The Accelerating Demand for 10 Gbps SuperSpeed USB 3.0

USB 3.0 is ubiquitous in new PCs as a standard feature, but it's commonly considered to have come later to the market than consumers would have preferred. Anyone who purchased a new Apple iPod and had to endure the transfer 10+ GB of data over a USB 2.0 connection would have preferred USB 3.0 speeds. Digital cameras take and store pictures that are 3 MB per image and more. Digital video cameras record video at the rate of about 10 minutes per gigabyte. HD video recorders use a “raw” file format that records even more detail in an uncompressed format, which creates noticeably larger files. So while USB 3.0 is ubiquitous and popular in new PCs, it would have been just as needed and popular three years ago. While we could ponder on the question, "Why is USB 3.0 so late to the market?" it's more informative for us to consider what consumers will need in 3 years.

Trends in Storage and Prices
The capacity of hard disk drives (HDDs) and solid state drives (SSDs) continues to increase, and prices per gigabyte to decrease. While HDDs will be the common way to store huge amounts of data, the price of SSDs will drop more quickly. The prevalence of "instant on" smartphones and tablets, which take advantage of SSD performance, has made consumers want the same from their laptops. SSDs also have the advantage of consuming less power which extends battery life. Basically, consumers are used to the performance and battery life offered by their devices using SSD, and this will drive even greater demand for SSDs over HDDs.

In addition to "instant on" performance and low power consumption, the price of SSDs is consistently going down, even with increasing performance. Today, a 256 GB SSD from Crucial or Sandisk sells for about USD$170 retail. This SSD can read data at 5.4 Gbps and write data at 4.4 Gbps using SATA 6 Gbps interfaces, which are faster than the effective USB 3.0 throughput rates of 3.2 to 3.5 Gbps. Assuming prices drop by about 50percent each year (as has been the trend so far), the retail price of a 256 GB SSD will drop to $21 within 3 years (Figure 1).  We can assume a retail margin of 30 percent for the retailer (not the flash memory maker), so the estimated cost of this memory to the SSD maker is $120.

And so, if the cost to the manufacturer is about $120 today, the cost for that same memory will drop 50percent a year to about $15 by 2016. Even if the drop is only 30percent a year, the cost drops to about $29. Either way, the integration of this much memory is highly compelling to consumer device manufacturers of cameras, smartphones, tablets, and "phablets" (i.e., smartphones with almost tablet-sized screens).

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Figure 1: Retail price and cost of 256 GB SSD with 50% and 30% price drops per year

Using a similar extrapolation which assumes the doubling of memory capacities each year at the same price point, $170 will buy a 2 TB SSD in 2016 (Figure 2).

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Figure 2: SSD capacity assuming $170 price

Looking at this trend, tablet and smartphone designers are making the obvious choice to increase their products' storage capacity. More importantly, system architects in a wide variety of consumer industries are integrating SSDs into their products while increasing their products' appeal by integrating higher-quality digital video cameras and digital cameras. Larger files, from photos and videos, in greater capacities of high-performance memory, leads to consumer demand to move the data more quickly. So begins the battle of the standards.

Competing Standards
In 2012, Apple launched monitors and PCs with the Thunderbolt standard, which supports 10 Gbps transfer speeds. As usual, Apple is ahead of everyone else. Thunderbolt supports video and data multiplexed through a single cable. MacBook Air or Pro PCs can be connected to either an Apple monitor or a Thunderbolt docking station. The same Thunderbolt cable carries a multiplexed 10 Gbps PCI Express (PCIe) connection that can carry data from the MacBook to the monitor and other devices plugged into the monitor or docking station. In addition, the PCIe connection allows the docking station or monitor to integrate a USB 3.0 host to connect to USB peripherals and/or Thunderbolt devices like HDDs. In this case, the USB 3.0 host is in the docking station, not inside the PC.

Apple uses Thunderbolt to fill its customers' need for a fast external interface. In fact, the next generation of Thunderbolt will go to 20 Gbps to carry 4K video to meet the demand for a faster interface.  The problem is that Thunderbolt is a closed standard. It requires discrete chips in both the host and client. It requires an active cable with chips embedded in the cable. Adding Thunderbolt increases a system's cost by $10-25.

On the other hand, integrating USB 3.0 has a much lower price point. In fact, every major PC manufacturer currently produces a USB 3.0 docking station based on a DisplayLink chip. The docking stations allow consumers to use existing USB 3.0 drivers concurrently with existing USB 2.0 and 3.0 peripherals. One USB 3.0 cable connected to a USB 3.0 docking station can support multiple USB 1.1, 2.0, and 3.0 peripherals, in addition to HDMI monitors. ASUS, HP, Fujitsu, Toshiba, Lenovo, and Dell built docking stations based on USB 3.0 to provide the same functions as Thunderbolt. The enhanced SuperSpeed USB 3.0 specification will provide the same ease-of-use and functionality, but at the increased speed of 10 Gbps. 

This brings us back to the most compelling use of the smartphones, tablets, and phablets: These mobile devices already can edit videos, play games, and manipulate spreadsheets. Using standard USB drivers, consumers can use mobile devices with their existing USB 3.0 docking stations to make the mobile devices their primary computing platform. The docking station lets them use a full-size keyboard, mouse, 30-inch monitor, and 3 TB SSD drive, effectively removing the limitations of a tiny screen.  As mobile devices become more powerful and include larger embedded SSDs, using 10 Gbps USB 3.0 in a single, small form factor connector becomes even more compelling to both low-end and high-end mobile devices.

Open-Standard 10 Gbps SuperSpeed USB 3.0
The new 10 Gbps SuperSpeed USB 3.0 specification will run at 10G, which matches Thunderbolt's stated performance. 10 Gbps SuperSpeed USB 3.0 will use the same legacy connectors as the original USB 3.0 as well as the same driver software. As an open standard, PC and consumer product makers can easily adapt to it. The USB-IF will continue its successful process of rolling out widespread, solid specifications (as it has with USB 1.1, 2.0, and 3.0) by working with multiple industry leaders for their technical input. They will back the new specification with a strong testing and certification process to ensure interoperability. Most importantly, consumers recognize USB as the interface on their phones, tablets, TVs, and cameras. 10 Gbps SuperSpeed USB 3.0 will be the standard consumers need just as they realize they need it.

Eric Huang worked on USB at the beginning in 1995 with the world's first BIOS that supported USB keyboards and mice while at Award Software. After a departure into embedded systems software for real-time operating systems, Eric returned to USB cores and software at inSilicon, the leading supplier of USB IP in the world. inSilicon was acquired by Synopsys in 2002. Eric served as Chairman of the USB On-The-Go Working Group for the USB Implementers Forum from 2004-2006.

Eric Huang received an M.B.A. from Santa Clara University and an M.S. in Engineering from University of California Irvine, and a B.S. in Engineering from the University of Minnesota. He is a licensed Professional Engineer in Civil Engineering in the State of California.


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