Method for scheduling wake/sleep cycles by a central device in a wireless network

1. A method for scheduling power save cycles by a central device in a wireless network comprising a plurality of wireless devices, said method comprising:

determining a system reference cycle as a minimum value of a delay constraint on a real-time service for each wireless device of said plurality of wireless devices that has a real-time service;

attributing a length of a power save cycle to each wireless device, wherein each power save cycle length is an integer multiple of the system reference cycle and wherein the integer value is varied to form a difference between the power save cycle length for each of the plurality of wireless devices;

assigning a sleep period and a wake period within the power save cycle of each wireless device using the predetermined power save cycle length; and

arranging the power save cycle of each wireless device to avoid collision of the wake period with those of other wireless devices.

2. The method according to claim 1 , wherein the step of arranging the power save cycle of each wireless device comprises adjusting the starting time of the power save cycle of each wireless device to avoid collision of the wake period with those of other wireless devices.

3. The method according to claim 1 , wherein one or more wireless devices have a service with a high priority.

4. The method according to claim 3 , wherein a real-time service has the high priority.

5. The method according to claim 4 , wherein the power save cycle length of a wireless device having real-time service is attributed as the maximum integer multiple of the system reference cycle under the constraint of being no larger than the maximum delay requirement on real-time service of the wireless device.

6. The method according to claim 4 , wherein the wake period of a wireless device is set based on the QoS requirement of the real-time service of the wireless device.

7. The method according to claim 1 , further comprising changing the power save cycle lengths of one or more wireless devices having larger power save cycle lengths to a smaller integer multiple of the system reference cycle when new wireless devices associate with the central device.

8. A method for scheduling power save cycles of a wireless device, comprising:

receiving from a central station scheduling data for a sleep/wake cycle, wherein a sleep/wake cycle length is defined as an integer multiple of a system reference cycle that is common for a plurality of wireless devices and that is set as a minimum value of a delay constraint on real-time service for each wireless device of said plurality of wireless devices that has a real-time service, and wherein the integer value is varied between wireless devices to form a difference between a power save cycle length for each wireless device; and

waking and setting to sleep the appropriate circuits as a function of the scheduling data using the predetermined sleep/wake cycle length.

9. The method according to claim 8 , wherein the power save cycle length is attributed as the maximum integer multiple of the system reference cycle under the constraint of being no larger than the maximum delay requirement on real-time service of the wireless device.

10. The method according to claim 8 , wherein the wake period of a wireless device is set based on the QoS requirement of the real-time service of the wireless device.

11. The method according to claim 8 , wherein the scheduling data changes the power save cycle length to a smaller integer multiple of the system reference cycle when other wireless devices associate with the central station.

12. A central device for scheduling power save cycles in a wireless network comprising a plurality of wireless devices, said central device being configured to:

determine a system reference cycle as a minimum value of a delay constraint on a real-time service for each wireless device of said plurality of wireless devices that has a real-time service;

attribute a length of a power save cycle to each wireless device, wherein each power save cycle length is an integer multiple of a system reference cycle and wherein the integer value is varied to form a difference between the power save cycle length for each of the plurality of wireless devices;

assign a sleep period and a wake period within the power save cycle of each wireless device using the predetermined power save cycle length; and

arrange the power save cycle of each wireless device to avoid collision of the wake period with those of other wireless devices.

13. The central device according to claim 12 , wherein the central device is configured to adjust the starting time of the power save cycle of each wireless device to avoid collision of the wake period with those of other wireless devices.

14. The central device according to claim 12 , wherein one or more wireless devices have a service with a high priority.

15. The central device according to claim 14 , wherein a real-time service has the high priority.

16. The central device according to claim 14 , wherein the power save cycle length of a wireless device having real-time service is attributed as the maximum integer multiple of the system reference cycle under the constraint of being no larger than the maximum delay requirement on real-time service of the wireless device.

17. The central device according to claim 14 , wherein the wake period of a wireless device is set based on the QoS requirement of the real-time service of the wireless device.

18. The central device according to claim 12 , wherein the device is further configured to change the power save cycle lengths of one or more wireless devices having larger power save cycle lengths to a smaller integer multiple of the system reference cycle when new wireless devices associate with the central device.