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3981-A2-GN31-20
November 1996
System Overview
Introduction
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Logical Description
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Network/Switch Interface
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Modem Bank
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Network Management
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Audio Timeout
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Introduction
The Wireless Data Gateway (WDG) is a modem pool
that acts as the termination point for cellular calls and the
origination point for PSTN calls. The WDG consists of
dial modems and a T1 access platform directly connected
to the T1 looparound trunks of a cellular switch.
The WDG dynamically matches the protocol of a
user’s modem to take full advantage of Enhanced
Throughput Cellular (ETC) or MNP 10 to enhance
performance. The WDG eliminates the impact of echo,
clipping, and cell handoff impairments to provide greater
reliability in mobile-to-host communications.
Calls originating from a cellular data user, identified
with a special prefix (such as *DATA), are routed through
the WDG. The WDG allows call information to be passed
through the system unimpaired. When the WDG detects
that the destination has answered with a data tone, the
WDG intercepts the data start-up sequence and inserts
itself into the VF path.
The WDG then establishes two separate data
connections, one with the originator and one with the
destination, each optimized for its particular line
conditions. See Figure 1-1.
Destination
Land
Modem
COMSPHERE 3610
Mobile Switch
WDG
PSTN
Error
Correcting
Protocol
Cellular
Error Correcting
Protocol
Originating
Cellular
Modem
T1
PSTN
T1
T1
T1
496-14617-02
Figure 1-1. WDG Overview
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