Service Manual

GSM-205-323
CTU
31st Oct 01
Technical Description: Horizon macro indoor
68P02902W07-B
CONTROLLED INTRODUCTION
Tech. 5–19
CTU
uplink/downlink
Downlink traffic data flow
Downlink TRAU data from the MCUF is received by the TDM function then
routed to the CCCP function where it is encoded (cyclic, block, and
convolutional), interleaved, and encrypted to GSM recommendations. Signalling
messages are also received from the RSS processor and encoded. These
traffic and control messages are built into air interface frames and then routed
back to the MCUF via the TDM function for baseband hopping. The CCCP
calculates a BBH routeing word, which informs the MCUF of the radio link to be
the source of its post hopped data. The post hopped data is then once again
sent back down to the appropriate CTU where it is received by the TDM function
and passed to the EQCP function. The EQCP inserts midamble and guard bits
to the data bits and forwards the data on to the modulator for transmission. The
EQCP also programs the CTU for the correct RF channel and transmit power
level for this transmitted burst.
Uplink traffic data flow
Baseband uplink traffic and control data messages are received by the CTU
interface function and sent to the EQCP where they are equalized. The EQCP
also calculates timing advance and RXLEV information, which is forwarded to
the RSS process. The recovered data bits are forwarded into the CCCP
process, where it is de-interleaved, decoded, and decrypted into TRAU frames.
Control messages are passed to the RSS function, while TRAU frames are sent
to the MCUF via the TDM interface.