Network Equipment
One possible network topology is shown in Figure 7-2.
The circuit between the MSC and BTS passes through the LEC central office, and in fact
may pass through multiple central offices. Within each office, it will in turn pass through
multiple pieces of transmission equipment. The Network Interface Unit (NIU) at the MSC
and the BTS may be a very simple device having only a remote loop back capability, or it
may provide very sophisticated performance monitoring capabilities. Its capabilities may or
may not be accessible to the wireless service provider technician. Some repeaters may exist
in the circuit when the signal is traveling long distances. Repeaters are full duplex devices
that regenerate or restore the pulse shape and amplitude.
Another possible configuration between BTS and MSC is shown in Figure 7-3.
This configuration uses a High-speed Digital Subscriber Line (HDSL) in the T1 circuit,
which enables full duplex T1 service over a single pair of wires without repeaters. In most
cases the wireless service provider technician may not be concerned with the repeaters or
HDSL.
Chapter 7 T1 Measurements
7-2
MSC
BTS
Figure 7-2.
One Possible T1 Network Topology
MSC
REPEATER
T1 BACKHAUL CIRCUIT
REPEATER
LEC
N
I
U
N
I
U
BTS
Figure 7-3.
BTS and MSC Configuration
