A
A5/1/2/3/8X
Encryption algorithms for GSM networks
AAL
ATM Adaptation Layer
ABR
Available Bit Rate
A-bis
Interface between the BSC and BTS in a GSM network
AB
Access Burst; used for random access and characterised by a longer guard period to allow for burst transmission from a MS that does not know the correct timing advance when first contacting a network
ACTE
Approvals Committee for Terminal Equipment
ACTS
Advanced Communications Technologies and Services – a European technology initiative
ACU
Antenna Combining Unit
ADPCM
Adaptive Differential Pulse Code Modulation; a form of voice compression that typically uses 32kbit/s
AFC
Automatic Frequency Control
AGCH
Access Grant Channel; downlink only, BTS allocates a TCH or SDCCH to the MS, allowing it access to the network
Air interface
In a mobile phone network, the radio transmission path between the base station and the mobile terminal
A-interface
Interface between the MSC and BSS in a GSM network
AM
Amplitude Modulation
AMPS
Advanced Mobile Phone System, the analogue mobile phone technology used in North and South America and in around 35 other countries. Operates in the 800MHz band using FDMA technology
AMR
Adaptive Multi-Rate codec. Developed in 1999 for use in GSM networks, the AMR has been adopted by 3GPP for 3G
Analogue
The representation of information by a continuously variable physical quantity such as voltage
ANSI
American National Standards Institute. An non-profit making US organisation which does not carry out standardisation work but reviews the work of standards bodies and assigns them category codes and numbers
ANSI-136
See D-AMPS
API
Application Program Interface
AoC
Advice of Charge
ARIB
Association of Radio Industries and Businesses. An organisation established by Japan’s Ministry of Posts and Communications to act as the standardisation authority for radio communication and broadcasting
ARPU
Average Revenue Per User
ASCII
American Standard Code for Information Interchange
ASIC
Application Specific Integrated Circuit
ASP
Application Service Provider
Asymmetric Transmission
Data transmissions where the traffic from the network to the subscriber is at a higher rate than the traffic from the subscriber to the network
A-TDMA
Advanced Time Division Multiple Access
ATM
Asynchronous Transfer Mode; a multiplexed information transfer and switching method in which the data is organised into fixed length 53-octet cells and transmitted according to each application’s instantaneous need
AUC
Authentication Centre; the element within a GSM network which generates the parameters for subscriber authentication
The Consumer Mobile Glossary
Advice of charge
A service which provides the user with information on the cost of calls from a mobile phone
Airtime
The amount of time a subscriber spends using his/her mobile phone
