Specifications
Base Site Controller
iDEN® System
2-18 68P81095E55-E August 08, 2000
The PCM voice packets for a call arrive at the XCDR on a single span (DS0). The
XCDR converts the packets to radio link packets and applies them to the timeslot
scheme used by the EBTSs. Because of the difference in the amount of data between
PCM (64 kbs) and the radio link timeslot (VSELP in a 16 kbs timeslot). The
timeslots can be shared. Four radio link packets can be applied to a single timeslot
with routing and signalling overhead. This sub-rated concentration allows 4
conversations to one DS0 on the T1 line (Figure 2-10).
Figure 2-10 4:1 Sub-Rated T1 Concentration
The number slots available for XCDR cards will vary with configuration.
Data Collection The BSC also provides limited call processing. The BSC monitors call metrics from
the EBTS and uses this data for facilitate the transfer of call routing between EBTS
sites during Interconnect calls. The BSC will route calls to the appropriate DACS so
it can route the call the appropriate EBTS. This function is handled by the BSC-CP
or the BSC - Enhanced Control Processor (BSC-ECP).
Control
Information
Handling
The BSC also routes data across the X.25 Operations and Maintenance network to
the OMC. Alarm and status information for the EBTSs is routed to the OMC for
collection and display. Administrative control commands such as cut-overs and
loads from the OMC are routed to a EBTS by the BSC. This function is handled by
BSC-CP or the BSC-ECP.
Multi-threading In cases where a a BSC-CP has access to more than one XCDRs, the traffic may be
routed two or more XCDRs (XCDR Multi-Threading) to reduce XCDR failure
downtime. Multi-threading allows for redundant XCDRs and helps optimize their
usage.
Generic
Processor
(GPROC)
(routes voice
packets)
MegaStream
Interface
(MSI)
(VSELP side)
BSC
Cross Connect
(KSW)
Transcoder
(XCDR)
(VSELP
<>
PCM)
1 11 1
2 2 22
3 3 3 3
64 kbs PCM
VSELP
EBTS
T1
VSELP sub-rated DS0
(X = control overhead)
frame positioning may vary
Downlink (to mobile) path shown.
Reverse for uplink (to MSC).
4 4 44
1 11 1
2 2 22
3 3 3 3
4 4 44
MegaStream
Interface
(MSI)
(PCM side From
MSC
)
64 kbs PCM
DS0
3
- (voice 3)
DS0
2
- (voice 2)
DS0
1
- (voice 1)
DS0
4
- (voice 4)
3
1 2
3
21
X 4
X
X
X
4
T. N. French