A method for implementation in a node configured for connection to a massive multiple-input, multiple-output (MIMO) array to provide spatially multiplexed channels in an unlicensed frequency band, the method comprising:
- storing, in a memory of the node, samples of non-spatially filtered signals received by the node during a first listen-before-talk (LBT) operation used to acquire the unlicensed frequency band;
- determining, based on a number of previously stored samples, a duration of a silent time interval during which the node collects samples of non-spatially filtered signals and stores the samples in the memory;
- and
- performing a second LBT operation to acquire the unlicensed frequency band using a spatial filter determined based on the samples stored in the memory.