Power efficient channel scheduling in a wireless network

• US 20030203740A1
• Filed: 04/17/2002
• Published: 10/30/2003
• Est. Priority Date: 04/17/2002
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Bahl, Paramvir, Adya, Atul, Padhye, Jitendra D.
• Granted Patent: US 7,110,783 B2
• Time in Patent Office: Days
• US Class Current: 455/516
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/0219 where the power saving management affects multiple terminals
• CPC Class Codes: H04W 52/0241 where no transmission is received, e.g. out of range of the transmitter
• CPC Class Codes: H04W 52/46 in multi hop networks, e.g. wireless relay networks
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/04 adapted for relaying to or from another terminal or user
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method and system for optimizing channel access scheduling for multiple wireless computing devices over a wireless network improves channel access efficiency with respect to a primary channel. An access point, or host computer, includes a host transceiver for receiving control information from the wireless computing devices over a low power channel. Upon receiving the control information, the access point applies a scheduling algorithm to schedule channel access for the wireless computing devices to transmit data over the primary communication channel. The wireless computing devices include a low power radio for receiving scheduling information via the low power channel during idle periods. When the scheduling information is received, the wireless computing device activates its primary channel network interface components to communicate data through the primary channel. When the computing device is idle, the device is configured to power down all of its components with the exception of the circuitry required to power the low power channel. As such, the low power channel is maintained in an active state for receiving scheduling information, such as an access schedule, during both idle and non-idle periods.

Claims

1. A method for channel access scheduling in a wireless network, wherein the wireless network comprises at least one wireless computing device, the wireless computing device having an interface to a primary communication channel and an interface to a secondary communication channel, the secondary communication channel being of lower power than the primary communication channel, the method comprising:

establishing a connection between a host transceiver at a host computer and a low power transceiver at the wireless computing device, the connection being established over the secondary channel;

transmitting a first group of control information over the secondary channel from the low power transceiver to the host transceiver;

receiving from the host transceiver a second group of control information at the low power transceiver, the second group of control information comprising scheduling information, wherein the scheduling information is transmitted in response to the control information sent by the low power transceiver; and

automatically activating the interface to the primary communication channel in accordance with the received scheduling information.

2. The method according to claim 1 wherein the scheduling information is derived based at least in part on the number of packets waiting in a queue for transmission over the primary channel.

3. The method according to claim 1 wherein the control information comprises data packet priority information.

4. The method according to claim 1 wherein the control information comprises data packet transmission deadline information.

5. The method according to claim 1 wherein the secondary channel is a low frequency channel having a carrier frequency less than that of the primary channel.

6. The method according to claim 1 wherein the primary channel employs a different radio frequency than the secondary channel for transmission.

7. The method according to claim 1 wherein the primary channel is a high power channel that is not substantially used to communicate transmission scheduling information.

8. The method according to claim 1 wherein the host computer comprises a wireless access point to another network.

9. The method according to claim 1 wherein the network that is interfaced through the wireless access point comprises at least one wired link.

10. The method according to claim 1 wherein in response to receipt of the scheduling information, the wireless computing device further transmits data over the primary channel.

11. The method according to claim 1 wherein the interface to the primary channel implemented at the wireless computing device comprises a network interface card.

12. The method according to claim 1 wherein the primary channel comprises an 802.11 based communication channel.

13. A method for scheduling data transmission in a wireless network, wherein the wireless network comprises at least one wireless computing device, the wireless computing device supporting a primary communication channel and a secondary communication channel, the secondary communication channel requiring less power to utilize than the primary communication channel, the method comprising:

establishing a connection between a host transceiver operating at a host computer and a low power transceiver operating at the wireless computing device, the connection being established over the secondary channel;

receiving a first data packet at the host computer from the low power transceiver over the secondary channel, the first data packet comprising transmission control information related to the primary channel;

in response to receipt of the control information, applying a scheduling algorithm at the host computer to determine a channel access schedule for the wireless computing device; and

sending the channel access schedule to the low power transceiver over the secondary channel, wherein the channel access schedule notifies the wireless computing device as to when the wireless computing device has access to the primary communication channel in order to transmit data.

14. The method according to claim 13 wherein the host computer is a wireless access point to a second network.

15. The method according to claim 14 wherein the second network comprises at least one wired link between two nodes of the network.

16. The method according to claim 13 wherein the control information comprises an indication of the number of packets waiting in a queue for transmission over the primary channel.

17. The method according to claim 13 wherein the control information comprises data packet priority information assigning a transmission priority to at least one packet.

18. The method according to claim 13 wherein the control information comprises data packet transmission deadline information.

19. The method according to claim 13 wherein the secondary channel is a low frequency channel.

20. The method according to claim 13 wherein the primary channel comprises an 802.11 based channel.

21. The method according to claim 13 wherein the primary channel supports a radio range and data rate higher than those of the secondary channel.

22. The method according to claim 13, wherein in response to receipt of the scheduling information the network interface card transmits data over the primary channel.

23. The method according to claim 13, wherein the primary channel employs a higher frequency carrier than the secondary channel.

24. A wireless network system for channel access control in a wireless network comprising:

an access point, wherein the access point is logically connected to a first radio component configured to transmit scheduling information over a secondary low power channel and a second radio component configured to transmit data over a higher power primary channel; and

a client device comprising;

a high power radio component that communicates data on a primary channel, wherein the data omits scheduling information related to primary channel access; and

a low power radio component that communicates control information to the access point over the secondary low power channel.

25. The wireless network system according to claim 24 wherein the primary channel and secondary channel employ mutually distinct carrier frequencies.

26. The wireless network system according to claim 24 wherein the wireless computing device is interfaced to the primary channel via a wireless network interface card.

27. A wireless network system for bandwidth scheduling in a wireless network, the system comprising:

an access point, wherein the access point is an interface to a network;

a host computer interfaced with the network through the access point, wherein the host computer is logically connected to a host transceiver communicably linkable to a plurality of wireless computing devices over a low power radio channel, the host computer being used to schedule the access of the plurality of wireless devices to a high power radio channel; and

a wireless computing device comprising a high power radio that communicates over the high power radio channel, and a low power radio that communicates control information to the access point via the low power radio channel to communicate the scheduling of the access of the plurality of wireless network devices to the high power radio channel.

28. The wireless network system according to claim 27 wherein a first one of the plurality of wireless computing devices is out of direct radio range of the host computer with respect to the low power radio channel and wherein a second one of the plurality of wireless computing devices is within direct radio range of the host computer with respect to the low power radio channel, and whereby the second one of the plurality of wireless computing devices facilitates communication of control and scheduling information between the out of range wireless computing device and the host computer.

29. A hand-held device for acting as a first node on a wireless network comprising:

a high power radio component that communicates data on a primary wireless channel, wherein the data omits scheduling information related to scheduling access to the primary wireless channel; and

a low power radio component that communicates scheduling information related to scheduling access to the primary wireless channel to a second node on the wireless network.

30. The device according to claim 29 wherein the scheduling information is derived based at least in part on information selected from the group consisting of a number of packets waiting in a queue for transmission over the primary channel, packet priority information, and data packet transmission deadline information.

31. The method according to claim 29 wherein the secondary channel is a low frequency channel having a carrier frequency less than that of the primary channel.

32. The method according to claim 29 wherein the primary channel comprises an 802.11 based communication channel.

33. An access point for interfacing a plurality of wireless devices to a network comprising;

an interface to a first wireless channel for transmitting and receiving data over the first wireless channel, wherein the data omits scheduling information related to scheduling access to the first wireless channel; and

an interface to a second wireless channel for transmitting and receiving scheduling information, wherein the scheduling information comprises scheduling information related to scheduling access to the first wireless channel.

34. The access point according to claim 33, wherein the interface to the first wireless channel consumes more power to transmit a bit over the first channel than the interface to the second channel consumes to transmit a bit over the second channel.

35. The access point according to claim 33, further comprising a network interface card comprising both the interface to the first wireless channel and the interface to the second wireless channel.

36. A network interface card comprising:

an first interface to a first wireless channel; and

a second interface to a second wireless channel.

37. The network interface card according to claim 36, wherein the first interface consumes more power to transmit a bit over the first channel than the second interface consumes to transmit a bit over the second channel.

38. The network interface card according to claim 37, wherein the first channel has a carrier frequency that differs from a carrier frequency of the second channel.

39. An operating system embodied in a computer-readable medium in the form of computer-readable instructions for performing a method comprising:

interfacing a host handheld device to a first network for transmitting and receiving data over the first wireless network; and

interfacing the host handheld device to a second network for transmitting and receiving scheduling information over the second wireless network, wherein the scheduling information comprises information usable to schedule access of the host handheld device to the first wireless network.

40. The operating system according to claim 39, wherein the first wireless network uses a higher power wireless signal than the wireless signal used by the second wireless network.