I

IEEE802.11 - A WLAN standard (or set of standard), operating at 2.4 GHz and with data rates of up to 1 Mbps

IF - Intermediate Frequency. Refers to the resulting signal in a superhet receiver after the incoming carrier is mixed with the oscillator signal.

Image Rejection - A measure of the ability of the receiver to reject RF signals present on the image frequency of the receiver. Image rejection is one of the purposes of front-end filtering in a superhet receiver.

IM Rejection - A measure of the ability of the receiver to reject signals which are capable of producing IM products.

Infrastructure - All parts of the cellular system, excluding the subscriber. Includes the MTSO, Base Stations, Cell Sites, and all links between them.

In-Band Signaling - A process in which audio tones between 300 and 3400 Hz provide supervisory and/or address signaling.

Interface - A common boundary between two or more systems, integrated circuits, or pieces of equipment that ensures a proper connection between them.

Intermodulation - Also referred to as "IM." The mixing of two or more signals, producing sums, differences and harmonic multiples. IM generally occurs in the gain amplifier ahead of the mixer stage within a receiver, but also occurs in any non-linear device.

IS-3 - The original analog cellular standard, now replaced by ANSI standard EIA/TIA-553 and TIA interim standard IS-91.

IS-41 - The protocol for 'roaming' within the USA, describing how services should 'hand over' between operators

IS-54 - The TDMA standard for U.S. digital cellular. A digital cellular system that squeezes three conversations into one cellular channel.

IS-88 - Narrowband Analog Cellular system developed by Motorola that squeezes three conversations into one cellular channel using analog frequency division multiplexing. First standardized in TIA interim standard IS-88, and now incorporated in IS-91.

IS-91 - Analog Cellular and PCS. The TIA version of the analog cellular standard, incorporating the functionality of IS-88 (narrowband analog) and IS-94 as well as PCS band operation.

IS-94 - Inbuilding Cellular. A standard for inbuilding operation of analog cellular systems using extremely low power. Now incorporated in IS-91.

IS-95 - The CDMA (Qualcomm) standard for U.S. digital cellular. A digital cellular system that squeezes between 10 and 20 conversations into one cellular channel by combining 30 KHz cellular channels into a single 1.25 MHz channel and using code division multiplexing to combine and recover the individual conversations.

IS-136 - TIA standard that provides dual mode (analog and digital) cellular services using the TDMA technology. An enhancement to IS-54 TDMA, that includes a more advanced control channel (known as the digital control channel (DCCH), to distinguish it from the 'analog' control channel, which although less sophisticated, is still digital!).

IS-634 - TIA standard for 800 MHz cellular base-station to switch interface. Supports CDMA.

IS-651 - TIA standard for an open interface between the PCS switching center and the radio base-station subsystem in a PCS network. Supports both GSM and CDMA.

ISM Band - Industry, Scientific and Medical Band. Unlicensed 902 - 928 MHz, 2.4 - 2.4835 GHz and 5.725 - 5.850 GHz bands, RF power up to 1 watt. Frequency hopping or direct sequence transmission allowed.

Isotropic Radiator - A completely non-directional antenna (one which radiates equally well in all directions.) This antenna exists only as a mathematical concept and is used as a known reference to measure antenna gain.

ITS - Intelligent Transportation Systems.

IVHS - Intelligent Vehicle Highway Systems.