Base station controller (BSC)

Base station controller (BSC)
• Manages a number of BTSs
• Uses the Abis interface to connect to BTSs
• BSCs reserve radio frequencies for
communication and manage handovers
between BTSs

Base station controller (BSC)
• A BSC along with the BTSs connected to it
and the mobile stations managed through
it forms a base station system (BSS)
• Also connected to an MSC in the
networking and switching layer using an
interface A
• Processing of signals
• Controlling signals to the connected BTSs
and control of handover of signals from
one BTS to another within a BSS
• Control and handover of the signals from
BSC to MSC

Important functions performed by
the BSC
• Mapping the signals of a channel─ at
given instant receives signals from a BTS
at 16 kbps through Abis and interfaces
them to an MSC at 16 kbps
• Alternatively, may have to interface to a
PSTN switching centre at 64 kbps through
a fixed line network─ mapped by
assigning a 16 kbps channel for 64 kbps
signals and vice versa
• Reserving radio frequencies
• Frequency hopping (For example, multiple
BTSs operate simultaneously by using the
different frequencies at a given instant
• Traffic control by continuous measurement
of the frequency channel spectrum being
used at a given instant
• Authentication, encryption, and decryption
of data
• Updating location registry for the MSs
Network subsystem (NSS)
• Acts as an interface between wireless and
fixed networks
• Mainly consists of switches and databases
and manages functions such as
handovers between BSS’s, worldwide user
localization, maintenance of user accounts
and call charges, and management of
roaming

Summary
• BTS main functions
• Formation of cells using appropriately
directed antennae
• Amplification of signals to acceptable
strength so that they can be transmitted
without loss of data
• Channel coding, Encryption and
decryption