Power Saving Methods - Infineon AIROC CYW43012 Manual

Low-power system design with AIROC™ Wi-Fi & Bluetooth® combo
chip and PSoC™ 6 MCU
WLAN power optimization techniques
Increasing the DTIM allows stations to conserve power more effectively at the cost of buffer space in the AP and
delays in the reception of multicast and broadcast frames by all stations, including stations in active mode.
It should be noted that the listen interval is recommended to be equal to (or less than) the DTIM period for the
STA to receive all unicast, multicast, and broadcast packets. This ensures an optimal power and latency
tradeoff.
Usually, the DTIM period is set as the number of beacon intervals in the AP. The default DTIM period for most
APs is either DTIM=1 (DTIM every beacon), DTIM=3 (DTIM every third beacon), or DTIM=10. In the case of DTIM=3,
the station needs to only wake from low-power mode to receive every third beacon and any ensuing queued
broadcast or multicast traffic.
Figure 2 explains the beacon interval, listen interval, and DTIM period in an infrastructure network.
AP
STA1
(Wakes up every DTIM)
STA2
(Not interested in broadcast/
multicast traffic)
Figure 2 802.11 infrastructure network operation
3.1.4

Power saving methods

Although the 802.11 transmitted power consumption is at least five times higher than the received power
consumption, even for medium transmit-duty-cycle applications, much of the energy in a battery-powered Wi-
Fi station is consumed by the receiver. Unless power save techniques are used, the 802.11 receiver may be
powered ON for significant periods of time while the station waits for network clients to respond to requests. It
does not take very long for a 130-mW receiver power consumption to discharge a battery.
Wi-Fi STAs use different mechanisms to save power. STAs with low duty cycle and long battery life
requirements, Wi-Fi sensors, for example, may use the standard 802.11 Power Save Poll (PS-Poll) mechanism.
STAs requiring higher throughput, wireless speakers, for example, may consider using a non-standard 802.11
power save mechanism. These methods are described in this section.
Note: STAs requiring a more fine-grained power save mechanism to differentiate power save for various
traffic priorities may consider using unscheduled automatic power save delivery (U-APSD) or Wi-Fi
multimedia (WMM) power save. AIROC™ CYW43012 Wi-Fi & Bluetooth® combo chip currently does
not support WMM power save.
Application note
DTIM period = 3 beacon interval
Beacon interval
Beacon with
TIM
DTIM
Listen Interval (STA1) = 3 beacon interval
STAs listening
to beacon
Listen Interval (STA2) = 4 beacon interval
11 002-27910 Rev. *C
2023-05-29