| CPC H04L 25/022 (2013.01) [H04L 25/0254 (2013.01)] | 14 Claims | 

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               1. An apparatus comprising: 
            at least one memory including computer program code; 
                at least one processor configured to execute the computer program code and cause the the apparatus to perform, 
                obtaining channel response data comprising a first channel frequency response of a channel over a first frequency spectrum, wherein the first channel frequency response is generated in response to a transmission over the channel or a simulation thereof; and 
                generating an estimate of a second channel frequency response of the channel over a second frequency spectrum in response to applying the channel response data to a machine-learning, ML, model, wherein the second frequency spectrum is different to the first frequency spectrum. 
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