Browse Prior Art Database

Cellular Digital Packet Data as a Sideband Control Channel

IP.com Disclosure Number: IPCOM000116110D
Original Publication Date: 1995-Aug-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 119K

Publishing Venue

IBM

Related People

Dunn, J: AUTHOR [+3]

Abstract

Disclosed is the use of Cellular Digital Packet Data (CDPD) as a sideband control channel extending between a portable cellular device and an intelligent central processor. The sideband control channel is used to maximize the use of cellular air time for calls by looking ahead and preassigning available data ports or voice resources; or if no ports are available, by making a reservation for the later use of a port. These features are particularly desirable because the owner of a cellular device is charged for air time used, even when wrong numbers and other calls are placed to his device, and when unanswered calls are placed from his device.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 51% of the total text.

Cellular Digital Packet Data as a Sideband Control Channel

      Disclosed is the use of Cellular Digital Packet Data (CDPD) as
a sideband control channel extending between a portable cellular
device and an intelligent central processor.  The sideband control
channel is used to maximize the use of cellular air time for calls by
looking ahead and preassigning available data ports or voice
resources; or if no ports are available, by making a reservation for
the later use of a port.  These features are particularly desirable
because the owner of a cellular device is charged for air time used,
even when wrong numbers and other calls are placed to his device, and
when unanswered calls are placed from his device.

      The Figure is a block diagram showing a network using a CDPD
channel 1 as a sideband control channel which can be accessed, for
example, by several portable cellular devices, such as an intelligent
personal communicator 2, a cellular notebook computer 3, and a smart
cellular phone 4.  These devices also access a standard cellular
Advanced Mobile Phone System (AMPS) channel 5, which accommodates
voice communications and data communications with devices using radio
modems.  Both CDPD channel 1 and AMPS channel 5 are connected to an
intelligent network 6, which is in turn connected to various
computing devices.  For example, intelligent network 6 is wired to a
workstation 7 and is connected to a stationary computing system 8
through a Public Switch Telephone Network (PSTN) 9.  The PSTN is also
connected, directly or indirectly, to other telephones and telephone
systems around the world, such as a company phone system 10.  While
an AMPS channel 5 is shown as an example, other types of networks can
alternately be used, as long as intelligent network 6 can process
data and voice calls on separate access links.

      The cellular devices establish a data conversation over CDPD
channel 1 with intelligent network 6, which provides a number used,
for example, to assign data ports or to distribute incoming calls to
an available operator through a software-defined Automatic Call
Distribution (ACD) system.  This method is efficient because the
incremental cost of the CDPD link is low, and because using CDPD
packets does not incur airtime charges as high as the alternative use
of AMPS communications.  This method provides a lookahead function,
distributing calls to numbers which have been checked to determine
availability, and a reservation function, balancing the call load.

      In a first example of the use of this network, the process of
making a data call to a port is begun when personal communicator 2
initiates a CDPD conversation with intelligent network 6,
transmitting a request for data call access.  Intelligent network 6
next contacts stationary computing system 8 over the PSTN 9,
requesting the assignment of an available port.  Intelligent network
6 then relays this i...