Communications network

Patent metadata

Field	Value
Publication number	US-10637601-B2
Application number	US-201515525864-A
Country	US
Kind code	B2
Filing date	Nov 10, 2015
Priority date	Nov 10, 2014
Publication date	Apr 28, 2020
Grant date	Apr 28, 2020

Abstract

A fixed communication network is disclosed in which a plurality of transmitters feed signals via tributary transmission lines of different lengths onto a shared network component. A timing reference signal is distributed to the transmitters. The shared network component in some embodiments takes the form of a transmission line. In order to enable the sharing of the capacity of the shared network component, each of the plurality of transmitters codes data for transmission in accordance with a code division multiple access scheme. The efficiency of usage of the shared network component is improved by synchronizing the arrival of the encoded bits at the shared network component. This is achieved by populating a store within each transmitter with a pre-set timing offset, and timing the transmission of data in accordance with the timing reference signal received by the transmitters and the pre-set timing offset.

First claim

The invention claimed is:

1. A fixed network comprising:
a trunk transmission line;
a plurality of tributary transmission lines, wherein a length of at least one of the tributary transmission lines is different from the other tributary transmission lines;
one or more signal couplers operable to couple the plurality of tributary transmission lines and the trunk transmission line; and
a plurality of transmitters each being operable to transmit a traffic data signal onto one of the tributary transmission lines, the traffic data signal representing traffic data symbols encoded in accordance with a code division multiple access (CDMA) coding scheme, each transmitter having access to a network timing signal and comprising a pre-set time offset store storing a pre-set time offset related to a measured signal travel time within the network specific to the respective transmitter,
wherein each of the transmitters is arranged in operation to transmit the traffic data signals onto the tributary transmission line at a time dependent upon the network timing signal and the pre-set time offset stored in the pre-set time offset store, to synchronize the encoded traffic data symbols on the trunk transmission line.

2. A network according to claim 1 wherein the trunk transmission line comprises a trunk optical fiber, the one or more signal couplers comprise optical couplers and the tributary transmission lines comprise tributary optical fiber.

3. A network according to claim 1 wherein the network timing signal comprises a clock signal.

4. A network according to claim 3 wherein a rate of the clock signal is equal to a symbol rate of the traffic to be encoded by each of the transmitters.

5. A transmission system for use in a fixed communications network which has a plurality of tributary transmission lines coupled by one or more signal couplers to a trunk transmission line, a length of at least one of the tributary transmission lines being different from the other tributary transmission lines, the transmission system comprising:
a modulator for transmitting a traffic data signal, representing traffic data encoded in accordance with a code division multiple access (CDMA) coding scheme, on one of the plurality of tributary transmission lines;
a pre-set time offset store storing a pre-set time offset related to a measured signal travel time within the fixed communications network for the transmission system; and
a timing regulator having access to the pre-set time offset store, the timing regulator being operable to control the transmission system to output the traffic data signal at a time dependent on a network timing signal and the pre-set time offset stored in the pre-set time offset store.

6. A transmission system according to claim 5 further comprising an encoder operable to encode traffic data symbols in accordance with a code division multiple access coding scheme.

7. A transmission system according to claim 6 wherein the timing regulator is arranged to receive the traffic data symbols and to delay the input of the traffic data to the encoder to a time dependent upon the network timing signal and the pre-set time offset stored in the pre-set time offset store.

8. A transmission system according to claim 7 wherein the timing regulator comprises:
a buffer; and
a buffer controller arranged in operation to buffer traffic data symbols until a time dependent upon the network timing signal and the pre-set timing offset, whereupon the traffic data symbols are passed to the encoder.

9. A timing regulator for use in association with one of a plurality of transmitters in a fixed communications network comprising a trunk transmission line, a plurality of tributary transmission lines, wherein a length of at least one of the tributary transmission lines is different from the other tributary transmission lines, and one or more signal couplers operable to couple the plurality of tributary transmission lines and the trunk transmission line, the transmitter being operable to transmit a traffic data signal onto one of the tributary transmission lines, the traffic data signal representing traffic data symbols encoded in accordance with a code division multiple access coding scheme, the timing regulator comprising:
a traffic data signals input interface;
a traffic data signals output interface;
a timing signal input interface; and
a pre-set time offset store storing a pre-set time offset related to a measured signal travel time within the fixed communications network for the transmitter,
wherein the timing regulator receives a network timing signal via the timing signal input interface, and is operable to receive input traffic data signals via the input interface and to control the transmitter to output traffic data signals from the traffic data signals output interface at a time dependent on the network timing signal and the pre-set time offset stored in the pre-set time offset store to synchronize the encoded traffic data symbols on the trunk transmission line.

10. A timing regulator according to claim 9 further comprising:
a traffic data buffer; and
a traffic data buffer controller arranged in operation to buffer traffic data for an amount of time dependent upon the network timing signal received via the timing signal input interface and the pre-set time offset, before transmitting the traffic data from the traffic data signals output interface.

Assignees

• British Telecomm

Inventors

• Zoualfaghari Mohammad

Classifications

• H04J14/005 Primary

  Optical Code Multiplex · CPC title

• H04J13/16

  Code allocation · CPC title

• H04B7/2628

  using code-division multiple access [CDMA] or spread spectrum multiple access [SSMA] (H04B7/2618 takes precedence) · CPC title