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Wireless Data Gateway
Logical Description
The WDG consists of three major functional areas:
Network/Switch Interface
Modem Banks
Network Management
See Figure 1-2.
Network
T1 or E1
Interface
Management
Figure 1-2. WDG Functional Areas
Network/Switch Interface
The Network/Switch Interface terminates two digital
T1 or E1 signals from the loop-around connections of a
mobile switch and provides a 4-wire E&M signaling
interface to the modem banks.
The interface is implemented using the ACCULINK
Access Controller (AAC).
The CSU WAN modules on the AAC terminate the
T1 signals.
The bus architecture of the AAC routes individual
DS0 slots of the T1 to a 4-wire analog interface on
4-wire E&M interface cards within the AAC.
Each pair of E&M ports map to a time slot on the
T1 looparound trunks.
Each 4-wire E&M card provides 8 analog interfaces
in the form of a 50-position connector.
1-2
Modem Bank
4-Wire
E&M
Modem Bank
Modem Bank
Network
496-14618-01
November 1996
Modem Bank
The modem bank terminates 4-wire E&M signals from
the Network/Switch Interface with paired analog modems
in a carrier. Modems are either idle or active.
When . . .
When two paired
modems are idle
When fax calling tone is
detected
When a modem goes
active (detects answer
tone)
When both modems are
active
T1 or E1 signal
enters here from
the switch's
looparound trunks.
A single DSO
(shown here as
TS1) is brought
out and bussed to
a port on the
4-wire E&M card.
Network
Interface Block
4W
TS1
E&M
E&M1-1
WAN1
TS1
E&M1-2
WAN2
The signals between
the Network Interface
block and the Modem
Bank use a 4-wire E&M
signaling arrangement.
Figure 1-3. Gateway Channel
Then . . .
The modems act as an E&M
pass-through circuit.
Transmit signals from one
E&M port on the AAC are
routed to the receive path of
the next E&M port.
The detecting modem
signals its partner not to
answer. The modems are in
fax pass-through mode.
It signals its partner modem
and they begin training.
The pass-through function is
disabled and the modems
terminate the signals from
the E&M ports on the AAC.
See Figure 1-3.
The 3811 Plus
modems
terminate the
modem signal
from the cellular
modem and
route the data to
another modem
through a DTE
crossover cable.
Modem Bank
3811 Plus
DTE
4W
Crossover
NIM
Cable
3811 Plus
496-14619-01
3981-A2-GN31-20
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