Method and a device for finding imperfections in an RF path

• US 8,811,928 B2
• Filed: 03/26/2007
• Issued: 08/19/2014
• Est. Priority Date: 03/26/2007
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Lennartson, Benny, Boncz, Lars
• Primary Examiner(s): Batista, Marcos
• Assistant Examiner(s): DONADO, FRANK E
• Application Number:
  US12/532,722
• Publication Number:
  US 20100081427A1
• Time in Patent Office: 2,703 Days
• US Class Current: 455/303
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04B 7/0684 using different training sequences per antenna
• CPC Class Codes: H04B 7/0822 according to predefined selection scheme

Abstract

The invention discloses a method (700) for finding differences in path loss between a plurality of RF paths between a first (120, 130) and a second (120, 130) transceiver in a wireless communications system (100). During defined 5 intervals of time (SACCH1-SACCH4), only one RF path is used to transmit from one of said transceivers to the other of said transceivers, and the receiving transceiver measures the strength of the signal received during at least a number of said intervals, thus making it possible to compare signal strength and thereby path loss between different RF paths, which in turn 10 makes it possible to find imperfections in one or more of said RF paths.

Claims

1. A method for finding differences in path loss between a plurality of radio frequency (RF) paths between a first transceiver and a second transceiver in a wireless communications system, the method comprising:

using different ones of the RF paths during respective different defined intervals of time to receive signals at one of the first and second transceivers from the other one of the first and second transceivers,

measuring first and second signal strengths of the signals received using respective first and second ones of the RF paths during first and second ones of said respective different intervals,

comparing the first and second signal strengths of the first and second RF paths using measurements from the first and second intervals,

wherein one of the first and second transceivers comprises a base station comprising different physical transmission antennas,

wherein a different one of the first and second transceivers comprises a mobile device,

and

wherein the different ones of the RF paths are defined by transmission from the different physical transmission antennas of the base station and/or by different transmission polarizations, and by reception at the mobile device; and

communicating between the first and second transceivers using a third RF path, and

not the first RF path and not the second RF path, between the first and second transceivers,

during a third interval that follows the first and second intervals,

the method further comprising;

determining an average difference between a third signal strength of the third RF path and the first signal strength;

determining an average difference between the third signal strength and the second signal strength; and

identifying greater attenuation provided by one of the different ones of the RF paths responsive to determining an average difference between the signal strengths of the different ones of the RF paths, respectively.

2. The method of claim 1,

where said first transceiver is the transmitting transceiver during said intervals,

where the second transceiver is the receiving transceiver during said intervals, and

where the method further comprises:

sending, via the second transceiver, reports on said measurements to the first transceiver.

3. The method of claim 2,

where the first transceiver and the second transceiver communicate with each other in specified data frames which have a certain extension in time,

where the second transceiver carries out the measurements of the received signal strength during at least a specified period of one of said data frames, and

where said intervals in which only one RF path is used at least in part coincide with the measurement periods of the second transceiver.

4. The method of claim 3, where the intervals that an RF path is used is a same as said period during which the second transceiver makes its measurements.

5. The method of claim 1,

where said second transceiver is the transmitting transceiver during said intervals, and

where the first transceiver is the receiving transceiver during said intervals.

6. The method of claim 5,

where the first transceiver and the second transceiver communicate with each other in specified data frames which have a certain extension in time,

where the first transceiver carries out measurements of the received signal strength during at least a specified period of one of said data frames, and

where said intervals in which only one RF path is used at least in part coincide with the measurement periods of the first transceiver.

7. The method of claim 6, where the intervals that an RF path is used is a same as said period during which the first transceiver makes its measurements.

8. The method of claim 1, where the comparing includes:

comparing the signal strengths from two different ones of said intervals, said two different ones of said intervals being from a same session between said first and second transceivers, where said two different ones of said intervals are two consecutive intervals.

9. The method of claim 1, further comprising:

sending reports on the measurements to a third node in the wireless communications system, the reports allowing for the signal strengths to be compared and conclusions to be drawn regarding path losses between the different RF paths.

10. The method of claim 1, further comprising:

compiling, via the first transceiver, reports on said measurements, the reports allowing conclusions to be drawn regarding path losses between the different RF paths.

18. The method of claim 1, wherein the different ones of the RF paths are defined by different transmission polarizations and by reception at the mobile device.

11. A transceiver for use in a wireless communications system, the transceiver comprising:

at least a first transmitter and a second transmitter, and

at least a first receiver and a second receiver, the at least the first transmitter and the second transmitter and the at least the first receiver and the second receiver being configured to provide communication with another transceiver in said wireless communications system, so that at least a first radio frequency (RF) path and a second RF path are available, in both the transmit and receive direction for said transceiver, for communication with said other transceiver in the wireless communications system,

where the transceiver further comprises;

a switch configured to switch between the first and second RF paths so that, during defined intervals of time, only one RF path, of the first and second RF paths, is used for transmission or reception in the communication with said other transceiver in the wireless communications system, wherein switching between the first and second RF paths comprises switching between either the first and second transmitters or between the first and second receivers,

wherein each defined interval comprises a measurement period,

wherein the switch is configured to switch between the first and second RF paths such that each measurement period corresponds to a change between the first and second RF paths, and

wherein the first and second RF paths correspond to first and second signal strengths, respectively; and

a processor configured to;

control communication with said other transceiver using a third RF path, and not the first RF path and not the second RF path, between the transceiver and said other transceiver, during a third measurement period that follows first and second measurement periods in which the first and second RF paths are used;

determine an average difference between a third signal strength of the third RF path and the first signal strength;

determine an average difference between the third signal strength and the second signal strength; and

identify greater attenuation provided by one of the first and second RF paths responsive to determining an average difference between the first and second signal strengths of the first and second RF paths.

12. The transceiver of claim 11,

where the switch enables the transceiver to only transmit on one RF path at a time during said intervals in time,

where the transceiver further comprises:

a receiver configured to receive measurement reports from said other transceiver on the signal strengths for the RF paths used for transmission during said intervals.

13. The transceiver of claim 11,

where the switch enables the transceiver to only receive on one RF path at a time during said intervals in time,

where the processor is configured to compile measurement reports on the signal strengths of the RF paths used for transmission.

14. The transceiver of claim 12, wherein the processor is configured to evaluate said reports to identify differences in RF path loss.

15. The transceiver of claim 12, further comprising:

a transmitter configured to transmit said reports to a third node in the wireless communications system.

19. The transceiver of claim 11,

wherein one of said transceiver and said other transceiver comprises a base station, and wherein both of the first and second RF paths correspond to the base station, and

wherein the average difference comprises a non-zero average value of a plurality of measured differences between the signal strengths of the first and second RF paths corresponding to a plurality of changes between the first and RF paths.

16. A method for finding differences between first and second radio frequency (RF) paths that are between a first transceiver and a second transceiver in a wireless communications system, the method comprising:

communicating between the first and second transceivers using the first RF path and not the second RF path during a first measurement period;

communicating between the first and second transceivers using the second RF path and not the first RF path during a second measurement period;

measuring first and second characteristics of the first and second RF paths, respectively, during the first and second measurement periods, respectively;

comparing the first and second characteristics of the respective first and second RF paths;

wherein one of the first and second transceivers comprises a base station comprising different physical transmission antennas,

wherein a different one of the first and second transceivers comprises a mobile device, and

wherein the different ones of the RF paths are defined by transmission from the different physical transmission antennas of the base station and/or by different transmission polarizations, and by reception at the mobile device; and

communicating between the first and second transceivers using a third RF path, and not the first RF path and not the second RF path, between the first and second transceivers, during a third measurement period that follows the first and second measurement periods,

wherein the first and second characteristics comprise first and second signal strengths, respectively,

the method further comprising;

determining an average difference between a third signal strength of the third RF path and the first signal strength;

determining an average difference between the third signal strength and the second signal strength; and

identifying greater attenuation provided by one of the first and second RF paths responsive to determining an average difference between the first and second characteristics of the respective first and second RF paths.

17. The method of claim 16, wherein comparing the first and second characteristics comprises identifying a difference in path loss between the first and second RF paths, the method further comprising reporting the difference in path loss from one of the first and second transceivers to the other one of the first and second transceivers.