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Wireless Networking Glossary
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U
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| UDH | Universal Data Header |
| UDP | User Datagram Protocol. Communications protocol that offers fewer features than TCP (for example, no handshaking, flow control or reliability mechanisms), in exchange for speedier delivery of data. Sometimes referred to as UDP/IP. DNS, SIP and SNMP rely on UDP. |
| UHF | Ultra High Frequency. Range of radio spectrum wherein band extends from 300 MHz to 3 GHz. Wavelengths corresponding to these limit frequencies are 1 meter and 10 centimeters. Extensively used for satellite communication and broadcasting, cellular telephone and paging systems, and by third-generation (3G) |
| Ultra Wideband | Technology for transmitting large amounts of digital data over a wide spectrum of frequency bands using less than 0.5 milliwatts of power across a distance of up to 230 feet. Carries signals through doors and other obstacles that tend to reflect signals at more limited bandwidths and higher power. Compared with Bluetooth. |
| UMTS | Universal Mobile Telecommunications System (a 3G initiative). See http://www.umts-forum.org/. It operates in 5 MHz channels at 3.84 Mcps with 200 kHz between channels. |
| UNI | User-Network Interface |
| U-NII Spectrum | Unlicensed National Information Infrastructure Spectrum. |
| Universal DSL | ADSL variant that does not require splitter at customer premises. Line is split at telco office, which cuts down installation costs. A.k.a. G.Lite. See ADSL. |
| Unlicensed Band Radio | Wireless communication device using one of several frequency bands reserved by local or global regulating authority for public use. Unlicensed band usage is free, allowing lower cost wireless services. Because it is free, it will likely become heavily used, resulting in interference and reduced performance. |
| Uplink | Path from terminal to base-station |
| URI | Uniform Resource Identifier. A superset of URL and URN. If an object is on the internet and does not have one of these it really doesn't exist. |
| URL | Uniform Resource Locator. Form of internet address usable by a browser. Of the format ":". http, ftp and mailto are examples of schemes. The remainder of the URL is defined by the scheme, with some restrictions on the characters that can be used. Illegal ASCII characters can be included with the %XX notation, where XX is the two digit hexadecimal value of the character. |
| URN | Uniform Resource Name |
| UTC | Universal Coordinated Time |