Multiple BSSID (MBSSID) was originally specified in the IEEE 802.11v and is a mandatory 802.11ax feature for Wi-Fi 6E-capable APs, which supports multiple SSIDs of an AP radio without broadcasting complete beacons for each single SSID configured on an AP.
This feature broadcasts information for multiple BSSIDs within a single beacon or probe response frame, instead of multiple beacons or probe response frames, for each corresponding single BSSID. This reduces the RF interference and overhead on air as the APs broadcast lesser numbers of beacons and probe responses.
Clear Channel Assessment (CCA) is a physical carrier-sensing technique used in wireless networks for channel sensing as part of their medium access mechanism. When a Wi-Fi station performs a physical carrier sense, it will listen to the channel to identify whether the channel is occupied with any other RF transmissions.
While CCA itself is implemented at the PHY layer, the primary impact of its performance is on MAC metrics such as throughput, latency, and power efficiency. Higher CCA increases Wi-Fi clients channel contention time to send and receive data on the negotiated channels which affects Wi-Fi Clients performance, for example, lower throughput, high latency, packet loss, and more power consumption etc.. Hence Zebra recommends using multiple BSSIDs.
The chart below depicts the Air Medium Consumption Level measured by CCA load and affected by Multi-BSSID Beacons that are enabled in the 6GHz network compared to the 5GHz network (which does not support this feature). Furthermore, it compares the levels in different traffic scenarios of before, during, and after voice calls. In the following example, the 6GHz and 5GHz networks are configured with 6 BSSIDs.
CCA Load Level Multi-BSSID Enable vs. Disable in Different Traffic Scenarios
