Service Manual

GSM-205-323
MCUF
31st Oct 01
Tech. 6–10
Technical Description: Horizon macro indoor
CONTROLLED INTRODUCTION
68P02902W07-B
ASIC
functionality
The Application Specific Integrated Circuit (ASIC) provides central switching
capabilities for the MCUF. It is capable of supporting up to 24 transceivers,
together with up to six network interfaces and two links to the on-board
processors, one link to the sync processor and a link to the redundant MCUF.
The link to the sync processor is used for code loading purposes only. The
ASIC supports baseband hopping across the 24 transceiver links.
The ASIC provides interface features associated with the transceiver links,
these include synchronization features to allow for delay in the link to the
transceivers, and the necessary framing and encoding to support the link.
All of the serial links into the ASIC are internal lines (I lines), 125 s framed,
with 32 eight bit timeslots per frame.
ASIC transceiver link features
The ASIC interfaces to a maximum of 24 transceiver links. The ASIC can switch
any timeslot on any of the transceiver links to any timeslot on other links
connected to the ASIC; transceiver links, network links, MCUF redundancy link
or processor links.
The ASIC provides the following features associated with the transceiver links:
 Link advance/delay compensation.
The ASIC will continually measure the round trip delay on each transceiver
link to calculate a timing advance for each link. The link advance is
applied, and can be adjusted, by the main processor via the processor
parallel interface.
 BBH data switching.
BBH switching is performed automatically on any timeslot configured as
BBH data. A single timeslot from the transceiver is selected for BBH
routeing information, and defines which transceiver link (0-23) should be
used for downlink.
 Timing reference insertion.
The ASIC receives timing pulses from the sync block and inserts the
appropriate bits into the transceiver downlink synchronization and framing
timeslots. The sync block will provide a version of the 6.12 s and 60 ms
signals that is advanced by 125 s for this purpose.
 Manchester coding/decoding.
The transceiver links are all Manchester coded/decoded by the ASIC. This
function can be switched on or off (default on) on a per link basis. The
disable feature is for applications outside of the MCUF module.