*Tech Article* 802.11 Wireless Rate Calculation

With the improvement of wireless technology, wireless rate has also increased. So how are the rates of common wireless technologies such as 802.11n, 802.11ac and 802.11ax calculated?

Referring to different wireless standards, the working frequency band and wireless speed of wireless products are different. The theoretical speed of each protocol can be referred to the following table:

Wireless Standard	Frequency Band	Wireless Rate
802.11a	5GHz	54Mbps
802.11b	2.4GHz	11Mbps
802.11g	2.4GHz	54Mbps
802.11n	2.4GHz and 5GHz	Up to 600Mbps
802.11ac	5GHz	Up to 6.93Gbps
802.11ax	2.4GHz and 5GHz	Up to 9.6Gbps

 

The dual-band routers and tri-band routers that are marketed generally refer to routers that use 802.11n and higher Wi-Fi technologies.

Before we introduce the Wi-Fi rate, we need to understand a few basic theoretical knowledge.

MIMO:  Multiple-input/multiple-output. (Number of lanes)

Channel width: Channel width basically controls how broad the signal is for transferring data. (Lane width)

QAM: Quadrature amplitude modulation (QAM) is the name of a family of digital modulation methods and a related family of analog modulation methods widely used in modern telecommunications to transmit information. (Vehicle speed)

 

802.11n:

802.11n technology can be applied in 2.4GHz and 5GHz frequency bands, and the theoretical rate can reach 600Mbps. Compared with the old version of the 802.11g protocol, the 802.11n rate is mainly improved by utilizing wider frequency bands and multiple antennas.

Channel width - 802.11n technology can double the wireless rate by bonding two 20MHz channels as one larger 40MHz channel.

Spatial Stream - Each additional antenna can be used by a router to make more use of one spatial stream, and the wireless rate can be doubled with Multi-Stream.

Taking cars and highways as the example, increasing the bandwidth is equivalent to increasing the width of a single lane, so the number of vehicles passing at the same time can be doubled. Each additional antenna is equivalent to adding one lane to the highway, which means that the number of vehicles passing at the same time can be doubled as well. The 4 MIMO technology supported by 802.11n means that the highway can be increased to the maximum of four lanes.

*Assuming a fixed parameter (64QAM, 40MHz, 1 MIMO) for 2.4GHz or 5GHz wireless network of 802.11n routers, then their theoretical maximum wireless rate is 150Mbps. For this situation, the maximum theoretical rate of the 802.11n router which is using 4 MIMO is 600 Mbps.

Wireless Rate (2.4GHz & 5GHz, 40MHz)

Antenna Configuration	802.11n Wireless Rate
Single Steam (1x1)	150Mbps
Dual Steam (2x2)	300Mbps
Three Steam (3x3)	450Mbps
Four Steam (4x4)	600Mbps

 

802.11ac

The speed increase of 802.11ac for 5 GHz networks is achieved by utilizing wider frequency bands and higher QAM modulation and demodulation, which can provide multiple antennas and achieve faster processing.

Channel width - The 802.11ac 5GHz wireless network commonly uses a bandwidth of 80MHz. So the theoretical wireless rate is twice as fast as the 40MHz 802.11n 5GHz wireless rate.

Spatial Stream - 802.11ac supports up to 8 spatial streams, which means that 802.11ac routers can have 8 antennas. The theoretical maximum rate of 8 MIMO technology used by 802.11ac is twice than that of the 4 MIMO technology used by 802.11n.

QAM - The modulation mode of 802.11ac has been improved from 64QAM modulation used by 802.11n to 256QAM. This technology can increase the 5GHz wireless rate by 1.33 times.

Taking highways as the example as above, 802.11ac is upgraded from four lanes to eight lanes, the lane width can be increased to twice, and the vehicles on the road travel faster. The result is faster traffic speeds and less congestion, resulting in a significant increase in total flow per unit time and a significant reduction in total travel time.

Wireless Performance Comparision (5GHz)

Antenna Configuration	802.11n(40MHz)	802.11ac(80MHz)
Single Steam (1x1)	150Mbps	433Mbps
Dual Steam (2x2)	300Mbps	866Mbps
Three Steam (3x3)	450Mbps	1300Mbps
Four Steam (4x4)	600Mbps	1733Mbps

 

According to the above table, the theoretical wireless speed of an 802.11n three-antenna device can be achieved by simply using an 802.11ac single-antenna device. The wireless rate has been greatly improved.

*Assuming a fixed parameter (256QAM, 80MHz, 1 MIMO) for 5GHz wireless networks of 802.11ac routers, then their theoretical maximum wireless rate is 433Mbps. For this situation, the maximum theoretical rate of the 5 GHz wireless network on the 802.11ac router which is using 8 MIMO is 3.4Gbps.

 

802.11ax

The improvement of the 802.11ax wireless rate is mainly achieved by changing the format of the OFDM symbol and improving the QAM modulation and demodulation mode.

Channel width - 802.11ax supports 160MHz bandwidth, which doubles the wireless rate compared to 80MHz, which is common to 802.11ac.

Change OFDM Symbol Format - 802.11ax changes the OFDM symbol length and symbol interval time. Therefore, in the same configuration, the wireless rate of 802.11ax is increased by 11% compared with 802.11ac.

QAM - The QAM modulation and demodulation mode of 802.11ax is upgraded from 256QAM of 802.11ac to 1024QAM. This technology can increase the wireless speed by 1.25 times in the same configuration.

Wireless Performance Comparision (5GHz)

Antenna Configuration	802.11n(40MHz)	802.11ac(80MHz)	802.11ax(80MHz)
Single Steam (1x1)	150Mbps	433Mbps	600Mbps
Dual Steam (2x2)	300Mbps	866Mbps	1200Mbps
Three Steam (3x3)	450Mbps	1300Mbps	1800Mbps
Four Steam (4x4)	600Mbps	1733Mbps	2400Mbps

 

Taking highways as the example again, 802.11ax still maintains 8 lanes, but the lane width doubles and the speed of the vehicle on the road is boosted to the fastest speed. The result is that more vehicles can be accommodated in a single lane, the speed of the vehicle is faster, and the total travel time is further reduced and the total flow is further increased.

*Assuming a fixed parameter (1024QAM, 160MHz, 1 MIMO) for 5GHz wireless networks of 802.11ax routers, then their theoretical maximum wireless rate is 1200Mbps. For this situation, the maximum theoretical rate of the 5 GHz wireless network on the 802.11ax router which is using 8 MIMO is 9.6Gbps.