The IEEE 802.11ay standard is the latest version of WiFi technology, which provides a much higher throughput rate than previous versions. Previous versions of Wi-Fi include 802.11ad, which was developed in 2012 and is the first multi-gigabit Wi-Fi technology. The 802.11ad standard uses millimeter waves to achieve high speeds, but its throughput and reliability are not sufficient for new applications such as augmented reality and virtual reality technology. Now the 802.11ay standard, which is an evolution of 802.11ad, has been released to meet expectations. In this article, we want to take a look at the achievements of the 802.11ay standard and before that, review the millimeter wave spectrum.
WiFi standards are developed by the IEEE standardization body and include two physical layers (PHY) and an access control layer (MAC). The physical layer transfers information between two points, and issues such as modulation, encoding, and digital-to-analog conversion. Usually the physical layer is unique to each WiFi version. The access control layer also has the task of preventing interference in the channel. Normally, the access control layer has been the same between different versions of Wi-Fi, although the use of millimeter frequencies that propagate in a directional direction makes it necessary to revise this layer. It should be noted that higher layer issues, including the network layer, are not included in WiFi standards.
The spectrum used in version 802.11ay is 60 GHz free bandwidth technology with bandwidths totaling 14 GHz. This range is divided into 2.16, 4.32, 6.48 and 8.64 GHz bands. Of course, the spectrum is not the same in different countries, although they are all around 60 GHz. The 802.11ay standard is scheduled to be released as of now (September 2018) and the final version will be released by September next year.
Technologies used in 802.11ay
Channel bonding and MIMO technologies play a key role in achieving 802.11ay goals. The first refers to the integration of multiple communication channels to increase throughput or reliability. For example, separate information may be sent to a destination on two different frequency bands, which greatly increases the data transfer rate. It is also possible to send the same set of information simultaneously on two different frequency bands, and since the channel state is different at different frequencies, this approach leads to a reliable increase. In other words, if one channel is down at the moment, another channel may be active at that moment.
In 802.11ad, there was no channel aggregation, and data transfer between two points was only possible on a 2.16 GHz band. The question may come to mind why this issue was not considered at that time? In response, we must mention the complexity of devices that work on two bands at the same time. In fact, each standard must conform to the hardware and software technologies of the time, otherwise it will not be implemented. It seems that the ability to work on two frequency bands has now reached the commercial construction stage, because in 802.11ay the integration of two 2.16 GHz channels is mandatory and three or four channels are optional.
Another key technology in the new version of WiFi is called MIMO, in which an array of multiple antennas send information in a way that reaches the destination in the desired way. For example, by applying a series of functions to signals, waves can be routed in a specific direction (without changing hardware). Due to the special characteristics of millimeter waves mentioned in the previous sections, the advantage of MIMO technology in sending directional information is quite obvious. MIMO technology also provides the ability to send multiple strings of information on a single channel. This feature can dramatically increase the data transmission capacity of a router.