JP3454219B2 - ISDN accommodation access control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ISDN accommodating access control device, and more particularly to an ISDN accommodating access control device using a wireless line.

[0002]

2. Description of the Related Art Conventionally, ISDN (Integrated Services Digital Network) communication has mainly been wired, but in recent years, wireless access networks have been advancing due to advances in wireless technology. For example, WL that makes the last stage to the subscriber terminal wireless
L (wireless local loop) system or FW
The A (fixed wireless access) system is currently one of the most noticed.

However, when the WLL (FWA) system is introduced into the ISDN accommodating access network,
There may be communication interruption (layer 1 error) due to occurrence of a wireless bit error due to a wireless-specific problem, for example, a natural environment such as rainfall or lightning. For example, as shown in FIG. 7, in an ISDN communication system that wirelessly communicates between an access terminal unit accommodating a subscriber terminal and a base station connected to the exchange, a layer is provided between the exchange and the subscriber terminal. 1 Information is exchanged, and as long as communication is performed, control / response signals are transmitted.

Here, a failure occurs in the wireless line between the access terminal unit and the base station, and control / response signals are no longer transmitted. As indicated by 201 and 202 in FIG. When a no signal or an abnormal signal is sent from the base station to the exchange for a certain period of time, the subscriber terminal and the exchange that have received the packet recognize that the layer 1 is abnormal (steps 203 and 204) and stop all communication. (Step 205). Such disconnection of the wireless line is an abnormality caused by wirelessly connecting the exchange and the subscriber's house, and the line quality is inevitably lower than that of the subscriber who is connected by wire.

As a conventional ISDN accommodating access control device that takes into consideration such a wireless communication disconnection, an ISDN accommodating access control device shown in the block diagram of FIG. 8 is known (Japanese Patent Laid-Open No. 1-292950). In this conventional device, a parity verification circuit 301 for performing a parity check of a status signal (ST bit) in a received signal received from a subscriber side, and a detection of out-of-synchronization of a frame pattern of the entire received signal, or a detection of the entire received signal. A fault detection circuit 302 that outputs a fault detection signal when it detects that the bit error exceeds a certain permissible value or the level of the received signal falls below a certain permissible level, and the ST bit that has passed in the parity verification circuit 301 The memory 304 to be accessed, the control gate 303 that temporarily disables the access when the fault detection signal is output, and the timer circuit 30 that confirms that the fault detection signal continues for a certain time or more.
5, and a timing generator 306 that generates an interface stop control signal (CO bit) for stopping the physical interface with the transmitting side on the partner side.
It has a selector 307 for selecting one of the CO bits from the memory 304 and the timing generator 306 using the output signal of the timer circuit 305 as a select signal, and a switch 308 to which a received signal, a signal from the selector 307 and the like are input. There is.

In this conventional apparatus, when the fault detection circuit 302 detects a fault in the receiving line, the CO bit is not sent under the control of the exchange 308, but the interface generated by the own timing generator 306. A CO bit for stopping is transmitted to the other subscriber side to stop the layer 1 interface on the subscriber side, and the memory 3
In ST 04, the ST bit before the failure occurs is not held and transmitted, and when the failure of the wireless receiving line is eliminated and the original state is restored, the CO bit and ST of the layer 1 between the subscriber side and the exchange side are Be able to return to the original state immediately after exchanging bits. As a result, when the failure of the wireless line is restored, it is possible to return to the original state in a shorter time than when the exchange 308 newly establishes the layer 1 interface according to a certain procedure, and thus the operation of the ISDN wireless line system with frequent communication interruptions is performed. It is intended to facilitate.

[0007]

However, in the above-mentioned conventional ISDN accommodating access control device, when a radio failure occurs, the control signal (CO bit) created by the timing generator 306 is used by the same radio line. Therefore, there is no guarantee that a normal control signal (CO bit) can be transmitted using the same wireless line when a wireless error occurs.
This control signal (CO bit) is also likely to be discarded due to radio interference, and if it is discarded, the intended purpose cannot be achieved.

Further, in the above-mentioned conventional ISDN accommodating access control device, since there is no recovery procedure when the radio line remains in failure, the I-side access line control device on the exchange side is provided.
There is a problem that the line disconnection continues for a long time between the SDN accommodating access control device and the subscriber side terminal side.

The present invention has been made in view of the above points,
By automatically switching wireless lines when a wireless failure occurs, ISD with high line quality even when using wireless lines
An object is to provide an N-accommodating access control device.

[0010]

In order to achieve the above-mentioned object, the present invention has an exchange that accommodates an ISDN connected to a base station, and an access terminal unit that wirelessly communicates with the base station connected to a subscriber terminal. In the ISDN system, the data from is received by the subscriber terminal through the base station and the access terminal unit, and the data from the subscriber terminal is received by the exchange terminal through the access terminal unit and the base station. For storing a fault in the wireless line between the access terminal unit and the base station; and when the first fault detecting unit detects a radio fault, After outputting the information stored in the first storage means to the subscriber terminal, the access terminal is provided with a first line setting means for setting a new wireless line, and exchanged from the subscriber terminal. Storage means for storing information to the wireless terminal, second failure detecting means for detecting a failure of the wireless line between the access terminal unit and the base station, and when the second failure detecting means detects a wireless failure. Is characterized in that the base station is provided with second line setting means for setting a new wireless line after outputting the information stored in the second storage means to the exchange.

According to the present invention, when the failure of the wireless line between the access terminal unit and the base station is detected, it is stored in the first and second storage means before the failure of the wireless line is detected. Normal information is output to the subscriber terminal and the exchange. That is, the subscriber terminal can be supplied with the information received by the access terminal unit before the occurrence of a wireless line failure from the exchange, and the exchange can receive the information received by the base station before the occurrence of a wireless line failure from the subscriber terminal. Information can be supplied. Further, after outputting the information stored in the first and second storage means, it is possible to switch to a new wireless line. Here, each of the first and second storage means stores layer 1 information.

Further, in order to achieve the above object, the present invention sets the switching setting from the wireless line currently in communication to the new wireless line by the first and second line setting means within the retransmission time of layer 2. It is characterized in that According to the present invention, when the layer 2 is retransmitted after switching to the new wireless line, the layer 2 communication is not interrupted and the communication can be continued as a normal operation.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. 1 is a block diagram of an embodiment of an ISDN accommodating access control device in an access terminal unit, FIG. 2 is a block diagram of an embodiment of an ISDN accommodating access control device in a base station, and FIG. 3 is a radio to which the present invention is applied. The system block diagram at the time of installing the ISDN accommodation access control apparatus using a line is shown.

First, the system configuration will be described with reference to FIG. 3. The exchange 4 accommodating the ISDN is connected to the base station 3, and the ISDN basic interfaces Dch and B are used.
The ch and layer 1 information are communicated. Access terminal unit 2
Is connected to the subscriber terminal 1, exchanges data of wireless data received from the base station 3 and transmits the data to the subscriber terminal 1, and wirelessly transmits the data received from the subscriber terminal 1 to the base station 3. To do. The base station 3 wirelessly transmits the data received from the exchange 4 and wirelessly transmits the data to the access terminal unit 2, and exchanges the wireless data received from the access terminal unit 2 and transmits the data to the exchange 4. In addition, the maintenance terminal 5
Connected to the base station 3 via a network,
The access terminal unit 2 and the subscriber terminal 1 are monitored and remotely controlled.

In the wireless state, the access terminal unit 2 constantly stores the layer 1 information controlled by the exchange 4 in the internal memory, while the base station 3 continuously stores the layer 1 information responded by the subscriber terminal 1. Stored in memory.
If a radio failure occurs between the base station 3 and the access terminal unit 2 during a call using the radio line a, for example, the radios provided in the access terminal unit 2 and the base station 3 are connected to each other. The fault detection unit detects a radio fault, and the access terminal unit 2 transmits the layer 1 information stored in the memory immediately before the detection of the radio fault to the subscriber terminal 1 and the base station 3 to the exchange 4. As a result, even if a radio failure occurs, the exchange 4 and the subscriber terminal 1 do not fall into the layer 1 suspended state.

In this state, the base station 3 and the access terminal unit 2
The wireless line a between them is automatically switched to the wireless line b. When the line setting of the wireless line b is completed, the layer 1 information output up to that point is returned to the normal state via wireless. In this way, when a wireless failure occurs, the wireless communication is switched by switching the wireless line while maintaining the layer 1 communication between the subscriber terminal 1 and the access terminal unit 2, and the exchange 4 and the base station 3. The ISDN communication can be continued without stopping the exchange 4 and the subscriber terminal 1. This Figure 3
WLL (FW
A) The system is introduced.

Next, the configuration of the access terminal unit 2 will be described with reference to FIG. The access terminal unit 2 includes an interface unit 21, a wireless interface unit 22, a wireless line setting unit 23, a wireless line opening unit 24, a wireless fault detecting unit 25, a layer 1 information separating unit 26, and a layer 1 information memory 27. The interface unit 21 is an internal data bus of the subscriber terminal 1 and the access terminal unit 2 and the wireless interface unit 2.
2 to perform data communication between the subscriber terminal 1 and the access terminal unit 2.

The wireless interface unit 22 performs wireless data conversion and wireless data communication between the access terminal unit 2 and the base station 3. The wireless line setting unit 23 performs wireless line allocation and setting of the access terminal unit 2 and the base station 3. The wireless line opening unit 24 performs a wireless line opening process for the access terminal unit 2 and the base station 3. The wireless fault detection unit 25 is connected to the internal bus of the access terminal unit 2, detects a fault in the wireless line, and if the fault is detected, instructs the wireless line release unit 24 to release the wireless line, and the layer 1 information memory. It issues an instruction to transmit the layer 1 information in the wireless normal state stored in 27 to the subscriber terminal 1 via the internal bus and the interface unit 21.

The layer 1 information separating section 26 is connected to the internal bus of the access terminal section 2 and the layer 1 information memory 27, separates only the layer 1 control information transmitted from the exchange 4 to the subscriber terminal 1, It is supplied to the information memory 27. The layer 1 information memory 27 is connected to the internal bus of the access terminal unit 2 and the layer 1 information separating unit 26,
Always the latest normal layer 1 input from the information separation unit 26
The information is stored, and normal layer 1 information is output according to an instruction from the radio failure detection unit 25.

Next, the configuration of the base station 3 will be described with reference to FIG. The base station 3 includes a wireless interface unit 31, a line switching unit 32, a wireless line setting unit 33, a wireless line opening unit 34, a wireless failure detecting unit 35, and a layer 1 information separating unit 3.
6, layer 1 information memory 37. The wireless interface unit 31 performs wireless data conversion and wireless data communication between the access terminal unit 2 and the base station 3. The line switch unit 32 is connected to the exchange 4, the internal bus of the base station 3 and the wireless interface unit 31, and uses data as a data communication route between the exchange 4 and the subscriber terminal 1 and a data communication route inside the base station 3. And transfer to the part.

The wireless line setting unit 33 is used by the access terminal unit 2
And the wireless line allocation and setting of the base station 3 are performed. The wireless line releasing unit 34 performs a wireless line releasing process of the access terminal unit 2 and the base station 3. The wireless fault detection unit 35 is connected to the internal bus of the base station 3 and detects a fault in the wireless line. When the fault is detected, the wireless line open unit 34 is instructed to open the wireless line. The layer 1 information in the wireless normal state stored in the internal bus and line switch unit 32
A command for transmission to the exchange 4 is issued via.

The layer 1 information separating section 36 is connected to the internal bus of the base station 3 and the layer 1 information memory 37, separates only the layer 1 control information transmitted from the subscriber terminal 1 to the exchange 4, and extracts the layer 1 information. Supply to the memory 37. The layer 1 information memory 37 is connected to the internal bus of the base station 3 and the layer 1 information separating section 36 and the layer 1 information combining section 38, respectively, and is always input from the layer 1 information separating section 36 from the latest subscriber terminal 1. The normal layer 1 information is stored, and the normal layer 1 information is output according to an instruction from the radio failure detection unit 35.

Next, the operation of this embodiment will be described with reference to the sequence diagram of FIG. First, it is assumed that ISDN communication is being performed between the subscriber terminal 1 and the exchange 4 (step 101). The state during ISDN communication is a state in which layers 1, 2, and 3 are normally communicating, and the call path is assumed to be transmitting Dch, Bch, and layer 1 information. The layer information separation unit 26 of the access terminal unit 2 separates only the layer 1 information from the exchange 4 that is constantly received and stores it in the layer 1 information memory 27, and also the layer information separation unit 36 of the base station 3. Also,
Only the layer 1 information from the subscriber terminal 1 that is constantly received is separated and stored in the layer 1 information memory 37.

The layer 1 information includes the exchange 4 and the subscriber terminal 1.
It is the activation / response information during the period and is transmitted as long as it is in communication. In addition, the setting of the wireless line may be instructed from the maintenance terminal 5 by a pre-assign method or a demand assign method.

When a wireless failure occurs in the ISDN communication state, the wireless failure detecting section 25 in the access terminal section 2 detects the wireless failure and issues an instruction to the wireless line releasing section 24 and the layer 1 information memory 27. First, the wireless line release unit 24 performs a wireless line release process (step 102),
Then, the layer 1 information (normal layer 1 information) stored in the layer 1 information memory 27 before the occurrence of the radio failure is output and transmitted to the subscriber terminal 1 via the interface unit 21 (step 103).

On the other hand, in parallel with this, in the base station 3 as well, the radio fault detection unit 35 detects a radio fault and issues an instruction to the radio line release unit 34 and the layer 1 information memory 37. To release the wireless line (step 104), then read the layer 1 information (normal layer 1 information) stored in the layer 1 information memory 37 up to the occurrence of the wireless fault, and set the line switch unit 32. It is transmitted to the exchange 4 via the server (step 105).

Since the layer 1 information transmitted to each of the subscriber terminal 1 and the exchange 4 is normal layer 1 information,
The subscriber terminal 1 and the exchange 4 do not recognize each other as a radio failure, and the subscriber terminal 1 recognizes that a path has been established with the exchange 4 as in the call, and the exchange 4 also has the subscriber terminal 1 as in the call. Recognize that the path has been set. Therefore, when the disconnection process is normally performed due to the layer 1 abnormality, in this embodiment, the exchange 4 and the subscriber terminal 1
Recognizes that the layer 1 path is normal, and therefore does not shift to the disconnection process.

Subsequently, the radio failure detection unit 35 issues a new radio line allocation instruction to the radio line setting unit 33. The wireless line setting unit 35 assigns a wireless line to the access terminal unit 2 (step 106). The access terminal unit 2 makes an allocation response to the allocation request for the new wireless line (step 107), and the wireless line setting unit 23 sets the ISD.
A wireless line path is set for transmitting Nch communication paths Dch, Bch, and layer 1 information (step 108). When the base station 3 receives the normal allocation response from the access terminal unit 2 (step 107), the wireless line setting unit 33 makes the ISD
A wireless line path is set for transmitting Dch, Bch, and layer 1 information, which are N speech paths (step 109). In addition,
The wireless line path may be assigned from the access terminal unit 2.

Then, immediately before the layer 1 communication is performed on the new wireless line, the output of the layer 1 information output from the layer 1 information memories 27 and 37 is stopped, and thereafter, the layer using the new wireless line is used. 1 information communication (step 110), subscriber terminal 1 and exchange 4 on the new wireless line
Communication is performed with (step 111). Also, by transferring the new wireless line information and the failure occurrence status to the maintenance terminal 5, the environment in which the device is installed can be grasped.

Here, the layer 2 operation will be supplemented.
Layer 2 is transmitted as a frame as shown in FIG. 6 and transfers control information. The layer 1 information is received without any signal and the communication is completely stopped, but the layer 2 retransmits by flow control. Therefore, even if there is no response from the other party, the layer 2 communication is not recognized as a disconnection unless a retransmission timeout occurs. .

For example, as shown in FIG. 5, in the wireless normal state, the exchange 4 transmits the layer 2 frame information to the subscriber terminal 1 (step 151), and in response thereto, the subscriber terminal 1 sends the exchange 4 to the exchange 4. When the layer 2 frame information is transmitted (step 152) and then the radio failure occurs, when the exchange 4 transmits the layer 2 frame information to the subscriber terminal 1 (step 153), the subscriber terminal 1 receives a response. Since there is no such information, the exchange 4 transmits the layer 2 frame information again (step 154).

When there is no response from the subscriber terminal 1 regarding the retransmission, the exchange 4 again transmits the layer 2 frame information (step 155). If the wireless line returns to the normal state immediately before this retransmission, the layer 2 frame information is received by the subscriber terminal 1 through the base station 3 (step 156). Therefore, the layer 2 frame is transferred from the subscriber terminal 1 to the exchange 4. An information response is sent (step 15).
7).

In this way, when a radio failure occurs, Layer 2
Even if the frame information response is interrupted, if the wireless line switching time in this embodiment is within the layer 2 retransmission time,
Layer 2 communication is not interrupted, and communication is continued as normal operation. Therefore, according to the present embodiment, even when a wireless failure occurs, the subscriber terminal 1 and the exchange 4 automatically switch the wireless line without recognizing the disconnection of the layer 1 communication and disconnect the layer 2 communication. Even if it is recognized, the transmission of the layer 2 frame information can be performed without any trouble by switching the wireless line within the layer 2 retransmission time, and the ISDN communication with high line quality can be continued.

The present invention is not limited to the above embodiment, and a plurality of subscriber terminals 1 may be provided, for example. However, in this case, it is necessary to provide a plurality of layer 1 information memories 27 in the access terminal unit 2 and a plurality of layer 1 information memories 37 in the base station 3. Moreover, the access terminal unit 2 may be movable.

[0035]

As described above, according to the present invention,
When a failure of the wireless line between the access terminal unit and the base station is detected, the normal information stored in the storage means before the failure of the wireless line is detected is output to the subscriber terminal and the exchange. Therefore, even if the wireless communication is cut off due to the failure of the wireless line, the subscriber terminal and the exchange do not recognize that the ISDN communication is cut off. In this state, the new wireless line is automatically switched to the ISDN communication. Can be continued, and an ISDN accommodating access control device with high line quality can be realized.

Further, according to the present invention, the setting for switching from the wireless line currently in communication to the new wireless line is performed by layer 2
Since it is performed within the retransmission time of, the layer 2 communication is not interrupted when the layer 2 is retransmitted after switching to a new wireless line, and the communication can be continued as a normal operation.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of an ISDN accommodating access control device in an access terminal unit.

FIG. 2 is a block diagram of an embodiment of an ISDN accommodating access control device in a base station.

FIG. 3 is a system configuration diagram in the case where an ISDN accommodating access control device using a wireless line to which the present invention is applied is installed.

FIG. 4 is a sequence diagram for explaining the operation of FIGS. 1 and 2.

FIG. 5 is a sequence diagram for explaining an operation of layer 2 communication.

FIG. 6 is a diagram showing an example of a frame.

FIG. 7 is a sequence diagram when a radio failure occurs in conventional ISDN communication.

FIG. 8 is a block diagram of an example of a conventional device.

[Explanation of symbols] 1 subscriber terminal 2 Access terminal section 3 base stations 4 exchanges 5 maintenance terminals 21 Interface part 22, 31 Wireless interface section 23, 33 Wireless line setting section 24, 34 Wireless circuit opening section 25, 35 Radio failure detection unit 26, 36 Layer 1 information separation unit 27, 37 Layer 1 information memory 32 line switch

Front page continuation (51) Int.Cl. ⁷ Identification code FI H04L 12/26 H04L 12/28 12/28 H04M 3/22 A H04M 3/22 H04B 7/26 K (58) Fields investigated (Int.Cl . ^7, DB name) H04M 3/00 H04M 3/16 - 3/40 H04L 12/00 - 12/28 H04L 12/44 - 12/46 H04L 12/50 - 12/66 H04B 7/24 - 7/26 H04B 17/00-17/02

Claims (6)

(57) [Claims] 1. An exchange containing an ISDN is connected to a base station, an access terminal unit for wirelessly communicating with the base station is connected to a subscriber terminal, and data from the exchange is passed through the base station and the access terminal unit. An ISDN system in which data received from the subscriber terminal and received from the subscriber terminal is received by the exchange through the access terminal unit and the base station, storing information from the exchange to the subscriber terminal. 1
Storage means, first failure detecting means for detecting a failure of a wireless line between the access terminal unit and the base station, and when the first failure detecting means detects a wireless failure,
After the information stored in the first storage means is output to the subscriber terminal, a first line setting means for setting a new wireless line is provided in the access terminal unit, Second to store information to the exchange
Storage means, second failure detection means for detecting a failure of a wireless line between the access terminal unit and the base station, and when the second failure detection means detects a wireless failure,
The base station is provided with second line setting means for setting the new wireless line after outputting the information stored in the second storage means to the exchange.
SDN accommodation access control device. 2. The ISDN accommodating access control device according to claim 1, wherein the first and second storage means respectively store layer 1 information. 3. The switching setting from the wireless line in communication up to now to the new wireless line by the first and second line setting means is performed within a retransmission time of layer 2. The ISDN accommodating access control device according to 1. 4. The first storage means comprises a first separation unit for separating layer 1 information transmitted from the exchange to the subscriber terminal, and the layer 1 separated by the first separation unit. A first memory for storing information, wherein the first line setting means performs a wireless line release processing for releasing a wireless line with the base station according to an instruction from the first failure detection means; The access terminal unit and a first wireless line setting unit for performing wireless line allocation and setting of the base station after the release process, wherein the second storage unit is a layer transmitted from the subscriber terminal to the exchange. A second separating unit that separates 1 information;
And a second memory for storing the layer 1 information separated by the second separating unit, wherein the second line setting means wirelessly communicates with the base station according to an instruction from the second failure detecting means. 2. A wireless line opening unit that performs a line opening process, and a second wireless line setting unit that performs wireless line allocation and setting of the access terminal unit and the base station after the opening process. The ISDN accommodating access control device described. 5. When a wireless failure is detected by the first and second failure detecting means, a new wireless line allocation request is made from one of the access terminal unit and the base station to the other, and the request and the The new wireless line is set in each of the access terminal unit and the base station in response to a request from the other of the access terminal unit and the base station, and then stored in the first storage unit. Outputting the information to the subscriber terminal and outputting the information stored in the second storage means to the exchange, and then shifting to communication using the new wireless line. The ISDN accommodating access control device according to claim 1. 6. The base station according to claim 1, wherein the base station is connected via a network to a maintenance terminal for monitoring and remote controlling the base station, the access terminal unit and the subscriber terminal. ISDN accommodating access control device.