Over-the-air test

1. An apparatus configured to form a weight for each signal path associated with an antenna of a plurality of antennas around a test zone in an over-the-air chamber by a comparison of a predetermined target electric field based on a radio channel model and an electric field obtainable by plane waves associated with the test zone, the plane waves being transmittable by the antennas and being based on at least one basis waveform in each signal path, a desired channel being formed between a transmitter and a device under test based on a superposition of the plane waves in the test zone, wherein each plane wave is based on a plurality of basis waveforms.

2. The apparatus of claim 1 , wherein at least two basis waveforms of at least one common plane wave are configured to be transmitted in one signal path.

3. The apparatus of claim 1 , wherein the apparatus is configured to form a weight for each signal path for each plane wave on based on a difference between a desired target electric field determined by the radio channel model and an electric field obtainable by each plane wave transmittable by the plurality of antennas, and to combine weights of each antenna for forming a weight of a plurality of plane waves for a signal path.

4. The apparatus of claim 1 , wherein the apparatus is configured to form a weight for each signal path for each plane wave by optimizing a difference between a desired target electric field determined by the radio channel model and an electric field obtainable by each plane wave transmittable by the plurality of antennas.

5. The apparatus of claim 1 , wherein the weight for each signal path is configured to determine directions, frequencies, phases, and amplitudes of the plane waves for an emulated radio channel being based on a superposition of plane waves in the test zone.

6. The apparatus of claim 1 , wherein the apparatus is configured to perform the comparison at a plurality of locations at a circumference of the test zone.

7. The apparatus of claim 1 , wherein the apparatus is configured to include a time dependent Doppler shift in the weight for each signal path.

8. The apparatus of claim 1 , wherein the apparatus is configured to form a weight for each signal path for different polarization planes based on the polarization planes of the plurality of antennas.

9. The apparatus of claim 7 , wherein the apparatus is configured to include crosstalk between different polarization planes in the weight for each signal path.

10. The apparatus of claim 7 , wherein the apparatus is configured to include at least one of weight for each signal path: transmitter's effects on transmission; and receiver's effect on reception.

11. The apparatus of claim 1 , wherein a weight generator is configured to save the weight for each signal path in a memory for emulation of a radio channel.

12. The apparatus of claim 1 , wherein the apparatus is configured to receive at least two signals having different radio channels, to form a weight for each radio channel and to combine weights for each signal path to form plane waves for each radio channel.

13. A method comprising forming a weight for each signal path associated with an antenna of a plurality of antennas around a test zone in an over-the-air chamber by comparing of a predetermined target electric field based on a radio channel model and an electric field obtainable by plane waves associated with the test zone, the plane waves being transmittable by the antennas and being based on at least one basis waveform in each signal path, a desired channel being formed between a transmitter and a device under test based on a superposition of the plane waves in the test zone, wherein each plane wave is based on a plurality of basis waveforms.

14. The method of claim 13 , wherein at least two basis waveforms of at least one common plane wave is transmittable in one signal path.

15. The method of claim 13 , the method further comprising forming a weight for each signal path for each plane wave based on a difference between a desired target electric field determined by the radio channel model and an electric field obtainable by each plane wave transmittable by the plurality of antennas, and combining weights for each antenna for forming a weight for a plurality of plane waves.

16. The method of claim 13 , the method further comprising forming a weight for each signal path for each plane wave by optimizing a difference between a desired target electric field determined by the radio channel model and an electric field obtainable by each plane wave transmittable by the plurality of antennas.

17. The method of claim 13 , the method further comprising determining by the weight for each signal path, directions, frequencies, phases, and amplitudes of the plane waves, an emulated radio channel being based on a superposition of plane waves in the test zone.

18. The method of claim 13 , the method further comprises performing the comparing at a plurality of locations at a circumference of the test zone.

19. The method of claim 13 , the method further comprises including a time dependent Doppler shift in the weight for each signal path.

20. The method of claim 13 , the method further comprising forming the weight for each signal path for different polarization planes based on the polarization planes of the plurality of antennas.

21. The method of claim 20 , the method further comprises including crosstalk between different polarization planes in the weights.

22. The method of claim 13 , the method further comprising including at least one of the following in the weight for each signal path: transmitter's effects on transmission; and receiver's effect on reception.

23. The method of claim 13 , the method further comprises receiving at least two signals of different radio channels, forming a weight for each radio channel and combining weights for each signal path to form plane waves for each radio channel.

24. An apparatus comprising: at least one processor and at least one non-transitory computer readable medium including a computer program code, the at least one non-transitory computer readable medium and the computer program code with the at least one processor are configured to cause the apparatus to perform operations comprising:

forming a weight for each signal path associated with an antenna of a plurality of antennas around a test zone in an over-the-air chamber by comparing of a predetermined target electric field based on a radio channel model and an electric field obtainable by plane waves associated with the test zone, the plane waves being transmittable by the antennas and being based on at least one basis waveform in each signal path, a desired channel being formed between a transmitter and a device under test based on a superposition of the plane waves in the test zone, wherein each plane wave is based on a plurality of basis waveforms.

25. An emulation system comprising:

an apparatus configured to form a weight for each signal path associated with an antenna of a plurality of antennas around a test zone in an over-the-air chamber by a comparison of a predetermined target electric field based on a radio channel model and an electric field obtainable by plane waves associated with the test zone, the plane waves being transmittable by the plurality of antennas and being based on at least one basis waveform in each signal path, a desired channel being formed between a transmitter and a device under test based on a superposition of the plane waves in the test zone, wherein each plane wave is based on a plurality of basis waveforms;

an emulator coupled to the apparatus for receiving the weight for each signal path; and

a transmitter coupled to the emulator for feeding a communication signal, the antennas being configured to receive signals from signal paths of the emulator and transmit plane waves based on signals from the emulator for forming an emulated radio channel between the transmitter and the device under test.

26. An emulation system of claim 25 , wherein the transmitter has at least one output coupled to the emulator for feeding the communication signal, each output referring to a unique radio channel; and

the apparatus being configured to form weights with respect to each output separately for forming plane waves for the plurality of antennas.

27. A transmission method comprising:

transmitting deterministic basis waveforms from antenna elements of an over-the-air chamber for forming a plurality of predetermined plane waves in a test zone, the predetermined plane waves forming an emulated radio channel for communication with a device under test in the test zone, a desired channel being formed between a transmitter and a device under test based on a superposition of the predetermined plane waves in the test zone, wherein each plane wave is based on a plurality of basis waveforms.