Synchronizing Clocks in a Communications Network

Patent metadata

Field	Value
Publication number	US-2017195110-A1
Application number	US-201514895162-A
Country	US
Kind code	A1
Filing date	Oct 2, 2015
Priority date	Oct 2, 2015
Publication date	Jul 6, 2017
Grant date	—

Abstract

A User Equipment comprises a master clock, for example a Precision Time Protocol, PTP, or Precision Time Control Protocol, PTCP, network clock. The User Equipment further comprises circuitry configured to set the master clock based on signals from a wireless communications network node and a time offset, wherein the time offset is based on the propagation delay between the wireless network node and the User Equipment. The circuitry is further configured to send timing information to a network device in a communications network having a slave clock, whereby the network device can synchronize its slave clock with respect to the master clock comprised within the User Equipment.

First claim

1 . A method, performed by a User Equipment, comprising:
receiving reference signals from a wireless communications network node; obtaining a time offset, wherein the time offset is based on the propagation delay of the reference signals; setting a master network clock comprised within the User Equipment based on the reference signals and the time offset; and sending timing information to a network device having a slave network clock in a communications network using the master clock.

2 . A method according to claim 1 , wherein the timing information is such that the network device in the communications network can synchronize its slave clock with respect to the master clock comprised within the User Equipment.

3 . A method according to claim 1 , wherein the master clock is at least one of: a Precision Time Protocol, PTP, network clock; and
a Precision Time Control Protocol, PTCP, network clock.

4 . A method according to claim 1 , wherein the timing information comprises one or more time stamps generated by the master clock.

5 . A method according to claim 1 , wherein sending the timing information to the network device comprises sending the timing information according to a time synchronization protocol specified in IEEE 1588.

6 . A method according to claim 1 , wherein the reference signals comprise at least one of:
Primary Synchronization Signals, PSS; Secondary Synchronization Signals, SSS;

7 . A method according to claim 1 , wherein obtaining the time offset comprises determining the time offset from at least one of:
location information of the User Equipment; and a Timing Advance value specified in TS 36.133.

8 . A method according to claim 1 , comprising setting the master clock by:
setting a first time part comprised within the User Equipment based on the reference signals; applying the time offset to the first time part; wherein the first time part provides a synchronization signal to the master clock.

9 . A method according to claim 8 , wherein the synchronization signal is an electrical signal comprising one or more synchronization pulses.

10 . A method according to claim 8 , wherein the first time part maintains time using time units specified by a radio access technology,
wherein the master clock maintains time using different time units from the first time part.

11 . A method according to claim 9 , further comprising providing an absolute time reference associated with the electrical signal comprising one or more synchronization pulses to the master clock.

12 . A User Equipment comprising:
a master clock; a receiving unit for receiving reference signals from a wireless communications network node; an obtaining unit for obtaining a time offset, wherein the time offset is based on the propagation delay of the reference signals; a setting unit for setting the master clock based on the reference signals and the time offset; and a sending unit for sending timing information to a network device having a slave clock in a communications network using the master clock.

13 . A system comprising:
a User Equipment according to claim 12 ; and a network device having a slave clock; wherein the network device comprises: a receiving unit for receiving the timing information from the User Equipment; and a synchronizing unit for synchronizing its slave clock with respect to the master clock comprised within the User Equipment based on the timing information.

14 . A system according to claim 13 , wherein the network device is configured according to a PROFINET I 0 protocol specified in IEC61784-2.

15 . A communications network comprising:
a first network device having a first slave clock; a second network device having a second slave clock; a first User Equipment according to claim 12 ; and a second User Equipment according to claim 12 ; wherein the first network device comprises a receiving unit for receiving the timing information from the first User Equipment and a synchronizing unit for synchronizing its slave clock with respect to the master clock comprised within the first User Equipment based on the timing information received from the first User Equipment; and wherein the second network device comprises a receiving unit for receiving the timing information from the second User Equipment and a synchronizing unit for synchronizing its slave clock with respect to the master clock comprised within the second User Equipment based on the timing information received from the second User Equipment.

16 . A communications network according to claim 15 , wherein the first network device is arranged to communicate with the second network device over a wireless communications network.

17 . A computer program configured to, when run on a processor, cause the processor to perform the method of claim 1 .

Assignees

• Ericsson Telefon Ab L M

Inventors

• Ruffini Stefano
• Breschel Michael
• Harmatos János
• Miklós György
• Sandgren Magnus

Classifications

• H04L7/0016 Primary

  correction of synchronization errors · CPC title

• H04W56/0015 Primary

  one node acting as a reference for the others · CPC title

• H04W56/0045

  compensating for timing error by altering transmission time · CPC title

• H04W84/20

  Leader-follower arrangements · CPC title

• H04W56/00

  Synchronisation arrangements · CPC title