Specifications

Interface Protocols
Operating Characteristics
August 08, 2000 68P81095E55-E 3-25
The diagram also illustrates the various protocols used throughout the network. As
shown in the diagram, the control and processing of different services is segregated
into different network entities. Services are implemented by single operational units
or in conjunction with other network elements (DAP and MSC).
• Dispatch calls are routed between EBTSs by the DAP
• Packet Data is routed by the DAP through the MDG to the internet
• Interconnect calls are controlled by the MSC using the VLR and HLR.
• Circuit Data is controlled by the MSC with the aid of the IWF.
• Short Message Service (SMS) is controlled at the MSC using the HLR
• Fixed Network Elements are monitored and administered by the OMC
Enhanced Base Transceiver System
The EBTS functionally converts the Radio Link to land-based protocols depending
on the call. Interconnect calls use a T1 DS0 structure. Dispatch calls use Frame
Relay. The physical connection is summarized in (Figure 3-18).
Figure 3-18 EBTS Pathways
Connection between the Base Radios and the antenna system is coaxial cable sized
and rated according to the output power of all the radios attached to the antennas.
This carries M16-QAM modulated VSELP/RLP traffic.
Connection between the Base Radios and the ACG is also coaxial but is sized and
rated for Carrier Sensing Multiple Access /Collision Detect (CSMA/CD) Ethernet.
This link carries VSELP/RLP Traffic, Operation and Maintenance Link (OML-
SNMP), Mobis signaling Packet Data and Circuit Data.
The connection between the EBTS and the FNE is over a direct link, microwave or
dedicated lines of another carrier. The multiple protocols for different services are
applied onto that single T1. A typical T1 setup uses:
• 1 DS0 with iSC/ACG Operations Signaling & Control (Mobis)
• 1 or more DS0s with 16 kbps Subrated Compressed (Circuit Data)
• 1 or more DS0s for Frame Relay (Dispatch and Packet Data)
• 1 DS0 for the Operations and Maintenance Link (OML SNMP)
RF (Coaxial)
iSC
ACG
iMU
Ethernet
LAN
EBTS
10base2
(Coaxial)
Ethernet
Dispatch
Frame Relay
(typically 6 spans max.
to MPS)
Interconnect
sub-rated DS0's
(1 to 18 spans
to BSC-XCDR)
1 DSO - Signaling
(Mobis to BSC-CP)
T1
24 spans
(1 per EBTS)
spare
RFDS
Base Radios
Base Radios
Base Radios
Base Radios
RF
(Coxial)
PSTN
(Leased Line)
OR
OR
DAC
CSMA/CD
1.544 Mps
framing: ESF
coding: B8ZS
DS0: 64 kbps
Clear channel capability
FNE
1 DS0
OML
(X.25 to OMC)
T. N. French