METHOD FOR SELECTING OPERATIONAL CHANNEL OF NETWORK COORDINATOR IN WIRELESS NARROW AREA NETWORK AND COORDINATOR USING THE SAME

• US 20100142396A1
• Filed: 12/28/2009
• Published: 06/10/2010
• Est. Priority Date: 06/28/2007
• Status: Active Grant

• Current Assignee: KT Corporation
• Original Assignee: KT Corporation
• Inventors: CHONG, Hak-Jin, KOH, Youn-Suk, HWANG, Chae-Eun, KIM, Yeon-Soo
• Granted Patent: US 8,325,665 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 72/04 Wireless resource allocation
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

A method for selecting an operational channel of a wireless narrow area network, a coordinator using the same, and a computer-readable recording media recording a program for realizing the method. More particularly, a method for selecting an operational channel of a wireless narrow area network in which one radio channel is occupied by a plurality of coordinators at different timings by selecting a predetermined period of a radio channel where a coordinator of the wireless narrow area network is used by another coordinator as own operational channel, a coordinator using the same, and a computer-readable recording media recording a program for realizing the method.

Claims

1. A method for selecting an operational channel of a wireless narrow area network, comprising:

checking a channel occupied state of another coordinator operated in an effective channel based on a beacon frame in a coordinator of the wireless narrow area network;

detecting an operable period based on a check result of the channel occupied state in the coordinator; and

determining a time offset according to the operable period detection result in the coordinator.

2. The method of claim 1, further comprising:

before said checking a channel occupied state,

checking whether a predetermined radio channel is pre-occupied;

checking whether the occupied radio channel is occupied by a homogeneous coordinator using the same format; and

selecting the radio channel occupied by the homogeneous coordinator as an effective channel.

3. The method of claim 1, wherein a reference slot timing for determining a time offset of the coordinator sharing the effective channel based on the beacon frame received through the effective radio channel, i.e., the effective channel, among the operational channels is determined.

4. The method of claim 3, wherein the reference slot timing is determined as a slot timing of a time offset ‘

0’

where there are the largest number of superframe durations which are consecutively connected among the time offsets ‘

0’

.

5. The method of claim 4, wherein local clock and slot synchronization are acquired and superframe information is collected through the beacon frame.

6. The method of claim 5, wherein it is checked whether different beacon frames are received according to the comparison result of ‘

the maximum beacon interval excluding a predetermined protection time’ and

a current timer.

7. The method of claim 6, wherein when the received preamble is a beacon frame in comparison of ‘

the maximum beacon interval excluding a predetermined protection time’ and

the current timer, it is checked that another beacon frame is received.

8. The method of claim 7, wherein the protection time is determined as the smallest superframe duration among the entire superframe durations including own superframe duration.

9. The method of claim 3, wherein an operable period according to a non-occupied block period and the non-occupied block period between the superframes is detected by arranging the superframes according to a time order based on the determined reference slot timing.

10. The method of claim 9, wherein said detecting an operable period, includes:

rearranging each superframe with the determined reference slot timing as a reference according to the time order;

sequentially determining a slot number by extensively transforming rearranged each superframe into ‘

a slot index on the maximum beacon interval’

; and

detecting an operable period for own superframe duration by determining a non-occupied block period between the superframes.

11. The method of claim 10, wherein the entire superframe received before the reference slot is arranged to be connected to the end of the rearranged superframe.

12. The method of claim 10, wherein a slot number is determined by comparing ‘

a summation of a slot number of an n-1^th superframe and a superframe duration of the n-1^th superframe’ and

‘

a time offset of an n^th superframe’

.

13. The method of claim 12, wherein when ‘

the time offset of the n^th superframe’

is larger than ‘

the summation of the slot number of the n-1^th superframe and the superframe duration of the n-1^th superframe’

, ‘

the time offset of the n^th superframe’

is determined as the slot number.

14. The method of claim 12, wherein when ‘

the time offset of the n^th superframe’

is smaller than ‘

the summation of the slot number of n-1^th superframe and the superframe duration of the n-1^th superframe’

, the slot number is determined in consideration of ‘

the time offset of the n^th superframe’ and

‘

the beacon interval of the n^th superframe’

.

15. The method of claim 10, wherein the operable period is detected by comparing ‘

the non-occupied block period existing between neighboring two superframe durations’ and

‘

own superframe duration’

.

16. The method of claim 9, wherein a time offset, i.e., own superframe start timing, is determined by checking a slot block for own superframe duration in the detected operable period.

17. The method of claim 16, wherein said determining a time offset includes:

selecting a check period of the operable period by comparing own beacon interval with a predetermined beacon interval; and

determining a time offset by checking a slot block for own superframe duration in the selected check period.

18. The method of claim 17, wherein the check period is selected by using a large and small relation among ‘

own beacon interval’

, ‘

the minimum beacon interval’

, ‘

the maximum beacon interval’ and

‘

a beacon interval of a superframe occupying a reference slot’

.

19. The method of claim 18, wherein the check period is determined as any one of ‘

own beacon interval’

, ‘

the maximum beacon interval’ and

‘

the beacon interval of the superframe occupying the reference slot’

according to the large and small relation among ‘

own beacon interval’

, ‘

the minimum beacon interval’

, ‘

the maximum beacon interval’ and

‘

the beacon interval of the superframe occupying the reference slot’

.

20. The method of claim 17, wherein a time offset is determined according to whether there is a slot block usable as an operable period by increasing the slot number 1 by 1 with respect to the entire non-occupied block periods within the check period.

21. The method of claim 17, wherein after the slot number of the time offset timing is determined, the time offset is determined through a modular operation of the slot number and ‘

the beacon interval of the superframe occupying the reference slot’

.

22. A coordinator of a wireless narrow area network, comprising:

a channel state checking means for checking a channel occupied state of another coordinator operated in an effective channel based on a beacon frame;

an operable period detecting means for detecting an operable period based on a check result of the channel occupied state in the channel state checking means; and

determining a time offset according to a detection result in the operable period detecting means.

23. The coordinator of claim 22, wherein the channel state checking means determines a time offset of the coordinator sharing the effective channel based on a beacon frame received through an effective radio channel, i.e., an effective channel, among the operational channels.

24. The coordinator of claim 22, wherein the operable period detecting means detects a non-occupied block period between superframes and an operable period according to the non-occupied block period by arranging the superframes according to a time order based on a reference slot timing determined in the channel state checking means.

25. The coordinator of claim 24, wherein the time offset determining means determines a time offset, i.e., own superframe start timing, by checking a slot block for own superframe duration in the operable period detected in the operable period detecting means.

26. A computer-readable recording media recording a program for realizing following functions in a coordinator having a processor, the functions comprising:

checking a channel occupied state of another coordinator operated in an effective channel based on a beacon frame;

detecting an operable period based on the check result of the channel occupied state; and

determining a time offset according to the operable period detection result.