User Manual

ArchitectureNortel Networks Confidential 3–57
S8000/S8002/S8006 BTS Reference Manual
The AMNU sends errors to the BSC by sending ”event report” messages through
the BTS. There are two types of these messages:
transient messages which are not acknowledged by the BSC
non–transient messages which must be acknowledged by the BSC and which are
repeated by AMNU until they are acknowledged
Transmission unit
Radio Signaling function
The main characteristics of this function are described below:
the radio access management (level 1)
It manages a dialog between the AMNU signaling functions and the signal
processing functions (SPU1 and SPU2) which are connected to the AMNU.
the radio management (level 2)
It manages the LAPDm level 2 signaling on the radio channels.
the radio resources management (level 3)
It provides mainly the level 2 management on the common channels and control
of level 2 functions on dedicated and common channels.
radio measurements management (level 3)
It provides the return of interference measurements carried out by the two
signal–processing units on the inactive dedicated channels and transmission of
these measurements to the AMNU.
Operation & Maintenance functions (O&M)
They provide configuration and unconfiguration of the TS and frequency
hopping functions.
Signal Processing function
The signal processing (SPU) function performs processing associated with the
transmission layer executes a number of functions, such as:
modulation/demodulation (8–PSK)
ciphering/deciphering of sent and received data
coding/decoding and interleaving/de–interleaving of data from the various
channels
mobile transmission timing advance function
discontinuous transmission (DTX)
BCCH filling
transmitter and receiver control