Why WiFi 7 can reach such a high peak rate is mainly due to the blessing of the following technologies:
(1) supports 16 concurrent MU-MIMO technology;
(2) Support carrier aggregation at 2.4GHz, 5GHz and 6GHz, with a maximum aggregation bandwidth of 320MHz；;
(3) Support 4096QAM modulation technology;
(4) Introducing HARQ technology;
MU-MIMO technology of 16 stream concurrent
Mu-MIMO (multi-user, multi-input and multi-output technology), multiple users can be concurrent in the same frequency band. In WiFi 6, the maximum number of concurrent streams supported by MU-MIMO is 8. WiFi 7 has increased this data to 16, so in theory, the rate can be doubled. This is like widening the number of lanes on a road from 8 lanes to 16 lanes, and doubling the number of vehicles that can pass at the same time.
Carrier aggregation technology, the maximum aggregation bandwidth is 320MHz.
In WiFi 6, the maximum aggregate bandwidth that can be supported is 160MHz. The maximum aggregate bandwidth supported by WiFi 7 is 320MHz. Carrier aggregation technology is also a conventional means to improve the rate of wireless communication system, and larger aggregation bandwidth means higher theoretical peak rate. This is like building an overpass at a crossroads, and the number of vehicles that can pass at the same time is doubled.
4096QAM modulation technology
QAM (quadrature amplitude modulation) modulation technology is the basis of current broadband communication system. Both Wifi communication and 3G/4G/5G mobile communication adopt QAM technology. WiFi 6 supports 1024QAM, which means that a symbol can carry data of 10bit. WiFi 7 supports 4096QAM, and one symbol can carry 12bit data. In contrast, the transmission efficiency has increased by 20%. However, the bit error rate of 4096QAM is higher than that of 1024QAM in the same environment, so it will only be used when the signal is very good. After the signal becomes worse, AP needs to adjust to low-order modulation to ensure a certain bit error rate.
HARQ technology
HARQ (Hybrid Automatic Repeat Request) plan not supported by WiFi 6 is supported by WiFi 7. HARQ has been supported in 3G/4G/5G mobile communication systems for a long time. In HARQ technology, if the receiver fails to demodulate a data packet, it will inform the sender to resend it, and at the same time, the receiver will save the data that failed to demodulate this time. When retransmitting, the sender uses the new redundant version to transmit, and the receiver combines and demodulates the received data twice, which can improve the success rate of demodulation.
It is reported that Broadcom and MediaTek will launch chips supporting WiFi 7 in early 2022.