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Twt Agreement

Please note that a customer may choose not to abide by the AP`s TWT settings and „request“ a TWT with the parameters specified for the agreement. If agreed, the AP responds with „ACCEPT TWT“. The AP can counter the offer with an alternative TWT. The customer chooses how long he wants to sleep after negotiating with the Access Point. As soon as the customer wants to establish the TWT agreement with the Access Point, the next sequence of steps is performed. An 802.11ax AP can negotiate with participating STAs the use of the TWT (Target Wake Time) function to set a certain time or a certain number of times for individual stations to access the media. The ASA and the PA exchange information containing an expected duration of activity. The PA thus controls the degree of conflict and overlap between ASAs that need access to the media. 802.11ax STAs can use TWT to reduce power consumption and switch to a sleep state until their TWT arrives.

In addition, an AP can also establish schedules and provide TWT values to STAs without there being individual TWT agreements between them. The standard calls this procedure Broadcast TWT operation (see Figure 13). Target wake-up time (TWT) is an energy-saving mechanism initially defined in amendment 802.11ah-2016. A TWT is an agreement negotiated between the Access Point (AP) and WiFi clients, based on expected traffic activity, to set a target reactivation time for customers in power saving mode (PS). A TWT reduces the time it takes for a customer in power-saving mode to be awake. This allows the customer to sleep longer and reduce energy consumption. Unlike legacy customer power-saving mechanisms, where sleeping customer devices have to wake up in microsecond intervals, TWT could theoretically allow client devices to sleep for hours. TWT is therefore an ideal energy-saving method for mobile and IoT (Internet of Things) devices that need to save a long battery life. For each 802.11ax client, there can be up to 8 planned reactivation agreements negotiated separately for different types of application data traffic. The standard has yet to define some of the mechanisms for ignoring overlapping BSS traffic, but implementation could include raising the threshold for signal detection signals for the clear signal evaluation (SD) channel for inter-BSS frameworks, while maintaining a lower threshold for intra-BSS traffic (see Figure 11). In this way, the traffic of neighboring BSS would not cause unnecessary conflicts of access to the channels. Customers use TWT settings from the last TWT item received, which is included in the corresponding AP management frameworks.

In this case, the client is also called „TWT Scheduled STA“. The AP is referred to as the „TWT Scheduling AP“ in Figure 1. Scenario of a high-density stage of users and mixed environments planned for 802.11ax use Testing the sensitivity of the 802.11ax-APs receiver represents an additional challenge, as the AP is a cadence and frequency reference. Therefore, the test instrument must be attached to the AP before packets are sent to the AP for packet error rate sensitivity tests. . . .

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