Distribution of inter/intra calibration signals for antenna beamforming signals
An example method of calibrating signals in an antenna array includes generating a calibration signal at a first radio sub unit (RSU), transmitting the calibration signal through a transmission path of a radio front end (RFE) of the first RSU, and receiving the calibration signal in a coupling and distribution layer of the first RSU. The method further includes providing the calibration signal from the coupling and distribution layer of the first RSU directly to a coupling and distribution layer of a second RSU, and processing the calibration signal at the second RSU.
1. A method of calibrating signals, comprising:
generating a calibration signal at a first radio sub unit (RSU);
transmitting the calibration signal through a transmission path of a radio front end (RFE) of the first RSU;
receiving the calibration signal in a coupling and distribution layer of the first RSU, the coupling and distribution layer comprising at least one power combiner, and/or at least one power divider;
providing the calibration signal from the coupling and distribution layer of the first RSU directly to a coupling and distribution layer of a second RSU; and
processing the calibration signal on the second RSU.
2. The method of claim 1 , further comprising providing the calibration signal to a calibration module of the second RSU for processing.
3. The method of claim 1 , wherein the calibration signal from the coupling and distribution layer of the first RSU is provided to the coupling and distribution layer of the second RSU over a hardwired connector.
4. The method of claim 3 , wherein the hardwired connector comprises a coaxial RF connector.
5. The method of claim 3 , wherein a connection between the first RSU and the second RSU is short, and wherein the hardwired connector is an adapter or a board to board connector.
6. The method of claim 1 , wherein the transmission path of the first RSU includes an antenna at its end.
7. The method of claim 6 , wherein the calibration signal of the first RSU is sampled as close to the antenna as possible.
8. The method of claim 1 , wherein the RSU includes an array of N antenna elements, and further comprising generating a set of N−1 additional calibration signals, so that there is a calibration signal associated with each of the N antenna elements.
9. The method of claim 8 , wherein each of the N calibration signals is sampled as close to its respective antenna element as possible.
10. The method of claim 9 , further comprising combining the N samples into a combined calibration signal, and providing the combined calibration signal to the coupling and distribution layer of the second RSU.
11. The method of claim 10 , wherein processing the calibration signal in the second RSU includes measuring an amplitude and phase of each of the N samples.
12. A coupling and distribution apparatus, comprising:
an antenna array coupled to a first radio sub-unit (RSU), the array including N antenna ports;
one or more layers of power combiners, configured to combine the N antenna ports into a single combined port;
a single first power divider coupled to the single combined port, the first power divider configured to divide the single combined port into two output paths, a first signal path coupled to a reference receiver of the first RSU, and a second signal path coupled to a second RSU.
13. The apparatus of claim 12 , wherein the second RSU is adjacent to the first RSU.
14. The apparatus of claim 12 , wherein the second signal path includes a hardwired connector connected between the coupling and distribution apparatus of the first RSU and a coupling and distribution apparatus of the second RSU.
15. The apparatus of claim 14 , wherein the hardwired connector comprises a coaxial RF connector.
16. The apparatus of claim 14 , wherein a connection between the first RSU and the second RSU is short, and wherein the hardwired connector is an adapter or a board to board connector.
17. The apparatus of claim 14 , wherein the hardwired connector is coupled to a radio front end (RFE) of a calibration module of the second RSU.
18. The apparatus of claim 17 , wherein the hardwired connector is coupled to an RX path of the calibration module of the second RSU.
19. The apparatus of claim 12 , further comprising an additional power combiner coupled to the first signal path and also to a signal path connected to a hardwired connector connected between the coupling and distribution apparatus and a coupling and distribution apparatus of a third RSU.
20. The apparatus of claim 19 , wherein the additional power combiner is configured to combine a calibration signal path from the third RSU and the output of the first power divider into a single signal path to the reference receiver of the first RSU.