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A beacon frame consists of an 802.11 MAC header, a body and a frame check sequence (FCS). [1] Some of the fields in the body 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.
Since beacon frames are sent using the mandatory 802.11 algorithm for carrier-sense multiple access with collision avoidance (CSMA/CA), the access point must wait if a client device is sending a frame when the beacon is to be sent. As a result, the actual time between beacons may be longer than the beacon interval.
All stations in the IBSS adopt a common value, aBeaconPeriod, that defines the length of beacon intervals or periods. This value, established by the station that initiates the IBSS, defines a series of Target Beacon Transmission Times (TBTTs) exactly aBeaconPeriod time units apart. Time zero is defined to be a TBTT.
In most wireless access points, default configuration for this interval is either 102.4 ms [citation needed] (Beacon interval = 100ms, DTIM = 1) or 204.8 ms [citation needed] (Beacon interval = 100ms, DTIM = 2) and the transmit rate is either 1 Mbit/s or 6 Mbit/s [citation needed], depending on the operating band and protection mode. The DTIM ...
In beacon-enabled networks, Zigbee routers transmit periodic beacons to confirm their presence to other network nodes. Nodes may sleep between beacons, thus extending their battery life. Beacon intervals depend on data rate; they may range from 15.36 milliseconds to 251.65824 seconds at 250 kbit/s, from 24 milliseconds to 393.216 seconds at 40 ...
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In the IEEE 802.11 wireless LAN protocols (such as Wi-Fi), a MAC frame is constructed of common fields (which are present in all types of frames) and specific fields (present in certain cases, depending on the type and subtype specified in the first octet of the frame).
The repetition interval which is repeated continuously, starts with a special control frame called Beacon Frame. When stations hear the beacon frame, they start their network allocation vector for the duration of the contention free period of the repetition period.