Access network system

Details Access network system Access network system

1999-12-30

2004-07-13

Duong, Frank (Department: 2666)

Multiplex communications

Diagnostic testing

C370S244000, C370S250000, C379S001010, C379S027010

Reexamination Certificate

active

06762998

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an access network system, and in particular to an access network system (subscriber line transmission system) having a test function for performing a maintenance management of an access line (subscriber line).
In recent years, data communication and the like using an access line have been generally utilized. Performing a maintenance management of such an access line during communication without any disconnection is important for realizing a high quality service in the communication.
2. Description of the Related Art
A conventional PSTN (Public Switched Telephone Network) access network system has used only on/off-hook (loop open/close) information of a user or subscriber terminal (telephone) as information for grasping a line or circuit availability status of a PSTN user.
Since an access line assumes a loop close status also in case of short-circuit for some fault, it has been impossible to determine whether the loop close status is due to the fault or a mere off-hook.
When testing the access line which is the off-hook (loop close) state, it has been required that a maintenance person regards that the line is busy and can not be tested, and retries a test when the access line assumes the on-hook (loop open) state.
When determining the line in the off-hook state to be abnormal, the maintenance person has been required to compulsorily test the access line and to determine whether the abnormality is due to a mere off-hook state or the above-mentioned short-circuit.
On the other hand, since a conventional ISDN (Integrated Services Digital Network) access network system has no factor for grasping a physical line status by the method, it has no means for determining whether the user actually uses the line or the fault occurs in the line when the line is busy.
Therefore, the maintenance person has suppressed transmitting and receiving calls by manually changing the mode of the access line to a maintenance mode to test the access line.
As mentioned above, in the conventional access network systems, the PSTN access line has been compulsorily tested by the maintenance person's determination, while the ISDN access line has been tested with being compulsorily switched over to the maintenance mode. Accordingly, even when the line is used without problems, a damage can occur such that the line is disconnected during conversation or data communication.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to grasp an availability status of an access line to be tested in an access network system which performs a maintenance management of the access line.
In order to achieve the above-mentioned object, an access network system, according to claim
1
, of the present invention comprises; a processor for performing a connection and a release process of a bearer channel and storing an allocation status of the bearer channel to be managed, and a system manager for determining an availability status of an access line based on the allocation status.
FIG. 1
shows an access network system
20
and a local exchange (switchboard)
30
operated by e.g. the V5.2 interface. The access network system
20
and the local exchange
30
are respectively composed of a physical layer in the layer
1
, a data link layer in the layer
2
, and e.g. BCC (Bearer Channel Connection) protocol entities (processors)
22
,
32
, system managers
25
,
35
, and resource managers
27
,
37
in the layer
3
. The local exchange
30
further has a PSTN/ISDN protocol entity
38
in the upper layer.
The BCC protocol entities
22
and
32
of the access network system
20
and the local exchange
30
mutually transmit/receive the messages of the BCC protocol prescribed at a V5.2 interface point according to a predetermined procedure when a user calls or is called, thereby connecting and releasing the bearer channel.
The processor
22
in the access network system
20
of the present invention stores and manages the allocation status of the bearer channel. The system manager
25
determines whether the availability status of the access line is “busy” when the allocation status of the bearer channel is “being allocated”. Thus, it becomes possible to grasp the availability status of the access line.
Also, in the present invention according to claim
2
, the processor
22
may determine the allocation status based on an ALLOCATION COMPLETE message and a DE-ALLOCATION COMPLETE message for the bearer channel.
Namely, the processor
22
can determine that the bearer channel is allocated by the “ALLOCATION COMPLETE message” of the bearer channel or that the bearer channel is released (not allocated) by the “DE-ALLOCATION COMPLETE message”, which are stored as the allocation status.
Thus, it becomes possible to easily grasp the allocation status of the bearer channel.
Also, in the present invention according to claim
3
, the access line may form a PSTN.
Thus, the availability status of the PSTN access line can be grasped.
Also, in the present invention according to claim
4
, the access line may form an ISDN-BRA (Basic Rate Access), i.e. N-ISDN.
Thus, the availability status of the ISDN-BRA access line can be grasped.
FIG. 2
shows a V5.2 protocol sequence in which a PSTN user terminal
10
calls a terminal
40
through the access network system
20
and the local exchange
30
connected by e.g. the V5.2 interface.
Messages M
1
-M
9
transferred between the access network system
20
and the local exchange
30
are protocol messages of the V5.2 interface prescribed by ETS300 324-1/300 347-1 of the ETSI (European Telecommunication Standard Institute) when the PSTN user calls.
Receiving an off-hook signal indicating a call originated from the user terminal
10
(at step S
1
), the access network system
20
exchanges an “ESTABLISH message M
1
” and an “ESTABLISH ACK message M
2
” with the local exchange
30
.
After this exchange, the local exchange
30
transmits an “ALLOCATION message M
3
” instructing the allocation of the bearer channel to an address (L3 address) of the layer
3
, while the access network system
20
returns an “ALLOCATION COMPLETE message M
4
” instructing that an allocation process is normally executed.
The local exchange
30
sends a dial tone (at step S
2
), so that the user terminal
10
can perform dialing (SIGNAL of 1st digit-last digit) (at step S
3
).
After ringing, the local exchange
30
returns a ringing back tone to the terminal
10
. When the called terminal
40
sends an off-hook signal to the local exchange
30
(at step S
4
), conversation is started and ended with an on-hook signal (at step S
5
).
The access network system
20
which has received the on-hook signal transfers a SIGNAL (on-hook) message M
5
, a DE-ALLOCATION message M
6
, a DE-ALLOCATION COMPLETE message M
7
, a DISCONNECT message M
8
, and a DISCONNECT COMPLETE message M
9
to/from the local exchange
30
to de-allocate or release the bearer channel.
Namely, the bearer channel is allocated to the user terminal
10
having originated calls, which is held during the communication.
Accordingly, it becomes possible to grasp the availability status of the user terminal
10
by storing the allocation status of the bearer channel for every user terminal
10
.
FIG. 3
shows a V5.2 protocol sequence in which an ISDN user terminal
10
connected by e.g. the V5.2 interface calls the terminal
40
through the access network system
20
and the local exchange
30
.
Messages M
11
-M
35
transferred between the access network system
20
and the local exchange
30
are prescribed by the above-mentioned ETS300 324-1/300 347-1.
The messages M
19
, M
22
-M
26
, and M
29
are the ones of the ISDN user-network protocol (DSS-1: Digital Signaling System No.1).
The abbreviations within the parentheses of the messages M
17
, M
18
, M
22
-M
26
, and M
29
respectively stand for as follows:
SABME: Set Asynchronous Balanced Mode,
UA: Unnumbered Ack,
CALL PROC: Call Proceeding,
ALERT: Alerting,
CONN: Connect,
DISC: Disconnect,
REL: Release,
RELCOM:

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