EDCA scenario
The EDCA access method provides for prioritized channel access. Each station will select from four sets of priority-controlling parameters for best-effort packets (normal), background packets (very low priority), video traffic, and voice traffic (highest priority). The AP has the same set of priority-controlling parameters, but may also transmit one time period earlier than any station. This is the secret behind HCCA polling (the AP can always transmit before any station) as well as one of the important principles in EDCA (the AP always wins contention for the channel).
Unlike HCCA, where the station must slave itself to the AP's polling schedule, the EDCA station may operate in a specialized power-save mode called unscheduled APSD, or UPSD. In this mode, the station sleeps until it has a VoIP frame ready to transmit (Fig. 2). The AP is expecting this behavior because of a prior signaling handshake conducted between the station and AP.
The power-up procedure at the station can occur with perfect timing, i.e., there's no schedule right-shift, or waiting for the poll, or timing effects caused by other stations or conflicting schedules. The station comes to full power and transmits the VoIP frame using the highest priority parameters available to it. It's reasonable to expect the uplink frame to launch with less than 2 ms of power-consuming delay. It's assumed that the AP is configured to avoid long bursts or other behavior that would increase this delay. This assumption must be taken for both HCCA and EDCA. Without it, either scheme will experience a schedule right-shift or a delay in the UPSD frame exchange.
The uplink frame is ACKed by the AP. The station can retransmit if necessary, and will stay awake until the AP sends down a VoIP frame or a null indication (meaning that there are no VoIP packets to send). Implementations on conventional AP hardware show that the turnaround time at the AP can be bounded to values less than 100 Μs, and improvements to this value should be expected. The lesson is that the effort to add this functionality to an off-the-shelf AP is minimal, especially when compared to the many complexities of maintaining a CBR polling schedule.
The new HPE Aruba 730 series Wi-Fi 7 access points tout high performance, enhanced security, location tracking capabilities, and more.
Verizon is demoing crowd analytics technology that uses 5G along with AI and mobile edge computing to give stadium operators insights into the flow of fans throughout a venue.
As we move closer to fully realizing the potential of Wi-Fi 7, it becomes evident that the RF, signaling, and throughput tests are not merely procedural checkpoints but the pillars of excellence in wireless communication.
