What is MIMO and MU-MIMO? What's the Difference?
Part I. What is MIMO?
MIMO refers to Multiple Input and Multiple Output, which is also called SU-MIMO. It adopts multiple antennas at the sending and receiving ends and forms an antenna system with multiple tunnels between two terminals. According to the number of issuing and receiving antennas, MIMO can be categorized into 4 types including SISO, SISM, MISO, and MIMO. Generally, the transmission speed can be improved by 50% maximumly by using more antennas to transmit and receive. These systems improve the WiFi standards.
Advantages of MIMO
● MIMO improves the data transmission rates of a single device without taking up extra frequency resources.
● MIMO is of extremely high using efficiency of frequency. It improves reliability and efficiency on the basis of making good use of the current frequency at the cost of increasing the handling complexity of sending and receiving ends.
● It promotes the boost of WiFi transmission rates greatly like from 54 Mbit/s (802.11g) to 300 Mbit/s or even 600 Mbit/s (802.11n).
Part II. What is MU-MIMO?
MU-MIMO means Multi-User Multiple Input Multiple Output. It allows a signal AP to communicate with multiple devices simultaneously. Unlike SU-MIMO, it only enables multiple antennas to communicate with one device. MU-MIMO was introduced with WiFi 5, only supporting 4*4 DL MU-MIMO. At present, the WiFi 6 adopts 8*8 DL MU-MIMO and brings in UL MI-MIMO. MU-MIMO is mainly used in scenarios with distribution-intensive users, concurrency of multiple users and large traffic, and relatively fixed terminal positions, including business offices, meeting centers, and electronic education.
1. Advantages of MU-MIMO
MU-MIMO can improve the throughput of the wireless network. When using MU-MIMO, the wireless network throughput is 2-3 times higher than that when using SU-MIO.
It allows multiple terminals to transmit data concurrently, which improves the efficiency of data transmission in wireless networks and reduces the waiting time of terminals on the timing sequence. Therefore, it can better meet the requirements of large traffic and low delay in applications like video or audio.
Due to the overall improvement in transmission efficiency brought by MU-MIMO, the wireless network has more free time or capacity to serve traditional Wi-Fi terminals (only SU-MIMO is supported). In other words, the application experience of traditional Wi-Fi terminals can also be improved.
The biggest difference between MIMO and MU-MIMO is that MU-MIMO can communicate with multiple users meanwhile instead of only one user like MIMO.
As shown in the image below, generally SU-MIMO issues signals like a ring from the center to the outside and communicates with devices in turn according to distance (not the absolute sense of distance, but more signal quality, etc.). When there are too many access devices, some devices have to be waiting and the network will lag.
However, MU-MIMO is different. Its signals are divided into multiple parts in the three dimensions of time domain, frequency domain and space domain, which is like sending multiple different signals at the same time. Thus, the MU-MIMO router can work with multiple devices simultaneously. In particular, as multiple signals do not interfere with each other, resources are maximized.
2. DL MU-MIMO and UL MU-MIMO
DL MU-MIMO refers to downlink MU-MIMO. WiFi 5 brings in MU-MIMO and only supports 4*4 DL. 8*8 DL MU-MIMO was increased in WiFi 6. By adopting the beamforming method at the sending end, DL MU-MIMO can separate data streams of different users and then simply the operation at the receiving end. This achieves the optimization of network resource utilization. It not only strengthens signal guidance but also reduces interference. It contributes to bringing the terminal users a better Internet experience without scrambling for bandwidth or breakdown for HD video/games delay, enjoying the real high-speed WiFi experience.
UL MU-MIMO is uplink MU-MIMO, which is newly introduced in WiFi 6. Different users can deliver uplink by using the same time frequency. In terms of receiving end, the data traffic can be considered as various antennas from one terminal, which forms a visual MIMO system, or UL MU0MIO.
Part III. What device supports MU-MIMO?
With the development of MU-MIMO and WiFi coverage, more and more wireless routers support MU-MIIMO. V-SOL wireless router HG5000-5G4AX also adopts WiFi 6 with MU-MIMO. There are 4x Gigabit LAN ports,1x Gigabit WAN port and a USB3.0 port. MU-MIMO allows multiple terminals to share the channel at the same time and achieve up to 4x capacity. The dual-band WiFi 6 router is capable of reaching a speed of up to 3Gbps and providing a buffer-free 4K/HD streaming and gaming experience.