Ericsson MINI-LINK BAS, Technical Description, Page: 72 / 174

MINI-LINK BAS 5-16
Technical Description EN/LZB 111 0542 P2B
Guard, preamble and FECs bits are added by the modem in the NU
when building up the upstream slots and are terminated in the NCU of
the RN.
Control timeslots are used in the MAC protocol for carrying queues
status (requests) from terminals to the RN. Control timeslots are made
of 8 minislots, which are 60 bits wide.
Requests in minislots are checked by a CRC-4 and if errors occur the
request is discarded.
Ranging slot has a specific format as it is used in the ranging
procedure. Terminal identity and unique word are functional for the
ranging procedure while a CRC-16 is foreseen for ranging information
validation.
Upstream ATM slot
480 bits/slot
10 20 424 8 18
Guard Preamble ATM cell CRC-8 FEC
60 60 60 60 60 60 60 60
Upstream control slot
Minislot#0 Minislot#1 Minislot#2 Minislot#3 Minislot#4 Minislot#5 Minislot#6 Minislot#7
10 20 24 4 2
Guard Preamble Request CRC-4 FEC
60 bits/Minislot
10 240 18
Guard Preamble Unique word Terminal Identity FEC
Upstream raging slot
Note: FEC bits are spread over the entire slot
Figure 5-7 Uplink TDMA Slot Structure