CDMA Glossary A-F
- Access Attempt
- A sequence of one or more access probe sequences on the Access Channel containing
the same message. See also access probe and access probe sequence.
- Access Channel
- A Reverse CDMA Channel used by mobile stations for communicating to base
stations . The Access Channel is used for short signaling message exchanges
such as call originations, responses to pages, and registrations.
- Access Channel Message
- The information part of an access probe conssiteing of the message body,
length field, and CRC.
- Access Channel Preamble
- A sequence of all-zero frames sent at the 4800 bps rate preceeding an Access
Channel message. It aids the base station receiver in detecting and syncronizing
the Access Probe.
- Access Channel Request Message
- An Access Channel message that is autonomously generated by a mobile station.
- Access Channel Response Message
- An Access Channel message that is generated to reply to a message received
from a base station.
- Access Channel Slot
- The assigned time interval for an access probe. An access channel slot consists
of an integer number of frames. The transmission of an access probe is performed
within the boundaries of an Access Channel slot.
- Access Probe
- One Access Channel transmission consisting of a preamble and a message.
The transmission is an integer number of frames in length and carries one
Access Channel message.
- Access Probe Sequence
- A sequence of one or more access probes. The transmitted power escalates
during an access probe sequence from a prescribed minimum power until acknowledged
by the base station, or until a presribed maxixum power is reached. One or
more repetitions of an access probe sequence constitute an access attempt.
- A link layer response by a mobile station or a base station confirming that
a signaling message was received correctly.
- Action time
- The time at which an action implied by a signaling message should take place.
- Active set
- The set of pilots associated with the CDMA Channels containing Forward Traffic
Channels assigned to a particular mobile station.
- A mechanism through which the mobile station maintains in its Neighbor Set
the pilots that have been recently sent to it from the base station and the
pilots whose drop timers have recently expired.
- A concealed 64-bit pattern stored in the mobile station. It is used to generate
and update the mobile station's shared secret data, which is used for authentication.
See also authentication and shared secret data.
- Analog Paging Channel
- A forward analog control channel that is used to page mobile stations and
- Analog Voice Channel
- A channel on which a voice conversation occurs and on which brief digital
messages may be sent from a base station to a mobile station or from a mobile
station to a base station.
- Application Layer
- The application layer of the IS-95 air interface provides control of the
cellular telephone system. Signaling messages originate and terminate at the
application layer. See also Layering, Physical layer and Link layer.
- Area Propatation Model
- A propagation model in which median transmission loss calculations are based
on generalized characteristics of the area surrounding the transmitter and
receiver, as well as the intervening area. Features such as local environment,
terrain roughness, building density are used to modify a median transmission
loss equation in order to adopt it to the service area.
- A procedure used by base stations to validate a mobile station identity
at system access and other times, and by mobile stations to validate a base
station identity when ordered to update the shared secret data.
- Autonomous Registration
- A method of registration in which the mobile station registers without an
explicit command from the base station.
- Base Station
- A fixed station used for communicating with mobile stations. Depending upon
the context, the term base station may refer to a cell, a sector within a
cell, an MSC, or other part of the cellular system. It is sometimes used loosely
in the standards to mean any land side functionality. See also Mobile
- BCH Code
- See Bose-Chaudhuri-Hocquenghem Code.
- See bit error rate.
- Bose-Chaudhuri-Hocquenghem Code (BCH Code)
- A large class of error-correcting cyclic codes. For any positive integers
m, m > 3, and t < 2m-1, there is a binary BCH code with a
block length n equal to 2m - 1 and n - k < mt parity check bits,
where k is the number of information bits. The BCH code has a minimum distance
of at least 2t + 1.
- Bit Error Rate (BER)
- Numerically equal to the number of errored bits divided by the total number
of bits. Care should be taken when reporting or interpreting "bit error
rate" in systems that use encapsulated data or otherwise add overhead
to the payload bits. It is normally not meaningful in the CDMA context because
whole frames are erased, or not, according to the result of the frame quality
check. See Frame Error Rate and Message
- Blank and burst
- The pre-emption of an entire Traffic Channel frame's primary traffic by
signaling traffic or secondary traffic.
- Failure of a telecommunication system to provide service in response to
a call attempt. Blocking in a CDMA system can be due to hard causes, such
as lack of a necessary resource, or to soft causes, such as excessive interference
in an air interface.
- Bits per second.
- Calling rate
- The number of originations per unit time in a designated service area. See
also Erlang load.
- Candidate set
- The set of pilots that have been received by the mobile station with sufficient
strength to be successfully demodulated, but have not been placed in the Active
Set by the Base station. See also Active Set, Neighbor Set, and Remaining
- See Code Division Multiple Access.
- CDMA Channel
- The set of channels transmitted between the base station and the mobile
stations within a given CDMA frequency assignment. See also Forward CDMA Channel
and Reverse CDMA Channel.
- CDMA Channel Number
- An 11-bit number identifying the center of the CDMA frequency assignment.
- CDMA Frequency Assignment
- A 1.23 MHz segment of spectrum centered at a discrete frequency identified
by the CDMA channel number. The allowable channels are centered on one of
the 30 kHz channels of the AMPS system.
- Loosely, one or more collocated base stations. They can service different
angular sectors, different frequencies, or both.
- Cell Site
- The physical location of a cell's radio equipment and supporting systems.
This term is also used to refer to the equipment located at the cell site.
- See Code Excited Linear Prediction
- Informal term used to refer to either a binary element of a spreading sequence,
or to the time interval that it occupies, or 1/1.2288 MHz = 813.8 ns, or,
at the speed of light, a distance of c/f = (0.3 m/ns)/1.2288 MHz = 244.1 meters.
- Channel Coder
- A device that adds redundancy to digital data before transmission for the
purpose of reducing the end-to-end error rate. See also Convolutional Coder.
- Channel Decoder
- A device that performs error correction on coded data by exploiting the
redundancy introduced by the channel coder. See also Viterbi Decoder.
- A fraudulent subscriber station created by copying a MIN-ESN pair from a
legitimate subscriber's over-the-air transactions.
- Code Channel
- One of the orthogonal subchannels of a CDMA Forward CDMA Channel. Code channel
zero is the pilot channel. Code channels 1 through 7 may be assigned to either
Paging Channels or Traffic Channels. Code channel 32 may be assigned to either
the Sync Channel or to Traffic Channels.
- Code Division Multiple Access
- A technique for spread-spectrum multiple access digital communication that
creates channels through the use of noise-like carrier waves.
- Code Excited Linear Prediction (CELP)
- A technique of voice coding that makes use of linear prediction filters
excited by a stimulus looked up from a pre-stored table, based on its similarity
to the residue from the LPC filter solution.
- Code Symbol
- A symbol from a finite alphabet that is the output of an error-correcting-code
encoder. Information bits enter the encoder and code symbols leave the encoder.
The alphabet may be binary, or may have larger dimensionality.
- A combination of encoder and decoder, frequently used in the context of
speech codec, meaning both components of the speech coding and decoding process,
operating in full duplex mode.
- Convolutional Code
- An error-correcting code that is generated by finite-field division of the
data sequence, regarded as a polynomial over a finite field, by a generator
polynomial. Such a division resembles a discrete convolution.
- Coverage Area
- A geographical area in which a mobile will receive satisfactory signal-to-noise
ratio (Eb/N0) in both forward and reverse links. Evaluation
of coverage for a CDMA system must take into account the effects of soft handoff
and multipath, as well as signal strength.
- See Cyclic Redundancy Code.
- Cyclic Redundancy Code (CRC)
- A class of linear error detecting codes that generate a parity check bits
as the remainder of a polynomial division of the data, regarded as a polynomial,
by a generator polynomial. They are often based on a BCH code, used only for
its error detection capability.
- Data Burst Randomization
- The pseudo-random process that determines which power control groups are
transmitted by a mobile station when its transmitted bit rate is less than
- The ratio, in dB, of the sideband power of a signal, measured in a given
bandwidth at a given frequency offset from the same signal, to the total power
of the signal. For a CDMA signal, the signal power is measured in a 1.23 MHz
- Power measured in dB relative to one milliwatt.
- Power measured in dB relative to one Watt.
- The process of unpermuting the symbols that were permuted by an interleaver.
- The process by which primary rate traffic is forced to a lower-than-maximum
rate and transmitted together with signaling or secondary traffic in the same
- Distance-Based Registration
- An autonomous registration method in which the mobile station registers
whenever it enters a cell whose distance from the cell in which the mobile
station last registered exceeds a given threshold.
- Guiding of electromagnetic radiation by refraction due to index gradients
in the atmosphere.
- The energy of an information bit. Eb is measured in Joules, or
equivalently in Watts per Hertz.
- Effective Antenna Elevation (Base Station)
- The height of the radiation center of the base station antenna above the
average elevation of the ground midway between the base station and the mobile.
Particular ranges of distance are invoked by the Federal Communications Commission
to define height above average terrain (HAAT) for various services.
- Effective Antenna Elevation (Mobile Station)
- The height of the radiation center of the mobile station antenna above the
- Effective Isotropic Radiated Power (EIRP)
- The transmitted power multiplied by the antenna gain referenced to an ideal
isotropic radiator. EIRP is larger that ERP in the same direction by the gain
of an ideal dipole relative to an isotropic radiator, which is 2.1 dB.
- Effective Radiated Power (ERP)
- The transmitted power multiplied by the antenna gain referenced to a half-wave
- See Effective Isotropic Radiated Power.
- Electronic Serial Number (ESN)
- A 32-bit number assigned by the mobile station equipment manufacturer, uniquely
identifying the mobile station equipment.
- Encoder Tail Bits
- Fixed value bits appended to a block of data in order to flush a convolutional
encoder so that it is left in a known state. Leaving the encoder in a known
state aids the decoding.
- A dimensionless unit of telephone traffic intensity. It is numerically equal
to the calling rate times the average holding time. It is named for the Norwegian
telephone engineer who first popularized the concept.
- Erlang B
- Also called Lost Calls Cleared model. A mathematical model of telephone
traffic blocking in which blocked calls are not queued. The Erlang B blocking
probability for N resources, calling intensity y Erlangs, is
- Cf. Erlang C Model and Poisson Blocking
- Erlang C
- Also called Lost Calls Delayed model. A mathematical model of telephone
traffic blocking in which blocked calls are queued. It is similar to the Poisson
Blocking Model, with which it is sometimes confused. The Erlang C blocking
probability for N resources, calling intensity y Erlangs, is
- (Need to figure out Erlang C Formula!)
- See Effective Radiated Power.
- See Electronic Serial Number.
- Fade Timer
- A timer kept by the mobile station as a measure of Forward Traffic Channel
continuity. If the fade timer expires, the mobile station drops the call.
- See Forward Error Correction
- See Frame Error Rate
- An indication sent on a CDMA Traffic Channel indicating that the user directed
the mobile station to invoke special processing.
- Flat Fading
- Radio signal fading characteristic of a multipath environment where the
delay spread is less than the reciprocal bandwidth of the signal. Under these
circumstances the fading is uniform across the bandwidth of the signal, and
thus is essentially just an amplitude change. Also known as frequency-independent
fading. Cf. Frequency Selective Fading, Rayleigh Fading, Ricean
- Foreign NID Roamer
- A mobile station operating in the same system (SID) but a different network
(NID) from the one in which service was subscribed. See also Foreign SID roamer.
- Foreign SID Roamer
- A mobile station operating in a system (SID) other than the one in which
service was subscribed. See also Foreign NID roamer.
- Forward CDMA Channel
- A CDMA Channel from a base station to mobile stations. The Forward CDMA
Channel comprises one or more code channels that are transmitted on a CDMA
frequency assignment using a particular pilot PN offset. The code channels
are associated with the Pilot Channel, Sync Channel, Paging Channels, and
Traffic Channels. The Forward CDMA Channel always includes a Pilot Channel
and may include a Sync Channel, up to seven Paging Channels, and up to 63
Traffic Channels. The total number of code channels, including the Pilot Channel,
cannot exceed 64.
- Forward Error Correction (FEC)
- A technique for improving performance of a digital communication channel
that applies an error-correcting code in the transmitter and performs correction
in the receiver without feedback to the transmitter. "Forward" here
refers to the lack of feedback, not the transmission direction.
- Forward Traffic Channel
- A code channel used to transport service option (usually voice) and signaling
traffic from the base station to the mobile station.
- A basic timing interval in a CDMA system. For the Access Channel, Paging
Channel, and Traffic Channels, a frame is 20 ms in duration. For the Sync
Channel a frame is 80/3 = 26.666 ms in duration.
- Frame Category
- A classification of a received Traffic Channel frame based upon transmission
data rate, the frame contents (primary traffic, secondary traffic, or signaling
traffic), and whether there are detected errors in the frame.
- Frame Erasure Rate
- Ratio of erased frames to total frames. Care should be used to distinguish
between frame erasure rate and frame error rate. They are similar, but not
identical. Erased frames usually are counted as errored frames, but not all
errored frames are erased, that is, some may be undetected by the receiver.
- Frame Error Rate (FER)
- Ratio of errored frames to total frames. For purposes of this calculation,
erased frames count as errored.
- Frame Offset
- A time skewing of Traffic Channel frames from System Time in integer multiples
of 1.25 ms. The maximum frame offset is 18.75 ms.
- Frame Quality Indicator
- The CRC check applied to 9600 bps and 4800 bps Traffic Channel frames.
- Frequency Selective Fading
- Radio signal fading characteristic of a multipath environment where the
delay spread is greater than the reciprocal bandwidth of the signal. Under
these circumstances the fading is non-uniform across the bandwidth of the
signal. The multipath produces deep notches in the spectrum, and thus strong
distortion of the time-domain signal shape. Cf. Flat
Fading, Rayleigh Fading, Ricean Fading.
- Fresnel Radius
- The radius r of the circle formed by the intersection of the first Fresnel
zone with a plane perpendicular to the line of sight between the transmitting
and receiving antennas. In meters it is given by
- Fresnel Zone
- 1. The region in space between successive ellipsoids of revolution whose
foci are the transmitting and receiving antennas. The ellipsoids are defined
as the locus of points such that the sum of distances to the transmitting
and receiving antennas differs from the line-of-sight distance by an interger
number of half-wavelengths.
2. The area formed by the intersection of the regions of definition 1 with
a plane perpendicular to the line of sight between the transmitting and receiving
| A-F | G-M | N-S
| T-Z |
| Index | Topics
| Glossary | Standards
| Bibliography | Feedback
Copyright © 1996-1999 Arthur H. M. Ross, Ph.D.,