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Wireless Connectivity: SU-MIMO vs. MU-MIMO

March 23, 2021
Grid digitalization is a growing trend and utilities are plugging in more wireless devices every day.

A recent article on remote workplaces grabbed my attention. It was focused on the long-term trends over the past year. It started off with mostly décor subjects, but there were good points, such as improved ergonomics. A dedicated desk with a comfortable chair was a big plus, but if you don’t have room for a desk, it suggested an adjustable workstation. It moved into some tech toys like noise-canceling headphones, but my attention was captured by the comments on the virtual office’s internet connection.

The virtual office is all about wireless connectivity and so is the rest of our Wi-Fi enabled world. We rely on our internet connection for every aspect of working remotely, video classes for students, e-shopping, streaming for entertainment, etc., so it needs to have consistent connectivity for highest performance. This description touched a nerve, I had recently noticed Wi-Fi limitations in my own cyber office.

Wireless Congestion

Have you ever heard of MIMO (multiple inputs, multiple outputs)? What about SU-MIMO (single-user MIMO) or MU-MIMO (multi-user MIMO)? These are terms that are typically applied to Wi-Fi networks when the talk shifts to wireless connectivity. Without getting into a lot of techie-jargon, the typical home Wi-Fi network has many devices hooked up to it. Each device needs connectivity and gets it via the internet access point. In most cases these connections are wireless, which has gotten more complicated with the pandemic.

In simple terms, home Wi-Fi devices need to access the internet, which becomes harder as devices increase. SU-MIMO forces each connected device to wait its turn to send and receive data, which slows down the network and performance suffers. It is so gradual that it’s hard to notice that it’s impacting your virtual office. That’s what happened to me and the performance of my system.

My video conferencing quality was down, but everybody complains about video conferencing. Also, my software platforms were not performing optimally and streaming and downloading were suffering. I did some serious head scratching after reading the article that focused my attention on my cyber office’s performance.

Just to be safe, I checked my computer first. I had built it a few years ago using high-performance gaming components. It was really overkill for the average engineering computer, but as they say, if it’s worth doing, it’s worth overdoing! My desktop was designed to be a screaming-fast computer and all my diagnostics confirmed it still was. It had to be my internet connection.

I did a couple of the internet speed tests and my connection’s speed was faster than what my provider was charging me for each month — value added. Next I needed to test the Wi-Fi quality, so I got out my trusty Wi-Fi analyzer and started testing – bingo, SU-MIMO had gotten me! That was the problem and I had done it to myself. I quickly found the Wi-Fi was congested and the router’s signal strength wasn’t uniform throughout the house.

Like most remote workers, I had been adding new Wi-Fi devices to my network without considering what I was doing to the system’s performance. The analyzer identified over 25 devices (computers, tablets, smartphones, smart-TVs, etc.) on my network and each device needed connectivity. I checked the nameplate on my router and found it was the SU-MIMO-based IEEE 802.11n standard.

My router couldn’t handle all the devices I had connected to it. As a result, my Wi-Fi system suffered interruptions and delays. My router needed upgrading to MU-MIMO technology. The latest generation is the IEEE 802.11ax standard or Wi-Fi 6 as it is known by the Wi-Fi Alliance. This next generation technology provides the MU-MIMO performance needed for connecting multiple devices for simultaneous data flow. It was created for device-crowded environments like mine.

I solved my Wi-Fi operational problems, but it got me thinking about the growing use of wireless technology in our smart grid. Grid digitalization is a growing trend and utilities are plugging in more wireless devices every day. The digital infrastructure is critical to the smart grid’s success. Like my virtual office, we have to pay attention to the mix of generations found in the digital infrastructure.

I had bought one of the best routers of 2010 and then forgot about it. As good as that technology was, it couldn’t handle 2020. Utilities expect equipment to last at least a decade, but is that reasonable for digital technology? It wasn’t for my virtual office!

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