Wireless Witch: The Truth About USB 3.0 and Wi-Fi Interference

Concerned about the USB 3.0 port on your router and wireless interference issues? Get the facts.

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Wireless routers are increasingly coming to market with USB 3.0 ports. I'm seeing this feature included quite often with many of the latest premium, dual-band 802.11ac Wi-Fi routers. A USB port on a router lets you connect a printer or external hard drive for sharing on the network. USB ports are handy because they make it very simple to set up a network printer on a home network or quickly expand sharable storage. However, there are some concerns that USB 3.0 on routers may be a source of signal interference for wireless devices.

Let's look at the reality behind this fear, and also at what the industry and you as a home user can do to combat interference issues with USB 3.0 and Wi-Fi.

Why USB 3.0?
Of course, the advantage of USB 3.0 over USB 2.0 is speed. Throughput rates can vary depending on hardware, software, and other factors, but generally USB 2.0 has a speed of about 40MBps while USB 3.0 can reach 400MBps—as shown in tests done mostly with data transfers to external drives. So there is a definite performance gain with USB 3.0. That means faster data transfers to and from attached external drives and faster network printing with USB 3.0-supported devices when connected to a router's USB 3.0 port.

What's the Problem?
However, you don't want to get those gains at sacrifice of wireless performance. After extensive communication with the leading wireless router 'makers' representatives and engineers, the consensus is that yes, there are interference issues between USB 3.0 and the 2.4 GHz band. Ken Loyd, director of consumer product for D-Link, provided some good background on the issue:

USB 3.0 has a 5Gbps signaling rate. The USB 3.0 specification requires USB 3.0 data to be scrambled and it requires spread-spectrum. The noise from USB 3.0 data spectrum can be high (in the 2.4-2.5GHz range). This noise can radiate from the USB 3.0 connector on a device (such as a PC or Router), the USB 3.0 connector on the peripheral device or the USB 3.0 [port]. If the antenna of a wireless device operating in this band is placed close to any of the USB 3.0 radiation channels, it can pick up the broadband noise. The broadband noise emitted from a USB 3.0 device can affect the SNR (signal-to-noise ratio) and limit the sensitivity of any wireless receiver whose antenna is physically located close to the USB 3.0 device. This may result in a drop in throughput on the wireless link.

In a nutshell—the noise from USB 3.0 interferes with the 2.4 GHz signal. However, the wireless industry is proactive about the problem. Just about all of the router makers I spoke with that offer routers with USB 3.0 ports have those ports shielded to alleviate that interference.

What Are Router Makers Doing?
In addition, router makers are taking other measures. According to Loyd, D-Link added an option to turn on and off the USB 3.0 port on the DIR-860L and DIR-868L routers. When enabled, it notifies users with a message that enabling USB 3.0 might adversely affect the 2.4GHz wireless signal.

Sandeep Harpalani, director of product marketing for core networking products for Netgear said, "Yes there is the issue of USB 3.0 interference with 2.4GHz band when there is [an] HDD connected to the port and especially when an active data transfer is happening. We have resolved this issue with better hardware design that isolates this noise and reduces the impact to almost negligible on our Wi-Fi routers with USB 3.0 like the R6250 (AC1600 WiFi router). In a non-optimized design the impact can be quite significant on the 2.4GHz band."

Belkin/Linksys emphasizes placement of the USB 3.0 port on its consumer routers. A spokesperson from the company said, "We develop and design our products to limit interference by the placement of the USB 3.0 port on our routers in relation to: the wireless antennas, throughput testing of USB 3.0, Wi-Fi performance testing and making changes to components or using additional components when necessary. We will continue to put our routers through rigorous testing to ensure they meet and exceed the expectations of our testing, certification testing and our customers."

Jason Owen, CEO of Amped Wireless explained to me how his company designed its latest wireless adapters to combat the issue, "We've done a lot of fine tuning on our upcoming USB 3.0 adapter that minimizes the 2.4G interference regardless of the user's USB 3.0 port. Our ACA1 High Power Dual Band AC Wi-Fi USB Adapter (due end of this month) features the longest range for an AC Wi-Fi dongle on the market. We use a very high quality, thick shielded USB 3.0 cable and attach the adapter to the laptop monitor or desk (away from the USB port) to avoid the noise caused by non-shielded or poorly grounded USB 3.0 ports."

What You Can Do
Manufacturers do seem to be on top of the issue. As an end user, if you believe or have confirmed you are having interference issues because of your router's 3.0 port and the 2.4 GHz band, here are a couple of suggestions:

Make sure you use a high-quality shielded USB 3.0 cable when connecting any devices to the USB 3.0 port.
When actively printing to a USB router-connected printer or performing a file copy or download from a USB 3.0 connected HDD, make sure that wireless clients are only connected to the 5 GHz band if they support dual-band.
It's probably not a bad idea to keep wireless clients at a respectable distance from any device that is performing a function and is connected to the router; such as a printer that's printing, or an external drive that's having data copied or read from. I haven't seen any hard numbers or assertions of distance helping, but it's possible perhaps operating a tablet, for example, at a distance of at least 20 feet away from the router when it has a USB device connected, may help.

I don't see this problem being a deal-breaker for the continuation of adding USB 3.0 capabilities to routers. As 802.11ac matures, I think that the 5GHz band is going to be used more and more. Also, it's likely the USB 3.0 specification will mature to deal with wireless interference issues. So go ahead, get that USB 3.0-enhanced router; the performance gains outweigh the throughput slowdown which should largely go unnoticed by users.