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UDP

See UDP.

Ultrawideband (UWB)

This wireless technology enables the transmittal of large amounts of digital data over a wide spectrum of frequency bands with very low power (less than 0.5 milliwatts) for a short distance (up to 230 feet). Ultrawideband also has the ability to carry signals through doors and other obstacles that tend to reflect signals at more limited bandwidths and a higher power. Also referred to as "ultra wideband."

UMTS (Universal Mobile Telecommunications System)

This refers to the European Union's version of IMT 2000. This third-generation (3G) technology is designed to provide broadband, packet-based transmission of text, digitized voice, video, and multimedia at data rates up to 2 Mbps. UMTS also is designed to offer a consistent set of services to mobile computer and phone users no matter where they are located in the world. It is based on the Global System for Mobile (GSM) communication standard and endorsed by major standards bodies and manufacturers.

See also IMT-2000.

Unified Messaging

This term refers to solutions that enable systems to handle voice, fax, and regular text messages as objects in a single mailbox that an end-user can access either with a regular email client or by telephone. If using a computing device (versus a telephone), the end-user can open and play back voice messages (assuming the computing device has multimedia capabilities), and faxed images can be saved or printed.

U-NII (Unlicensed National Information Infrastructure) Bands

In the U.S., the FCC has set aside three bands of spectrum in the 5 GHz range for unlicensed use. Those bands, which are commonly referred to as the U-NII bands, consist of three 100 MHz bands between 5.15 GHz and 5.8 GHz. The U-NII bands are very attractive for wireless networking because they provide a part of the spectrum upon which vendors can base their products, and end-users do not have to obtain FCC licenses to operate the products.

Universal Datagram Protocol (UDP)

Part of the TCP/IP suite, UDP is an alternative to the Transmission Control Protocol (TCP), but when compared with TCP, UDP offers only a limited amount of service when messages are exchanged between computers in a network that uses the Internet Protocol (IP). For example, UDP does not provide the service of dividing a message into packets (datagrams) and reassembling it at the other end, and it doesn't provide sequencing of the datagrams.

Universal Power Supply (UPS)

Generally a device that allows a system to maintain operation when changes to the power supply would otherwise interrupt the function of that system. They can range from a 9 Volt battery backup to a generator.

Unlicensed Spectrum

Airwaves that a regulatory body, such as the FCC, hasn't allocated for exclusive use by one user.

UPS

See Universal Power Supply (UPS).

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