Loopback testing in frequency division duplex systems

• US 10,193,618 B2
• Filed: 03/02/2015
• Issued: 01/29/2019
• Est. Priority Date: 03/02/2015
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Cederholm, Daniel, Trojer, Elmar, Berg, Miguel
• Primary Examiner(s): Amara, Mohamed K
• Application Number:
  US15/553,991
• Publication Number:
  US 20180054254A1
• Time in Patent Office: 1,429 Days
• CPC Class Codes: H04B 10/071 using a reflected signal, e.g. using optical time domain reflectometers [OTDR]
• CPC Class Codes: H04B 3/46 Monitoring; Testing
• CPC Class Codes: H04L 43/50 Testing arrangements
• CPC Class Codes: H04M 1/24 Arrangements for testing
• CPC Class Codes: H04M 3/30 for subscriber's lines , for the local loop

Abstract

A communication device and method therein for loopback testing. The device comprises a transmitter and a receiver and applies FDD for communication over one or more lines. The method comprises degrading a linearity of the transmitter, as compared to the linearity during normal operation. The method further comprises transmitting at least one test signal in a transmit frequency band, such that at least one signal is created in a receive frequency band, wherein the created at least one signal is a distortion product of the at least one test signal; and further, receiving a response to the at least one created signal in the receive frequency band.

Claims

1. A method for loopback testing, performed by a device in a communication system, the device comprising a transmitter and a receiver and applying frequency division duplex (FDD) for communication, the method comprising:

degrading a linearity of the transmitter as compared to the linearity of the transmitter during normal operation by inducing one or more amplifiers of the transmitter to operate in a more non-linear region of their transfer function;

transmitting at least one test signal in a transmit frequency band, such that at least one signal is created in a receive frequency band, wherein the at least one created signal is a distortion product of the at least one test signal; and

receiving a response to the at least one created signal in the receive frequency band for performing loopback testing irrespective of a requirement for one or more additional switching circuitry to bypass transmit or receive filters.

2. The method according to claim 1, wherein the degrading of the linearity of the transmitter comprises one or more of:

increasing a gain of one or more amplifiers in a transmitting chain;

amplifying the at least one test signal provided to one or more amplifiers in the transmitting chain;

reducing a supply voltage of one or more amplifiers in the transmitting chain; and

adjusting a bias of one or more amplifiers in the transmitting chain.

3. The method according to claim 1, being a Time Domain Reflectometry method or a Frequency Domain Reflectometry method.

4. The method according to claim 1, wherein the at least one created signal in the receive frequency band, being a distortion product, is a harmonic or an intermodulation product.

5. The method according to claim 1, further comprising:

performing a calibration based on the at least one test signal.

6. A communication device for loopback testing, the communication device being operable in a communication system, and comprising a transmitter and a receiver and being configured to apply frequency division duplex (FDD) for communication, the communication device being further configured to:

degrade a linearity of the transmitter as compared to the linearity of the transmitter during normal operation by inducing one or more amplifiers of the transmitter to operate in a more non-linear region of their transfer function;

transmit at least one test signal in a transmit frequency band, such that at least one signal is created in a receive frequency band, wherein the at least one created signal is a distortion product of the at least one test signal; and

receive a response to the at least one created signal in the receive frequency band for performing loopback testing irrespective of a requirement for one or more additional switching circuitry to bypass transmit or receive filters.

7. The communication device according to claim 6, being configured to degrade the linearity of the transmitter by one or more of:

increasing a gain of one or more amplifiers in a transmitting chain;

amplifying the at least one test signal provided to one or more amplifiers in the transmitting chain;

reducing a supply voltage of one or more amplifiers in the transmitting chain; and

adjusting a bias of one or more amplifiers in the transmitting chain.

8. The communication device according to claim 6, wherein the at least one created signal in the receive frequency band, being a distortion product, is a harmonic or an intermodulation product.

9. The communication device according to claim 6, being further configured to perform a calibration based on the at least one test signal.

10. A non-transitory computer readable storage medium comprising instructions which, when executed on at least one processor, cause a communication device comprising a transmitter and a receiver and applying frequency division duplex (FDD) for communication to perform loopback testing, comprising:

degrading a linearity of the transmitter as compared to the linearity of the transmitter during normal operation by inducing one or more amplifiers of the transmitter to operate in a more non-linear region of their transfer function;

transmitting at least one test signal in a transmit frequency band, such that at least one signal is created in a receive frequency band, wherein the at least one created signal is a distortion product of the at least one test signal; and

receiving a response to the at least one created signal in the receive frequency band for performing loopback testing irrespective of a requirement for one or more additional switching circuitry to bypass transmit or receive filters.

11. The non-transitory computer-readable storage medium according to claim 10, wherein the instructions which, when executed on the at least one processor, further cause the degrading of the linearity of the transmitter by one or more of:

increasing a gain of one or more amplifiers in a transmitting chain;

amplifying the at least one test signal provided to one or more amplifiers in the transmitting chain;

reducing a supply voltage of one or more amplifiers in the transmitting chain; and

adjusting a bias of one or more amplifiers in the transmitting chain.

12. The non-transitory computer-readable storage medium according to claim 10, wherein the instructions which, when executed on the at least one processor, cause loopback testing to be performed by a Time Domain Reflectometry method or a Frequency Domain Reflectometry method.

13. The non-transitory computer-readable storage medium according to claim 10, wherein the instructions which, when executed on the at least one processor, further cause the at least one created signal in the receive frequency band, being a distortion product, to be a harmonic or an intermodulation product.

14. The non-transitory computer-readable storage medium according to claim 10, wherein the instructions which, when executed on the at least one processor, further cause the communication device to perform a calibration based on the at least one test signal.