Bandwidth transfer switching system

Details Bandwidth transfer switching system Bandwidth transfer switching system

2002-01-04

2004-01-06

Pham, Chi (Department: 2667)

Multiplex communications

Pathfinding or routing

Combined circuit switching and packet switching

C370S354000, C370S355000, C370S356000

Reexamination Certificate

active

06674749

ABSTRACT:

TECHNICAL FIELD
The present invention relates generally to telecommunications, and more particularly to network communications over public telephone switching systems.
BACKGROUND ART
FIG. 1
(background art) is a block diagram depicting the existing infrastructure
10
of the public switched telephone network (PSTN). Various devices may communicate via the existing infrastructure
10
, and users today often have and use multiple such devices. In
FIG. 1
a telephone
12
a,
facsimile
12
b,
modem
12
c,
computer
12
d,
and special service device
12
e
are shown connected to a PSTN
14
and another telephone
12
a,
facsimile
12
b,
modem
12
c,
computer
12
d,
and special service device
12
e
are shown also connected to the PSTN
14
. The telephones
12
a
and facsimiles
12
b
are analog type devices which may communicate with respective like devices. In
FIG. 1
the modems
12
c
stylistically depict the still common situation of digital devices (not shown) producing digital signals that are converted to and from analog type signals, but otherwise communicating using analog techniques. In contrast, the computers
12
d
and special service devices
12
e
shown here stylistically depict true digital type devices.
While the presence of computers
12
d
in the existing infrastructure
10
is relatively well known, some readers may not be familiar with the special service devices
12
e.
These are relatively common today, but little appreciated. Some examples include remote monitor able utility meters and alarm systems. Such special service devices
12
e
typically require a much lower data transfer rate than systems like the computers
12
d.
For communications between the respective sets of like devices, the analog “traffic” may be entirely via the PSTN
14
. In contrast, the digital traffic for the computers
12
d
may start on the PSTN
14
and then proceed via an Internet protocol network (IP network
18
). Similarly, the digital traffic for the special service device
12
e
may start on the PSTN
14
and then proceed via a signal switching network, like the SS
7
network
20
shown.
FIG. 2
(background art) is a block diagram depicting the most common digital, or “Internet call,” connection methodology. Digital devices (not shown here) produce digital signals which the modems
12
c
convert to analog type signals. The modems
12
c
connect to ingress switches
22
via conventional voice circuits or (commonly) plain old telephone service lines (POTS lines
24
). The ingress switches
22
may connect directly to an egress switch
26
, via POTS lines
24
, or to a tandem switch
28
that further connects to the egress switch
26
via an interoffice trunk
30
. The egress switch
26
is connected to an Internet service provider point-of-presence (ISP POP
32
) via POTS lines
24
. Often the ISPs will have multiple POTS lines
24
or ISDN primary rate interface configured into hunt groups, and this is the case depicted in FIG.
2
. Finally, the ISP POP
32
connects to the IP network
18
. Of course, digital communications going the other direction travel essentially the reverse path.
FIG. 3
(prior art) is a block diagram depicting the presently popular network evolution model, wherein the IP network
18
evolves to become a single common packet backbone. Analog devices like telephones
12
a
and facsimiles
12
b
(
FIG. 1
) have their signals converted to digital data packets. The same can be done for the analog output of modems
12
c
(FIG.
1
), but would generally be pointless. Existing digital devices like the computers
12
d
would continue to connect to the IP network
18
, and the special service devices
12
e
would evolve into types that could also connect to the IP network
18
. New digital audio-video devices, like digital voice phones
12
f
and video units
12
g
(e.g., cameras, or “CAMs” as they are often termed in the industry) can similarly connect directly to the IP network
18
. Unfortunately, there are problems with this evolution model. In particular, and as discussed more extensively elsewhere herein, it obsoletes the current investment in PSTN technology and it introduces a number of transitional technical problems.
FIG. 4
is a block diagram depicting a more suitable network evolution model. The various communications devices (
12
a-g
) connect to an access network
34
, and the access network
34
connects to the PSTN
14
(essentially the major central element already in the existing infrastructure
10
), the IP network
18
, the SS
7
network
20
and also a broadband network
36
. The IP network
18
can handle most existing bandwidth digital communications, and the broadband network
36
can handle high bandwidth communications such as digital video. Under this alternate network evolution model the broadband network
36
would initially be optional, and only added as needed.
FIG. 5
(background art) is a block diagram of a conventional current digital loop carrier communications architecture (DLC architecture
40
). At a customer premises
42
a LAN
44
includes network devices
46
and what will here be termed customer premises equipment (CPE
48
; such as a channel service unit/data service unit, analog/ISDN/xDSL type modems etc.). The customer premises
42
may also include plain old telephone service (POTS) devices, such as the telephone
12
a
which is shown.
The next segment in the communications architecture is the local loop
50
. It primarily includes a remote terminal
52
. Connecting digital traffic from the CPE
48
to the remote terminal
52
is one or more T1/E1/DSx lines
54
(which here may generically include all digital “copper wire” protocols as well, e.g., xDSL and ISDN). Carrying analog (e.g., voice, facsimile, and modem) POTS traffic to the remote terminal
52
are one or more POTS lines
24
. A plurality of such customer premises
42
is typically serviced by each remote terminal
52
.
Following this in the communications architecture is the central office
56
, which includes a central office terminal
58
that connects to a central office switch
60
(larger central offices typically include multiple central office terminals
58
and multiple central office switches
60
, and central offices may even have remote terminals
52
directly connected into the central office switches
60
). Optionally, Internet routers
62
from Internet service providers (ISP's), may also be connected to the central office switch
60
.
For simplicity in discussion, the Internet is used as a generic example of a specialized application network here, but it should be appreciated that many other examples exist. Alarm systems and video conferencing networks are two common ones, and ones which might respectively use the SS
7
network
20
(
FIGS. 1 and 4
) and the broadband network
36
(FIG.
4
). For convenience in discussion, such dispersed networks that operate through, or in some segments parallel to, the public telephone switching system are herein termed wide area networks (WAN
64
).
Continuing with
FIG. 5
(background art), a plurality of local loops
50
are typically serviced by each central office terminal
58
, and a plurality of specialized networks devices (e.g., Internet routers
62
) may be serviced by each central office switch
60
. Today, the remote terminal
52
to central office terminal
58
, the central office terminal
58
to central office switch
60
, and the central office switch
60
to Internet router
62
connections are typically all also T1/E1/DSx lines
54
.
FIG. 5
includes the specialized network example of an ISP's Internet routers
62
in turn connected to other devices (not shown) by a 10/100/1000 base-T line in the WAN
64
. This example presumes the modern practice of directly connecting specialized network devices directly to the central office switch
60
with T1/E1/DSx lines
54
. Older installations, smaller ISP's, and other specialized networks may still employ modem banks.
Within this conventional architecture, the recent approach to increasing switching system bandwidth has bee

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