Telephonic communications – Diagnostic testing – malfunction indication – or electrical... – Testing of subscriber loop or terminal
Reexamination Certificate
1999-12-22
2004-05-18
Nguyen, Duc (Department: 2643)
Telephonic communications
Diagnostic testing, malfunction indication, or electrical...
Testing of subscriber loop or terminal
C379S029010, C379S027020, C379S027030
Reexamination Certificate
active
06738455
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus and method for testing subscriber lines and equipment, and more particularly to an apparatus and method for testing subscribers lines and equipment being served by telecommunications devices that are linked by an interface.
2. Description of the Related Art
Today's network systems have increased in size and complexity to serve diverse user needs for telecommunications services. To achieve efficient operations and maintenance of transmission channels in such a circumstance, telecommunication carriers centrally manage maintenance information at their service centers, monitoring alarm signals from transmission equipment deployed over a wide coverage area, as well as receiving complaint calls from customers. If any failure is reported, they should conduct an appropriate test to locate each problem in a prompt and proper manner.
The ITU-T and ETSI, standardization organizations in this technical field, provide universal data communication interface standards known as V series recommendations. Among those recommendations, V5 interface standards define a set of requirements for digital communications between a local exchange (LE) and an access network (AN), where the term “access network” refers to a sub-network comprising a central terminal (CT) and remote terminals (RT) to allow individual subscribers to make access to a public switched network. V5 standards provide open interface specifications to enable multi-vendor solutions for telecommunications systems, where LE and AN equipment from different vendors can interoperate.
The V5 recommendations actually include two types of interface specifications: V5.1 and V5.2.
FIG. 11
schematically shows a system model using the V5.1 interface. This system includes an access network (AN)
300
which comprises a central terminal (CT)
301
and a remote terminal (RT)
302
being interconnected by a fiber optic cable Lo. The access network
300
is connected to a local exchange (LE)
200
via a 2.048 Mbps digital trunk L
1
that conforms to the V5.1 interface standards. In addition to analog telephone equipment, ISDN-BRA digital data terminals are coupled to the remote terminal
302
. Here, “ISDN-BRA” refers to 2B+D basic rate access services of ISDN. The V5.1 interface supports only one 2.048 Mbps digital trunk L
1
, which permits, for example, 30 channels of 64 kbps digital telephone lines to be connected to the RT
302
. Accordingly, two 2.048 Mbps links would be required to accommodate 60 channels.
In contrast to
FIG. 11
,
FIG. 12
schematically shows a system model using the V5.2 interface. This system includes an access network (AN)
300
, which comprises a central terminal (CT)
301
and a remote terminal (RT)
302
interconnected by a fiber optic cable Lo. The central terminal
301
is connected to a local exchange (LE)
200
via a 2.048 Mbps digital trunk L
2
that conforms to the V5.2 interface standards. The remote terminal
302
serves analog telephone equipment and digital data terminals for ISDN-BRA and ISDN-PRA services. Note that “ISDN-PRA” stands for 23B+D or 24B/D primary rate access of ISDN.
Compared with the V5.1-based system of
FIG. 11
, this V5.2-based system has two major differences. First, a line concentrator
302
a
is incorporated in the RT
302
. Second, it is possible to have two or more 2.048 kbps digital trunks to connect between the central terminal
301
and local exchange
200
. (Actually, it has at least two trunks L
2
for dual redundancy capabilities; one for active channels and the other for protection channels.)
Referring back to
FIG. 11
, suppose, for example, that the RT
302
has to handle 120 channels of 64 kbps digital terminals. This does not necessarily means that four 2.048 Mbps digital trunks L
1
are required, since it is unlikely that all the available digital terminals use connection services at the same time. In reality, average traffic is expected to be much lower than the theoretical peak bandwidth that the remote terminal
302
may require to handle 1
20
, 64 kbps channels. If the assessment of traffic does not necessitate the use of V5.1 interface, the V5.2 interface with line concentration capabilities would be the right choice, since it does not pre-assign the bearer channels to subscribers and thus provides more economical solutions.
While defining physical, electrical, and procedural requirements for digital interface, the V5 recommendations lack the specification of subscriber test methods. Suppose, for example, that a maintenance person stationed at the local exchange
200
is attempting to probe a particular subscriber terminal that is connected to the access network
300
. The V5 digital link L
1
or L
2
, however, does not allow him/her to send necessary test parameters to the terminal, because of the lack of specifications for testing telecommunications equipment over a V5 interface. Conventionally, he/she has to use two separate test stations to run a subscriber test, connecting one to the local exchange
200
and the other to the central terminal
301
.
FIG. 13
shows a typical configuration of a conventional subscriber test system for V5 interface. In this system, two subscriber test stations
100
and
101
are coupled to a local exchange (LE)
200
and a central terminal (CT)
301
, respectively. Besides terminating and switching circuits and trunks, the local exchange
200
directly serves its local subscriber terminals, which will be referred to herein as “LE-side subscribers.” The first test station
100
is thus called the “LE-side subscriber test station.”
On the other hand, the central terminal
301
, as part of an access network (AN)
300
, handles calls to/from subscriber terminals connected to a remote terminal (RT)
302
shown in the bottom of FIG.
13
. Those terminals will be referred to herein as “AN-side subscribers,” and the second test station
101
is thus called the “AN-side subscriber test station.” The local exchange
200
and central terminal
301
are interconnected by a 2.048 Mbps digital trunk L that is compatible with the V5 interface specifications. The central terminal
301
is linked to a remote terminal
302
via a fiber optic cable Lo.
Being unable to use the V5 digital link L for testing purposes, as mentioned earlier, the conventional subscriber test system performs a test by using both the LE-side subscriber test station
100
and AN-side subscriber test station
101
simultaneously to probe an LE-side subscriber under test and an AN-side subscriber under test, respectively. One disadvantage of such a conventional subscriber test system is that the maintenance person has to use different test stations to manipulate both the LE-side and AN-side subscriber terminals. This work environment imposes heavier loads on the maintenance person and spoils the efficiency of his/her tasks. Another disadvantage is that the information regarding individual subscribers is not centrally managed, but distributed in separate databases in the local exchange
200
and access network
300
. It is therefore difficult to ensure consistency between the two databases because they could be updated separately. Possible data inconsistency could cause inappropriate behavior of the test system, such as testing an incorrect target subscriber, resulting in degraded quality of customer services.
SUMMARY OF THE INVENTION
Taking the above into consideration, an object of the present invention is to provide a subscriber test apparatus which provides improved efficiency and quality in maintenance work.
To accomplish the above object, according to the present invention, there is provided an apparatus for conducting a subscriber test for subscribers connected to such telecommunications devices that are linked by an interface. This apparatus comprises: (a) a subscriber test controller which controls a process of a subscriber test by sending related test parameters and identification data to be used to identify a target subscriber to be tested, and (b) a subscribe
Fujitsu Limited
Katten Muchin Zavis & Rosenman
Nguyen Duc
LandOfFree
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