Timing synchronization for small cells with limited backhaul

Patent metadata

Field	Value
Publication number	US-10129844-B2
Application number	US-201615333752-A
Country	US
Kind code	B2
Filing date	Oct 25, 2016
Priority date	Oct 30, 2015
Publication date	Nov 13, 2018
Grant date	Nov 13, 2018

Abstract

A telecommunication system includes base stations, a backhaul network transmitters, a backhaul network in communication with the base stations, and a synchronizing system in communication with the base stations. The base stations are configured to transmit/receive signals to/from user equipment and the backhaul network is configured to convey information to and from at least one of the base stations. The synchronizing system is configured to synchronize a communication timing between the base stations over a synchronizing network. The synchronizing network is separate from the backhaul network and is configured to provide the communication timing between the synchronizing system and a corresponding synchronization port at each of the base stations.

First claim

What is claimed is:

1. A telecommunication system comprising:
base stations configured to transmit/receive signals to/from user equipment;
a backhaul network in communication with the base stations and configured to convey information to and from at least one of the base stations;
a synchronizing system in communication with the base stations and configured to synchronize a communication timing between the base stations over a synchronizing network, the synchronizing network is separate from the backhaul network and is configured to provide the communication timing between the synchronizing system and a corresponding synchronization port at each of the base stations, the synchronizing system comprising one of a network switch or a pulse-per-second splitter in communication with the synchronization ports at each of the base stations,
wherein, when the synchronizing system comprises the pulse-per-second splitter, a first base station designated as a first grandmaster base station after waking up is configured to:
transmit the communication timing from the synchronization port at the first base station to the synchronizing system over the synchronizing network;
after transmitting the communication timing from the synchronization port at the first base station, identify a second base station in the communication network as a second grandmaster base station by detecting a double-length identification sequence transmitted from the second base station to the synchronizing system over the synchronizing network; and
resolve with the second base station identified as the second grandmaster base station over a backhaul link whether one of:
the first base station will remain the first grandmaster base station and the second base station will transition to become a slave base station; or
the first base station will transition to become the slave base station and the second base station will remain the second grandmaster base station.

2. The telecommunication system of claim 1 , wherein when the synchronizing system comprises the network switch, the synchronizing system comprises:
a global positioning system; and
a grandmaster clock in communication with the global positioning system and configured to receive a current time from the global positioning system,
wherein the network switch is in communication with the grandmaster clock and configured to receive the communication timing from the grandmaster clock and transmit the communication timing to the base stations over the synchronizing network.

3. The telecommunication system of claim 2 , wherein the synchronization port at each base station comprises an Ethernet port configured to receive a precision time protocol signal from the network switch.

4. The telecommunication system of claim 2 , wherein the network switch is configured to transmit a precision time protocol signal to the base stations over the synchronizing network, the precision time protocol signal comprising the communication timing.

5. The telecommunication system of claim 1 , wherein when the synchronizing system comprises the pulse-per-second splitter, the synchronizing system comprises:
a global positioning system; and
a grandmaster clock in communication with the global positioning system and configured to receive a current time from the global positioning system,
wherein the pulse-per-second splitter is in communication with the grandmaster clock and configured to receive the communication timing from the grandmaster clock and transmit the communication timing to the base stations over the synchronizing network.

6. The telecommunication system of claim 5 , wherein the synchronization port at each base station comprises a pulse-per-second port configured to receive a pulse-per-second signal from the pulse-per-second splitter.

7. The telecommunication system of claim 5 , wherein the pulse-per-second splitter is configured to transmit a pulse-per-second signal to the base stations, the pulse-per-second signal comprising the communication timing.

8. The telecommunication system of claim 1 , wherein when the synchronizing system comprises the network switch, the network switch is configured to:
receive the communication timing transmitted from the first base station designated as the first grandmaster base station; and
transmit the communication timing to the base stations other than the first grandmaster base station.

9. The telecommunication system of claim 8 , wherein the synchronization port at each base station comprises an Ethernet port configured to:
receive a precision time protocol signal from the network switch; or
transmit the precision time protocol signal to the network switch.

10. The telecommunication system of claim 8 , wherein the network switch is configured to:
receive a precision time protocol signal from the first grandmaster base station, the precision time protocol signal comprising the communication timing; and
transmit the precision time protocol signal to the base stations other than the first grandmaster base station.

11. The telecommunication system of claim 1 , wherein when the synchronizing system comprises the pulse-per-second splitter in communication with the synchronization ports at each of the base stations, the pulse-per-second splitter configured to:
receive the communication timing transmitted from the first base station designated as the first grandmaster base station; and
transmit the communication timing to the base stations other than the first grandmaster base station.

12. The telecommunication system of claim 11 , wherein the synchronization port at each base station comprises a pulse-per-second port configured to:
receive a pulse-per-second signal from the pulse-per-second splitter; or
transmit the pulse-per-second signal to the pulse-per-second splitter.

13. The telecommunication system of claim 11 , wherein the pulse-per-second splitter is configured to:
receive a pulse-per-second signal from the first grandmaster base station, the pulse-per-second signal comprising the communication timing; and
transmit the pulse-per-second signal to the base stations other than the first grandmaster base station.

14. A method comprising:
receiving, at a first base station, information over a backhaul network, the first base station comprising one of multiple base stations in a telecommunication network;
transmitting communication signals from the first base station to user equipment over an air interface;
receiving, at the first base station, a communication timing from a synchronizing system over a synchronizing network, the synchronizing system in communication with the base stations and configured to synchronize the communication timing between the base stations over the synchronizing network, the synchronizing network is separate from the backhaul network and is configured to provide the communication timing between the synchronizing system and a corresponding synchronization port at each of the base stations;
when a second base station initially wakes up, determining, by control hardware of the second base station, whether any of the other base stations in the communication network are identified as a first grandmaster base station within a predetermined period of time;
when the control hardware fails to identify one of the other base stations as the first grandmaster base station within the predetermined period of time:
designating, by the control hardware, the second base station as the first grandmaster base station;
transmitting the communication timing from the synchronization port at the second base station to the synchronizing system over the sy

Assignees

• Google Inc
• Google Llc

Inventors

• Wang Jibing
• Peroulas James

Classifications

• H04W56/0015 Primary

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

• G01S19/14

  specially adapted for specific applications · CPC title

• H04W84/042

  Public Land Mobile systems, e.g. cellular systems · CPC title

• H04L7/0087

  Preprocessing of received signal for synchronisation, e.g. by code conversion, pulse generation or edge detection · CPC title

• H04L7/0008

  Synchronisation information channels, e.g. clock distribution lines · CPC title