How Will Target Wake Time Help Mobile Devices And IoT In 802.11ax?
As mentioned in a previous post, 802.11ax adds some exciting power saving enhancements and improved resource scheduling features including scheduled sleep and wake times, which is borrowed from 802.11ah. Let’s dive a little deeper.
Target Wake Time (TWT) allows devices to negotiate when and how often they will wake up to send or receive data. TWT increases device sleep time and, in turn, substantially improves battery life. In 802.11ax, the 802.11ah TWT mechanism has been modified to support triggered-based uplink transmission, meaning it supports non-AP stations that have not negotiated any implicit agreement with the AP.
Target Wake Time (TWT) will be very useful for both mobile devices and IoT devices. TWT uses negotiated policies based on expected traffic activity between 802.11ax clients and an 802.11ax AP to specify a scheduled wake time for each client. 802.1ax IoT clients could potentially sleep for hours or days at a time to conserve battery life.
You will recall 802.11ac required 80MHz capable clients, 802.11ax supports 20MHz-only clients. This will provide support for low power, low complexity devices (IoT), wearable devices, sensors and automation, medical equipment, etc. Devices like these do not need high bandwidth operations. The 20MHz only devices only communicate on the primary 20MHz so you can have a package exchange of just these clients, normal clients are in the upper secondary.
These features likely will make it into first-generation products.