Power saving frame transmission method

• US 7,477,616 B2
• Filed: 01/31/2005
• Issued: 01/13/2009
• Est. Priority Date: 01/31/2005
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Wang, Huayan Amy, Sakoda, William
• Primary Examiner(s): Le; Danh C
• Application Number:
  US11/047,100
• Publication Number:
  US 20060171341A1
• Time in Patent Office: 1,443 Days
• Field of Search: 370/311, 370/328, 370/338, 370/346, 370/203, 370/412, 455/574, 455/343.4, 455/352, 713/323
• US Class Current: 370/311
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 74/04 Scheduled access hybrid access H04W74/02
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method that enables the power saving frame transmission comprising an AP informing a plurality of stations within its range in a WLAN about a plurality of scheduled service periods during which the AP has access to a channel in a scheduled service time, receiving the information about the plurality of scheduled service periods by the plurality of stations and deciding about initiating or not initiating a frame transmission, whether or not an acknowledgement and an immediate response expected from other APs pertaining to said WLAN are received prior to a subsequent scheduled service time, wherein the frame is transmitted in a cooperative frame transmission scenario.

Claims

1. A system, comprising:

wireless computing stations, each of the stations utilizing a power save mode and a wake mode; and

an access point transmitting a wireless signal including schedule data on a wireless communication channel, the schedule data indicative of a service period start time and a service period interval for each of the stations,

wherein each of the stations switch from the power save mode to the wake mode at a corresponding service period start time and remain in the wake mode for a corresponding service period interval, and

wherein, during the corresponding service period interval, each of the stations communicates frames with the access point,

wherein a wireless medium is maintained in an idle state during a time prior to an initiation of the service period, and

wherein the wireless medium is maintained idle in a contention-free mode of operation of the system.

2. The system of claim 1, wherein, when the access point uses an enhanced distributed channel access (EDCA) mechanism, the access point waits for an arbitration interframe spacing (AIFS) after the corresponding service period start time before transmitting a frame.

3. The system of claim 1, wherein, during the corresponding service period interval, a corresponding one of the stations responds td a frame received from the access point by transmitting an acknowledgement frame with a data frame piggybacked thereon.

4. The system of claim 1, wherein the frames are one of media and data frames.

5. The system of claim 1, wherein the wireless signal including the schedule data is one of a broadcast frame, a management frame and a data frame.

6. The system of claim 1, wherein the schedule data is contained in a field in an IEEE 802.11 frame.

7. The system of claim 6, wherein the field is one of a header and a trailer.

8. A system, comprising:

wireless computing stations, each of the stations utilizing a power save mode and a wake mode; and

an access point transmitting a wireless signal including schedule data on a wireless communication channel, the schedule data indicative of a service period start time and a service period interval for each of the stations,

wherein each of the stations switch from the power save mode to the wake mode at a corresponding service period start time and remain in the wake mode for a corresponding service period interval, and

wherein, during the corresponding service period interval, each of the stations communicates frames with the access point,

wherein a wireless medium is maintained in an idle state during a time prior to an initiation of the service period, and

wherein, when the access point uses a hybrid coordination function (HCF) controlled channel access (HCCA) mechanism, the access points waits for a point coordination function (PCF) interframe spacing (PIFS) after the corresponding service period start time before transmitting a frame.

9. A method, comprising:

receiving, in a wireless station of a plurality of wireless stations a wireless network, schedule information identifying at least one service period;

maintaining a wireless medium idle during a time prior to an initiation of the at least one service period; and

sending a frame on the wireless medium after a start of the at least one service period, the sending of the frame occurring without a procedure for contending for the wireless medium being performed, wherein the wireless medium is maintained idle in a contention-free mode of operation of the network.

10. The method of claim 9, wherein all wireless stations in the plurality of wireless stations are co-operative stations.

11. The method of claim 9, wherein the wireless medium is idle at the start of the at least one service period.

12. The method of claim 9, wherein:

the wireless station receives the schedule information from an access point, and the access point transmits the schedule information without waiting for another frame to complete transmission through the wireless medium.

13. The method of claim 12, wherein:

the access point uses an enhanced distribution channel access (EDCA) mechanism, the access point waits for an arbitration interframe spacing (AIFS) after the corresponding service period start time before transmitting the frame.

14. The method of claim 9, wherein the frame includes one of a media frame and a data frame.

15. The method of claim 9, wherein the schedule information is transmitted in one of a broadcast frame, a management frame, and a data frame.

16. A method, comprising:

receiving, in a wireless station of a plurality of wireless stations a wireless network, schedule information identifying at least one service period;

maintaining a wireless medium idle during a time prior to an initiation of the at least one service period; and

sending a frame on the wireless medium after a start of the at least one service period, the sending of the frame occurring without a procedure for contending for the wireless medium being performed,

wherein the wireless station receives the schedule information from an access point, and the access point transmits the schedule information without waiting for another frame to complete transmission through the wireless medium, and

wherein the access point uses a hybrid coordination function (HCF) controlled channel access (HCCA) mechanism, the access point waiting for a point coordination function (PCF) interframe spacing (PIFS) after the corresponding service period start time before transmitting the frame.