The 802.11 physical layer standard defines some common operations of the wireless network at the physical layer, such as QoS, security, and roaming.

Three APs are deployed on the first floor of a building. The channels from left to right are 1, 6, and 11, respectively. The channels of the three APs deployed on the second floor should be divided into () from left to right.

Which of the following statement are correct about the classification of the antenna?
(Multiple choice)

The following service models can provide end-to-end QoS services, but the scalability is not good.

Which of the following description about Fit AP is correct?