A radio unit (RU) device is provided. The device includes a radio frequency (RF) transceiver, a fronthaul transceiver, memory, comprising one or more storage media, for storing instructions, and one or more processors communicatively coupled to the RF transceiver, the fronthaul transceiver and the memory, wherein the instructions, when executed by the one or more processors individually or collectively, cause the device to obtain reference signals via the RF transceiver, obtain a transformed covariance matrix of the reference signals with respect to noise and interference through random embedding for dimensionality reduction, obtain an extraction matrix through the subspace decomposition of the transformed covariance matrix, perform pre-combining using the extraction matrix to pre-combine uplink signals acquired via the RF transceiver, and transmit data of the pre-combined uplink signals to a digital unit (DU) via the fronthaul transceiver, and wherein the random embedding is used to transform a first dimension of the number of reception layers of the RU into a second dimension of a number smaller than the number of reception layers.