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There are 79 names in this directory beginning with the letter S.
S-OFDMA: Scalable Orthogonal Frequency D

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.

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 Cha

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 Ac

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.

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.

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 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: 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

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 Televisi

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 P

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-PP: Short Message Service – Point to

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.

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.

SNIR: Signal to Noise + Interference Rat

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).

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.


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.

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