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For example, a station can tell another station to set up a block acknowledgement by sending an ADDBA Request action frame. The other station would then respond with an ADDBA Response action frame. Wi-Fi Neighbor Awareness Networking (NAN), also known as Wi-Fi Aware, service discovery frames are NAN-specific public action frames. [4]
IEEE 802.11 RTS/CTS (request to send/clear to send) is the optional mechanism used by the 802.11 wireless networking protocol to reduce frame collisions introduced by the hidden node problem. Originally the protocol fixed the exposed node problem as well, but later RTS/CTS does not, but includes ACKs.
The Wi-Fi IEEE 802.11 RTS/CTS is one handshake protocol that is used. Clients that wish to send data send an RTS frame, the access point then sends a CTS frame when it is ready for that particular node. For short packets the overhead is quite large, so short packets do not usually use it, the minimum size is generally configurable.
It is particularly important for wireless networks, where the alternative with collision detection CSMA/CD, is not possible due to wireless transmitters desensing (turning off) their receivers during packet transmission. CSMA/CA is unreliable due to the hidden node problem. [3] [4] CSMA/CA is a protocol that operates in the data link layer.
802.11 Beacon frame. A beacon frame is a type of management frame in IEEE 802.11 WLANs. It contains information about the network. Beacon frames are transmitted periodically; they serve to announce the presence of a wireless LAN and to provide a timing signal to synchronise communications with the devices using the network (the members of a service set).
According to the 802.11 standards, a delivery traffic indication message (DTIM) period value is a number that determines how often a beacon frame includes a DTIM, and this number is included in each beacon frame. A DTIM is included in beacon frames, according to the DTIM period, to indicate to the client devices whether the access point has ...
It is not uncommon to have multiple levels of frame synchronization, where a series of frames is assembled into a larger "superframe" or "major frame". Individual frames are then "minor frames" within that superframe. Each frame contains a subframe ID (often a simple counter) which identifies its position within the superframe.
Wireless LANs without this standard send system management information in unprotected frames, which makes them vulnerable. This standard protects against network disruption caused by malicious systems that forge disassociation requests (deauth) that appear to be sent by valid equipment [ 2 ] such as Evil Twin attacks .