Claims

1. A method (200) for wirelessly calibrating/testing a beamforming network (104) of a multi-antenna receiver of a device under test (100), the method comprising:

wirelessly transmitting (202) a first signaling information between the device under test (100) and a device tester (130), the first signaling information indicating a calibration request, wherein the first signaling information is transmitted by the device under test (100) or the device tester (130);

estimating (204), in response to the first signaling information, channel transfer function matrices between active antenna ports (110) of the multi-antenna receiver of the device under test (100) and antenna ports (134) of the device tester (130) using reference signals wirelessly transmitted from the device tester (130) to the device under test (100), and transmitting the estimated channel transfer function matrices or an information derived therefrom from the device under test (100) to the device tester (130);

wirelessly transmitting (206) a second signaling information between the device under test (100) and the device tester (130), the second signaling information indicating a precoded transmission request, wherein the second signaling information is transmitted by the device under test (100) or the device tester (130); and

wirelessly transmitting (208), in response to the second signaling information, precoded reference signals from the device tester (130) to the device under test (100) using precoder matrices selected or determined based on the estimated channel transfer function matrices or the information derived therefrom, to obtain interference free channels between the device tester (130) and the device under test (100) allowing the reference signals to be received independently at each of the active antenna ports (110) of the multi-antenna receiver of the device under test (100).

2. The method (200) according to claim 1, wherein the multi-antenna receiver of the device under test (100) comprises a beamforming network (104) comprising a plurality of antenna ports (110) and a plurality of RF ports (112).

3. The method (200) according to claim 2, wherein the method comprises:

wirelessly transmitting, in response to the first signaling information, a third signaling information, the third signaling information indicating at least one out of active antenna ports (110), active RF ports (112) and a configuration of the beamforming network (104).

4. The method (200) according to one the claims 2 to 3, wherein the method comprises:

determining the frequency response of the beamforming network (104) using the received reference signals and using specific beamforming network (104) operating parameters.

5. The method (200) according to claim 4, wherein the method comprises:

wirelessly transmitting a fourth signaling information from the device under test (100) to the device tester (130), the fourth signaling information comprising the determined frequency response of the beamforming network (104) or an information derived therefrom.

6. The method (200) according to one of the claims 2 to 5, wherein estimating the channel transfer function matrices comprises connecting each active antenna port to exactly one RF port of the beamforming network (104) of the device under test (100).

7. The method (200) according to one of the claims 2 to 6, wherein the method comprises:

activating a first group of antenna ports (110) of the beamforming network (104) of the device under test (100) to obtain the active antenna ports (110), while deactivating the other antenna ports (110) of the beamforming network (104).

8. The method (200) according to claim 7, wherein the method comprises:

activating a second group of antenna ports (110) of the beamforming network (104) of the device under test (100), while deactivating the other antenna ports (110) of the beamforming network (104); and

estimating channel transfer function matrices between the second group of antenna ports (110) of the multi-antenna receiver of the device under test (100) and antenna ports (134) of the device tester (130) using reference signals wirelessly transmitted from the device tester (130) to the device under test (100), and transmitting the estimated channel transfer function

matrices or an information derived therefrom from the device under test (100) to the device tester (130).

9. The method (200) according to one of the claims 7 to 8, wherein the second signaling information further indicates the active antenna ports (110) of the multi-antenna receiver of the device under test (100).

10. The method (200) according to claim 9, wherein the method comprises:

activating another group of antenna ports (110) of the beamforming network (104) of the device under test (100), while deactivating the other antenna ports (110) of the beamforming network (104); and

wirelessly transmitting precoded reference signals from the device tester (130) to the device under test (100) using precoder matrices selected or determined based on the estimated channel transfer function matrices or the information derived therefrom, to obtain interference free channels between the device tester (130) and the device under test (100) allowing the reference signals to be received independently at each of the antenna ports (110) of the second group of active antenna ports (110).

11. A method (230) for wirelessly calibrating/testing a beamforming network (104) of a multi-antenna transmitter of a device under test (100), the method comprising:

wirelessly transmitting (232) a first signaling information between the device under test (100) and a device tester (130), the first signaling information indicating a calibration request, wherein the first signaling information is transmitted by the device under test (100) or the device tester (130);

estimating (234), in response to the first signaling information, channel transfer function matrices between active antenna ports (110) of the multi-antenna transmitter of the device under test (100) and antenna ports (134) of the device tester (130) using reference signals wirelessly transmitted from the device under test (100) to the device tester (130);

selecting or estimating (236) equalizer matrices using the estimated channel transfer function matrices or the information derived therefrom.

12. The method (230) according to claim 11, wherein the multi-antenna transmitter of the device under test (100) comprises a beamforming network (104) comprising a plurality of antenna ports (110) and a plurality of RF ports (112);

wherein the reference signals are wirelessly transmitted from the device under test (100) to the device tester (130) using specific beamforming network operating parameters.

13. The method (230) according to claim 12, wherein the method comprises:

wirelessly transmitting, in response to the first signaling information, a second signaling information, the second signaling information indicating at least one out of active antenna ports (110), active RF ports (112) and a configuration of the beamforming network (104).

14. The (230) method according to one of the claims 12 to 13, wherein each active antenna port of the beamforming network (104) is connected to exactly to one RF port of the beamforming network (104).

15. The (230) method according to one of the claims 12 to 14,

activating a first group of antenna ports (110) of the beamforming network (104) of the device under test (100) to obtain the active antenna ports (110), while deactivating the other antenna ports (110) of the beamforming network (104).

16. The method (230) according to claim 15, wherein the method comprises:

activating a second group of antenna ports (110) of the beamforming network (104) of the device under test (100), while deactivating the other antenna ports (110) of the beamforming network (104); and

estimating channel transfer function matrices between the second group of active antenna ports (110) of the multi-antenna transmitter of the device under test (100) and antenna ports (134) of the device tester (130) using reference signals wirelessly transmitted from the device under test (100) to the device tester (130).

17. The method (230) according to one of the claims 11 to 16, wherein the method comprises:

wirelessly transmitting a third signaling information from the device tester (130) to the device under test (100), the third signaling information indicating that the estimation of the channel transfer function matrices is finished.

18. The method (230) according to one of the claims 11 to 17, wherein the method comprises:

wirelessly transmitting a fourth signaling information from the device under test (100) to the device tester (130), the fourth signaling information indicating a calibration data request;

wherein the equalizer matrices or the information derived therefrom is transmitted from the device tester (130) to the device under test (100) in response to the fourth signaling information.

19. A method (260) for wirelessly calibrating a receive module of a multi-antenna receiver of a device under test (100), the method comprising:

wirelessly transmitting (262) a first signaling information between the device under test (100) and a device tester (130), the first signaling information indicating a calibration request, wherein the first signaling information is transmitted by the device under test (100) or the device tester (130);

estimating (264), in response to the first signaling information, channel transfer function matrices between RF ports (112) of the multi-antenna receiver of the device under test (100) and antenna ports (134) of the device tester (130) using reference signals wirelessly transmitted from the device tester (130) to the device under test (100), and transmitting the estimated channel transfer function matrices or an information derived therefrom from the device under test (100) to the device tester (130);

wirelessly transmitting (266) a second signaling information between the device under test (100) and the device tester (130), the second signaling information indicating a precoded transmission request, wherein the second signaling information is transmitted by the device under test (100) or the device tester (130); and

wirelessly transmitting (268), in response to the second signaling information, reference signals from the device tester (130) to the device under test (100) using precoder matrices selected or determined based on the estimated channel transfer function matrices or the

information derived therefrom, to obtain interference free channels between the device tester (130) and the device under test (100) allowing the reference signals to be received independently at each of the RF ports (112) of the multi-antenna receiver of the device under test (100).

20. The method (260) according to claim 19, wherein the multi-antenna receiver of the device under test (100) comprises a beamforming network (104) comprising a plurality of antenna ports (110) and a plurality of RF ports (112).

21. The method (260) according to claim 20, wherein the method comprises

activating a group of antenna ports (110) of the beamforming network (104) of the device under test (100) to obtain active antenna ports (110), while deactivating the other antenna ports (110) of the beamforming network (104), and connecting the active antenna ports (110) to the RF ports (112); and/or

setting specific beamforming network operating parameters.

22. The method (260) according to one of the claims 20 and 21, wherein the method comprises:

measuring performance metrics specifying the performance of the device under test (100).

23. A method (270) for wirelessly calibrating a transmit module of a multi-antenna transmitter of a device under test (100), the method comprising:

wirelessly transmitting (272) a first signaling information between the device under test (100) and a device tester (130), the first signaling information indicating a calibration request, wherein the first signaling information is transmitted by the device under test (100) or the device tester (130);

estimating (274), in response to the first signaling information, channel transfer function matrices between RF ports (112) of the multi-antenna transmitter of the device under test (100) and antenna ports (134) of the device tester (130) using reference signals wirelessly transmitted from the device under test (100) to the device tester (130);

selecting or estimating (276) equalizer matrices using the estimated channel transfer function matrices or the information derived therefrom.

24. The method (270) according to claim 23, wherein the multi-antenna transmitter of the device under test (100) comprises a beamforming network (104) comprising a plurality of antenna ports (110) and a plurality of RF ports (112).

25. The method (270) according to claim 24, wherein the method comprises:

activating a group of antenna ports (110) of the beamforming network (104) of the device under test (100) to obtain active antenna ports (110), while deactivating the other antenna ports (110) of the beamforming network (104), and connecting the active antenna ports (110) to the RF ports (112); and/or

setting specific beamforming network operating parameters.

26. The method (270) according to one of the claims 23 to 25, wherein the method comprises:

wirelessly transmitting a second signaling information from the device tester (130) to the device under test (100), the second signaling information indicating that the estimation of the channel transfer function matrices is finished.

27. The method (270) according to one of the claims 23 to 26, wherein the method comprises:

measuring metrics specifying the transmit performance of the device under test (100) using the selected or estimated equalizer matrices.

28. A method (280) for wirelessly calibrating antennas of a multi-antenna transceiver of a device under test (100), the method comprising:

wirelessly transmitting (282) a first signaling information between the device under test (100) and a device tester (130), the first signaling information indicating a calibration request, wherein the first signaling information is transmitted by the device under test (100) or the device tester (130);

wirelessly transmitting (284) reference signals between the device under test (100) and the device tester (130) using one active antenna port of the multi-antenna transceiver or using one RF port of the multi-antenna transceiver and a fixed beamforming network (104), wherein the reference signals are transmitted by the device under test (100) or the device tester (130);

measuring (286) at least one out of amplitude and phase of an antenna pattern for a first relative orientation between antennas of the device tester (130) and antennas of the device under test (100),

changing (288) the relative orientation between antennas of the device tester (130) and antennas of the device under test (100) from the first relative orientation to a second relative orientation;

iteratively repeating (289) the steps of wirelessly transmitting reference signals, measuring at least one out of amplitude and phase of the antenna pattern and changing the relative orientation until a predetermined termination criterion is reached.

29. The method (280) according to claim 28, wherein the multi-antenna transceiver of the device under test (100) comprises a beamforming network (104) comprising a plurality of antenna ports (110) and a plurality of RF ports (112).

30. The method (280) according to one of the claims 28 and 29, wherein the method comprises:

wirelessly transmitting a second signaling information from the device under test (100) to the device tester (130), the second signaling information indicating the antenna ports (110) or RF ports (112) to be measured.

31. The method (280) according to one of the claims 28 to 30, the method comprising:

wirelessly transmitting a third signaling information from the device tester (130) to the device under test (100), the third signaling information indicating a measured antenna pattern.

32. A method (290) for wirelessly calibrating/testing a digital receiver module of a multi-antenna receiver of a device under test (100), the method comprising:

wirelessly transmitting (291) a first signaling information between the device under test (100) and a device tester (130), the first signaling information indicating a calibration request, wherein the first signaling information is transmitted by the device under test (100) or the device tester (130);

estimating (292), in response to the first signaling information, channel transfer function matrices between active antenna ports (110) or RF ports (112) of the multi-antenna receiver of the device under test (100) and antenna ports (134) of the device tester (130) using reference signals wirelessly transmitted from the device tester (130) to the device under test (100);

wirelessly transmitting (293) a second signaling information between the device under test (100) and the device tester (130), the second signaling information indicating a precoded transmission request, wherein the second signaling information is transmitted by the device under test (100) or the device tester (130); and

wirelessly transmitting (294), in response to the second signaling information, reference signals from the device tester (130) to the device under test (100) using precoder matrices selected or determined based on the estimated channel transfer function matrices or the information derived therefrom, to obtain interference free channels between the device tester (130) and the device under test (100) allowing the reference signals to be received independently at each active antenna port (110) or RF port (112) of the multi-antenna receiver of the device under test (100).

33. The method (290) according to claim 32, wherein the multi-antenna receiver comprises an analog beamforming network (104) comprising the plurality of antenna ports (110) and the plurality of RF ports (112);

wherein the digital receiver module of the multi-antenna receiver is connected to the plurality of RF ports (112) of the analog beamforming network (104).

34. The method (290) according to claim 33, wherein the method comprises:

setting the analog beamforming network (104) to specific beamforming network operating parameters and maintaining the operating parameters of the analog beamforming network (104) fixed in a calibrating/testing mode used during calibrating/testing the digital receiver module of the multi-antenna receiver.

35. The method (290) according to claim 34, wherein the method comprises:

changing precoder matrices used for transmitting the precoded reference signals from the device tester to the device under test using multipath propagation channel models, to simulate a multipath propagation channel between the device tester (130) and the device under test (100); and

wirelessly transmitting a third signaling information from the device under test (100) to the device tester (130), the third signaling information indicating specific beamforming network operating parameters the device under test (100) would apply in a normal operation mode to the analog beamforming network (104) responsive to the simulated multipath propagation channel in order to adapt the analog beamforming network (104) in the normal operation mode to the multipath propagation channel, wherein the device under test (100) maintains the operating parameters of the analog beamforming network (104) fixed in the calibrating/testing mode used during calibrating/testing the digital receiver module of the multi-antenna receiver.

36. The method (290) according to one of the claims 32 to 35, wherein the method comprises:

measuring performance metrics specifying the performance of the digital receiver module of the multi-antenna transceiver.

37. The method (290) according to claim 36, wherein the method comprises:

varying transmit parameters of reference signals wirelessly transmitted from the device tester (130) to the device under test (100), in order to measure the performance metrics specifying the performance of the digital receiver module of the multi-antenna receiver.

38. The method (290) according to one of the claims 33 to 37, wherein the method comprises:

activating a group of antenna ports (110) of the analog beamforming network (104) of the device under test (100) to obtain active antenna ports (110), while deactivating the other antenna ports (110) of the analog beamforming network (104).

39. A method for wirelessly calibrating/testing a digital transmitter module of a multi-antenna transmitter of a device under test (100), the method comprising:

wirelessly transmitting a first signaling information between the device under test (100) and a device tester (130), the first signaling information indicating a calibration request, wherein the first signaling information is transmitted by the device under test (100) or the device tester (130);

estimating, in response to the first signaling information, channel transfer function matrices between active antenna ports or RF ports (112) of the multi-antenna transmitter of the device under test (100) and antenna ports (134) of the device tester (130) using reference signals wirelessly transmitted from the device under test (100) to the device tester (130);

selecting or estimating (236) equalizer matrices using the estimated channel transfer function matrices or the information derived therefrom.

40. The method according to claim 32, wherein the multi-antenna transmitter comprises an analog beamforming network (104) comprising the plurality of antenna ports (110) and the plurality of RF ports (112);

wherein the digital transmitter module of the multi-antenna transmitter is connected to the plurality of RF ports (112) of the analog beamforming network (104).

41. The method according to claim 40, wherein the method comprises:

setting the analog beamforming network (104) to specific beamforming network parameters and maintaining the parameters of the analog beamforming network (104) fixed in a calibrating/testing mode used during calibrating/testing the digital transmitter module of the multi-antenna receiver.

42. The method according to claim 41, wherein the method comprises:

changing the equalizer matrices used to receive equalized reference signals from the device under test, the reference signals transmitted from the device under test to the device tester using multipath propagation channel models, to emulate a multipath propagation channel between the device under test (100) and the device tester (103); and

wirelessly transmitting a third signaling information from the device under test (100) to the device tester (130), the third signaling information indicating specific beamforming network operating parameters the device under test (100) would apply in a normal operation mode to the analog beamforming network (104) responsive to the emulated multipath propagation channel in order to adapt the analog beamforming network (104) in the normal operation mode to the multipath propagation channel, wherein the device under test (100) maintains the operating parameters of the analog beamforming network (104) fixed in the calibrating/testing mode used during calibrating/testing the digital receiver module of the multi-antenna receiver.

43. The method according to one of the claims 39 to 42, wherein the method comprises:

measuring performance metrics specifying the performance of the digital transmitter module of the multi-antenna transmitter.

44. The method according to claim 43, wherein the method comprises:

varying transmit parameters of reference signals wirelessly transmitted from the device under test (100) to the device under tester, in order to measure the performance metrics specifying the performance of the digital transmitter module of the multi-antenna transmitter.

45. The method according to one of the claims 39 to 44, wherein the method comprises:

activating a group of antenna ports (110) of the analog beamforming network (104) of the device under test (100) to obtain active antenna ports (110), while deactivating the other antenna ports (110) of the analog beamforming network (104).

46. Computer program for performing the method according to one of the claims 1 to 45.

47. Device under test (100), comprising:

a beamforming network (104) having a plurality of antenna ports (110) and a plurality of RF ports (112);

a plurality of antennas (102) connected to the plurality of antenna ports (110) of the beamforming network (104);

an RF module (106) connected to the plurality of RF ports (112) of the beamforming network (104); and

a processor configured to perform the method according to one of the claims 1 to 45.

48. The device under test (100) according to claim 47, wherein the device under test (100) is an user equipment or a base station.

49. Device tester (130), comprising:

a beamforming network (136) having a plurality of antenna ports (134) and a plurality of RF ports;

a plurality of antennas (132) connected to the plurality of antenna ports (134) of the beamforming network (136);

an RF module connected to the plurality of RF ports of the beamforming network (136); and

a processor configured to perform the method according to one of the claims 1 to 45.

50. The device tester (130) according to claim 49, wherein the device tester (130) is an user equipment, a base station or a dedicated device tester.