CDMA Glossary G-M

Global Challenge Procedure

An exchange of information between a mobile station and a base station for the purpose of authenticating the mobile station identity. The base station broadcasts a challenge and each mobile station responds with its unique response when performing a system access. Cf. Unique Challenge-Response Procedure.

Global Positioning System (GPS)

A US government satellite system that provides location and time information to users. See Navstar GPS Space Segment / Navigation User Interfaces ICD-GPS-200 for specifications.

GPS

See Global Positioning System.

Handoff

The act of transferring control of a mobile station from one base station to another. See also Soft Handoff, Hard Handoff.

Handover

Synonym for Handoff.

Hard Handoff

A handoff characterized by a temporary disconnection of the Traffic Channel. Hard handoffs occur when the mobile station is transferred between disjoint Active Sets, the CDMA frequency assignment changes, the frame offset changes, or the mobile station is directed from a CDMA Traffic Channel to an analog voice channel. Cf. Soft Handoff.

Hash Function

A mathematical function used by the mobile station to select one out of N available resources. The hash function ensures statistically uniform use of the resources.

Height Above Average Terrain (height AAT)

See Effective antenna elevation.

HLR

See Home Location Register.

Home Location Register (HLR)

The database in a wireless communication network that contains registration and user profile information for the system subscribers.

Home System

The system which is transmitting a system identification (SID) which is recognized by the mobile station as its Home SID, normally the system in which service was subscribed (see System Identification).

Idle Handoff

The act of transferring reception of the Paging Channel from one base station to another, when the mobile station is in the Mobile Station Idle State.

Implicit Registration

A registration achieved by a successful transmission of an origination or page response on the Access Channel.

IMSI

See International Mobile Subscriber Station Identity.

Interleaving

The process of reordering code symbols for transmission. Interleaving decorrelates channel fading between adjacent symbols as they enter the decoder, thereby improving the effectiveness of the code.

International Mobile Subscriber Station Identity (IMSI)

A method of identifying stations in the land mobile service as specifed in ITU-T Recommendation E.212.

kHz

Kilohertz (10³ Hertz).

ksps

Kilosymbols per second (10³ symbols per second).

Layering

A conceptual structuring of communication protocols. A layer is defined in terms of its communnication protocol to a peer layer in another entity, and the services it provides to the next higher layer in its own entity.

Layer 1

See Physical layer.

Layer 2

See Link layer.

Layer 3

See Application layer.

LFSR

See Linear Feedback Shift Register

Linear FeedbackShift Register (LFSR )

A logic circuit that produces pseudo-random binary sequences. They are used to produce the Short Code and Long Code that are used for spreading and for other purposes in the CDMA system. See the LFSR page for more details.

Linear Predictive Coding

A low bit rate coding technique for analog signal sources, usually speech, that models the production process by a filter whose parameters change slowly with time. It is a component of CELP coders. See Code Excited Linear Prediction.

Link Layer

The link layer of the IS-95 air interface provides for the reliable transmission and reception of signaling messages, including error detection, partial duplicate detection and loss. See also Layering, Physical layer, and Application layer.

Log Normal Distribution

The distribution of a random variable whose logarithm follows a normal distribution. A log-normal distribution is characterized by two parameter: its median and its standard deviation. The logarithm radix is often taken as 10, so that both the median and the standard deviaion are conveniently measured in decibel values, m and s. The density function of such a log-normal variable X is then:

In the dB measure this is

where Y = 10 log X.

Long Code

A maximal length sequence with period 2⁴²-1. A unique phase of the long code identifies each mobile station. It is used for data scrambling on the Forward CDMA Channel, spreading on the Reverse CDMA Channel, and other purposes. See also Maximal length sequence.

Long Code Mask

A 42-bit binary number that creates the unique long code phase. See also public long code, private long code, public long code mask, and private long code mask.

LPC

See Linear Predictive Coding.

LSB

Least significant bit.

Maximal Length Sequence (m-sequence)

A periodic binary sequence of period 2ⁿ-1, n a positive integer, with no internal periodicities and other curious mathematical properties [Golomb]. A maximal length sequence can be generated by either of two equivalent linear feedback shift register configurations (see LFSR).

Mcps

Megachips per second (10⁶ chips per second).

MER

See Message Error Rate

Message

In IS-95, a data structure consisting of a length field, message body (or payload), and CRC for detection of errors.

Message Error Rate

Ratio of errored messages to total messages. This is a concept having limited value because an errored message may be incorrectly fragmented or coalesced with a neighboring message by the receiver, making the message counts incorrect.

MHz

Megahertz (10⁶ Hertz).

MIN

See Mobile Identification Number.

Mobile Assisted Handoff (MAHO)

A means of initiating handoff based on signal quality measurements performed by the mobile station and reported to the base station.

Mobile Identification Number (MIN)

The 34-bit number that is a digital representation of the 10-digit directory number assigned to a mobile station.

Mobile Station

A subscriber station in the Domestic Public Cellular Radio Telecommunications Service, normally intended to be used while in motion or during halts at unspecified points. The category my include both true mobile stations, handheld portable stations, fixed stations, and other devices.

Mobile Station Class

A code that defines mobile station maximum transmitter power, slotted operation capability, and dual-mode CDMA/AMPS capability.

Mobile Station Identification Number (MSIN)

A part of the E.212 IMSI identifying the mobile station within its home network. See ITU-T Recommendation E.212.

Mobile Switching Center (MSC)

A configuration of equipment designed to provide interconnection services among wireless subscriber stations, and between wireless subscriber stations and the public switched telephone network via one or more base stations under its control.

Mobile Telephone Switching Office (MTSO)

An out-of-fashion synonym for Mobile Switching Center.

Modulation Symbol

A symbol from a discrete alphabet that identifies a unit of modulation. In the Forward CDMA Channel, the modulation symbols are binary, each one representing one interleaved binary symbol from the rate 1/2 convolutional encoder. In the Reverse CDMA Channel the modulation symbols are six-bit entities comprised of interleaved bits from the rate 1/3 encoder; the six bits select one of the 64-Walsh functions for transmission.

MOS Mean Opinion Score

The result of a subjective voice quality test, often used to compare speech codec algorithms, where listeners associate a one to five quality score to speech samples. The arithmetic mean for a large number of samples is the resulting MOS number. Care must be used when comparing MOS scores taken in different tests, as the results for any particular cohort depend very much on the mix of algorithms under test.

ms

Millisecond (10^-3 second).

MSB

Most significant bit.

MSC

See Mobile Switching Center

MSIN

See Mobile Station Identification Number.

MTSO

See Mobile Telephone Switching Office.

Multiplex Option

One of the alternative designs of the multiplex sublayer. Multiplex options permit tailoring such characteristics as the data rate set, frame structure, frame partitioning rules, and rate decision rules for special applications.

Multiplex Sublayer

One of the conceptual layers of the system that multiplexes and demultiplexes primary traffic, secondary traffic, and signaling. The multiplex sublayer resides between the physical layer and the link layer in the conceptual protocol stack.

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