JPH1117688A - Transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transmit ATM signals and telephone signals by using identical ATM subscriber network, without damaging transmission quality by separating the ATM signals and the telephone signals in an ATM subscriber network terminating equipment, connecting the AT signals to an ATM network and connecting the telephone signals to a PDH network which is operated by a clock different from the one in the ATM network. SOLUTION: To a subscriber terminal 1, a digital terminal 4 connected to the ATM network 3 is connected, and also an analog telephone set 6 connected to the PDH network 5 is connected. An ATM subscriber terminating equipment 2 is connected to the ATM network 3, multiplexes the telephone signals to PDH signals, and connects them to the PDH network 5. Then, the telephone signals provided with a band of 3.1 kHz are transmitted by a clock synchronized with the clock of the PDH network 5. Further, the telephone signals are converted into PCM signals, multiplexed with the ATM signals, and transmitted and received as the ATM signals. Consequently, the telephone signals and the ATM signals are transmitted by using the ATM subscriber network without degrading the quality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission system for an ATM subscriber network, and more particularly, to a method for transmitting 3.1 kHz using an ATM subscriber network.
Transmits telephone signals with a bandwidth of z and converts ATM signals to ATM
The present invention relates to a transmission system having a subscriber terminal for connecting a telephone signal to a PDH network which is an existing synchronous digital network by connecting to a network, and an ATM subscriber network terminator.

[0002]

2. Description of the Related Art As a method of transmitting a telephone signal having a bandwidth of 3.1 kHz using an ATM subscriber network, connecting the ATM signal to the ATM network, and connecting the telephone signal to the existing PDH network, A terminal modulates an ATM signal into an analog signal by using a modem, FDM multiplexes the modulated signal with a telephone signal having a bandwidth of 3.1 kHz, and transmits the resultant signal. 2. Description of the Related Art There is known a method of separating an ATM signal into an ATM signal and connecting a telephone signal to an existing PDH network.

[0003]

A first problem is that, in the prior art, an ATM signal is converted into an analog signal and transmitted, so that an error occurs in the ATM signal due to noise on a transmission line.

[0004] The reason for this is that an ATM signal, which is a digital signal, is multiplexed with a telephone signal, which is an analog signal.
This is because the M signal is converted into an analog signal.

A second problem is that the conventional technique cannot be applied to an ATM subscriber network using an optical fiber.

The reason is that optical communication using an optical fiber is generally used for digital communication, and a special technique is required for transmitting an analog signal.

An object of the present invention is to convert a telephone signal having a bandwidth of 3.1 kHz into a digital signal, multiplex the digital signal with an ATM signal, and transmit the multiplexed signal through an ATM subscriber network. The ATM signal is connected to an ATM network, and the telephone signal is connected to a PDH network operating at a clock different from that of the ATM network.
M signal and telephone signal have the same A without loss of transmission quality
An object of the present invention is to provide a transmission system for transmitting data using a TM subscriber network.

[0008]

According to the present invention, a transmission system comprises:
A transmission system for transmitting a telephone signal having a band of 3.1 kHz using a TM subscriber network, connecting an ATM signal to an ATM network, and connecting the telephone signal to a PDH network which is an existing synchronous digital network. Converting an analog signal of 3.1 kHz into a PCM signal, converting the PCM signal into an ATM cell, multiplexing the ATM cell with the ATM signal,
ATM transmission means for transmitting a signal to an ATM subscriber network;
The ATM signal is received from the TM subscriber network and the received ATM is received.
The specified cell is separated from the signal, the PCM signal in the cell is separated and written into the buffer, and the PCM signal is read out from the buffer using a clock described later to be 3.1 kHz.
A subscriber terminal having an ATM receiving means for generating a clock control signal by detecting a phase difference between a write clock and a read clock of a buffer, and generating a clock in accordance with the clock control signal;
Receiving an ATM signal from a subscriber terminal via a subscriber network, separating a designated cell from the received ATM signal,
PDH transmitting means for separating a PCM signal in a cell, multiplexing the PCM signal with a PDH signal which is an existing synchronous digital signal and outputting the same to a PDH network, separating a PCM signal from the PDH signal, and separating the separated PCM signal ATM cells are multiplexed into ATM cells, and ATM signals are multiplexed into ATM cells.
And an ATM subscriber network terminating device having at least PDH receiving means for transmitting to the TM subscriber network.

The subscriber terminal of the transmission system according to the present invention is an ATM terminal.
A clock synchronized with the clock of the PCM signal transmitted by the subscriber network cleaning device is generated. More specifically, a phase comparator (8 in FIG. 2) for comparing a write clock for writing a PCM signal received from the ATM subscriber network termination device to a buffer (19 in FIG. 2) and a read clock for reading from the buffer is used. Have.

Further, the telephone signal is converted into a PCM signal to
Another feature is that the data is converted into a TM cell, multiplexed with an ATM signal, and transmitted and received as an ATM signal. More specifically, it has an A / D converter (7 in FIG. 2) and a D / A converter (20 in FIG. 2) for converting a telephone signal into a PCM signal.
An ATM cell unit that multiplexes a CM signal into an ATM signal (FIG. 2)
11) and an ATM decelerator (17 in FIG. 2).

Another feature is that the PCM signal of the PDH network is converted into an ATM cell, multiplexed with the ATM signal, and transmitted and received as an ATM signal. More specifically, P
A PDH separation unit (28 in FIG. 3) that separates the DH signal into a PCM signal, a PDH multiplexing unit (27 in FIG. 3) that multiplexes the PCM signal into a PDH signal, and an AAL5 cell that converts the PCM signal into ATM cells. 3 (30 in FIG. 3) and an AAL5 decelerating unit (25 in FIG. 3).

The transmission system according to the present invention uses a clock and an ATM for converting a telephone signal into a PCM signal in a subscriber terminal.
PCM receiving and generating a clock control signal by comparing with a clock of a PCM signal received from a subscriber network terminating device
By generating a clock synchronized with the clock of the signal, a clock synchronized with the clock of the PDH network is generated.

[0013] Further, according to the transmission method of the present invention, a subscriber terminal converts a telephone signal into a PCM signal, converts it into an ATM cell, multiplexes the ATM signal with the ATM signal, transmits the multiplexed signal to an ATM subscriber network terminator, and subscribes to the ATM. Multiplexing to PDH signal without conversion to analog signal in the network
In the M subscriber network terminating device, the PDH signal is separated into PCM signals, converted into ATM cells, multiplexed with ATM signals, and transmitted to the subscriber terminals.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an example of an ATM subscriber network constituted by a subscriber terminal 1 and an ATM subscriber network terminating device 2 according to the present invention. A digital terminal 4 connected to the ATM network 3 is connected to the subscriber terminal 1 installed in the subscriber's house.
An analog telephone 6 connected to the DH network 5 is connected.
The ATM subscriber network terminator 2 terminates the ATM subscriber network and connects to the ATM network 3, and terminates the telephone signal transmitted by using the ATM subscriber network to multiplex the telephone signal into a PDH signal to generate a PH signal.
Connect to DH network 5.

[0016]

FIG. 2 shows an example of the configuration of a subscriber terminal 1 according to the present invention. The A / D converter 7 converts a telephone signal of the analog telephone 6 having a band of 3.1 kHz into a PCM signal using the clock generated by the clock generator 8 (see ITU-T Recommendation G.711). In the present embodiment, the digital signal connected to the ATM network 3 and the PCM signal described above are converted to AAL5 (ATM5).
Cellification into ATM cells using adaptation layer 5)
An example of decellularization from an ATM cell is shown (ITU-
T Recommendation I. 363). That is, the digital signal is A
The cell is converted into an ATM cell by the AL5 cell conversion unit 9 and P
The CM signal is packetized by the packet generator 10 and then cellized by the AAL5 cell generator 11,
The signal is multiplexed into an ATM signal by an M
It is transmitted by the M transmitter 13 to the ATM subscriber network. The ATM signal received by the ATM receiver 14 is separated by an ATM separator 15 into a cell having a digital signal as a payload and a cell having a PCM signal as a payload, and the cell having a digital signal as a payload is converted into an AAL5 decellularizer 16. The AAL5 decellularization unit 17 converts a cell having a PCM signal as a payload into a packet.

Generally, the clock of the ATM network 3 and the PDH network 5
Are different from each other, when the telephone signal of the analog telephone 6 is digitized in the subscriber terminal 1 using the clock of the ATM network 3, an error occurs due to the phase difference of the clock when connecting to the PDH network 5. Resulting in.

The packet decomposing unit 18 is adapted to transmit the PCM in the packet.
The signal is separated and the PCM signal is input to the buffer 19,
The / A converter 20 reads out the PCM signal from the buffer 19 according to the clock generated by the clock generator 8. The phase comparator 21 compares the phase difference between the write clock and the read clock of the buffer 19 and generates a clock control signal for lowering the clock frequency when the write clock is faster than the read clock, and the write clock is higher than the read clock. If it is slow, a clock control signal for increasing the clock frequency is generated. The clock generator 8 generates a clock synchronized with the clock of the PCM signal received from the ATM subscriber network terminating device according to the clock control signal, thereby generating a clock synchronized with the clock of the PDH network 5 and A / D conversion. To the converter 7 and the D / A converter 20. The D / A converter 20 converts the PCM signal into an analog signal and outputs it.

FIG. 3 shows an example of the configuration of an ATM subscriber network terminating apparatus according to the present invention. The ATM signal of the ATM subscriber network received by the ATM receiver 22 is separated by an ATM separator 23 into cells output to the ATM network and cells having a PCM signal obtained by digitizing a telephone signal as a payload. A
The cells output to the TM network are output to the ATM network by the ATM transmitter 24 as they are. A cell having a PCM signal as a payload is converted into a packet by the AAL5 decellularization unit 25 and converted into a PCM signal by the packet disassembly unit 26. The PDH multiplexing unit 27 includes a packet decomposing unit 26.
Output PCM signal, for example, 2.048 Mbps
Multiplexed with the PDH signal and output to the PDH network (ITU
-T Recommendation G. 732). An input signal from the PDH network is received by the PDH separation unit 28, decomposed into a PCM signal, and input to the packet generation unit 29. The packet generator 29 generates a packet from the PCM signal, and the AAL5 cell generator 30 converts the packet into ATM cells.
The ATM multiplexing unit 31 multiplexes the ATM cell generated by the AAL5 cell conversion unit 30 and the ATM cell received by the ATM receiver 32, and the ATM transmitter 33 converts the ATM signal into an AT signal.
Output to M subscriber network.

FIG. 4 shows an example of the configuration of a cell when a PCM signal transmitted and received between the subscriber terminal 1 and the ATM subscriber network terminating device 2 is converted into an ATM cell using the AAL5 (ITU-I). T Recommendations I.361 and I.366).
In this example, 32 bytes of the PCM signal are converted into one cell, but other configurations are also possible.

[0021]

The first effect is that a telephone signal having a band of 3.1 kHz can be transmitted using the ATM subscriber network without deteriorating the quality.

The reason is that a telephone signal having a band of 3.1 kHz is digitally converted by a clock synchronized with a clock of the PDH network and transmitted.

The second effect is that the ATM signal can be transmitted without deteriorating the quality.

The reason is that a telephone signal having a band of 3.1 kHz is converted into a PCM signal, multiplexed with an ATM signal, and
This is because an ATM signal is transmitted without being converted into an analog signal by being transmitted and received as a TM signal.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of an ATM subscriber network configured using a subscriber terminal and an ATM subscriber network terminating device of the present invention.

FIG. 2 is a block diagram showing a configuration of an embodiment of a subscriber terminal according to the present invention.

FIG. 3 is a block diagram showing a configuration of an embodiment of the ATM subscriber network terminating apparatus of the present invention.

FIG. 4 is a diagram showing a configuration example of an ATM cell transmitted / received between a subscriber terminal and an ATM subscriber network terminating apparatus according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 subscriber terminal 2 ATM subscriber network terminating device 3 ATM network 4 digital terminal 5 PDH network 6 analog telephone 7 A / D converter 8 clock generation unit 9 AAL5 cell conversion unit 10 packet generation unit 11 AAL5 cell conversion unit 12 ATM multiplexing Decomposition unit 13 ATM transmitter 14 ATM receiver 15 ATM separation unit 16, 17 AAL5 decellularization unit 18 Packet decomposition unit 19 Buffer 20 D / A converter 21 Phase comparator 22 ATM receiver 23 ATM separation unit 24 ATM transmitter 25 AAL5 decellularizing unit 26 packet decomposing unit 27 PDH multiplexing unit 28 PDH demultiplexing unit 29 packet generating unit 30 AAL5 cellifying unit 31 ATM multiplexing unit 32 ATM receiver 33 ATM transmitter

Claims (7)

[Claims] 1. A telephone signal having a bandwidth of 3.1 kHz is transmitted using an ATM subscriber network. The ATM signal is connected to an ATM network, and the telephone signal is connected to a PDH network which is an existing synchronous digital network. In the transmission system in the system, an analog signal of 3.1 kHz is converted into a PCM signal, the PCM signal is converted into an ATM cell, the ATM cell is multiplexed with an ATM signal, and the ATM signal is transmitted to an ATM subscriber network. ATM transmission means and A from the ATM subscriber network
A TM signal is received, a designated cell is separated from the received ATM signal, a PCM signal in the cell is separated and written into a buffer, and a PCM signal is read out from the buffer using a clock described later to be 3.1 kHz. A subscriber terminal having ATM receiving means for generating a clock control signal by detecting a phase difference between a write clock and a read clock of the buffer, and generating a clock in accordance with the clock control signal; Receiving an ATM signal from a subscriber terminal via a subscriber network, separating a specified cell from the received ATM signal, separating a PCM signal in the cell,
PDH transmitting means for multiplexing a signal into a PDH signal which is an existing synchronous digital signal and outputting the multiplexed signal to a PDH network;
Separating the PCM signal from the DH signal;
Converting the signal into ATM cells and converting the ATM cells to ATM cells.
An ATM subscriber network terminating device having at least PDH receiving means for multiplexing the ATM signal and transmitting the ATM signal to an ATM subscriber network. 2. The ATM transmitting means converts an analog signal of 3.1 kHz into a PCM signal.
/ D conversion means; ATM cell conversion means for converting the PCM signal into ATM cells; ATM multiplexing means for multiplexing the ATM cells into ATM signals; and transmission means for transmitting the ATM signal to an ATM subscriber network. The transmission method according to claim 1, further comprising a subscriber terminal including: 3. The ATM receiving means comprises: a receiving means for receiving an ATM signal from an ATM subscriber network; an ATM separating means for separating a specified cell from the received ATM signal; and a PCM signal in the cell. ATM decellularizing means for writing to the buffer means, and reading out the PCM signal from the buffer means using a clock generated by a clock generating means to be described later from the buffer means, and
D / A conversion means for converting to an analog signal of Hz, phase comparison means for detecting a phase difference between a write clock and a read clock of the buffer means to generate a clock control signal, and generating a clock according to the clock control signal 2. The transmission system according to claim 1, further comprising: a subscriber terminal including at least the A / D converter and a clock generator that supplies the clock to the D / A converter. 4. An ATM receiving means for receiving an ATM signal from a subscriber terminal via an ATM subscriber network, an ATM separating means for separating a specified cell from the received ATM signal, ATM decellularizing means for separating the PCM signal in the cell, and converting the PCM signal into an existing synchronous digital signal P
2. The transmission system according to claim 1, further comprising: an ATM subscriber network terminating device including at least: 5. A PDH receiving means, a PDH separating means for separating a PCM signal from the PDH signal, and an AT for converting the separated PCM signal into an ATM cell.
An ATM subscriber network terminating device comprising at least: an M cell converting means; an ATM multiplexing means for multiplexing the ATM cell into an ATM signal; and an ATM transmitting means for transmitting the ATM signal to an ATM subscriber network. 1. The transmission method according to 1. 6. A telephone signal having a bandwidth of 3.1 kHz is transmitted using an ATM subscriber network, and the ATM signal is connected to the ATM network to convert the telephone signal into an existing synchronous digital network P.
In a subscriber terminal in an ATM subscriber network connected to a DH network, a 3.1 kHz analog signal is converted into a PCM signal.
/ D conversion means; ATM cell conversion means for converting the PCM signal into ATM cells; ATM multiplexing means for multiplexing the ATM cells into ATM signals; and transmission means for transmitting the ATM signal to an ATM subscriber network. ATM transmitting means including: ATM receiving means for receiving an ATM signal from an ATM subscriber network; ATM separating means for separating a specified cell from the received ATM signal; Reading out the PCM signal from the buffer means, using a clock generated by a clock generating means described later, from the buffer means;
D / A conversion means for converting to an analog signal of Hz, phase comparison means for detecting a phase difference between a write clock and a read clock of the buffer means to generate a clock control signal, and generating a clock according to the clock control signal And a clock generating means for supplying the A / D converting means and the D / A converting means to the subscriber terminal. 7. A telephone signal having a bandwidth of 3.1 kHz is transmitted using an ATM subscriber network, and the ATM signal is connected to the ATM network to convert the telephone signal into an existing synchronous digital network P.
An ATM subscriber network terminating device in an ATM subscriber network connected to a DH network, comprising: a receiving means for receiving an ATM signal from a subscriber terminal via the ATM subscriber network; and a cell designated from the received ATM signal. ATM separating means for separating the PCM signal in the cell; ATM decellularizing means for separating the PCM signal in the cell;
PDH multiplexing means for multiplexing with a DH signal and outputting to a PDH network; PDH transmitting means including: a PDH separating means for separating a PCM signal from the PDH signal; and converting the separated PCM signal into ATM cells. AT
An ATM characterized by comprising PDH receiving means including at least M cell means, ATM multiplexing means for multiplexing the ATM cells into ATM signals, and transmitting means for transmitting the ATM signals to an ATM subscriber network. Subscriber network terminator.