said child wireless terminals to said current temporary parent wireless terminal corresponding to the test data; and

storing said set of electric field strength data collected from said child wireless terminals in a data base.

9. A method according to claim 8, wherein said step (b) includes:

summing of electric field strength data for the executed cycles for each of said child wireless terminals; and

designating at least one of said child wireless terminals as said current temporary parent wireless terminal based on the summing results for said child wireless terminals.

10. A method according to claim 1, wherein said step (d) includes:

selecting at least one of said child wireless terminals as said current temporary parent wireless terminal based on said sets of state determination data for said child wireless terminals for the executed cycles of said step (b);

broadcasting an identifier of said current temporary parent wireless terminal to said child wireless terminals;

comparing the transmitted identifier and an own identifier in each of said child wireless terminals;

setting the child wireless terminal to said current temporary parent wireless terminal when the transmitted identifier and the own identifier are coincident with each other in each of said child wireless terminals;

broadcasting a data base to said child wireless terminals, said data base storing said state determination data for said child wireless terminals obtained when said step (b) has been already executed, as said sets of state determination data for the executed cycles of said step (b); and

storing said data base therein by said current temporary parent wireless terminal.

11. A method according to claim 9, wherein said step (e) includes:

referring to said data base to select a minimum value from among the state determination data obtained when said step (b) is executed K cycles, for each of said plurality of wireless terminals; and

designating as said true parent wireless terminal one of said plurality of wireless terminals having a maximum value of said minimum values.

12. A method according to claim 1, wherein said state determination data is a remaining battery power quantity data and a transmission rate data, and wherein said step (e) includes:

designating as said true parent wireless terminal one of said plurality of wireless terminals having the highest transmission rate and the remaining battery power quantity data more than a predetermined value.

13. A method according to claim 12, wherein said step (a) includes selecting at least one of said plurality of wireless terminals of the network as said current temporary parent wireless terminal in response to a parent wireless terminal change request, and

wherein said method further comprises the step of issuing said parent wireless terminal change request when the remaining battery power quantity becomes less than the predetermined value.

14. A method according to claim 1, further comprising the steps of:

broadcasting a sync signal for establishing synchronization between said true parent wireless terminal and each of the other wireless terminal;

transmitting an identifier of each of the other wireless terminals to said true parent wireless terminal; and

setting a flag for the transmitted identifier in a data base.

15. An ad hoc network system comprising a plurality of wireless terminals, each of which comprises:

a setting unit for setting said wireless terminal to a current temporary parent wireless terminal or a true parent wireless terminal when a parent terminal instruction is received, and to a child wireless terminals when a parent terminal instruction is not received;

a data collecting unit for collecting a set of state determination data from each of said child wireless terminals when said wireless terminal is set to said current temporary parent wireless terminal, said state determination data including at least one of a wireless terminal state data of each of said child wireless terminals and a communication state data with each of said child wireless terminals; and

a parent wireless terminal selecting unit for selecting at least one of said child wireless terminals as a current temporary parent wireless terminal based on already collected sets of state determination data for said child wireless terminals, and selecting one of said child wireless terminals as a true temporary parent wireless terminal based on already collected sets of state determination data for said child wireless terminals, when the collecting operation is repeated K cycles (K is a positive integer), and for broadcasting said parent terminal instruction to said child wireless terminals.

16. An ad hoc network system according to claim 15, wherein said setting unit includes:

an informing unit for broadcasting an identifier of said current temporary parent wireless terminal to said child wireless terminals when at least one of said plurality of wireless terminals or said child wireless terminals is selected as said current temporary parent wireless terminal.

17. An ad hoc network system according to claim 16, wherein said setting unit further includes:

a synchronization establishing unit for establishing synchronization with said current temporary parent wireless terminal or said true parent wireless terminal when said wireless terminal is set to said child wireless terminal;

an own identifier storing unit for storing an identifier of said wireless terminal; and

a transmitting unit for transmitting the own identifier of said wireless terminal from said own identifier storing unit to said current temporary parent wireless terminal or said true parent wireless terminal as a connection request.

18. An ad hoc network system according to claim 15, wherein said state determination data is at least one of a remaining battery power quantity data as the wireless terminal state data and a transmission rate data, an error rate data and an electric field strength data as the communication state data to produce said state determination data.

19. An ad hoc network system according to claim 15, wherein said data collecting unit includes:

an informing unit for broadcasting a state determination data notifying request to said child wireless terminals;

a data base; and

a storing unit for storing said set of state determination data from said child wireless terminals in said data base.

20. An ad hoc network system according to claim 19, wherein said data collecting unit includes:

a detecting unit for detecting a remaining battery power quantity to produce a remaining battery power quantity data; and

a transmitting unit for transmitting said remaining battery power quantity data as said wireless terminal state data to said current temporary parent wireless terminal in response to said state determination data notifying request when said wireless terminal is set to said child wireless terminal.

21. An ad hoc network system according to claim 19, wherein said data collecting unit includes:

a test data generating unit for generating a test data when said wireless terminal is set to said current temporary parent wireless terminal;

a communication unit for broadcasting said test data to said child wireless terminals when said wireless terminal is set to said current temporary parent wireless terminal, for returning the test data to said current temporary parent wireless terminal when said wireless terminal is set to said child wireless terminal, and for receiving said test data from each of said child wireless terminals; and

a detecting unit for detecting a transmission rate of communication with each of said child wireless terminals from the received test data to produce a transmission rate data as said communication state data.

22. An ad hoc network system according to claim 19, wherein said data collecting unit includes:

a test data generating unit for generating a test data when said wireless terminal is set to said current temporary parent wireless terminal;

a transmitting and receiving unit for broadcasting said test data to said child wireless terminals when said wireless terminal is set to said current temporary parent wireless terminal, for returning the test data to said current temporary parent wireless terminal when said wireless terminal is set to said child wireless terminal, and for receiving said test data from each of said child wireless terminals; and

a detecting unit for detecting an error rate of communication with each of said child wireless terminals from the received test data to produce an error rate data as said communication state data.

23. An ad hoc network system according to claim 15, wherein said data collecting unit includes:

a test unit for generating a test data when said wireless terminal is set to said current temporary parent wireless terminal;

a communication unit for broadcasting said test data to said child wireless terminals; and

a detecting unit for detecting electric field strength when said test data received from said current temporary parent wireless terminal to produce an electric field strength data as said communication state data, and

wherein said communication unit transmits said electric field strength data to said current temporary parent wireless terminal.

24. An ad hoc network system according to claim 23, wherein said parent wireless terminal selecting unit further sums of electric field strength data for the executed cycles of the collection operation for each of said child wireless terminals, and issues said parent terminal instruction for designating at least one of said child wireless terminals as said current temporary parent wireless terminal based on the summing results for said child wireless terminals.

25. An ad hoc network system according to claim 15, wherein said parent wireless terminal selecting unit broadcasts an identifier of said current temporary parent wireless terminal to said child wireless terminals, and broadcasts a data base to said child wireless terminals, said data base storing said set of state determination data for said child wireless terminals obtained when the collecting operation has been executed, and

wherein said setting unit compares the transmitted identifier and an own identifier in each of said child wireless terminals, sets said wireless terminal to said current temporary parent wireless terminal when the transmitted identifier and the own identifier are coincident with each other, and stores said data base therein by said current temporary parent wireless terminal.

26. An ad hoc network system according to claim 24, wherein said parent wireless terminal selecting unit refers to said data base to select a minimum value of said state determination data for each of said plurality of wireless terminals when the collecting operation is executed K cycles, and designates, as said true parent wireless terminal, one of said plurality of wireless terminals having a maximum value of said minimum values.

27. An ad hoc network system according to claim 15, wherein said state determination data is a remaining battery power quantity data and a transmission rate data, and

wherein said parent wireless terminal selecting unit includes designates, as said true parent wireless terminal, one of said plurality of wireless terminals having the highest transmission rate and the remaining battery power quantity data more than a predetermined value.

28. An ad hoc network system according to claim 27, wherein said parent wireless terminal selecting unit issues said parent terminal instruction when the remaining battery power quantity of the own true parent wireless terminal becomes less than the predetermined value.