Specifications

Enhanced Base Transceiver System
iDEN® System
2-6 68P81095E55-E August 08, 2000
Site-to-Site Frame
Synchronization
Timing is a critical issue to assure the proper transfer of voice and data calls between
cell sites. To assure proper processing, each site must have highly accurate time
information to provide a timing offset to adjust for the signal propagation time across
the network. By using the common GPS timing pulse as a network clock, circuits
and software in the EBTS can assure that input and output data streams within the
iDEN system are synchronized.
Interface
Conversion
The radio link is a voice and data is a digital signal. This over-the-air data stream is
specific to the radio link and must be converted to more a traditional data stream to
be transported across the network. The EBTS converts the radio link voice or control
data between radio link timeslots and the data packets that can be applied to T1/E1
links between the EBTS and the rest of the network. The EBTS network interface
consists of 64 kbps DS0/timeslots that are either T1 (24 DS0s) or E1 (32 DS0s). The
allocation of DS0s on a single T1from the EBTS to the central network will depend
on the number of BRs, the total traffic loading and the traffic mix at the EBTS. The
information the EBTS passes to the iDEN network through T1/E1 facilities includes:
• Network Management (status/control, and statistics)
• Telephone Interconnect Traffic
• Inter-Working Function Traffic
• Dispatch Traffic
• Packet Data Traffic
Compressed voice for Interconnect and circuit switched dial-up networking data is
sent in a 16 kilo-bit-per-second (kbs) sub-rated (shared DS0) format. Dispatch and
Packet Data packets are sent in Frame-Relay format. T1/E1 Requirements are:
• T1 Speed: 1.544 Mps, framing: ESF, coding: B8ZS, DS0: 64 kbps, Clear
channel capability
• E1 Speed: 2.048 Mps, coding: HDB3
This functionality is discussed in greater in separate manuals.
Switching
Functions
For calls in the range of a single EBTS, the EBTS handles and controls handover in
conjunction with the MS. The EBTS handles intra-site (sector-to-sector) handovers
between sectors of the same site. For handovers involving multiple sites, the
handover metrics are passed to the BSC-MSC or the DAP-MPS (Appendix D,
Handover).
Operation,
Maintenance, and
Administration
Part of the EBTS is the network management agent. The operation maintenance and
administration functions are managed by the OMC-R. The OMC-R is responsible
for performing the EBTS network management functions such as:
• Configuration Management (code download)
• Fault Management (alarm processing and re-configuration support)
• Performance Management (statistics gathering).
Configuration Management allows for parallel BR downloads. This allows software
downloads to each BR in the EBTS simultaneously and reduces downtime.
Statistics are sent to the OMC-R every 30 minutes. Alarms, state events, and faults
are sent as they occur.