On October 3rd, the WiFi Alliance officially incorporated WiFi based on the IEEE 802.11ax standard into its main lineup, making it the sixth-generation WiFi technology, namely WiFi 6.

       As the sixth-generation WiFi technology, just how powerful is WiFi 6? Before delving into this question, we need to have a little digression. While the WiFi Alliance was determining the sixth-generation WiFi, in order to make it easier for users to understand, they officially announced a new naming standard using numbers.

       In the latest naming system released by the WiFi Alliance, the original complex technical naming method has been replaced by a sequence of numbers in ascending order of size (and also of performance strength). Users can identify the performance of WiFi standards, including speed, throughput, and user experience, by the size of the numbers. For example, in terms of performance, it is obvious that WiFi 6 > WiFi 5.

This approach can also be used to specify previous WiFi standards, allowing users to identify devices that use the corresponding WiFi standards. For example, 802.11n or 802.11ac. The numerical sequence includes:

       ● WiFi 6 is used to identify devices that support the 802.11ax technology.

       ● WiFi 5 is used to identify devices that support 802.11ac technology.

       ● WiFi 4 is used to identify devices that support the 802.11n technology.

       Additionally, in the process of identifying the network connections of WiFi devices, new UI icons have also been utilized. The icons will be represented by displaying the WiFi signal indicator and the connected number. When users move between WiFi networks that offer different user experiences, the icons will also be adjusted accordingly. When the user device displays a signal indicator icon with the number 6, it indicates that the device is using WiFi 6.

The enhancement of WiFi 6 technical capabilities

       WiFi 6, also known as 802.11ax, initially proposed its first version in November 2016 and the second version in September 2017. However, neither of these versions received the approval of more than 75% of the members of the 802.11ax working group. The current third version, also known as version 3.0, is still under discussion and is expected to be officially standardized in 2019.

       Although the formal standardization has not been completed, it does not hinder the technological development of 802.11ax.

       Compared with the previous generation (802.11ac), 802.11ax aims primarily to increase the average throughput of users by at least 4 times in dense user environments. This naturally requires significant improvements in technical capabilities. Regarding specific technical enhancements, this article mainly analyzes from three aspects: MU-MIMO, OFDMA, and MCS.

       First up is the MU-MIMO technology. MU-MIMO stands for Multi-User Input/Output technology and is mainly applied in 802.11ac WAVE2. Compared to the MIMO (Multi-Antenna Transmission) technology used in 802.11n, it mainly improves the situation where router antennas are idle, allowing the router to split the antennas and independently transmit data to different devices.

       One of the main features of the 802.11ac Wave 2 launched in 2015 was the application of MU-MIMO technology, which enabled its AP nodes to simultaneously send data packets to multiple clients that supported MU-MIMO, solving the problem that wireless routers previously could only communicate with one terminal at a time. The maximum specification supported by 802.11ac Wave 2 at that time was 4×4 MU-MIMO, which could simultaneously share downlink MU-MIMO data packets with 4 terminals.

       In comparison, 802.11ax features 8×8 MU-MIMO, which enables 8 terminals to share uplink and downlink MU-MIMO data packets simultaneously. Additionally, when devices adopting the 802.11ax standard send data packets from the AP to the terminals, a single data packet can be sent to multiple terminal nodes, and these terminal nodes can also coordinate and simultaneously send data packets to the AP end and the network uplink. The data packets arrive at the AP simultaneously, and the AP can decode and simultaneously receive all the data packets, thus improving efficiency.

       Then comes OFDMA technology. The 802.11ac and previous WiFi standards all use OFDM (Orthogonal Frequency Division Multiplexing) modulation, which is one of the implementation methods of multi-carrier transmission schemes. In networks using this method, there is only one standard data packet in the same frame. When transmitted to the client, regardless of the size of the frame, from the perspective of the network protocol, the additional system overhead in channel transmission is the same. Additionally, in an OFDM system, users occupy the entire channel. As the number of users increases, data requests from users will conflict with each other, resulting in poor service quality when these users send request data.

       802.11ax adopts OFDMA (Orthogonal Frequency Division Multiple Access) modulation technology, which is an evolution of OFDM technology. OFDMA is now widely used in cellular networks. It can combine various sized data packets from a modulation perspective, reducing system overhead through sharing, and can support both uplink and downlink simultaneously, thereby improving efficiency. At the same time, the symbol length of OFDMA has also been increased. The symbol length of each modulation signal becomes four times that of 802.11ac. With longer modulation lengths, in the presence of multiple paths, the AP end and the client have more opportunities to fully utilize the multiple paths and combine signals reflected from different angles through a wider window. This enhances the decoding capability and the stability of reception in practical applications, especially in long-distance transmission scenarios with strong multiple paths.

       Improvement of MCS (Modulation and Coding Strategy). This refers to QAM, which is orthogonal amplitude modulation. It is the combination of orthogonal carrier modulation technology and multi-level amplitude keying. The maximum support for 802.11ac is 256-QAM, while 802.11ax can support up to 1024-QAM. Due to the higher density of the modulation code, the amount of data carried is also greater. Compared with 802.11ac, 802.11ax has increased the data carrying capacity by 2 to 3 times. From a data perspective, the associated rate of a single spatial stream with 80M bandwidth has increased from 433Mbps to 600.4Mbps, and the theoretical maximum associated rate (160M bandwidth, 8 spatial streams) has increased from 6.9Gbps to around 9.6Gbps.

       802.11ax supports both 2.4GHz and 5GHz frequency bands, and also inherits the backward compatibility feature of WiFi. Regarding the specific performance comparison between 802.11ac and 802.11ax in terms of frequency band, channel bandwidth, FFT size, subcarrier spacing, and data transmission rate, please refer to the following table:

The application scenarios of WiFi 6

       According to Jason Tao, the product management director of Qualcomm, the advantages of the 802.11ax standard will be most evident in densely populated urban environments, enterprise-level applications, and network splitting for operators.

       One aspect is the highly dense usage environment in cities. 802.11ax significantly enhances its performance for applications in offices, apartments, dense residential areas, and even outdoor settings.

       The second is enterprise-level applications. This is also one of the most promising application scenarios for the 802.11ax standard, which has been widely adopted recently. Because enterprise-level applications have moved almost all critical business processes to the WiFi network, wired network connections are rarely seen. Whether it is the terminal devices connecting to the cloud or the electronic classrooms applied in the education field, they are all realized on the WiFi network. 802.11ax makes these services more reliable than before and supports a larger number of clients. For example, in an electronic classroom, if there were 100 or more students in a large class, the challenges of transmitting videos or the interaction between up and down would be relatively large. With 802.11ax, the reliability and usage effect of the application scenarios will be greatly improved.

       Thirdly, the newly added application scenarios have played an important auxiliary role in the network traffic diversion of operators. The LTE network has indeed significantly improved the internet access and data traffic of mobile terminals. However, the LTE network is relatively expensive in terms of bandwidth and network deployment for operators. Therefore, in many cases, operators prefer to divert some of their services to the WiFi network because the WiFi network is more cost-effective. However, the previous WiFi network had challenges in terms of stability or bandwidth. With the evolution of 802.11ax technology, the user experience of the application scenarios diverted from the LTE network will be better than before.