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What is Orthogonal Frequency Division Multiple Access (OFDMA)?

WiFi standards continue to evolve to support our growing need for faster, more reliable wireless connectivity. One of the latest features is called Orthogonal Frequency Division Multiple Access (OFDMA).
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Let's together untie the meaning of this tongue twister to explain how it works and why it's such a good idea to buy a router with OFDMA support.

What Is OFDMA in WiFi?

OFDMA, or Orthogonal Frequency Division Multiple Access, is a technology in WiFi 6 (802.11ax) and WiFi 7 (802.11be). The purpose of this technology is to allow a single OFDMA-enabled router to communicate simultaneously with multiple devices.

To better understand why the OFDMA WiFi technology exists, you can imagine a single-lane road where only one car can pass at a time. Any obstruction on the road that causes any of the cars currently driving on it to slow down or stop will delay all other cars on the same road. That's not ideal considering how many users are typically connected to the same router these days. Unfortunately, that's exactly how older routers work.

What Is OFDMA

When you enable OFDMA on your WiFi 6 or WiFi 7 router, you essentially increase the number of available lanes for cars to drive on, allowing multiple devices to communicate with the router at the same time without the possibility of one device slowing down all other devices.

What's the Difference Between OFDM and OFDMA?

Before OFDMA there was OFDM (Orthogonal Frequency Division Multiplexing). Both of these WiFi technologies are designed to improve the efficiency and reliability of wireless communication, but OFDMA takes things to the next level by allowing more than one device to transmit data at the same time.

How Does OFDMA Work?

The analogy above creates a helpful mental model of what OFDMA is in WiFi, but it doesn't really explain how it works under the hood. So let's open it and have a quick peek, shall we?

As you may know, WiFi frequency bands (such as 2.4 GHz and 5 GHz) are divided into multiple channels to prevent signal interference. An OFDMA router takes a WiFi channel and partitions it into multiple sub-channels. It then dedicates these sub-channels (called sub-carriers) to specific devices, allowing them to communicate with the router simultaneously.

How Does OFDMA Work

What's important is that each device can have a different number of sub-channels allocated to it based on its data transmission requirements. For example, a device that's used only for basic web browsing can probably get by with just two sub-channels, while a smart TV that's used to stream 4K video may need a lot more. These groups of sub-channels are called Resource Units (RU), and WiFi 6 and WiFi 7 routers are smart enough to allocate them automatically.

MU-MIMO Versus OFDMA

Both MU-MIMO and OFDMA are WiFi technologies that enable simultaneous bi-directional communication between multiple devices and a single router. OFDMA does this by sub-dividing a channel into sub-channels. MU-MIMO, on the other hand, creates multiple data streams using multiple physical antennas.

How Does MU-MIMO Work

MU-MIMO and OFDMA are most effective when used together. That's because MU-MIMO is more effective for high-bandwidth applications like high-definition video streaming and online gaming thanks to its ability to increase network capacity, while OFDMA's latency-reducing capabilities make it ideal for low-bandwidth applications, such as connecting IoT devices.

OFDMA MU-MIMO
Full name Orthogonal Frequency Division Multiple Access Multi-User Multiple Input Multiple Output
Operating principle Sub-divides a channel Uses different spatial streams
Use of antennas Not antenna-based Primarily based on antennas
Benefit Better frequency reuse, reduced latency, and increased efficiency Increases capacity and efficiency
Application Low-bandwidth applications High-bandwidth applications
First implemented WiFi 6 (802.11ax) WiFi 6 (802.11ax)

Advantages and Disadvantages of OFDMA

OFDMA is often described as the most important technology enhancement introduced in WiFi 6 because it offers many useful benefits. That said, the technology also has a few downsides you should be aware of.

Advantages

  • Lower latency: Arguably the biggest advantage of OFDMA routers is their reduced latency, which is especially important in real-time applications such as IoT, online gaming, or audio/video conferencing.
  • Higher throughput: By dividing a single channel into multiple subcarriers and assigning them to different users, OFDMA can increase the total maximum throughput of a network.
  • Increased network capacity: By allowing multiple users to simultaneously transmit and receive data, OFDMA can increase network capacity, allowing for more devices to connect to a network without compromising performance.
  • Improved power efficiency: OFDMA can help reduce power consumption in mobile devices by enabling them to transmit and receive data more efficiently, leading to longer battery life.
  • Backward compatibility: When you enable OFDMA on your wireless router, you don't prevent legacy devices that don't support WiFi 6 or WiFi 7 from connecting to your network.

Downsides

  • Requires a WiFi 6 or newer router: OFDMA is a feature of the WiFi 6 (802.11ax) standard and is not supported by older routers. As such, you may need to purchase a new router to take advantage of it.
  • Higher CPU usage: The increased complexity of OFDMA compared with OFDM means that OFDMA-enabled routers need beefier CPUs to process the same amount of data.

Of course, the advantages of OFDMA will manifest only if your wireless network is designed and implemented correctly. That's why you should always perform a wireless network assessment using an easy-to-use WiFi analyzer app like NetSpot.

NetSpot

With the help of NetSpot, you can perform a site survey to identify the perfect location for your router, and you can also analyze other networks in your area so that you know how to adjust your network settings in order to reduce signal interference.

To Sum It Up

The evolution of WiFi standards goes hand in hand with the evolution of our wireless needs. Even standard home routers now regularly connect dozens of devices to the internet, including computers, mobile devices, video gaming consoles, and smart home appliances.

OFDMA helps eliminate performance bottlenecks by assigning each connected device its own dedicated sub-channel. This makes OFDMA routers worth the extra cost for all users that seek to achieve the best online experience possible.

Orthogonal Frequency Division Multiple Access (OFDMA) — FAQs

What does OFDMA mean?

OFDMA means Orthogonal Frequency Division Multiple Access.

Should I have OFDMA on my router?

If you're planning to buy a new WiFi router, then you should prioritize models that offer OFDMA support because the technology can significantly increase the efficiency of your WiFi network.

Does OFDMA make a difference?

Yes, OFDMA makes a huge real-world difference, especially when it comes to network latency. In fact, the technology has been demonstrated to deliver a latency reduction of up to 99 percent.

Should I enable OFDMA?

Definitely! If your WiFi router supports OFDMA, then we strongly recommend you enable it to take advantage of its latency-reducing and efficiency-increasing benefits.

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