Power saving medium access in congested network environments
A Wi-Fi device in a WLAN network includes a processor and a transceiver adapted to be coupled to an antenna, and a power saving medium access in congested network environments algorithm that is activated after a Wi-Fi connection is established with its access point (AP). A Traffic Indication Map (TIM) bitmap in a TIM information element received in a beacon frame from the AP is analyzed to determine whether more than a predetermined number of bits (X) are set to indicate the AP has ≥1 buffered frame for ones of the Wi-Fi devices to conclude whether the WLAN is in a congested environment. When in a congested environment, transmissions responsive to the beacon are postponed by entering a sleep mode for a random period of time (P). After P expires, the sleep mode is exited and a poll frame is transmitted to the AP to try to gain medium access.
1 . A method comprising:
receiving, by a device, a beacon frame, the beacon frame comprising a traffic indication map (TIM) bitmap indicating a number of waiting devices;
in response to determining that the number of waiting devices is greater than a threshold:
determining, by the device, a period of time based on the number of waiting devices and a random number;
transitioning the device to a sleep mode for the period of time,
waking up the device after the period of time, and
after waking up the device, transmitting a poll frame; and
in response to determining that the number of waiting devices is less than or equal to the threshold, transmitting the poll frame without transitioning the device to the sleep mode.
2 . The method of claim 1 , wherein determining that the number of waiting devices is greater than a threshold comprises determining that the TIM bitmap includes more than a predetermined number of bits set.
3 . The method of claim 1 , wherein determining the number of waiting devices is greater than a threshold comprises determining that a number of devices waiting to pull data is higher than a predetermined number.
4 . The method of claim 1 , further comprising determining the period of time responsive to a time for data frame pulling.
5 . The method of claim 1 , further comprising determining the period of time responsive to adding the random number with a backoff time.
6 . The method of claim 5 , wherein the backoff time is a random number.
7 . The method of claim 1 , wherein the device complies with an IEEE 802.11 communications standard.
8 . The method of claim 1 , wherein receiving the beacon frame comprises wirelessly receiving the beacon frame from an access point (AP).
9 . The method of claim 1 , wherein the period of time is greater than 10 milliseconds (ms).
10 . The method of claim 8 , wherein the period of time is between 20 ms and 40 ms.
11 . The method of claim 1 , wherein determining the period of time comprises determining the period of time by:
P=Nsta*T data+ Z*S+BO,
wherein Nsta represents the number of bits set of the TIM bitmap, Tdata represents a time for data frame pulling, Z represents the random number, S represents a constant, and BO represents a backoff time.
12 . The method of claim 1 , wherein determining the period of time first is further performed responsive to a time for data frame pulling.
13 . A device comprising:
a transceiver; and
a processing unit coupled to the transceiver and configured to:
receive a beacon frame via the transceiver, the beacon frame comprising a traffic indication map (TIM) bitmap indicating a number of waiting devices;
in response to determining the number of waiting devices is greater than a threshold:
determine a period of time based on the number of waiting devices and a random number;
transition the device to a sleep mode for the period of time,
wake up the device after then period of time, and
after waking up the device, transmit a poll frame using the transceiver; and
in response to determining that the number of waiting devices is less than or equal to the threshold, transmit the poll frame without transitioning the device to the sleep mode.
14 . The device of claim 13 , wherein the processing unit is configured to determine that the number of waiting devices is greater than a threshold when the TIM bitmap includes more than a predetermined number of bits set.
15 . The device of claim 13 , wherein the processing unit is configured to determine the period of time responsive to a backoff time.
16 . The device of claim 13 , wherein the processing unit is configured to determine the period of time responsive to a time for data frame pulling.
17 . The device of claim 13 , wherein the processing unit is configured to determine the period of time by:
P=Nsta*T data+ Z*S+BO,
wherein Nsta represents the number of bits set of the TIM bitmap, Tdata represents a time for data frame pulling, Z represents the random number, S represents a constant, and BO represents a backoff time.
18 . The device of claim 13 , wherein the device complies with an IEEE 802.11 communications standard.
19 . The device of claim 13 , wherein determining the period of time first is further performed responsive to a time for data frame pulling.
20 . A non-transitory computer-readable storage medium storing instructions configured to cause at least one processor of a device to:
receive a beacon frame comprising a traffic indication map (TIM) bitmap indicating a number of waiting devices; and
in response to determining that the number of waiting devices is greater than a threshold:
determine a period of time based on the number of waiting devices and a random number;
transition the device to a sleep mode for a period of time;
wake up the device after then period of time; and
after waking up the device, transmit a poll frame.