Hardware Reference
In-Depth Information
In addition to the modified connector assemblies, the USB 3.0 cable icon shown in
Figure 14.12
denotes cables that are compliant with the USB 3.0 specification.
Figure 14.12. SuperSpeed USB 3.0 cable icon.
The USB 3.0 specification also includes provisions for optical connectors, which might be used by
some devices in the future.
USB On-The-Go
In December 2001, the USB-IF released a supplement to the USB 2.0 standard called
USB On-The-
Go
. This was designed to address the one major shortcoming of USB—that a PC was required to
transfer data between two devices. In other words, you could not connect two cameras and transfer
pictures between them without a PC orchestrating the transfer. With USB On-The-Go, devices that
conform to the specification still work normally when they are connected to a system, but they also
have additional capabilities when connected to other devices supporting the standard.
Although this capability can also work with USB-based PC peripherals, it was mainly added to
address issues using USB devices in the consumer electronics area, where a PC might not be
available. Using this standard, devices such as digital video recorders can connect to other recorders
to transfer recorded movies or shows, items such as personal organizers can transfer data to other
organizers, and so on. USB On-The-Go greatly enhances the usage and capabilities of USB, both in
the PC and in the consumer electronics markets. USB On-The-Go has been included in smartphones,
for example, allowing them to easily and directly interface to USB devices such as flash drives,
without the use of a PC.
Wireless USB
Wireless USB (WUSB) is just what the name denotes: USB without wires. WUSB is based on
ultrawideband (UWB) radio technology, which the military originally developed in 1962 for secure
radio communications and radar use. Recognizing the usefulness of this radio technology for the
public, in 2002 the Federal Communications Commission released frequencies from 3.1GHz to
10.6GHz for general-purpose UWB use.
In June 2003, a group called the Multiband OFDM (orthogonal frequency division multiplexing)
Alliance Special Interest Group (MBOA-SIG) formed to develop a UWB physical layer interface
standard. The MBOA-SIG completed its UWB physical layer 1.0 specification in November 2004
and subsequently merged with another group called the WiMedia Alliance in March 2005. The
WiMedia Alliance had originally formed in 2002 to promote the standardization and adoption of
UWB wireless standards.
In February 2004, several companies, including Agere, HP, Intel, Microsoft, NEC, Philips, and
Samsung, together announced the formation of the Wireless USB Promoter Group and began working
on the WUSB specification, which would use the common WiMedia MB-OFDM (multiband
orthogonal frequency division multiplexing) UWB radio platform for the physical connection layer.
The WUSB Promoter Group subsequently developed and released the WUSB 1.0 specification on
