Wi-Fi networks are like crowded streets. One vehicle traveling too slowly causes everyone else to jam up. This is a problem many hotspot users will have noticed. Because the only result is horribly slow Internet. The Wi-Fi-6 technologies Multiple Input Multiple Output (MIMO) and Orthogonal Frequency Division Multiple Access (OFDMA) put an end to this.
They operate as traffic controllers for data packets and keep things flowing efficiently. But how does that work?
MIMO: Parallel data streams for more efficiency
When multiple Wi-Fi users want to send and receive data in parallel, MIMO technology is especially useful. Why? It leads to greater efficiency when transmitting large data packets. MIMO uses different transmitters and receivers to implement multiple parallel data links, known as spatial streams.
Up until the first wave of Wi-Fi 5 products, access points only supported MIMO technology for single users. Since then, the MU-MIMO principle has become established. The prefix “MU” means multi user, meaning that all of the available spatial streams are distributed simultaneously between several different devices. These are no longer served successively, but in parallel. In one sense you could say that the traffic controller has opened up some new lanes. Another advantage: As of Wi-Fi 6, MU-MIMO is available in both the downlink and uplink directions. Meaning, there is oncoming traffic, which is also transmitted simultaneously.
Furthermore, latency and throughput are improved—important aspects for bandwidth-hungry real-time applications such as virtual reality. The notation “8 x 8” indicates the number of the transmitting and receiving antennas, i.e. the number of available lanes. 8 x 8 MIMO describes 8 transmit and 8 receive antennas. Such a high number of antennas is usually available only at the access-point end. Generally speaking, MU-MIMO-enabled end devices such as notebooks or tablets have three antennas at most. This means that two streams can be bundled to provide the device with a higher data rate. Smartphones usually have just one or two antennas. Due to the different number of antennas on the clients, transmissions can be scheduled to multiple smartphones simultaneously, corresponding to the number of available streams.
OFDMA: Fewer packets, faster Internet
Furthermore, Wi-Fi 6 introduces the more complex technology known as Orthogonal Frequency Division Multiple Access. This technology is already in use with LTE/4G mobile technologies. OFDMA splits the frequency range of a Wi-Fi channel into several frequency blocks to create sub-channels. These can be just 2-MHz wide, so they do not block the entire channel width of 20, 40, 80 or even 160 MHz width for the small amounts of data they transmit. On the other hand, the Wi-Fi 6 access point is able to bundle them together and use them to transport data. The traffic controller knows how to form carpools. Since Wi-Fi channels are now a scarce commodity anyway, exploiting them efficiently in this way relieves some of the load on the already crowded spectrum.
With these two technologies, Wi-Fi 6 offers nowadays the highest possible performance for multiple users all at the same time—with MU–MIMO and OFDMA as reliable traffic controllers.
Read more about Wi-Fi 6 in our previous blog post: Think big – Wi-Fi 6 .
The author Joachim Prick is Product Manager Wi-Fi at LANCOM Systems.