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

1. A method for scheduling wake/sleep cycles by a central device in a wireless network comprising at least one mobile device, said method comprising:

determining a system reference cycle as a minimum value of a delay constraint on a real-time service for each mobile device of said at least one mobile device that has a real-time service;

attributing a wake/sleep cycle length to each mobile device, wherein each wake/sleep cycle length is an integer multiple of the system reference cycle and wherein the integer value is varied to form a difference between the wake/sleep cycle length for each of the mobile devices;

assigning a sleep period and a wake period within the wake/sleep cycle of each mobile device using the predetermined wake/sleep cycle length; and

arranging the wake/sleep cycle of each mobile device to avoid collision of the wake period with those of other mobile devices.

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

3. The method according to claim 1 , wherein one or more mobile 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 wake/sleep cycle length of a mobile 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 mobile device.

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

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

8. A method for scheduling wake/sleep cycles of a mobile device, comprising:

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

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

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

12. A central device for scheduling wake/sleep cycles in a wireless network comprising a plurality of mobile 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 mobile device of said plurality of mobile devices that has a real-time service;

attribute a wake/sleep cycle length to each mobile device, wherein each wake/sleep cycle length is an integer multiple of a system reference cycle and wherein the integer value is varied to form a difference between the wake/sleep cycle length for each of the mobile devices;

assign a sleep period and a wake period within the wake/sleep cycle of each mobile device using the predetermined wake/sleep cycle length; and

arrange the wake/sleep cycle of each mobile device to avoid collision of the wake period with those of other mobile devices.

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

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

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

16. The device according to claim 14 , wherein the wake/sleep cycle length of a mobile 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 mobile device.

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

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