Dielectric waveguide signal transfer function compensation

A method, in a first antenna node coupled to an upstream antenna node or to a control unit via first and second dielectric waveguides and coupled to a downstream antenna node via third and fourth dielectric waveguides, the antenna node comprising (i) first radiofrequency (RF) circuitry and corresponding one or more antennas for selectively transmitting RF signals received via the first dielectric waveguide or receiving RF signals via the one or more antennas and coupling the received RF signals to the first dielectric waveguide, and (ii) second RF circuitry and corresponding one or more antennas for selectively transmitting RF signals received via the second dielectric waveguide or receiving RF signals via the one or more antennas and coupling the received RF signals to the second dielectric waveguide, and (iii) third RF circuitry for selectively forwarding RF signals received via the first and second dielectric waveguides to the third and fourth dielectric waveguides or forwarding RF signals received via the third and fourth dielectric waveguides to the first and second dielectric waveguides, the method comprising:

• receiving, from the control unit or the upstream antenna node, a signal instructing the first antenna node to loopback an RF test signal;
• and,
• in response to the signal, looping back an RF test signal received via the first dielectric waveguide to the second dielectric waveguide.

A control node for determining calibration parameters to correct for frequency responses of one or more dielectric waveguides coupling the control node to a first antenna node or to a series of antenna nodes including the first antenna node, the control node comprising:

• first and second dielectric waveguide interfaces, each being configured to selectively transmit and receive radiofrequency (RF) signals via a respective dielectric waveguide, to and from a first antenna node;
• first radiofrequency (RF) circuitry operatively coupled to the first dielectric waveguide interface and configured to selectively transmit RF signals via the first dielectric waveguide interface or receive RF signals via the first dielectric waveguide interface;
• second RF circuitry operatively coupled to the second dielectric waveguide interface and configured to selectively transmit RF signals via the second dielectric waveguide interface or receive RF signals via the first dielectric waveguide interface;
• baseband circuitry and upconversion circuitry configured to generate RF signals from baseband signals;
• and
• processing circuitry operatively coupled to and configured to control the first and second RF circuitry, baseband circuitry, and upconversion circuitry to:
• transmit, via the first dielectric waveguide an RF test signal having a signal bandwidth covering a bandwidth of interest;
• receive, via the second dielectric waveguide interface, a looped-back version of the transmitted RF test signal;
• and
• estimate a first one-way frequency response corresponding to the first (or second) dielectric waveguide interface, based on the RF test signal and the received loop-back version of the transmitted RF test signal.