信 标 b e a c o n 作用，beacon frames

是不是 设备的意思？

Beacon帧间隔调整作用

BeaconInterval调高有助于无线网路效能client端省电 ；调低可以加快STA连结上去速度，在漫游环境和一些STA连线变动比较大场合.

Beacon frame is one of the management frames in IEEE 802.11 based WLANs. It contains all the information about the network. Beacon frames are transmitted periodically to announce the presence of a wireless LAN. Beacon frames are transmitted by the Access Point (AP) in an infrastructureBSS. In IBSS network beacon generation is distributed among the stations.

Components of a Beacon frame[edit]

Beacon frames consist of MAC header, Frame body and FCS. Some of the fields are listed below.

• Timestamp

After receiving the beacon frame all the stations change their local clocks to this time. This helps with synchronization.

• Beacon interval

This is the time interval between beacon transmissions. The time at which a node (AP, station when in  ad hoc or P2P GO mode) must send a beacon is known as Target Beacon Transmission Time (TBTT). Beacon interval expressed in  Time Unit (TU). It is a configurable parameter in the AP and typically configured as 100 TU. ^[1]

• Capability information

Capability information field spans to 16 bits and contain information about capability of the device/network. Type of network such as AdHoc or Infrastructure network is signaled in this field. Apart from this information, it announces the support for polling, as well as the encryption details.

• SSID
• Supported rates
• Frequency-hopping (FH) Parameter Set
• Direct-Sequence (DS) Parameter Set
• Contention-Free (CF) Parameter Set
• IBSS Parameter Set
• Traffic indication map (TIM)