Doppler-based beam training interval adaptation

A second apparatus comprising:

• at least one processor;
• and
• at least one memory including computer program code;
• the at least one memory and the computer program code configured to, with the at least one processor, cause the second apparatus at least to perform:
• maintaining, in the memory, information on a radio-aware digital twin for a physical environment comprising a first terminal device, one of an access node and a second terminal device, and one or more terminal devices capable of movement under control of the radio-aware digital twin;
• predicting, using the radio-aware digital twin, a Doppler spectrum for a propagation channel between the first terminal device and the one of the access node or the second terminal device;
• and
• transmitting, to a device associated with the propagation channel over at least one communication network and/or at least one communication link, predicted Doppler spectrum information for the propagation channel, wherein the device associated with the propagation channel is the first terminal device or the one of the access node or the second terminal device and the predicted Doppler spectrum information includes at least information on one or more Doppler frequencies of the predicted Doppler spectrum resulting from reflections from at least one of the one or more terminal devices.

A method comprising:

• obtaining predicted Doppler spectrum information for a propagation channel between a first terminal device and one of an access node or a second terminal device calculated using a radio-aware digital twin for a physical environment, wherein the physical environment comprises the first terminal device, the one of the access node or the second terminal device and one or more terminal devices capable of movement under control of the radio-aware digital twin and the predicted Doppler spectrum information includes at least information on one or more Doppler frequencies of a predicted Doppler spectrum resulting from reflections from at least one of the one or more terminal devices;
• causing performing of measurements of one or more reference signals by a device associated with the propagation channel over the propagation channel to a form a channel estimate, wherein the device associated with the propagation channel is the first terminal device or the one of the access node or the second terminal device;
• calculating a measured Doppler spectrum based on the channel estimate;
• filtering out the one or more Doppler frequencies of the one or more peaks of the predicted Doppler spectrum from the measured Doppler spectrum;
• and
• adjusting a beam refinement interval of the device associated with the propagation channel based on the filtered measured Doppler spectrum or at least a part thereof.