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Wireless Technology Terms Glossary and Dictionary [S-Z]

S/I: Signal-to-interference ratio
Signal-to-interference ratio (S/I) is the ratio of power in a signal to the interference power in the channel. The term is usually applied to lower frequency signals, such as voice waveforms, but can also be used to describe the carrier wave. See also carrier-to-interference ratio.

S/N: Signal-To-Noise Ratio
Signal-To-Noise Ratio (S/N) is a measure of the power of a signal versus noise. A higher ratio means that there is more signal relative to noise.

SABP: Service Area Broadcast Protocol
Service Area Broadcast Protocol (SABP) is a 3G UMTS protocol for information broadcasting services, which allows cellular operators to deliver information such as stock prices, traffic information, weather reports and emergency alerts to mobile users within selected cells of the network.

SACCH: Slow Associated Control Channel
Slow Associated Control Channel (SACCH) is a GSM signalling channel that provides a relatively slow signalling connection. The SACCH is associated with either a traffic or dedicated channel. The SACCH can also be used to transfer Short Message Service (SMS) messages if associated with a traffic channel.

SALT: Speech Application Language Tags
The Speech Application Language Tags (SALT) specification largely overlaps the VoiceXML specification and both are under review by the same W3C working group. Both specifications share some common functionality, but SALT includes multi-modal capabilities for inputting and outputting data, making speech and traditional data I/O more interchangeable.

Sampling is the process performed in the conversion of analog waveforms to a digital format. It converts a continuous time signal into a discrete time signal or sequence of numbers.

SAT: Set-up Audio Tone
Set-up Audio Tone (SAT) is an audio tone in the 6 kHz range added to the downlink or forward channel in analog cellular systems. The mobile detects and returns the tone. The SAT tone is used to determine channel continuity, and only one SAT tone is usually assigned to a base station or sector.

A satellite is a specialized wireless receiver/transmitter that is launched by a rocket and placed in orbit around the earth. They are used for such diverse purposes as weather forecasting, television broadcast, amateur radio communications, Internet communications, and the Global Positioning System.

Satellite Communication
Satellite Communication refers to the use of orbiting satellites to relay data between multiple earth-based stations. Satellite communications offer high bandwidth and a cost that is not related to distance between earth stations, long propagation delays, or broadcast capability.

Satellite Internet
Satellite Internet refers to utilize telecommunications satellites in Earth orbit to provide Internet access to consumers. Satellite Internet service covers areas where DSL and cable access is unavailable. Satellite offers less network bandwidth compared to DSL or cable, however. In addition, the long delays required to transmit data between the satellite and the ground stations tend to create high network latency, causing a sluggish performance experience in some cases. Network applications like VOIP, VPN and online gaming may not function properly over satellite Internet connections due to these latency issues.

Satellite phone
Satellite phone is a type of wireless mobile telecommunications system using satellites as base stations. Such systems have the ability of providing service to the oceans and other remote areas of the globe.

Scattering is a phenomenon that occurs when the medium through which a radio wave travels consists of objects with dimensions small compared to the wavelength and diffuses the wave as it propagates through it.

SCCH: Signaling Control Channel
Signaling Control Channel (SCCH) is a logical channel used in the PDC system to convey signalling information between the mobile and the network.

SCH: Synchronization Channel
Synchronization Channel (SCH) is a logical channel used by mobile stations to achieve time synchronization with the network. SCH is used in GSM, cdma2000, and W-CDMA systems.

SDCCH: Stand-alone Dedicated Control Channel
Stand-alone Dedicated Control Channel (SDCCH) is used in the GSM system to provide a reliable connection for signalling and Short Message Service (SMS) messages. The Slow Associated Control Channel(SACCH) is used to support this channel.

SDMA: Space Division Multiple Access
Space Division (or Diversity) Multiple Access (SDMA), also known as multiple beam frequency reuse, employs spot beam antennas to reuse frequencies by pointing the antenna beams using the same frequency in different directions.

SDP: Service Discovery Protocol
In the Bluetooth protocol stack, the Service Discovery Protocol (SDP), also known as Bluetooth SDP, provides special means for applications in the Bluetooth environment to discover which services are available and to determine the characteristics of those available services. The SDP defines how a Bluetooth client's application shell acts to discover available Bluetooth servers' services and their characteristics. The protocol defines how client can search for a service based on specific attributes without the client knowing anything of the available services. The SDP provides means for discovery of new services becoming available when the client enters an area where a Bluetooth server is operating. The SDP also provides functionality for detecting when a service is no longer available.

Sector is a coverage area associated with a base station having its own antennas, radio ports and control channels. The concept of sectors was developed to improve co-channel interference in cellular systems, and most wireless systems use three sector cells.

Sector Antenna
Sector Antenna is an antenna type that radiates in only a specific direction. Multiple sector antennas are commonly used in point-to-multipoint situations.

Service area
Service area is the specified area over which the operator of a wireless communications network or system provides services.

SF: Spreading Factor
The Spreading Factor (SF) is the ratio of the chips to baseband information rate. Spreading factors vary from 4 to 512 in FDD UMTS. Spreading factor in dBs indicates the process gain. The lower the spreading factor the higher the data rate.

SFHMA: Slow Frequency Hopped Multiple Access
Slow Frequency Hopped Multiple Access (SFHMA) is a spread-spectrum system where the hop (dwell) time is much greater the information symbol period. When hopping is coordinated with other elements in the network, the multiple access interference in the network is greatly reduced.

SFN: Single Frequency Network
A single-frequency network (SFN) is a broadcast network where several transmitters simultaneosly send the same signal over the same frequency channel. Analogue FM and AM radio broadcast networks as well as digital broadcast networks can operate in this manner. The aim of SFNs is efficient utilization of the radio spectrum, allowing a higher number of radio and TV programs in comparison to traditional multi-frequency network (MFN) transmission. An SFN may also increase the coverage area and decrease the outage probability in comparison to an MFN since the total received signal strength may increase to positions midway between the transmitters.

SGF: Signaling Gateway Function
Signaling Gateway Function (SGF), a component in the IP Multimedia Subsystem, provides signaling conversion (in both directions) between Signaling System 7 (SS7) and IP networks.

SGSN: Serving GPRS Support Node
The Serving GPRS Support Node (SGSN) is the node which, in some sense, carries out the same function as the Local Agent in Mobile IP. However, an SGSN is actually considerably more complex since it also does the full set of interworking with the connected radio network. This means that the functions carried out by the SGSN vary quite considerably between GSM and UMTS.

Shadow fading
Shadow fading is a phenomenon that occurs when a mobile moves behind an obstruction and experiences a significant reduction in signal power.

SHF: Super High Frequency
Super High Frequency (SHF) is the RF spectrum between 3 GHz and 30 GHz.

SiGe: Silicon-Germanium Technology
Silicon-Germanium Technology (SiGe) makes it possible to design complex chips that integrate the functions of a cellular telephone, an e-mailbox and an Internet browser into a handheld information device with rapid data-transfer capability.

Signal Booster
Signal Booster compensates for loss of effect (weakening of the signal in the coaxial cable) between the outer antenna and the phone. It can apply to both incoming and outgoing signals.

Signal Diversity
Signal Diversity is a process by which two small dipole antennas are used to send and receive, combining their results for better effect.

Signal loss
Signal loss is the amount of signal strength that's lost in antenna cable, connectors, and free space. Signal loss is measured in decibels.

Signal Strength
Signal Strength is the strength of the radio waves in a wireless network.

Silent Alert
Silent Alert is the non-audible signal in a beeper, which discretely notifies individuals of incoming pages, typically by vibration.

SIM Card
Subscriber Identity Module (SIM) Card is used in the GSM phones to carry all critical information about the phone and subsriber.

SIM: Subscriber Identity Module
Subscriber Identity Module (SIM) is a component of a Mobile System (MS) in a GSM network that contains all the subscriber information.

SIMO: Single Input Multiple Output
Single Input Multiple Output (SIMO) is a form of smart antenna technology for wireless communications in which a single antenna at the transmitter and multiple antennas are used at the destination (receiver). An early form of SIMO, known as diversity reception, has been used by military, commercial, amateur, and shortwave radio operators at frequencies below 30 MHz since the First World War. The other forms of smart antenna technology include Single Input Single Output(SISO), Multiple Input Multiple Output (MIMO) and Multiple Input Single Output (MISO).

Simulcast refers to broadcasting a message over multiple transmitters throughout a geographical region at precisely the same time.

SINR: Signal to Interference plus Noise Ratio
Signal to Interference plus Noise Ratio (SINR) is the ratio of the received strength of the desired signal to the received strength of undesired signals (noise and interference).

SISO: Single Input Single Output
Single Input Single Output (SISO) is a form of antenna technology for wireless communications in which a single antenna at both the transmitter and at the destination (receiver) are used.

Site survey
Site survey is a survey conducted at the location for a new WLAN in an effort to avoid what could be time-consuming and costly problems down the road. It involves diagramming the network, checking the building and testing the equipment.

SLF: Subscription Locator Function
Subscription Locator Function (SLF), a component in the IP Multimedia Subsystem (IMS), locates the database containing subscriber data in response to queries from the I-CSCF (Interrogating-Call Session Control Functions) or application server (AS).

Slotted ALOHA
Slotted ALOHA is an access technique synchronizing the transmitters to time-slots in the channel and having the transmitter wait until the next available slot to send its packet.

Slow fading
Slow fading is a long-term fading effect changing the mean value of the received signal. Slow fading is usually associated with moving away from the transmitter and experiencing the expected reduction in signal strength.

SM: Spatial Multiplexing
Spatial Multiplexing (SM) is a transmission technology developed by Stanford University and Iospan Wireless in California exploiting multiple antennas at both the BS and CPE to dramatically increase the bit rate in a wireless radio link with no additional power or bandwidth consumption. Under certain conditions, SM offers linear increase in spectrum efficiency with the number of antennas.

Smart phone
Smart phone is a wireless phone with text and Internet capabilities. Smart phones can handle wireless phone calls, hold addresses and take voice mail and can also access information on the Internet and send and receive e-mail and fax transmissions.

SMATV: Satellite Master Antenna Television
Satellite Master Antenna Television (SMATV) refers to the transmission of television programming to a Satellite Master Antenna installed on top of an apartment building, a hotel, or at another central location from where it serves a private group of viewers. The transmission usually is done in C-band to 1.5 or 2 meter dishes.

SMG: Special Mobile Group
Special Mobile Group (SMG) is a standards body within ETSI that develops specifications related to mobile networking technologies, such as GSM and GPRS.

SMLC: Serving Mobile Location Center
Serving Mobile Location Center (SMLC), either a separate network element or integrated functionality in the Base Station Controller(BSC), contains the functionality required to support Location Services (LCS). The SMLC manages the overall coordination and scheduling of resources required for the location of a mobile unit. The SMLC may control a number of Location Measurement Unit (LMU) for the purpose of obtaining radio interface measurements to locate or help locate Mobile Station (MS) subscribers in the area that it serves.

SMLCPP: Serving Mobile Location Center Peer-to-Peer Protocol
Serving Mobile Location Center Peer-to-Peer Protocol (SMLCPP) is a transport protocol for the communication between the Serving Mobile Location Centers (SMLCs). The main functions of SMLCPP are: (1) allowing an SMLC to ask for and obtain information about Radio Interface Timing (RIT), as known from measurements done by LMUs not under its direct control; (2) allowing an SMLC, that controls deciphering keys in the location area, to sent them to other SMLCs in the same location area.

SMPP: Short Message Peer to Peer
Short Message Peer to Peer (SMPP) is a protocol for exchange short messages between SMS peer entities such as short message service centers. SMPP is often used to allow third parties (e.g. value-added service providers like news organisations) to submit messages, often in bulk.

SMR: Specialized Mobile Radio
Specialized Mobile Radio (SMR) is a dispatch radio and interconnect service for businesses, covering frequencies in the 220 MHz, 800 MHz and 900 MHz bands.

SMS: Short Message Service
Short Message Service (SMS) refers to the service that allows the transmission of short text messages among mobile devices such as cell phones, fax machines and BlackBerry devices. SMS was originally designed as part of GSM, but is now available on a wide range of networks, including 3G networks. There are two forms of SMS: Short Message Service - Point-to-Point (SMS-PP) and Short Message Service - Cell Broadcast (SMS-CB). The message length is 140 bytes. Larger contents (known as long SMS or concatenated SMS) can be sent segmentedly over multiple messages, in which case each message will start with a user data header (UDH) containing segmentation information.

SMS-CB: Short Message Service - Cell Broadcast
Short Message Service - Cell Broadcast (SMS-CB), a form of Short Message Service for the delivering of short messages over the mobile networks, allows messages (advertising, public information, etc.) to be broadcast to all mobile users in a specified geographical area.

SMS-PP: Short Message Service - Point to Point
Short Message Service - Point to Point (SMS-PP), a form of Short Message Service for the delivering of short messages over the mobile networks, provides, allows messages to be sent from an individual to another.

SNIR: Signal to Noise + Interference Ratio
Signal-to-Noise + Interference Ratio (SNIR) is the ratio of usable signal being transmitted to the undesired signal (noise) plus interference from other or the same channels. It is a measure of transmission quality. The ratio of good data (signal) to bad (noise + intereference) on a line is expressed in decibels (dB).

SNR: Signal-to-noise Ratio
Signal-to-noise Ratio (SNR) is the ratio of usable signal being transmitted to the undesired signal (noise). It is a measure of transmission quality. The ratio of good data (signal) to bad (noise) on a line is expressed in decibels (dB).

S-OFDMA: Scalable Orthogonal Frequency Division Multiple Access
Scalable Orthogonal Frequency Division Multiple Access (SOFDMA or S-OFDMA) is a flavor of the Orthogonal Frequency Division Multiplexing (OFDM), which is a technique for transmitting large amounts of digital data over a radio wave.

SHO: Soft Handoff
Soft Handoff (SHO) refers to two base stations -- one in the cell site where the phone is located and the other in the cell site to which the conversation is being passed, but both are held on the call until the handoff is completed. The first cell site does not cut off the conversation until it receives information that the second is maintaining the call.

Software Access Point
Software Access Point is a wireless-enabled computer running special software that enables it to act exactly like an wireless access point.

Space diversity
Space diversity is a diversity technique widely used in wireless systems since the very beginning. It consists of two receiving antennas physically (spatially) separated to provide de-correlated receiving signals.

SPACH: SMS Point-to-point CHannel
SMS Point-to-point Channel (SPACH) is a logical channel as a part of FDCCH (Forward Digital Control Channel) used to send signaling and control information from the cell site to the user receiver. SPACH can be further divided into three logical channels: ARCH, SMSCH and PCH.

Spectrum refers to a continuous range of frequency for electromagnetic waves.

Spectrum Allocation
Spectrum Allocation refers to that government designation of a range of frequencies for a category of use or uses. Allocation, typically accomplished in years-long FCC proceedings, tracks new technology development. However, the FCC can shift existing allocations to accommodate changes in spectrum demand. As an example, some UHF television channels were recently reallocated to public safety.

Spectrum Assignment
Spectrum Assignment refers to the government authorization for use of specific frequencies or frequency pairs within a given allocation, usually at stated geographic location(s). Mobile communications authorizations are typically granted to private users, such as oil companies, or to common carriers, such as cellular and paging operators.

Spectrum Reuse
Spectrum Reuse means re-applying the already assigned over-the-air spectrum to Cable TV programs. Historically, the over-the-air spectrum has been assigned to many purposes other than that of carrying TV signals. This has resulted in an inadequate supply of spectrum to serve the needs of viewers. Cable can reuse spectrum that is sealed in its aluminum tubes.

Spectrum spreading
Spectrum spreading is the process of increasing the occupied spectrum of a signal well beyond the needed to transmit the information.

Speech coding
Speech coding is an electronic process of sampling and digitizing a voice signal.

Spread spectrum
Spread spectrum is a form of wireless communications in which a signal's frequency is deliberately varied. This increases bandwidth and lessens the chances of interruption or interception of the transmitted signal.

SR: Spread Rate
Spread rate (SR), also known as the chip rate, is the rate of the digital code used to spread the information. The spreading rate is typically at least 100 times the information rate.

SRNC: Serving Radio Network Controller
Serving Radio Network Controller (SRNC or Serving RNC) is a type of Radio Network Controller (RNC) in a 3G mobile wireless network. The key functons of the Serving RNC: terminates the mobile link layer communications, terminates the IU, and exerts Admission Control over new mobiles or services attempting to use the Core Network over its IU interface. Admission Control ensures that mobiles are only allocated radio resources (bandwidth and signal/noise ratio) up to what the network has available.

SS: Subscriber Station
A Subscriber Station (SS) refers to a generalized equipment set providing connectivity between subscriber equipment and a Base Station in the mobile wireless network.

SSB: Single-sideband modulation
Single-sideband modulation (SSB) is a refinement of the technique of amplitude modulation designed to be more efficient in its use of electrical power and bandwidth. It is closely related to vestigial sideband modulation (VSB). To produce an SSB signal, a filter removes one of the sidebands. Most often, the carrier is reduced (suppressed) or removed entirely. Assuming both sidebands are symmetric, no information is lost in the process. What remains still contains the entire information content of the AM signal, using substantially less bandwidth and power, but cannot now be demodulated by a simple envelope detector.

SSD: Shared Secret Data
Shared Secret Data (SSD) is part of an encryption process supporting authentication of mobile phones. It uses an encryption key installed in the phone at the time of activation and known to the system through an entry in the HLR, that protects signalling and identity information. It can also be used to establish a voice privacy key.

SSI: Service Set Identifier
A Service Set Identifier (SSI) is a sequence of characters unique to a specific network or network segment that's used by the network and all attached devices to identify themselves and allow devices to connect to the correct network when more than one independent networks are operating in nearby areas.

SSID: Service Set Identifier
Service Set Identifier (SSID) is a set of 32 characters that give a unique name to a WLAN. All wireless devices on a WLAN must employ the same SSID in order to communicate with each other. The SSID on wireless clients can be set either manually, by entering the SSID into the client network settings, or automatically, by leaving the SSID unspecified or blank. A network administrator often uses a public SSID, that is set on the access point and broadcast to all wireless devices in range. Some newer wireless access points disable the automatic SSID broadcast feature in an attempt to improve network security.

STAP: Space-Time Adaptive Processing
Space-Time Adaptive Processing (STAP) is a signal processing technique that enhances the ability of radars to detect targets that might otherwise be obscured by clutter or by jamming. To implement STAP requires sampling the radar returns at each element of an antenna array, over a dwell encompassing several pulse repetition intervals. STAP is for applications such as Sensor Craft, Targets Under Trees, and space-based radar programs.

STBC: Space Time Block Coding
Space time block coding (STBC) is a technique used in wireless communications to transmit multiple copies of a data stream across a number of antennas and to exploit the various received versions of the data to improve the reliability of data-transfer. The fact that transmitted data must traverse a potentially difficult environment with scattering, reflection, refraction and so on and, as well as, be corrupted by thermal noise in the receiver means that some of the received copies of the data will be "better" than others. This redundancy results in a higher chance of being able to use one or more of the received copies of the data to correctly decode the received signal. In fact, STBC combines all the copies of the received signals in an optimal way to extract as much information from each of them as possible.

STC: Space Time Coding
Space Time Coding (STC) is a method employed to improve the reliability of data transmission in wireless communication systems using multiple transmit antennas. STCs rely on transmitting multiple, redundant copies of a data stream to the receiver in the hope that at least some of them may survive the physical path between transmission and reception in a good enough state to allow reliable decoding.

STD: Selective Transmit Diversity
Selective Transmit Diversity (STD) is a transmit diversity technique using multiple base stations to originate the signal and provide spatial diversity on the downlink. In STD, the transmitter selection is based on a QoS measurement made at the mobile station. See also transmit diversity, TDTD and TSTD.

STTC: Space --Time Trellis Coding
Space --Time Trellis Coding (STTC) is a type of space --time coding (STC) used in multiple-antenna wireless communications. This scheme transmits multiple, redundant copies of a trellis (or convolutional) code distributed over time and a number of antennas ("space"). These multiple, "diverse" copies of the data are used by the receiver to attempt to reconstruct the actual transmitted data. For a STC to be used, there must necessarily be multiple transmit antennas, but only a single receive antennas is required; nevertheless multiple receive antennas are often used since the performance of the system is improved by so doing.

Sub Network
Sub Network is a way of denoting a group of network layers that appear as one to a higher protocol layer.

Supplementary services
Supplementary services is a group of network layer protocol functions that provide call independent functions for mobile phones. These include: call forwarding, follow-me, advice of charge, reverse charging, etc.

Symbian is a software licensing company that develops and supplies the advanced, open, standard operating system -- Symbian OS -- for data-enabled mobile phones.

Based on XML, SyncML enables data synchronization between mobile devices and networked services. SyncML is transport, data type and platform independent. SyncML works on a wide variety of transport protocols, including HTTP and WSP (part of WAP), and with data formats ranging from personal data (such as vCard and vCalendar) to relational data and XML documents. The SyncML consortium was set up by IBM, Nokia and Psion and is sponsored by Symbian.

TACS: Total Access Communication System
Total Access Communication System (TACS) is the European version of AMPS -- the 1G technology for mobile wireless. ETACS was an extended version of TACS with more channels. TACS and ETACS are now obsolete in Europe, having been replaced by the more scalable and all-digital GSM system.

TAMS: Track and Manage Service
Track and Manage Service (TAMS) offers scheduled reporting on the status reports of industry standard sensors, GPS position and other event status reports.

TAP: Telocator Alphanumeric Protocol
Telocator Alphanumeric Protocol (TAP) is a simple protocol dedicated to the forwarding of alphanumeric pages. Although the features and capabilities of TAP are in TDP, the TAP protocol may co-exist with TDP. The TAP protocol may be utilized to forward binary data to RF-linked computers if input is formatted and processed.

TCH/F: Traffic Channel - full rate
Traffic Channel - full rate (TCH/F) is a traffic channel using full rate voice coding.

TCH/H: Traffic Channel - half rate
Traffic Channel - half rate (TCH/H) is a traffic channel using half rate voice coding.

TCH: Traffic Channel
Traffic Channel (TCH) is a logical channel that allows the transmission of speech or data. In most second generation systems, the traffic channel can be either full or half rate.

TCM: Trellis Code Modulation
Trellis Coded Modulation (TCM) is one of the coded modulation techniques used in digital communications. It combines the choice of a modulation scheme with that of a convolutional code together for the purpose of gaining noise immunity over encoded transmission without expanding the signal bandwidth or increasing the transmitted power.

TCP: Telocator Conversion Processor
Telocator Conversion Processor (TCP) is a front end processor which executes the Telocator Format Conversion (TFC) process.

TCS: Telephony Control Protocol Specification
The Telephony Control Protocol Specification (TCS) is a protocol in the Bluetooth protocol stack that defines ways to send audio calls between Bluetooth devices. It also controls the device mobility management procedures. It can be used to create a three-in-one phone:

  1. On the move, a mobile phone connected to a cellular network;
  2. At home, a cordless phone connected to a PSTN via a gateway or base station;
  3. At the office, an intercom.

TD-CDMA: Time Division, Code Division Multiple Access
Time Division, Code Division Multiple Access (TD-CDMA) is a 3G proposal combining elements of TDMA and CDMA. It is developed and used primarily in China, combining time division multiplexing with CDMA techniques.

TDD: Time Division Duplex
Time Division Duplexing (TDD) refers to a transmission scheme that allows an asymmetric flow for uplink and downlink transmission which is more suited to data transmission. In a Time Division Duplex system, a common carrier is shared between the uplink and downlink, the resource being switched in time. Users are allocated one or more timeslots for uplink and downlink transmission.

TDMA: Time Division Multiple Access
Time Division Multiple Access (TDMA) divides a radio frequency available to a network into time slots and then allocates slots to multiple calls. So one frequency can support multiple, simultaneous data channels, using bandwidth more efficiently than earlier technologies. Available in 800-MHz or 1900-MHz frequencies, TDMA is used by the GSM digital cellular system.

TDN: Temporary Directory Number
Temporary Directory Number (TDN) is a temporary identification number assigned to a mobile while attached to the network.

TDP: Telocator Data Protocol
Telocator Data Protocol (TDP) is a suite of protocols used for sending messages from a computer, through a paging system, to a mobile receiving computer. Together, these protocols define the flow of messages from input devices through several processing steps until the entire message is received by an RF-linked computer. The set is compromised of several protocols, including TME, TRT, and TMC.

TD-SCDMA: Time Division Synchronous Code Division Multiple Access
Time Division Synchronous Code Division Multiple Access (TD-SCDMA) is a new technology developed by Siemens and the China Academy of Telecommunication Technology (CATR). TD-SCDMA is part of the ITU 3G standard harmonization and will likely be adopted by some operators in China. This proposed standard is 1.6 MHz wide and uses multiple timeslots, synchronous CDMA, and new detection and interference cancellation schemes.

TDTD: Time Division Transmit Diversity
Time Division Transmit Diversity (TDTD) is a technique utilizing multiple transmit stations to originate the downlink signal and improve performance. The transmit station used can be determined by either a fixed pattern or based on a QoS measurement made at the mobile. See also STD and TSTD.

Telematics means the integration of wireless communications, vehicle monitoring systems and location devices.

TFC: Telocator Format Conversion
Telocator Format Conversion (TFC) describes how binary data messages may be forwarded to RF-linked computers through the use of TAP protocol.

TID: Tunnel Identifier
Tunnel Identifier (TID), containing an MM Context ID and an NSAPI, is used to identify a GTP tunnel between two GSNs in a GPRS network. A tunnel is created whenever an SGSN sends a Create PDP Context Request in a GPRS network.

TIA: Telecommunications Industry Association
Telecommunications Industry Association (TIA) is one of the Telecommunications standards setting bodies in the United States.

Time dispersion
Time dispersion is a manifestation of multipath propagation that stretches the signal in time so that the duration of the received signal is greater than the transmitted signal.

Time diversity
Time diversity is the technique used by CDMA systems to overcome the effects of multipath fading. Through the use of a rake receiver, individual elements or fingers can be offset in time to account for different arrival times of multipath signals.

TinyOS is an open source component-based operating system and platform targeting wireless sensor networks. TinyOS is an embedded operating system, written in NesC programming language, as a set of cooperating tasks and processes. It is designed to be able to incorporate rapid innovation as well as to operate within the severe memory constraints inherent in sensor networks. It is intended to be incorporated into smartdust.

TIPP: Telocator Interswitch Paging Protocol
Telocator Interswitch Paging Protocol (TIPP) is a TCP/IP-based inter-PMP protocol utilized to move information across a network of PMP's TKIP: Temporal Key Integrirty Protocol.

Temporal Key Integrity Protocol (TKIP) is part of the IEEE 802.11i encryption
standard for wireless LANs security. TKIP utilizes RC4 stream cippher with 128 bit key for encryption and 64 bit key for authentication. TKIP is the next generation of WEP (Wired Equivalency Protocol). TKIP provides per-packet key mixing, a message integrity check and a re-keying mechanism, thus fixing the flaws of WEP.

TMC: Telocator Mobile Computer Protocol
Telocator Mobile Computer Protocol (TMC) is the protocol that operates between the Radio Frequency (RF) receiver and the mobile computer, which is the ultimate recipient of data sent from the Message Entry Device (MED).

TME: Telocator Message Entry Protocol
Telocator Message Entry Protocol (TME) defines the protocol operating between the Message Entry Device (MED) and Paging Message Processor (PMP).

TMSI: Temporary Mobile Station Identity
Temporary Mobile Station Identity (TMSI) is an identification number assigned to a mobile station while it is attached to the network. This number is maintained in the VER and SIM while the mobile is attached to the network and is used to route calls to and from the mobile.

TMSI: Temporary Mobile Subscriber Identity
Temporary Mobile Subscriber Identity (TMSI) is the identity that is most commonly sent between the mobile and the network. It is a randomly allocated number that is given to the mobile at the moment it is switched on. The number is local to a location area, and so it has to be updated, each time the mobile moves to a new geographical area. The network can also change the TMSI of the mobile at any time. And it normally does so, in order to avoid the subscriber from being identified, and tracked by eavesdroppers on the radio interface.

TM-UWM: Time-Modulated Ultra-Wide Band
Time-Modulated Ultra-Wide Band (TM-UWM), developed by Time Domain, uses short, coded pulses transmitted over a wide range of frequencies, making it useful for a broad range of applications from networking to through-the-wall radar and secure communications.

TNPP: Telocator Network Paging Protocol
Telocator Network Paging Protocol (TNPP) is a protocol used for moving pages from one paging system to another over the standard lines.

TOA: Time OF Arrival
Time OF Arrival (TOA) is a location technique that uses GSM timing to triangulate the position of a handset relative to active base stations. Accuracy is good indoors and in areas of dense base-station coverage, and TOA can be used with legacy handsets. Specialized equipment is needed at the base station, however, and planning, deployment, and maintenance costs can be high.

Transcoding refers to the operation of changing data from one format to another, such as an XML to HTML, so the output will be displayed in an appropriate manner for the device.

Transmission Frequency
Transmission Frequency is the rate in hertz at which a radio transmitter repeats a signal pattern. It is also a code number that the wireless service company assigns to represent a single frequency or set of frequencies.

Transmit Power
Transmit Power is the amount of power used by a radio transceiver to send the signal out. Transmit power is generally measured in milliwatts, which you can convert to dBm.

Transmitter is a device that generates radio waves and sends them to the antenna.

TrGW: Translation Gateway
Translation Gateway (TrGW) is a component used in the IP Multimedia Subsystem (IMS) network, which provides translation of IPv4/IPv6 address and port numbers, as well as translation of IPv4 and IPv6 protocols.

Tri-band refers to a wireless phone that works on three bands. CDMA and TDMA tri-band phones work on 1900MHz and 800MHz digital frequencies, and 800MHz analog cellular -- popular standards in the United States. Tri-band GSM phones are all digital, operating on 1900Mhz in the United States and 1800Mhz and 900Mhz in other countries.

Tri-mode: Triple mode (tri-mode)
Triple mode (Tri-mode) is a combined analog and digital mobile phone. Allows operation of the phone in the existing analog system at 800 MHz and in digital systems at both 800 MHz and 1900 MHz.

TRT: Telocator Radio Transport protocol
Telocator Radio Transport protocol (TRT) describes the format of data which is forwarded to RF receivers. This transport style protocol allows a receiver to collect several separate message inside different pages and then piece them together into one proper message. The manner in which this data is inserted into any particular radio pager encoding format is specific to the particular manufacturer's radio receiver.

TSTD: Time Switched Transmit Diversity
Time Switched Transmit Diversity (TSTD) is a technique utilizing multiple transmit stations to originate the downlink signal and improve performance. The transmit station used is determined by a fixed selection pattern similar to frequency hopping. See also STD and TDTD.

TTA: Telecommunications Technology Association
Telecommunications Technology Association (TTA) is a telecommunications standards setting body in Korea.

TTC: Telecommunications Technology Committee
Telecommunications Technology Committee (TTC) is a private-sector corporate body established in 1985 to prepare domestic standards relevant to Japanese telecommunications.

TTG: Transmit/receive Transition Gap
Transmit/receive Transition Gap (TTG), a concept in the mobile wireless networking, is a gap between the last sample of the downlink burst and the first sample of the subsequent uplink burst in a time division duplex (TDD) transceiver. This gap allows time for the base station (BS) to switch from transmit to receive mode. During this gap, the BS is not transmitting modulated data but simply allowing the BS transmitter carrier to ramp down, the transmit/receive (Tx/Rx) antenna switch to actuate, and the BS receiver section to activate.

TTI: Transmission Time Interval
Transmission Time Interval (TTI) is a parameter in UMTS (and other digital telecomunication networks) related to encapsulation of data from higher layers into frames for transmission on the radio link layer. TTI refers to the length of an independently decodable transmission on the radio link. The TTI is related to the size of the data blocks passed from the higher network layers to the radio link layer.

Turbo Code
Turbo code is a class of high-performance error correction codes finding use in deep-space satellite communications and other wireless communication applications where designers seek to achieve maximal information transfer over a limited-bandwidth communication link in the presence of data-corrupting noise. There are two types of turbo codes, Block Turbo Codes (BTCs) and Convolutional Turbo Codes (CTCs), which are quite different since they use different component codes, different concatenation schemes and different SISO algorithms.

TWO - WAY Communication
Two - Way Communication occur between communications of radio stations, each having a transmitter and receiver. The stations may be in fixed locations, mobile or portable ones, or in any combination.

UCD: Uplink Channel Descriptor
Uplink Channel Descriptor (UCD) is a concept in the IEEE 802.16 (WiMAX) network, which describes the uplink burst profile (i.e., modulation and coding combination) and preamble length for each UL burst.

UDLP: UniDirectional Link Protocol
UniDirectional Link Protocol (UDLP) is used by inexpensive, receive-only antennas to receive data via satellite.

UE: User Equipment
User Equipment (UE) refers to eqiment in a wireless network that enables users to communicate through wireless communication networks.

UGS: Unsolicited Grant Service
Unsolicited Grant Service (UGS) is one of the five QoS service types defined in the IEEE 802.16 WiMAX. The 802.16 protocol supports five types of QoS -- UGS (Unsolicited grant service), rtPS (Real time polling Service), ertPS (Extended Real-time POLLING SERVICE), nrtPS (Non-real-time polling service and BE (Best effort service). The Unsolicited Grant Service (UGS) is designed to support real-time service flows that generate fixed-size data packets on a periodic basis, such as T1/E1 and Voice over IP without silence suppression. The service offers fixed-size grants on a real-time periodic basis, which eliminate the overhead and latency of SS requests and assure that grants are available to meet the flow's real-time needs.

UHF: Ultra High Frenquency
Ultra High Frenquency (UHF) refers to the RF spectrum between 300 MHz and 3 GHz.

UICC: USIM Integrated Circuit Card
USIM Integrated Circuit Card (UICC) is the chip card used in mobile terminals in 3G telecom network systems. The UICC is an essential component for UMTS, just as the SIM for GSM. Extending the concept of the SIM card, the UICC contains the USIM application and also provides a platform for other IC Card applications. It ensures the integrity and security of all kinds of personal data, enabling secure support for all kinds of multi-application schemes.

UIM: User Identity Module
User Identity Module (UIM), also known as R-UIM, is the SIM card equivalent planned for W-CDMA handsets. UIM supports roaming between CDMA and GSM networks.

Ultra Wideband
Ultra Wideband is a wireless networking approach that broadcasts millions of tiny pulses at trillionth-of-second intervals using very low power over enormous swaths of spectrum. In comparison, traditional radios broadcast continuously on tiny bits of spectrum. Ultra Wideband is commonly abbreviated to UWB.

UMSC: UMTS Mobile Switching Center
UMTS Mobile Switching Center (UMSC), a type of Mobile Switching Center (MSC), is the place that provides UMTS 3G wireless telephony switching services and controls calls between telephone and data systems.

UMTS: Universal Mobile Telecommunications System
Universal Mobile Telecommunications System (UMTS) is a 3G cellular network technology that uses WCDMA (Wideband Code Division Multiple Access) technologies. The transmission rates range from a theoretical 384K bit/sec for mobile phones to 2M bit/sec for stationary devices.

UL: Uplink
Uplink (UL) is the transmission path from the mobile station up to the base station.

UPT: Universal Personal Telecommunications
Universal Personal Telecommunications (UPT) is a set of standards developed by the CCITT for wireline personal communications.

Urban cells
Urban cells is the coverage provided by base stations located in urban areas. The radius of these cells is usually much smaller than suburban and rural cells due to the more difficult propagation environment.

USDC: United States Digital Cellular
United States Digital Cellular (USDC), also known as IS-54 (Interim Standard 54), was developed to replace the AMPS standard, particularly in urban areas where AMPS did not provide adequate channel capacity. USDC allows the co-existence of AMPS so that providers can gradually phase out AMPS as needed. USDC utilizes TDMA to offer phone and paging service over a 25 kHz channel divided into two time slots.

USIM: Universal Subscriber Identity Module
Universal Subscriber Identity Module (USIM), also known as Upgrade SIM, is a component in the UMTS 3G network that securely stores the key identifying a mobile phone service subscriber, as well as subscription information, saved telephone numbers, preferences, text messages and other information. It is equivalent to the Subscriber Identity Module (SIM) in the GSM 2G wireless network.

USIM: Upgrade SIM
Upgrade SIM (USIM), also known as Universal Subscriber Identity Module, is an enhanced version of the SIM card, which is for use with IMT-2000/UMTS 3G network.

UTRA: UMTS Terrestrial Radio Access
UMTS Terrestrial Radio Access (UTRA) is a term used for UMTS radio access solution, applied to W-CDMA and TD-CDMA.

UTRAN LTE: UMTS Terrestrial Radio Access Network Long Term Evolution
UMTS Terrestrial Radio Access Network Long Term Evolution (UTRAN LTE), sometimes also referred to as 3G LTE or Super-3G, is the 3GPP radio technology evolution architecture.

UTRAN: UMTS Terrestrial Radio Access Network
UMTS Terrestrial Radio Access Network (UTRAN) is the radio access network based on the UTRA standard term describing the Radio Network Controllers and Node Base stations of a UMTS network. The UMTS network, built around an IP-optimized core network carrying all traffic types. UTRAN will support both UTRA Frequency Division Duplex (FDD) and Time Division Duplex (TDD) radio interfaces allowing flexible, high-bandwidth support, and will be connected to an IP-optimized core network through a UTRAN Gateway.

UUT: Unit Under Test
Unit Under Test (UUT) refers to some type of electrical apparatus connected to test instrumentation. The apparatus can range from a simple circuit to a complex subsystem such as a mobile phone, base station or MSC.

UWB: Ultra-Wide-Band
Ultra-Wide-Band (UWB), also called digital pulse, is a wireless technology defined in IEEE 802.15.3 for transmitting digital data over a wide swath of the radio frequency spectrum with very low power. Because of the low power requirement, it can carry signals through doors and other obstacles that tend to reflect signals at more limited bandwidths and a higher power. It can carry large amounts of data (maximum bandwidth of 1Gbps) and can be used for multimedia content transfer, high-resolution radar, ground-penetrating radar, and radio locations systems.

UWC: Universal Wireless Consortium
Universal Wireless Consortium (UWC) is an organization of vendors and operators promoting and implementing the IS-136 digital standard. Also specifying the future development of the standard and facilitating roaming agreements between IS-136 operators.

Universal Wireless Communications 136 (UWC-136) is proposed by the TIA and adopted by the ITU for 3G TDMA standard. It allows the US TDMA community to migrate from 1st (IS-136) to 3rd (UWC-136) generation systems. The standard uses a wideband TDMA technique.

UWCC: Universal Wireless Communications Consortium
Universal Wireless Communications Consortium (UMCC) is an industry group supporting IS-136 time division multiple access and IS-41 wireless intelligent network technology.

VAD: Voice Activity Detector
Voice Activity Detector (VAD) is the device that detects voice activity and allows DTX to operate. VAD, in conjunction with DTX reduces power consumption in the mobile station and RF interference in the system by muting the transmitter when there is no voice to transmit.

V-Band, also known as Q-Band, is a radio bandwidth range between 40 GHz t0 50 GHz.

vCARD is a standard defining the format of an electronic business card. All devices supporting vCard can exchange information such as phone numbers and addresses. For instance, a user with a vCard-aware phonebook application on a handheld computer can easily transfer names and phone numbers to a vCard-aware mobile phone.

VHF: Very High Frequency
Very High Frequency (VHF) is the RF spectrum between 30 MHz and 300 MHz.

Viterbi algorithm
Viterbi algorithm is a technique for searching a decoding trellis to yield a path with the smallest distance. This is also known as maximum likelihood decoding.

VLR: Visitor Location Register
Visitor Location Register (VLR) contains all subscriber data required for call handling and mobility management for mobile subscribers currently located in the area controlled by the VLR. The VLR communicates with the HLR of the subscriber to request data about that subscriber.

VMAC: Virtual Media Access Control
Virtual Media Access Control (Virtual MAC or VMAC) is an algorithm that passively monitors the radio channel and estimates locally achievable service levels. The VMAC estimates key MAC level statistics related to service quality such as delay, delay variation, packet collision, and packet loss.

Vocoder refers to a voice encoder which is a device that codes and decodes the human voice (sound waves) into digital transmission. Higher vocoder speeds offer enhanced sound quality.

Voice Activated Dialing
Voice Activated Dialing is a feature that permits you to dial a phone number by speaking it to your wireless phone instead of punching it in yourself. The feature contributes to convenience as well as driving safety.

Voice Channel
Voice Channel is a channel used for transmission of voice data from a base station to a cellular phone (forward voice channel) or from a cellular phone to a base station (reverse voice channel).

VoWIP: Voice over Wireless IP
Voice over Wireless IP (VoWIP) is the combination of VoIP with 802.11 wireless LANs to create a wireless telephone system. VoWIP enables businesses to leverage their wireless LANs to add voice communications, enabling companies to deploy and manage voice and data over a single wireless backbone. VoWIP applications require some reservation of bandwidth to support the real-time nature of voice. Proprietary standards like Spectralink Voice Priority (SVP) are today's solution; however, the IEEE is developing the 802.11e standard for quality of service as a long-term solution.

VoxML: Voice Markup Language
Voice Markup Language (VoxML) is a technology from Motorola for creating a voice dialog with a Web site in which a user can call a Web site by phone and interact with it through speech recognition and Web site responses.

VSB: Vestigial Sideband
Vestigial sideband (VSB) is a type of amplitude modulation technique that encodes data by varying the amplitude of a single carrier frequency. Portions of one of the redundant sidebands are removed to form a vestigial sideband signal. Television broadcasts (regardless of NTSC, PAL, or SECAM analog video format) use this method if the video is transmitted in AM, due to the enormous bandwidth used. It may also be used in digital transmission, such as the ATSC-standardized 8-VSB. The Milgo 4400/48 modem used vesitigial sideband and phase-shift keying to provide 4800 bit/s transmission over a 1600 Hz channel.

VSELP: Vector Sum Excited Linear Predictive
Vector Sum Excited Linear Predictive (VSELP) is a type of speech coding using an excitation signal generated from three components: the output of a long-term, pitch filter and two codebooks. VSELP was used in the IS-54 standard and operated at a rate of 8 kbps.

WAE: Wireless Application Environment
The Wireless Application Environment (WAE) is the top most level in the Wireless Application Protocol (WAP) suite, which combines both the WWW and Mobile Telephony technologies. WAE provides the operators and service providers an interoperable environment on which they can build applications and services for handheld client devices. WAE includes the micro-browser that contains functionality for using not only WML and WML Script as previously stated, but also Wireless Telephony Application, namely WTA and WTAI -- telephony services and programming interfaces as well as content formats including well-defined data formats, images, phone book records and calendar information.

Walsh Code
Walsh Code is a group of spreading codes having good autocorrelation properties and poor crosscorrelation properties. Walsh codes are the backbone of CDMA systems and are used to develop the individual channels in CDMA. For IS-95, here are 64 codes available. Code 0 is used as the pilot and code 32 is used for synchronization. Codes 1 though 7 are used for control channels, and the remaining codes are available for traffic channels. Codes 2 through 7 are also available for traffic channels if they are not needed. For cdma2000, there exists a multitude of Walsh codes that vary in length to accommodate the different data rates and Spreading Factors of the different Radio Configurations.

WAP Forum
The WAP Forum has consolidated into the Open Mobile Alliance (OMA) and no longer exists as an independent organization.

WAP: Wireless Access Point
A wireless access point (WAP), also known as Access Point (AP), is a device that "connects" wireless communication devices together to create a wireless network. WAPs act as a central transmitter and receiver of WLAN radio signals. Access points used in home or small business networks are generally small, dedicated hardware devices featuring a built-in network adapter, antenna, and radio transmitter. Access points support Wi-Fi wireless communication standards. Many WAPs can be connected together to create a larger network that allows "roaming".

WAP: Wireless Application Protocol
The Wireless Application Protocol (WAP) is a set of specifications, developed by the WAP Forum, that lets developers using Wireless Markup Language build networked applications designed for handheld wireless devices. WAP was designed to work within the constraints of these devices: a limited memory and CPU size, small, monochrome screens, low bandwidth and erratic connections. WAP browsers are intended to be implemented on small mobile devices such as cell phones, pagers, and PDAs. Instead of developing content in HTML and JavaScript, WAP developers use WML and WMLScript.

War chalking
War chalking refers to marking buildings or sidewalks with chalk to show others where it's possible to access an exposed company wireless network. These access points are typically found through war driving.

War driving
War driving (wardriving) is the process of traveling around looking for wireless access point signals that can be used to get network access. Some computer hackers are content to simply map any open, unsecured WLANs they find. Others have adopted the practice of warchalking, tagging nearby pavement to allow others to tap in and steal bandwidth from those hotspots.

WASP: wireless application service provider
Wireless Application Service Provider (WASP) provides hosted wireless applications so that companies will not have to build their own sophisticated wireless infrastructures.

W-ATM: Wireless Asynchronous Transfer Mode network
Wireless ATM network (W-ATM) was a concept of using wireless as physical layer to transmit ATM cells. This concept never took off.

Wavelength is the length of one complete wave of an alternating or vibrating phenomenon, generally measured from crest to crest or from trough to trough of successive waves.

WBMP: Wireless Bitmap
Wireless Bitmap (WBMP) is WAP graphic format optimized for mobile computing devices. A WBMP image is identified using a TypeField value, which describes encoding information (such as pixel and palette organization, compression, and animation) and determines image characteristics according to WAP documentation.

WAP Binary XML (WBXML), a compact representation of XML, is part of the presentation logic in Wireless Application Protocol (WAP). WBXML significantly improves the efficiency of transmitting XML over narrow bandwidth networks, where data size is of paramount importance.

WCA: Wireless Communications Association
The Wireless Communications Association (WCA) represents the fixed broadband wireless access industry worldwide. Its mission is to advance the interests of the wireless systems that provide data (including Internet and e-commerce), voice and video services on a subscription basis through land-based towers to fixed reception/transmit devices.

WCDMA: Wideband-Code Division Multiple Access
Wideband Wideband-Code Division Multiple Access(W-CDMA or WCDMA), also known as UMTS in Europe, is a 3G standard for GSM in Europe, Japan and the United States. It's also the principal alternative being discussed in Asia. It supports very high-speed multimedia services such as full-motion video, Internet access and video conferencing. It uses one 5-MHz channel for both voice and data, offering data speeds of up to 2 Mbps.

WDF: Wireless Data Forum
Wireless Data Forum (WDF) is an industry group based in New Zealand dedicated to promote and educate New Zealand companies on many options and solutions available to them through the use of Wireless Data.

WDP: Wireless Datagram Protocol
The Wireless Datagram Protocol (WDP), a protocol in WAP architecture, covers the Transmission Layer Protocols in an Internet model. As a general transport service, WDP offers to the upper layers an invisible interface independent of the underlying network technology used. In consequence of the interface common to transport protocols, the upper layer protocols of the WAP architecture can operate independent of the underlying wireless network. By letting only the transport layer deal with physical network-dependent issues, global interoperability can be acquired using mediating gateways.

WDS: Wireless Distribution System
Wireless Distribution System (WDS) is a technology that enables access points to communicate with one another in order to extend the range of a wireless network. WDS is appearing in 802.11g-based access points.

WECA: Wireless Ethernet Compatibility Alliance
Wireless Ethernet Compatibility Alliance (WECA) is the former name of the Wi-Fi Alliance of vendors promoting 802.11 wireless networking standards and compatibility.

WEP: Wired-Equivalent Privacy
Wired Equivalent Privacy (WEP) is a security protocol, specified in the IEEE Wireless Fidelity (Wi-Fi) standard, 802.11b, that is designed to provide a wireless local area network (WLAN) with a level of security and privacy comparable to what is usually expected of a wired LAN. WEP is based on a security scheme called RC4 that utilizes a combination of secret user keys and system-generated values. The original implementations of WEP supported the so-called 40-bit encryption, having a key of length 40 bits and 24 additional bits of system-generated data (64 bits total). Research has shown that 40-bit WEP encryption is too easy to decode, and consequently product vendors today employ 128-bit encryption (having a key length of 104 bits, not 128 bits) or better.

WiBro, standing for Wireless Broadband, is a wireless broadband internet technology being developed by the Korean telecoms industry. In February, 2002, the Korean government allocated 100 MHz of electromagnetic spectrum in the 2.3 GHz band, and in late 2004, WiBro Phase 1 was standardized by the TTA (Telecommunications Technology Association) of Korea.

WiDEN: Wideband Integrated Dispatch Enhanced Network
Wideband Integrated Dispatch Enhanced Network (WiDEN) is a software upgrade developed by Motorola for its iDEN-enhanced specialised mobile radio (or ESMR) wireless telephony protocol. WiDEN allows compatible subscriber units to communicate across four 25 kHz channels combined, for up to 100 kbit/s of bandwidth. The protocol is generally considered as a 2.5G wireless cellular technology.

Wi-Fi Alliance
Wi-Fi Alliance is a non-profit international association formed in 1999 to certify interoperability of WLAN products based on the IEEE 802.11 specification. Currently, the Wi-Fi Alliance has over 200 member companies from around the world, and over 1,000 products have received Wi-Fi certification since the certification began in March of 2000. The goal of the Wi-Fi Alliance's members is to enhance the user experience through product interoperability.

Wi-Fi: Wireless Fidelity
Wireless Fidelity (WiFi or Wi-Fi), originally Nick named for 802.11b for wireless LAN with bandwith up to 11 Mbps, now refers to the entire wireless LAN technologies including 802.11a, 802.11b, 802.11g and 802.11n etc. Wi-Fi is actually the industry name for wireless LAN (WLAN) communication technology related to the IEEE 802.11 family of wireless networking standards.

WIM: WAP Identity Module
WAP Identity Module (WIM) is the security module implemented in the SIM card for WAP applications. WIM provides security services for WAP applications, and allows you to use digital signature. SIM cards with security module are provided by the SIM card issuer.

WiMax, abreviated from Worldwide Interoperability for Microwave Access, is a popular name of the 802.16 wireless metropolitan-area network standard, including both 802.16-2004 for fixed WiMAX and 802.16-2005 for mobile WiMAX. WiMax has a range of up to 31 miles. Data rates for WiMax can reach up to 75 Mbps (Fixed) or 15 Mbps (Mobile). A number of wireless signaling options exist ranging anywhere from the 2 GHz range up to 66 GHz. WiMax is primarily aimed at making broadband network access widely available without the expense of stringing wires (as in cable-access broadband) or the distance limitations of Digital Subscriber Line. WiMax technology can deliver high-speed Internet access to rural areas and other locations. WiMax also offers an alternative to satellite Internet services.

WiMedia Alliance
WiMedia Alliance is an industrial association with a focus on UWB (Ultra WideBand) wireless technologies to promote and enable the rapid adoption and standardization of UWB worldwide for high-speed wireless, multimedia-capable personal-area connectivity in the PC, CE and mobile market segments; to provide a neutral and open forum for multiple industry segments to establish requirements, specifications and best practices for usability and interoperability; to promote worldwide UWB spectrum regulations; and to develop, maintain, enhance and reference technical specifications.

WIN: Wireless Intelligent Network
Wireless Intelligent Network (WIN) refers to a set of advanced services provided on a wireless network such as Prepaid, LNP, etc.

Wireless Bridge
Wireless Bridge is a networking bridge used to connect two or more separate networks. A wireless bridge functions in the same way but can be used in situations in which running a wire or cable would be impractical or prohibitively expensive, such as creating a 10-mile point-to-point link.

Wireless FireWire
Wireless FireWire, also known as wireless 1394, is a wireless version of the high speed FireWire communications protocol defined in the IEEE 1394. It allows multiple FireWire devices to communicate wirelessly over IEEE 802.15.3 (UWB) Wireless Personal Area Networks (WPANs). The wireless 1394 specification adapts the IEEE 1394 and P1394.1 bridging standards to the high bandwidth wireless network connectivity enabled by IEEE 802.15.3.

Wireless Channel
Wireless Channel refers to dividing allocated spectrum into sub-spectrums. For example, 802.11b and 802.11g devices have three nonoverlapping channels. 802.11a devices have eight nonoverlapping channels.

Wireless Gateway
Wireless Gateway is a device that can share an Internet connection, serve DHCP, and bridge between wired and wireless networks. Wireless Gateway may also be called as "wireless router," or "base station." Wireless Network Adaptor Wireless Network Adaptor is the inerface that connects a PC with wireless network, for example, a wireless NIC is a wireles adaptor.

Wireless router
Wireless routers are actually routers with Ethernet plus wireless access points so that they have both wired and/or wireless at the same time. Another combination is to build a DSL or cable modem with the wireless access point, in which the wireless access point is used to communicate with local PCs and other devices and the DSL and cable modem will communicate with the Inernet.

WISP: Wireless ISP
Wireless ISP (WISP) is a company that provides wireless Internet access for public. WISPs typically install Wi-Fi wireless hotspots in airports, hotels and other public businessplaces. These hotspots provide Internet access and local area network (LAN) printing for mobile network devices like laptops, handheld computers and cell phones.

WLAN: Wireless local-area networks (Wireless LAN)
Wireless local-area networks (WLAN or wireless LAN) use radio waves to connect a user device to a LAN, which extends an existing wired local area network. WLAN provides Ethernet connections over the air and operate under the 802.11 family of specifications developed by the IEEE. WLANs are built by attaching a device called the access point (AP) to the edge of the wired network. Clients communicate with the AP using a wireless network adapter similar in function to a traditional Ethernet adapter. The WLAN technology is defined by the IEEE 802.11 family of specifications, namely, 802.11, 802.11a, 802.11b, 802.11g and 802.11n. All use the Ethernet protocol and CSMA/CA (carrier sense multiple access with collision avoidance instead of CSMA/CD) for path sharing.

WLL: Wireless Local Loop
Wireless Local Loop (WLL), also called radio in the loop (RITL) or fixed-radio access (FRA) or fixed-wireless access (FWA), is the use of wireless connections as the last mile for delivering plain old telephone service (POTS) to customers.

WMF: Wireless Message Format
Wireless Message Format (WMF) is a standard format for presenting data received through a paging system to mobile computers. The application at the MED uses this format to encode binary data and control information to be sent to a remote device. This information is received completely intact by the MCD.

WML: Wireless Markup Language
Wireless Markup Language (WML), based on HTML and XML, delivers Internet content to small wireless devices, such as browser-equipped cellular phones and handheld devices, which typically have very small displays, slow CPUs, limited memory capacity, low bandwidth and restricted user-input capabilities. WML demands less memory and processing power from browsers than HTML and JavaScript. WML also includes features that tailor it for the relatively small display sizes of today's wireless devices. WML and HTML differ in significant ways. Although WML strips some features from HTML and co-opts others, WML also incorporates some powerful programming constructs not found in HTML like variables, tasks, and events. WML implements a stricter tag syntax than HTML and includes a DTD for use with XML parsers.

WOS: Wireless Office Systems
Wireless Office Systems (WOS) is a technology that allows the user to transfer calls to a mobile telephone.

WPA: Wi-Fi Protected Access
Wi-Fi Protected Access (WPA) is a data encryption specification for 802.11 wireless networks that replaces the weaker WEP. Created by the WiFi Alliance before a 802.11i security standard was ratified by the IEEE, it improves on WEP by using dynamic keys, Extensible Authentication Protocol to secure network access, and an encryption method called Temporal Key Integrity Protocol (TKIP) to secure data transmissions. WPA provides roughly comparable security to VPN tunneling with WEP, with the benefit of easier administration and use.

WPA2: Wi-Fi Protected Access 2
Wi-Fi Protected Access 2 (WPA2) is an enhanced version of WPA. It is the official 802.11i standard that was ratified by the IEEE in June, 2004. It uses the Advanced Encryption Standard instead of TKIP (see above). AES supports 128-bit, 192-bit and 256-bit keys.

WPABX: Wireless Private Automatic Branch Exchange
Wireless Private Automatic Branch Exchange (WPABX) is a customer premise telephone switching system using wireless technology to link the individual user stations to the central switching unit. The WPABX is capable of interfacing to a telephone central office with trunk groups and routing calls based on a 3- or 4-digit telephone extension number.

WPAN: Wireless Personal-Area Network
Wireless Personal-Area Network (WPAN) is a personal area network using wireless connections. WPAN is used for communications among devices such as telephones, computer and its accessories, as well as personal digital assistants, within a short range. The reach of a PAN is typically within 10 meters. Technologies enabling WPAN include Bluetooth, ZigBee, Ultra-wideband(UWB), IrDA, HomeRF, etc.

WRAN: Wireless Regional Area Network
Wireless Regional Area Network (WRAN) technology targets at wireless broadband (remote) access for geographically dispersed, sparsely populated areas. The transmission range can be up to 100Km, Non Line of Sight (NLOS) due to use of TV broadcast bands as License Exempt (LE) spectrum. The WRAN technology is useful for remote access to grid computer sites and to independent telcos operating in developing countries, rural or non- metropolitan areas. WRAN specifications are defined by the IEEE802.22 working committee.

WSP: Wireless Session Protocol
The Wireless Session Protocol (WSP), a protocol in the Wireless Application Protocol (WAP) suite, provides the Wireless Application Environment a consistent interface with two services: connection-oriented service to operate above the Transaction Layer Protocol (WTP) and a connectionless service that operates above either secure or non-secure datagarm service (WDP). Currently, the protocols of the WSP family provide HTTP/1.1 functionality and semantics in a compact encoding, long lived session state with session suspend-and-resume capabilities, a common facility for reliable and unreliable data push as well as a protocol feature negotiation. These protocols are optimised to be used in low-bandwith bearer networks with relative long latency in order to connect a WAP client to a HTTP server.

W-TDMA: Wideband Time Division Multiple Access
Wideband Time Division Multiple Access (W-TDMA) is a technique based on time division transmission which is similar to that used by GSM but provides a much higher transmission rate. It was submitted as a solution for UMTS radio interface, but was rejected.

WTLS: Wireless Transport Layer Security
The Wireless Transport Layer Security (WTLS) protocol, protocol in the Wireless Application Protocol (WAP) suite, is based on Transport Layer Security (TLS) or formely known as Secure Sockets Layer (SSL). It is designed to be used with other WAP protocols and to support narrow-band networks. It uses data encryption with a method that is negotiated at the start of the session to provide privacy, data integrity, authentication and denial-of-service protection. The latter is needed in cases when data is replayed or not properly verified. When that happens, WTLS detects the misuse and rejects the data in order to make many typical denial-of-service attacks harder to accomplish.

WTP: Wireless Transaction Protocol
The Wireless Transaction Protocol (WTP), a protocol in the Wireless Application Protocol (WAP) suite, operates efficiently over either secure or non-secure wireless datagram networks. It provides three different kinds of transaction services, namely, unreliable one-way, reliable one-way and reliable two-way transactions. This layer also includes optional user-to-user reliability by triggering the confirmation of each received message. To reduce the number of messages sent, the feature of delaying acknowledgements can be used.

WUSB: Wireless USB
Wireless USB (WUSB) is the wireless extension to USB (Universal Serial Bus) intended to combine the speed and security of wired technology with the ease-of-use of wireless technology. Wireless USB, based on Ultra-WideBand (UWB) defined by IEEE 802.15.3, is capable of sending 480 Mbps or even higher bandwidth at distances up to 3 meters, and 110 Mbps at up to 10 meters. It operates in the 3.1--10.6 GHz band-range and spreads communications over an ultra-wideband of frequencies.

WWAN: Wireless WAN
Wireless Wide Area Network (WWAN) is a wireless network that uses cellular network technologies such as GPRS / CDMA2000 / GSM / CDPD / Mobitex to transfer data. These cellular technologies are offered regionally, nationwide, or even globally and are provided by a wireless service provider. Various computers now have integrated WWAN capabilities with a cellular radio (GSM/CDMA) built in, which allows the user to send and receive data via mobile wireless.

X-band is the bandwith between 7 GHz to 8 GHz, which usually is used by military satellites.

Yagi Antenna
Yagi Antenna is an antenna type that radiates in only a specific direction. Yagi antennas are used only in point-to-point situations.

ZDO: ZigBee Device Object
ZigBee Device Object (ZDO), a protocol in the ZigBee protocol stack, is responsible for overall device management, and security keys and policies. The ZDO is like a special application object that is resident on all ZigBee nodes. ZDO has its own profile, known as the ZigBee Device Profile (ZDP), which the application end points and other ZigBee nodes can access.

ZigBee, defined in the IEEE 802.15.4, is the technology used in the low data rate Wireless Personal Area Network (WPAN) for home control, building automation industrial automation. ZigBee covers up to 330 feet (about 100 meters) in the bandwidth of 20 to 250 kbps.

Zone Paging
Zone Paging is a feature in many paging systems that allows you to page a specific department or an area without disturbing other people.

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