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What is Wireless USB?


What is Wireless USB (WUSB)? Feature
Concept Wireless USB vs. Wireless LAN (IEEE 802.11a/b/g)


What is Wireless USB (WUSB)?

Unlike legacy interfaces such as SCSI, the USB interface does not require ID assignment, and also supports "hot swapping" (plugging in/out without turning off the power). Favored for its simplicity, USB has been widely adopted by various electronic devices, including personal computers, PC peripherals, digital cameras, and gaming consoles.
With the late advancement of wireless technology eliminating the need for physical connections using cables, end users can now enjoy greater freedom in the way they use various devices. The shift to wireless communication offers great potential in providing new conveniences, and in expanding or even creating a new market.

"Wireless USB (WUSB)" was developed as a new interface standard that expands the connectivity of the USB interface with the latest wireless technology. Likewise with IEEE 802.11a/b/g wireless LAN having replaced much of the wired LAN amongst personal computers and digital home appliances, Wireless USB is expected to become widely adopted, contributing to the revitalization of the digital market.
Wireless USB is sure to bring about new usage for USB.


Wireless connection

Wireless USB offers high-speed wireless connection with UWB (Ultra Wide Band), while maintaining the operability, convenience, and driver software compatibility of USB 2.0.



Feature

Wireless USB (WUSB) uses the WiMedia-compatible UWB (Ultra Wide Band) method, a high-speed, broadband technology for short-distance communication. Aimed to become the "wireless version of USB 2.0," Wireless USB offers the following advantages of USB 2.0.


Wireless Connection with Transfer Rate Equivalent to USB 2.0 (480 Mbps)

Wireless USB offers transfer rate equivalent to that of USB 2.0, with a "theoretical maximum transfer rate of 480 Mbps for a distance of up to approximately 3 m, sufficient for a typical connection between a personal computer and a peripheral device." Wireless USB simplifies the installation of printers, external storage devices, and other equipment requiring high-speed transfers of large amounts of data, and also eliminates the need to carry around cables for transferring data to and from digital audio players, digital cameras, and other portable devices.


Same Ease-of-use as Existing USB Devices

The Wireless USB (WUSB) standard has much in common with existing USB standards. The same driver software can be used in most cases, making it possible for existing systems to adopt WUSB easily by simply adding an internal or external WUSB module.


Low Power Consumption, Minimal Development Cost

Using the WiMedia-compliant UWB method, Wireless USB offers high-speed wireless communication while minimizing power consumption by the transmission/reception circuits. In the presence of multiple personal computers and peripheral devices, unlike wireless systems designed for many-to-many communication, Wireless USB predetermines a one-to-many master/slave relationship between the "host" (PC, gaming console, etc.) and the "device" (peripheral devices), thereby limiting the scope of the network. Furthermore, CMOS technologies can be utilized in manufacturing the RF processing block, enabling the use of existing production lines for a reduction of manufacturing cost, and facilitating future integration.


Security

Host devices that support Wireless USB (WUSB) can communicate with each other without requiring special settings. This also means that the transmitted data can be freely received, stolen, or tampered with by anyone within the transmission range, unless adequate security measures are taken. To ensure a level of security comparable to that of wired communication, WUSB uses special procedures for communication between the host and the devices.



Concept

Inherited Concepts

  • Transfer is scheduled by the host USB controller.
  • Host controllers cannot be connected directly with each other.
  • Up to 127 USB devices can be connected to a single USB host controller.
  • Supports four basic transfers: Control, Bulk, Interrupt, and Isochronous.
  • Transactions are constructed from three packets: Token, Data, and Handshake.
  • In principle, the upper layers of the driver stack can be the same as for wired USB.

Newly Introduced Concepts

  • Effective power management due to the elimination of cables.
  • A mechanism for limiting the connection of USB devices to the intended USB host controller, and a data encryption technology for preventing interception.
  • Equal sharing of communication bandwidth between multiple UWE devices.
  • Adoption of USB 2.0's "split transaction concept" for all packets, as a countermeasure for increased error rate due to wireless communication.
  • Addition of a handshake phase to Isochronous transfers, as a countermeasure for increased error rate due to wireless communication.


Wireless USB vs. Wireless LAN (IEEE 802.11a/b/g)

With the IEEE 802.11a/b/g wireless LAN, the theoretical maximum transfer rate is 54 Mbps, even for the higher-speed IEEE 802.11a/g standards. With the increasing demand for streaming of high-definition videos and data transfer to external storage devices, there is a strong need for a faster wireless communication method.

As with USB 2.0, Wireless USB offers a maximum transfer rate of 480 Mbps, providing enough bandwidth to allow external storage devices, scanners, and other peripheral devices to "go wireless." Wireless USB can also be utilized to create compact, next-generation laptop PCs with minimal I/O ports, or digital AV equipment capable of wirelessly transmitting high-definition videos.
Since Wireless USB is designed to provide high-speed transfer within a relatively short range of 10 m, it will likely coexist with wireless LAN, which is designed for a communication range of approximately 100 m.