Wireless Developer Network Glossary
Signal-To-Noise Ratio - A measure of the power of a signal versus noise. A lower ratio means there is more noise relative to signal.
SIM - Subscriber Identity Module. Synonymous with smart card.
Smart Card - A plastic card containing important data about a person's identity to allow access to a network or premises. Also, a card containing subscriber information, often inserted into GSM phones for roaming to different countries.
SMR - Specialized Mobile Radio. A dispatch radio and interconnect service for businesses. Covers frequencies in the 220 MHz, 800 MHz and 900 MHz bands.
SMS - Short Message Service. A feature of PCS phones(primarily GSM) that allows users to receive and sometimes transmit short text messages using their wireless phone.
SOAP - SOAP (Simple Object Access Protocol) is a way for a program running in one kind of operating system (such as Windows NT) to communicate with a progam in the same or another kind of an operating system (such as Linux) by using the World Wide Web's Hypertext Transfer Protocol (HTTP)and its Extensible Markup Language (XML) as the mechanisms for information exchange.
Soft Handoff - Procedure in which 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- both hold onto 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.
Spectrum Allocation - Federal government designation of a range of frequencies for a category of use or uses. For example, the FCC allocated the 1900 MHz band for personal communications services. 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 - Federal government authorization for use of specific frequencies or frequency pairs within a given allocation, usually at stated a 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 auctions and/or frequency coordination processes, which consider potential interference to existing users, may apply.
Spread Spectrum - Jamming-resistant and initially devised for military use, this radio transmission technology "spreads" information over greater bandwidth than necessary for interference tolerance and is now a commercial technology.
SQL - A standard interactive and programming language for getting information from and updating a database.
SRAM - Static RAM. A memory technology used in pagers and handsets. So named because it requires no refresh cycle, as required by dynamic RAM (DRAM) and therefore consumes less power. SRAM maintains data only while power is applied.
Symbian - The joint venture between Ericsson Inc., Motorola Inc., Nokia Corp. and Psion to develop new operating systems based on Psion's EPOC32 platform for small mobile devices including wireless phones or handheld personal computers.