The major difference after IEEE 802.11ac Wave 1 evolves to 802.11ac Wave 2 (that is, 802.11ac 2.0) is that the latter introduced multi-user multiple-input multiple-output (MU-MIMO). MU-MIMO increases the network resource utilization and significantly improves the communication quality. The following elaborates MU-MIMO.
MU-MIMO allows a router to send data to a maximum of 4 Wi-Fi
terminals at the same time and set up an independent "spatial stream"
for each client, increasing network resource utilization. Therefore, it
is regarded as an innovative technology in the wireless development
process in the industry. Note that both the router and Wi-Fi terminals
need to support MU-MIMO
A conventional single-user MIMO (SU-MIMO) router can communicate with only 1 device at a time. With the advent of a fully-connected era and continuous increase of Wi-Fi terminals, an SU-MIMO router has to communicate with Wi-Fi terminals one by one in turn. Each access device keeps preempting resources, the router is overloaded, and the access rate for each device is slow.
In addition, a router generally has 3 to 4 antennas, and an access terminal generally has only 1 or 2 antennas. Because the SU-MIMO router can communicate with only 1 Wi-Fi terminal at a time, it is difficult for a Wi-Fi terminal to occupy all transmission channels. As a result, some antennas of the router are idle.
For example, the overall theoretical transmission rate of a router that supports the IEEE 11ac 4x4 MU-MIMO is up to 1733 Mbps. When the router is connected to and transmits data to a Wi-Fi terminal (with 1 antenna) that does not support MU-MIMO, the maximum theoretical transmission rate is only 433 Mbps. The remaining 1.3 Gbps capacity is idle at that time. If both the router and the Wi-Fi terminal support MU MIMO, the router can be connected to and transmit data with a maximum of 4 Wi-Fi terminals at the same time. In this way, the total capacity of the router is fully utilized.
Advantages of MU-MIMO
Increases the network capacity and spectrum utilization.
MU-MIMO can effectively boost the total capacity of a wireless router by 2 to 3 times that in the SU-MIMO era.
Meets high bandwidth requirements of applications such as the video service.
MU-MIMO eliminates idle MIMO intervals and improves the data transmission efficiency on the network. Therefore, it can better meet the requirements of video, audio, and other bandwidth-hungry applications.
Improves user experience of traditional Wi-Fi terminals.
The overall efficiency improvement brought by MU-MIMO enables more idle time or capacity on the network to serve traditional Wi-Fi terminals (that support only SU-MIMO). That is, the application experience of traditional Wi-Fi terminals can also be improved
