Communications system

Details Communications system Communications system

1998-08-27

2003-05-13

Olms, Douglas (Department: 2661)

Multiplex communications

Communication techniques for information carried in plural...

Combining or distributing information via time channels

C370S536000, C370S537000

Reexamination Certificate

active

06563842

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to a communications system and, more particularly, to a communications system in which a plurality of transmission devices provided on the subscriber side and a single transmission device provided on the side of a switch are connected by high-speed digital transmission lines and subscriber terminals are connected to the transmission devices on the subscriber side, whereby the subscriber terminals are accommodated by the switch.
In currently existing subscriber-based optical transmission systems, the configuration is such that a plurality of COT transmission devices (COT is the abbreviation of “Central Office Terminal”) are provided on the side of a switch, a plurality of RT transmission devices (RT is the abbreviation of “Remote Terminal”) are provided on the subscriber side and each COT transmission device and its corresponding RT transmission device are connected by a single high-speed digital transmission line (e.g., a high-speed optical transmission line). The RT transmission devices are deployed at remote locations, such as in office buildings, towns and villages.
FIG. 10
is a block diagram illustrating the configuration of a subscriber-based optical transmission system according to the prior art. The system includes an exchange
1
having a switch
2
and COT transmission devices
3
A-
3
N, ordinary household telephones or public telephones
4
A-
4
N provided at remote locations, RT transmission devices
5
A-
5
N provided at remote locations and optical transmission lines
6
A-
6
N for connecting the COT transmission devices
6
and corresponding RT transmission devices.
The RT transmission devices
5
A-
5
N respectively include subscriber circuits
7
1
-
7
n
connected to corresponding telephones, CODECs (coder/decoders)
8
1
-
8
n
for converting analog signals, which enter from the subscriber circuits, to digital signals and converting digital signals, which enter from the side of the transmission lines, to analog signals, channel units
9
1
-
9
n
for performing a unipolar/bipolar conversion and for inserting and extracting various control data, a multiplexer/demultiplexer
10
for multiplexing digital signals, which enter from the CODECs via the channel units, and sending the multiplexed signals to the side of the optical transmission lines, and for demultiplexing multiplexed data, which enters from the side of the optical transmission lines, and outputting the demultiplexed signals to prescribed channels units, and optical terminal equipment
11
for converting electric signals to optical signals and sending the optical signals to the optical transmission lines
6
A-
6
N, and for converting optical signals, which enter from the optical transmission lines, to electric signals and outputting the electric signals.
The COT transmission devices
3
A-
3
N respectively include channel units
12
1
-
12
n
for performing a unipolar/bipolar conversion and for inserting and extracting various control data, a multiplexer/demultiplexer
13
for multiplexing digital signals, which enter from the switch
2
via the channel units, and sending the multiplexed signals to the side of the optical transmission lines, and for demultiplexing multiplexed data, which enters from the side of the optical transmission lines, and outputting the demultiplexed signals to the switch, and optical terminal equipment
14
for converting electric signals, which enter from the multiplexer/demultiplexer, to optical signals and sending the optical signals to the optical transmission lines
6
A-
6
N, and for converting optical signals, which enter from the optical transmission lines
6
A-
6
N, to electric signals and outputting the electric signals.
FIG. 11
is a block diagram illustrating the detailed construction of an RT transmission device.
Remote telephones
4
A with which the RT transmission device
5
A is provided are divided into n groups of m telephones each. The m telephones
4
11
-
4
1m
of a first group are connected to subscriber circuits
7
11
-
7
1m
of a first group and the subscriber circuits
7
11
-
7
1m
are in turn connected to CODECs
8
11
-
8
1m
. The CODECs
8
11
-
8
1m
convert voice signals, which enter from the telephones
4
11
-
4
1m
, to 64-Kbps digital signals and input the digital signals to the multiplexer/demultiplexer
10
via channel devices
9
11
-
9
1m
. The multiplexer/demultiplexers
10
of the respective groups concentrate and time-division multiplex (m≦32) 64-Kbps digital signals of a maximum of 32 channels, which have entered via the m channel units
9
11
-
9
1m
, and output the multiplexed signals on signal lines L
1
-L
n
as 2-Mbps digital signals. A multiplexer/demultiplexer
10
′ further multiplexes the 2-Mbps time-division multiplexed data, which enters from the multiplexer/demultiplexers
10
of the 1st-nth groups via the signal lines L
1
-L
n
, to 34-Mbps or 150-Mbps data (assumed here to be 34-Mbps data) and outputs the data to the optical transmission line
6
A from the optical transmission unit
11
.
Further, 34-Mbps time-division multiplexed data, which has entered from the switch
2
via the optical transmission line
6
A and optical transmission unit
11
, is demultiplexed to 2-Mbps time-division multiplexed data by the multiplexer/demultiplexer
10
′, and this data enters the multiplexer/demultiplexers
10
of the 1st-nth groups. The multiplexer/demultiplexer
10
of each group converts the 2-Mbps time-division multiplexed data to 64-Kbps digital data of a maximum of 32 channels and inputs the digital signals to prescribed CODECs via the channel devices. Each CODEC to which a digital signal has been input converts the digital signal to an analog signal and inputs the analog signal to a telephone.
FIG. 12
is a block diagram showing the construction of the exchange. The COT transmission devices
3
A-
3
N are provided to correspond to the remote RT transmission devices
5
A-
5
N and are connected to the RT transmission devices
5
A-
5
N via the optical transmission lines
6
A-
6
N. Further, the COT transmission devices
3
A-
3
N are connected to the switch
2
via n-number of the 2-Mbps signal lines L
1
-L
n
. The 34-Mbps time-division multiplexed data sent from the RT transmission devices
5
A-
5
N enter the COT transmission devices
3
A-
3
N via the optical transmission lines
6
A-
6
N. The optical transmission unit
14
in each of the COT transmission devices
3
A-
3
N converts the optical signal to an electric signal and inputs the electric signal to the multiplexer/demultiplexer
13
. The latter demultiplexes the 34-Mbps time-division multiplexed data to 2-Mbps digital signals and inputs the demultiplexed signals to the switch
2
via the channel units
12
1
-
12
n
and signal lines L
1
-L
n
. The multiplexer/demultiplexers
13
of the respective COT transmission devices
3
A-
3
N multiplex the 2-Mbps digital signals, which have entered from the switch
2
via the signal lines L
1
-L
n
and channel units
12
1
-
12
n
, to 34-Mbps data and send the data to the optical transmission lines
6
A-
6
N from the optical transmission units
14
.
In accordance with this subscriber-based optical transmission system, (1) the RT transmission devices
5
A-
5
N correspond to the COT transmission devices
3
A-
3
N within the exchange
1
, and (2) the 2-Mbps time-division multiplexed data on the signal lines L
1
-L
n
(
FIG. 11
) within the RT transmission device
5
A matches the 2-Mbps time-division multiplexed data on the signal lines L
1
-L
n
(
FIG. 12
) within the exchange
1
. Similarly, the 2-Mbps time-division multiplexed data on the signal lines L
1
-L
n
within the RT transmission devices
5
B-
5
N matches the 2-Mbps time-division multiplexed data on the signal lines L
1
-L
n
connected to the COT transmission devices
3
B-
3
N within the exchange
1
.
As a result, regardless of the fact that the COT transmission devices
3
A-
3
N on the switch side and the RT transmission device
5
A-
5
N at the remote areas are connected by the single optical transmission lines
6
A-
6
N, the arrangeme

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