Whereas with unicast broadcasts the access point and client can negotiate the optimum transfer rate between them, multicast and broadcast transmissions communicate in just one direction: From the access point to the client. The clients cannot report back the access point with their actual maximum transmission speeds.
The access point has two options for setting the transmission rate for multicast and broadcast transmissions:
- Fixed bit rate: The transfer rate is set so that the slowest client in the WLAN can receive error-free transmissions even under unfavorable conditions. This can lead to the situation that the LANCOM transmits at a lower rate sends than environmental conditions and the clients would actually allow. As a result, the access point slows down the communications in the WLAN unnecessarily.
- Automatic bit rate: By setting the transmission rate to auto, the access point collects information about the transmission rates of the various WLAN clients. Clients automatically notify the access point of this rate with each unicast communication. The access point takes the lowest transmission rate from the list of associated clients and applies this to all multicast and broadcast transmissions.
