OFDMA—Heart of 802.11ax
OFDMA—Heart of 802.11ax
Wi-Fi innovation is a battle of speed with each generation of Wi-Fi standard getting faster and faster. The ever increasing number of bandwidth-hungry gadgets at home makes a faster and more robust network essential. The latest 802.11ax Wi-Fi standard (also known as Wi-Fi 6) promises higher speeds and a greater connection capacity and is being acclaimed as the optimal solution for dense usage scenarios.
So how is it possible? While improving on some of the existing methods, 802.11ax also introduces a new one, Orthogonal Frequency-Division Multiple Access (OFDMA), a key feature that lifts network capacity substantially.
How Did OFDMA Develop?
OFDMA provides support for multiple users accessing the internet simultaneously and greatly boosts network capacity. It is developed from OFDM and further revamps the nuts-and-bolts of OFDM. OFDM is used in the current Wi-Fi standards (11a/g/n/ac).
Then how does OFDM work?
The core of OFDM is to divide the whole available carrier spectrum into a number of sub-carriers. This generates significant increases in capacity and efficiency. Imagine a highway (your bandwidth) in which only one lane of trucks are allowed to carry goods (data) to one customer (client device) at a time, even if the trucks are not fully loaded. What a waste of space, both in terms of highway and vehicles. The solution to this is to divide the highway into several lanes, which is what OFDM does. It divides the available spectrum into many sub-carriers for several data streams to transmit in parallel. Besides, these independent data streams do not interfere with each other.
How Has OFDMA Improved Upon OFDM?
OFDM is not enough for us now. The 802.11ax Wi-Fi standard introduces OFDMA to increase the amount of data a router can handle. OFDMA follows the sub-carrier method and takes it further to boost spectrum efficiency even higher, providing a much better internet experience. Take a look:
OFDM (on the left) allocates a whole sub-carrier to the user for a time slot, no matter whether the sub-carrier is made full use of. Only one client is receiving data packets for that time slot, hogging a whole sub-carrier. It’s like one of those trucks we mentioned earlier going out with only half a load of cargo. When there are a lot of clients and a large amount of small-size packets, one client must wait a long time for its turn to send and receive data while a lot of bandwidth is wasted.
By contrast, OFDMA (on the right) divvies up these sub-carriers into smaller resource units and allocates them cross-band to meet the individual needs of each client. This means several devices can communicate simultaneously. Furthermore, OFDMA combines small-size packets (combining the packets of User 0, 1, and 2 as the diagram above shows), which yields significant increases in capacity. While combining, OFDMA also prioritizes this data according to time-sensitivity and urgency. Therefore, data with higher importance is handled first.
In conclusion, OFDM entails a large amount of wait time and waste of spectrum resources. OFDMA outperforms OFDM in its more fine-grained assignments of resources and better quality of network.
What Are the Advantages of OFDMA?
As a supplement to the previous part, this part summarizes the essential advantages of OFDMA. It provides:
- A faster network, since devices are transmitting in sync.
- Higher capacity, as OFDMA provides up to 4× more capacity.
- Flexibility of deployment across various frequency bands, as you can use multiple frequencies at once according to the demands of your network.
- Better internet experience in dense Wi-Fi landscapes.
What Can We Get from an 802.11ax Router?
The 802.11ax standard allows many devices to communicate simultaneously. If there are many devices accessing the internet in your home, an 802.11ax router is also your choice. You can enjoy lag-free 4K video and download stuff from NAS at the same time while your kids are playing Xbox and another family member is having a Skype conference call. It also produces dramatic increase in network speed compared to current Wi-Fi standards in dense usage scenarios like airports, stadiums and campuses.
TP-Link has launched and will continue to launch new models 802.11ax router so as to meet diversified demands. It’s hoped that in the near future, we can all enjoy the benefits of 802.11ax and get a better online experience.