Synchronizing multiple-input/multiple-output signals in distributed antenna systems

Patent metadata

Field	Value
Publication number	US-11825433-B2
Application number	US-202117348297-A
Country	US
Kind code	B2
Filing date	Jun 15, 2021
Priority date	May 21, 2015
Publication date	Nov 21, 2023
Grant date	Nov 21, 2023

Abstract

The present disclosure describes devices, systems, and methods for synchronizing multiple-input/multiple-output (“MIMO”) signals or other signals in telecommunication systems. Some aspects may involve transmitting signals between a head-end unit and remote units of a telecommunication system. A first delay of a signal path between the head-end unit and a first remote unit of the remote units may be determined to be greater than each delay of signal paths between the head-end unit and other remote units. Based on the first delay, the telecommunication system may be configured to delay transmission of additional signals such that the additional signals are simultaneously transmitted to another unit by either the head-end unit or the remote units.

First claim

What is claimed is:

1. A distributed antenna system for a telecommunication system, the distributed antenna system comprising:
a plurality of remote units configured to transmit downlink signals to terminal devices and receive uplink signals from the terminal devices;
a head-end unit configured to distribute the downlink signals to the plurality of remote units and receive the uplink signals from the plurality of remote units; and
a processing device configured to:
implement a physical layer device to communicate multiple-input/multiple-output (MIMO) signals comprising Ethernet-framed data using a clock as a time reference;
transmit between one of the head-end unit and at least one of the remote units of the plurality of remote units a message comprising an instruction to transmit a responsive message at a first time;
identify a second time at which the responsive message was received;
determine that a first delay of a signal path between the head-end unit and a first remote unit of the plurality of remote units is greater than each delay of other delays of other signal paths between the head-end unit and other remote units;
determine if a difference of the first delay from the other delays in the other signal paths is greater than a threshold; and
instruct at least one of the head-end unit and at least one remote unit of the plurality of remote units, based on the first delay when a difference of the first delay from the other delays is not greater than the threshold and on another delay value below the threshold when the difference of the first delay from the other delays is greater than the threshold, to delay transmissions.

2. The distributed antenna system of claim 1 , wherein the delay of transmissions includes delaying one of additional downlink signals and uplink signals such that the at least one of additional uplink signals and downlink signals are simultaneously transmitted by either the head-end unit or remote units.

3. The distributed antenna system of claim 1 , wherein the delay of transmissions includes the delay of additional downlink signals such that the downlink signals are transmitted simultaneously by the remote units.

4. The distributed antenna system of claim 1 , wherein the delay of transmissions includes the delay of additional uplink signals such that the additional uplink signals are simultaneously transmitted to base stations by the head-end unit.

5. The distributed antenna system of claim 1 , wherein the clock is settable using an IEEE 1588 protocol utilized for synchronizing Ethernet communications between the head-end unit and the remote units.

6. The distributed antenna system of claim 1 , wherein the processing device is further configured to determine processing delays based on a first processing delay caused by processing circuitry of the head-end unit and a second processing delay caused by processing circuitry of each of the plurality of remote units.

7. The distributed antenna system of claim 1 , wherein the processing device is configured to delay the transmissions with at least one buffer.

8. The distributed antenna system of claim 1 , wherein the at least one remote unit of the plurality of remote units is configured to implement a delay in a MIMO set as instructed by the head-end unit to synchronize transmissions from the plurality of remote units to the terminal devices.

9. A method of synchronizing multiple-input and multiple output signals in a distributed antenna system of a telecommunication system, the method comprising:
generating a time reference;
transmitting Ethernet-framed data in multiple-input/multiple output (MIMO) signals between a head-end unit and a plurality of remote units, the signals including the time reference;
determining that a first delay of a signal path between the head-end unit and a first remote unit of the plurality of remote units is greater than each delay of signal paths between the head-end unit and other remote units of the plurality of remote units based on the time reference;
wherein determining that a first delay of a signal path between the head-end unit and a first remote unit of the plurality of remote units is greater than each delay of signal paths between the head-end unit and other remote units of the plurality of remote units based on the time reference further includes for each remote unit of the plurality of remote units,
transmitting between the head-end unit and the remote unit a message comprising an instruction to transmit a responsive message at a first time using the time reference,
identifying a second time at which the responsive message is received by the head-end unit or the remote unit,
determining a delay from a difference between the first time and the second time, and
identifying a greatest delay associated with the remote units;

determining if a difference of the first delay from delays in other signal paths is greater than a threshold; and
configuring, based on the first delay when the difference between the first delay from the delays in the other signal paths is not greater than the threshold and based on another delay that is below the threshold when the difference between the first delay from the delays in the other signal paths is greater than the threshold, the telecommunication system to delay transmission of additional signals such that the additional signals are simultaneously transmitted the remote units.

10. The method of claim 9 , wherein determining the delay associated with each remote unit further comprises:
combining the delay for each remote unit with a first processing delay caused by processing circuitry of the head-end unit and by a second processing delay caused by processing circuitry of the remote unit.

11. The method of claim 9 , further comprising:
using an IEEE 1588 protocol in setting the time reference.

12. The method of claim 9 , wherein configuring the telecommunication system to delay the transmission of the additional signals further comprises;
using a buffer to delay the additional signals.

13. The method of claim 9 , wherein the additional signals are additional uplink signals and the additional uplink signals are simultaneously transmitted to base stations by the head-end unit.

14. The method of claim 9 , wherein the additional signals are additional downlink signals and the additional downlink signals are delayed so the downlink signals are transmitted simultaneously by the plurality of remote units.

15. The method of claim 9 , further comprising:
using a clock as the time reference.

16. The method of claim 9 , wherein the delay of the transmission of additional signals from the plurality remote units to simultaneously transmit the additional signals from the remote units is implement at least in part in the remote units from instructions from the head-end unit.

Assignees

• Andrew Wireless Systems Gmbh

Inventors

• Hanson Van Erick

Classifications

• H04W56/0025 Primary

  synchronizing potentially movable access points · CPC title

• H04W56/004 Primary

  compensating for timing error of reception due to propagation delay · CPC title

• H04W56/0045

  compensating for timing error by altering transmission time · CPC title

• H04W56/0065

  using measurement of signal travel time · CPC title

• H04W88/085

  Access point devices with remote components · CPC title