SWITCHING SUB-SYSTEM FOR DISTRIBUTED ANTENNA SYSTEMS USING TIME DIVISION DUPLEXING

• US 20150249513A1
• Filed: 10/30/2013
• Published: 09/03/2015
• Est. Priority Date: 10/30/2013
• Status: Active Grant

• Current Assignee: Andrew Wireless Systems GmbH (CommScope Holding Company, Inc.)
• Original Assignee: Andrew Wireless Systems GmbH (CommScope Holding Company, Inc.)
• Inventors: Kummetz, Thomas, Dussmann, Alfons, Schwab, Daniel
• Granted Patent: US 9,271,289 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04J 3/0638 Clock or time synchronisation among nodes; Internode synchronisation synchronization for ring networks H04L12/422; data switching networks with synchronous transmission H04L12/43
• CPC Class Codes: H04J 3/0685 Clock or time synchronisation in a node; Intranode synchronisation
• CPC Class Codes: H04L 5/1469 using time-sharing
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 88/085 Access point devices with remote components

Abstract

A switching control module can optimize time division duplexing operations of a distributed antenna system (“DAS”). The switching control module can include a measurement receiver and a processor. The measurement receiver can measure signal powers of downlink signals in a downlink path of the DAS. The processor can determine start times for downlink sub-frames transmitted via the downlink path based on downlink signal powers measured by the measurement receiver exceeding a threshold signal power. The processor can identify a clock setting that controls a timing of switching signals used for switching the DAS between an uplink mode and a downlink mode. The processor can statistically determine a switching time adjustment for the clock setting based on switching time differentials between the clock setting and the start times. The processor can update the clock setting based on the switching time adjustment.

Claims

1. A switching control module comprising:

a measurement receiver configured for measuring a signal power in a downlink path of a distributed antenna system; and

a processor communicatively coupled to the measurement receiver, wherein the processor is configured for optimizing time division duplexing operations of the distributed antenna system by;

identifying a clock setting that controls a timing for generating switching signals that instruct at least one switch in an uplink path or the downlink path of the distributed antenna system to switch the distributed antenna system between an uplink mode and a downlink mode,

determining multiple start times or end times for respective downlink sub-frames transmitted via the downlink path, wherein the processor is configured for determining each start time or end time based on the signal power measured by the measurement receiver exceeding a threshold signal power, and

updating the clock setting based on a switching time adjustment statistically determined from multiple switching time differentials, wherein each of the switching time differentials comprises a respective difference between the clock setting and a respective start time or end time.

2. The switching control module of claim 1, wherein the switching time adjustment comprises a mean switching time differential from a statistical distribution of the switching time differentials.

3. The switching control module of claim 1, further comprising a comparator device having an input coupled to the measurement receiver and an output coupled to the processor, wherein the comparator device is configured for comparing the threshold signal power with a power measurement received from the measurement receiver via the input and providing a signal to the processor via the output that is indicative of whether the power measurement exceeds the threshold signal power.

4. The switching control module of claim 1, wherein the processor is further configured for determining an initial clock setting, wherein determining the initial clock setting comprises:

obtaining multiple downlink sub-frame samples, wherein each downlink frame sample corresponds to a respective power measurement by the measurement receiver;

determining a ratio between downlink sub-frames and uplink sub-frames for signals communicated via the distributed antenna system; and

determining the initial clock setting based on the ratio.

5. The switching control module of claim 4, wherein the processor is further configured for determining the initial clock setting based on the ratio by:

identifying a time division duplexing configuration utilizing the ratio; and

selecting the initial clock setting based on the time division duplexing configuration.

6. The switching control module of claim 4, wherein the processor is configured for determining the start times or end times subsequent to determining the initial clock setting and updating the initial clock setting based on the switching time adjustment.

7. The switching control module of claim 1, wherein the processor is further configured for providing multiple switching signals based on the updated clock setting.

8. A time division duplex switching sub-system disposed in a remote antenna unit of a distributed antenna system, the time division duplex switching sub-system comprising:

at least one switch positioned in at least one of a downlink path from a master unit to an antenna of the remote antenna unit or an uplink path from the antenna to the master unit, the at least one switch configured for selectively connecting the antenna to the uplink path or the downlink path;

a measurement receiver communicatively coupled to the downlink path and configured for measuring a signal power in the downlink path; and

a processor communicatively coupled to the measurement receiver and to the at least one switch, wherein the processor is configured for optimizing time division duplexing operations of the distributed antenna system by;

identifying a clock setting that controls a timing for generating switching signals that instruct at least one switch in an uplink path or the downlink path of the distributed antenna system to switch the distributed antenna system between an uplink mode and a downlink mode,

determining multiple start times or end times for respective downlink sub-frames transmitted via the downlink path, wherein the processor is configured for determining each start time or end time based on the signal power measured by the measurement receiver exceeding a threshold signal power, and

updating the clock setting based on a switching time adjustment statistically determined from multiple switching time differentials, wherein each of the switching time differentials comprises a respective difference between the clock setting and a respective start time or end time.

9. The time division duplex switching sub-system of claim 8, wherein the switching time adjustment comprises a mean switching time differential from a statistical distribution of the switching time differentials.

10. The time division duplex switching sub-system of claim 8, further comprising a comparator device having an input coupled to the measurement receiver and an output coupled to the processor, wherein the comparator device is configured for comparing the threshold signal power with a power measurement received from the measurement receiver via the input and providing a signal to the processor via the output that is indicative of whether the power measurement exceeds the threshold signal power.

11. The time division duplex switching sub-system of claim 8, wherein the processor is further configured for determining an initial clock setting, wherein determining the initial clock setting comprises:

obtaining multiple downlink sub-frame samples, wherein each downlink frame sample corresponds to a respective power measurement by the measurement receiver;

determining a ratio between downlink sub-frames and uplink sub-frames for signals communicated via the distributed antenna system;

identifying a time division duplexing configuration utilizing the ratio; and

selecting the initial clock setting based on the time division duplexing configuration.

12. The time division duplex switching sub-system of claim 11, wherein the time division duplex switching sub-system is configured for determining the initial clock setting based on the distributed antenna system being in an offline mode.

13. The time division duplex switching sub-system of claim 12, wherein the processor is configured for determining the start times or end times subsequent to determining the initial clock setting and updating the initial clock setting based on the switching time adjustment.

14. The time division duplex switching sub-system of claim 8, wherein the processor is further configured for providing multiple switching signals based on the updated clock setting.

15. A method comprising:

identifying a clock setting that controls a timing for providing switching signals to at least one switch positioned in an uplink path or a downlink path of a distributed antenna system that the at least one switch to switch the distributed antenna system between an uplink mode and a downlink mode;

determining multiple start times or end times for respective downlink sub-frames transmitted via the downlink path, wherein each start time or end time is determined based on a measured signal power in the downlink path exceeding a threshold signal power; and

updating the clock setting based on a switching time adjustment statistically determined from multiple switching time differentials, wherein each of the switching time differentials comprises a respective difference between the clock setting and a respective one of the start times or end times.

16. The method of claim 15, wherein the switching time adjustment comprises a mean switching time differential from a statistical distribution of the switching time differentials.

17. The method of claim 15, further comprising providing multiple switching signals based on the updated clock setting.

18. The method of claim 15, further comprising determining an initial clock setting by:

obtaining multiple downlink sub-frame samples, wherein each downlink frame sample corresponds to a respective signal power measurement for the downlink path;

determining a ratio between downlink sub-frames and uplink sub-frames for signals communicated via the distributed antenna system; and

determining the initial clock setting based on the ratio.

19. The method of claim 17, wherein determining the initial clock setting based on the ratio comprises:

identifying a time division duplexing configuration utilizing the ratio; and

selecting the initial clock setting based on the time division duplexing configuration.

20. The method claim 18, further comprising setting the distributed antenna system to an offline mode, wherein the initial clock setting is determined and the clock setting is updated in the offline mode.

21. The method of claim 20, further comprising:

setting the distributed antenna system to an online mode;

determining multiple additional start times or end times for respective additional downlink sub-frames transmitted via the downlink path in the online mode;

updating the clock setting based on an additional switching time adjustment determined from multiple additional switching time differentials, wherein each of the additional switching time differentials comprises a respective difference between the clock setting and a respective one of the additional start times or end times; and

providing multiple switching signals to the at least one switch based on the clock setting as updated in the online mode.