USB 3.1 And Its Disruptive USB Type-C Connector

USB is as ubiquitous a connector standard as you can find, but a new generation is coming with the 3.1 specification, which portends a future where USB offers a single-cable solution for audio, video, data and power on "every conceivable platform and mobile device," or so the press materials claim.

There are three "pillars" to the new spec: SuperSpeed USB (10 Gb/s), USB Power Delivery and the actual USB Type-C connector.

USB Type-C Connector

The changes that USB 3.1 bring are most obviously seen in USB Type-C, because there's an entirely new connector that fits into a port whether upside-down or right-side up, which eliminates the primary frustration with USB ports since they first appeared on devices years ago. Somehow, even though you had a 50/50 chance of guessing the orientation of your USB cable correctly, your failure rate was around 95 percent. (Or was that just me?)

USB Type-C Connector

It's a simple fix; the new USB Type-C cables have a single CC wire inside, but each connector has two CC pins. When you plug the connector into a port, the CC wire can then make a connection regardless of the plug's orientation.

The new connector is also physically quite small, measuring 8.4 mm wide by 2.6 mm high, making it a fine size for any device, be it a laptop, a slim 2-in-1 or a thin smartphone. Obviously, the existing USB Type-A connector is a bit too large to be elegantly used in many of today's svelte devices, but the smaller micro AB connector is potentially too flimsy. The USB Implementers Forum (USB-IF) believes that the Type-C connector solves both problems, and the connector's 10,000-cycle durability will be sufficiently robust to handle the rigors of use in our mobile computing lives.

USB Type-C is compatible with previous iterations of USB, at least in that it supports all prior protocols from USB 2.0 onward, including the drive stack, capabilities and infrastructure.

Obviously, though, the USB Type-C connector isn't backward-compatible physically; it will require adapters that have, for example, Type-C on one end and Type-A on the other, or one that offers Type-C and standard Type-B on respective ends. And so on.

USB Type-C Connector

In time, all devices will phase out current USB ports in favor of Type-C ports, but that could take a long while. It also means that as users' various computers and other USB-equipped devices age, they'll need a veritable stockpile of adapters to ensure that a slightly older device can connect with a newer one. Is that an inevitability of forward progress and change? Yes. Will it be a pain in the neck? Also yes.

Further, it's not entirely clear when those new ports will make their debut on new computers and peripherals, so it's not as if you can time a purchase to coincide with USB Type-C connectors' debut. However, the USB-IF believes we'll begin seeing devices on the market rocking the new connectors sometime "early" next year.

SuperSpeed USB

Setting aside the speedbumps on the road to change, there's plenty in the new USB spec to eagerly anticipate, not the least of which is speed. The new SuperSpeed USB boasts transfer speeds of 10 Gb/s and is designed to offer connectivity to everything from mice to storage to 4K displays.  

That's a refreshing amount of speed and doubles that of the previous USB 3.0 standard's 5 Gb/s, but even at 10 Gb/s, USB 3.1 lags behind Thunderbolt 2 and its 20 Gb/s. However, Jeff Ravencraft, President and COO of the USB-IF, made it clear that USB isn't losing a speed race here, because it isn't competing in one.

"We designed SuperSpeed USB so that when the time is right, if we need more performance, we can turn the dial up on it. That's already been future-proofed into the cables and connectors and the spec," he said. "We know that SuperSpeed USB will go beyond 20 Gb/s in the future."

However, Ravencraft said that blazing-fast speeds aren't necessary or even practical for most everyday uses. For general consumer products out there today, he said, "SuperSpeed 10 Gb/s is more than enough performance for the everyday user."

USB Power Delivery 2.0

USB charging has been a handy tool for some time, but USB 3.1 comes with a boost in USB Power Delivery 2.0 (USB-PD) to 100 W. The new iteration of USB-PD promises backward compatibility to USB 2.0 and up, and it co-exists with USB Battery Charging 1.2.

The new spec also allows for devices to negotiate power, so not only is there more potential juice to pump through the new Type-C cable, but two devices can intelligently decide which one powers which.

"For instance, you may have a workstation or a monitor that can deliver up to 100 W of power; and you might have a cell phone that will never be able to deploy 100 W of power," said Ravencraft. There's a power delivery chip in the phone, as well as one in the hub in the monitor. The phone and monitor will "see" each other and define what capability the other has, and then they'll "decide" which device will provide the power and which will consume it. In that case, obviously, the phone should be the recipient of power from the monitor.

Further, the power direction is switchable without the need to change the physical cable direction; it's a two-way street with a traffic cop ensuring that everything flows properly.

Further Building On USB 3.1

A powerful aspect of the USB 3.1 spec is that not only does it bring new capabilities on its own, it enables and even encourages further innovation from others through Alternate Modes (Alt Modes) and Media-Agnostic USB (MA-USB).

In a nutshell, Alt Mode enables device makers to add more connectivity through the USB Type-C cable connector. This is an exciting capability, because OEMs can use Alt Modes creatively with devices. For example, VESA recently announced that it used Alt Mode to enable DisplayPort over the Type-C cable and connector.

DisplayPort Alt Mode

Of course, companies must acquire a standard or vendor ID (SVID) from the USB-IF for any implementation of Alt Mode.

A final key feature of the new USB reality is MA-USB, a spec that was first published in March. "MA-USB allows wireless devices and docking stations to communicate using the USB protocol — and all the goodness in the USB protocol stack and infrastructure — without a physical USB connection or cable," said Ravencraft. Notably, he added, "It's been built to deliver wireless gigabit transfer rates while leveraging the USB infrastructure."

Simply put, MA-USB enables the use of USB capabilities with no cable. It works over WiGig 60 GHz radios, WiFi 2.4 GHz and 5 GHz radios, ultra wideband radios and more, and it's compliant and compatible with USB 2.0 and later, including SuperSpeed 10 Gb/s.

The USB-IF worked closely with the WiFi and WiGig Alliances (which are now united) on MA-USB, building on the WiGig serial extension spec to ensure that it truly was media agnostic — that Ethernet, USB, WiGig, WiFi and so on would work over it.  

MA-USB is a clever bit of technology, really, as it shifts the hard work of discovery, association and authentication to the media it runs on top of. Security is an issue, of course, but MA-USB relies on the wireless medium to keep things locked down; thus, the signal's security is as reliable as the medium sending it, for better or for worse.

Taken together, all of the above technologies portend significant steps forward in the world of connectivity. Ubiquity can be difficult to come by with any new technology or specification (especially one that includes a new physical connector), but USB is so widely used that it's just a matter of time before USB Type-C, USB SuperSpeed and USB-PD 2.0 land on mountains of new computers and peripherals.

Update: To fix a previous error, we followed up with the USB-IF to clarify the theoretical maximum performance of USB 3.1. Currently, the group told us that USB 3.1 can hit 9.5-9.7 Gbps when you factor in a 4-5 percent overhead -- this, versus a 20 percent or more overhead on previous iterations of USB. "USB Type-C cables and connectors have been tested for performance levels up to 40 Gbps and we believe there is the capability to scale beyond those levels," a representative told us. "To note, 40 Gbps is achieved with two lanes. USB Type-C cables and connectors are rated at 20 Gbps per lane."

We removed the incorrect information previously included in the article.

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  • Jaroslav Jandek
    The biggest thing for me is the orientation-agnostic connector. Like half the times, I am plugging the cable the other way...
  • jdlobb
    So does the 100W power spec mean that it will be able to feed data AND power to a monitor so that the monitor itself won't need any additional cable, simply the USB 3.1 connection to the desktop, because if so that is a HUGE deal.
  • anro15
    The 100W is theoretical. But that assumes you have the spare power overhead in the device you wish to draw it from.

    It seems unlikely that manufacturers would automatically build in such an overhead given increased costs and power supply sizes. Though I can see certain products making it a selling point, i.e. a docking monitor for business laptops.
  • Solandri
    The 100W is theoretical. But that assumes you have the spare power overhead in the device you wish to draw it from.

    It seems unlikely that manufacturers would automatically build in such an overhead given increased costs and power supply sizes. Though I can see certain products making it a selling point, i.e. a docking monitor for business laptops.
    I believe once the ports and cables become commonplace, manufacturers will build in the overhead (at least on certain ports). The advantage of powering the device via the USB port isn't just the convenience. It means you can use the computer's PSU to act as the AC/DC converter, instead of needing a separate AC adapter power brick for each peripheral.
  • zanny
    speeds in excess of 1 GB/s (that's with a capital "B," mind you), but Ravencraft said that blazing-fast speeds aren't necessary

    "SuperSpeed 10 Gb/s is more than enough performance for the everyday user."

    10Gb/s == 1.25GB/s. 1.25 > 1.
  • beayn
    After 20+ years of being a tehnician, I suddenly realized recently that current USB ports are actually standard on 99% of computers. The hollow part of the connector is always facing up on the motherboard, even on laptops. Now that I know this, I always get it right! It's handy when reaching in the back of a computer under a desk and trying to blindly hook up a usb cable. I have no idea why I didn't notice this sooner.
  • Exovane

    Actually Gigabit is equal to 1,000,000,000 bits (~954 MB/s), when a Gigabyte is proclaimed it is actually 1,073,741,824 bits. (8 bits per byte, 1024 bytes per kilobyte, 1024 kilobytes per megabyte etc) so yes, 10 Gb/s < 1GB/s.
  • khaledegy200
    Man, screw all the other features, NO MORE plugging the USB in the third try.
  • coloradoleo76
    We're all pitchforks and torches when ISPs say that we don't want/there is no use for faster internet speed, but when they say that?

    I understand that there might not be product available to take advantage, but doesn't making available cutting edge technology foster a use for it?
  • Achoo22
    Exovane said:
    Actually Gigabit is equal to 1,000,000,000 bits (~954 MB/s), when a Gigabyte is proclaimed it is actually 1,073,741,824 yes, 10 Gb/s < 1GB/s.

    Cute, but false. Bytes are defined as being collections of 8-bits. This is true whether you believe the Giga prefix means 10^9 or 2^30.