8.2 Multi-Role

If more than one Wi-Fi role is activated, the scenario is called multi-role. A second role presence has an impact on the behavior and performance of the system, the performance of each role is highly dependent on the activity of the second role. As an example, consider an AP + station combination, with the AP role as a victim and the station role as the aggressor. When the AP has one station connected and any kind of traffic is running, its throughput performance depends on what the station role is doing. If the station role is not connected and is invoking a periodic scan for detecting a suitable AP and router for connection, it will impact the role performance of the AP at the point when it invokes a scan, but not between scan intervals. If the station role runs high throughput traffic, it will equally share the bandwidth with the AP role. However, it also depends on any peer AP and station devices they are connected to.

Additionally, the operation band and RF mode have an influence on system behavior and throughput performance. Because each role is independent of the other in most role combinations, they can operate on the same or different channel/band using the same or different RF mode, depending on the peer device. Consider the AP + station example, the system is configured to MIMO RF mode, such that both roles can use this role. However, the station role is connected to an AP that supports only SISO20 RF mode, while a station that is connected to the AP role is able to operate in MIMO RF mode. As a result, the throughput performance is not shared equally, as the MIMO RF mode has a higher throughput rate, despite equal time sharing.

Table 21 represents the typical combinations of WLAN roles and RF modes. The results may vary for other combinations of WLAN roles and RF modes.