Power-saving mechanism for periodic traffic streams in wireless local-area networks
First Claim
1. A method of saving power in a wireless Local Area Network (WLAN) including an Access Point (AP) and at least one station, the method comprising:
- receiving, at an AP, a Power Save (PS) Poll from a station;
retrieving a frame from a highest priority buffer having frames for said station;
receiving a frame control field of a frame transmitted uplink to the AP, the frame control field having a Power Management (PM) bit reset, wherein after said frame having a PM bit reset is received, said AP fills a transmit buffer with copies of frames ordered by priority;
transmitting frames from said transmit buffer to said station in accordance with an order of priority; and
removing said frames from said transmit buffer as the copies of frames are transmitted, wherein said removing is done when the PM bit for said station is set in a frame control field of a frame transmitted uplink to the AP;
transmitting fewer than all frames in the transmit buffer to the station during a period in which the station is awake; and
while there is still at least a portion of traffic buffered in the transmit buffer at the access point for transmission to the station, transmitting an end-of-wake period indication to the station to notify the station that the station can go to sleep.
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Accused Products
Abstract
A novel method for coordinating the delivery of frames to and the receipt of frames from a power-saving station in a wireless local-area network (LAN) is disclosed. The illustrative embodiment establishes a wake-up schedule for a power-saving station based on a temporal period and temporal offset that reduces the frequency with which multiple stations in a network wake up simultaneously, thereby reducing traffic delays and power consumption. The illustrative embodiment is particularly well-suited to networks with traffic that has delay/jitter quality-of-service (QoS) requirements (i.e., voice calls, videophone calls, etc.).
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Citations
17 Claims
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1. A method of saving power in a wireless Local Area Network (WLAN) including an Access Point (AP) and at least one station, the method comprising:
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receiving, at an AP, a Power Save (PS) Poll from a station; retrieving a frame from a highest priority buffer having frames for said station; receiving a frame control field of a frame transmitted uplink to the AP, the frame control field having a Power Management (PM) bit reset, wherein after said frame having a PM bit reset is received, said AP fills a transmit buffer with copies of frames ordered by priority; transmitting frames from said transmit buffer to said station in accordance with an order of priority; and removing said frames from said transmit buffer as the copies of frames are transmitted, wherein said removing is done when the PM bit for said station is set in a frame control field of a frame transmitted uplink to the AP; transmitting fewer than all frames in the transmit buffer to the station during a period in which the station is awake; and while there is still at least a portion of traffic buffered in the transmit buffer at the access point for transmission to the station, transmitting an end-of-wake period indication to the station to notify the station that the station can go to sleep. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of saving power in a wireless Local Area Network (WLAN) including an Access Point (AP) and at least one station, the method comprising:
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determining a length of an awake period of a station wherein said station permits additional frames to be sent from said AP to said station when said station sends a frame to said AP, said frame having a Power Mode (PM) bit set and wherein said AP stops sending frames to said station when said station sends a frame having said PM bit set, wherein after said frame having a PM bit reset is received, said AP fills a transmit buffer with copies of frames ordered by priority, transmitting frames from said transmit buffer to said station in order of priority; and
removing said copies of frames from said transmit buffer in response to transmitting copies of said frames in transmit buffer to the station, wherein said removing is done when the PM bit for said station is set in a frame control field of a frame transmitted uplink to the AP;subsequent to the station acquiring an upload channel to communicate with the access point, receiving upload frames from the station at the access point; wherein the upload frames received on the upload channel are interleaved with frames downloaded on a download channel from the access point to the station, the method further comprising; subsequent to transmitting the frames from the transmit buffer to the station, sending a notification to the station indicating that the transmit buffer is empty; and receiving frames at the access point from the station on an upload channel. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method of saving power in a wireless Local Area Network (WLAN) including an Access Point (AP) and at least one station, the method comprising:
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receiving, at an AP, a Power Save (PS) Poll from a station; retrieving a frame from a highest priority buffer having frames for said station; receiving a frame control field of a frame transmitted uplink to the AP, the frame control field having a Power Management (PM) bit reset, wherein after said frame having a PM bit reset is received, said AP fills a transmit buffer with copies of frames ordered by priority; transmitting frames from said transmit buffer to said station in accordance with an order of priority; and removing said frames from said transmit buffer as the copies of frames are transmitted, wherein said removing is done when the PM bit for said station is set in a frame control field of a frame transmitted uplink to the AP subsequent to the station acquiring an upload channel to communicate with the access point, receiving upload frames from the station at the access point; and wherein the upload frames received on the upload channel are interleaved with frames downloaded on a download channel from the access point to the station.
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Specification