In the WLAN infrastructure that supports Wi-Fi 5 (802.11ac) or earlier and regardless of the Wi-Fi generation of the wireless devices, the AP and devices must wait for the air medium to be free before each and next data transmission can occur. If the AP and the device are both 2x2, the transmission speed can be at the maximum rate of the 2x2 communication capability between them. Meaning, the airtime for each transmission between the AP and the device is shorter and the medium is free in a shorter time for the next potential transmission. However, if the device is 1x1, the maximum rate of communication between the AP and the device is determined by the 1x1 modulation scheme which has a lower speed. This leads to longer airtime for each transmission and longer wait time for each and next potential transmission.
When the Wi-Fi 6-enabled devices are connected to a WLAN infrastructure that also supports Wi-Fi 6 (802.11ax), there is no contention in airtime. The OFDMA technology in Wi-Fi 6 mitigates the airtime contention challenge to some degree by allowing simultaneous data transmission to multiple devices. However, the maximum rate is still determined by the maximum modulation scheme of 2x2 or 1x1.
Even though a 1x1 is capable of carrying the traffic of time-sensitive application in terms of speed and pace, the main aspects that need attention are the nearby congregation and potential amount of the 1x1 links between the APs and devices in the network ecosystem. This may dynamically impact the air medium, and then may impact the traffic utilization and capacity, potentially leading to latency to or from one or more of the applications.
For example, when many devices are likely to be connected to the same strong AP and each of these devices are sending and receiving time-senstitive application data at the same time, the 2x2 devices are less likely to be suffering air medium contention, whereas the data streaming speed for the 1x1 devices might be impacted. In another example, in the networks which must serve high-throughput applications next to the ongoing operating voice, regardless of the number of users, utilization of the high-throughput applications has lesser impact on the voice in the network ecosystem of 2x2 links as compared to the 1x1.
No formula can be used to compute the exact capacity and performance of the 1x1. When 1x1 devices are considered for time-sensitive application deployments, running pre-tests in the deployed WLAN of the respective use-cases or in the heaviest RF conditions and capacity is important to evaluate the performance.