Abstract: A communication device for providing an explicit channel state information, CSI, feedback in a wireless communication system includes a transceiver to receive, from a transmitter a radio signal via a radio time-variant frequency MIMO channel, the radio signal including downlink reference signals according to a reference signal configuration, and downlink signals including the reference signal configuration, and a processor. The processor estimates the CSI using measurements on the downlink reference signals of the radio channel according to the reference signal configuration over one or more time instants/slots, constructs a frequency-domain channel tensor using the CSI estimate, performs a higher-order principal component analysis, HO-PCA, on the channel tensor, identifies a plurality of dominant principal components of the channel tensor, thereby obtaining a compressed channel tensor, and reports to the transmitter the explicit CSI including the dominant principal components of the channel tensor.

Abstract: There are disclosed techniques (e.g., apparatus, methods) for estimating an impulse response of a linear system. An apparatus is configured to generate a transmit signal on the basis of a first sequence. The apparatus is configured to obtain a receive signal and to multiply the receive signal with a second sequence, to obtain a modified receive signal, wherein the second sequence is different from the first sequence. The apparatus is configured to analog-to-digital, ADC, convert an integration result in order to obtain a sample value, the integration result being based on an integration of the modified receive signal over a period of time. The apparatus is configured to obtain an estimate of the impulse response on the basis of a plurality of sample values.

Abstract: A communication device for providing an explicit channel state information, CSI, feedback in a wireless communication system includes a transceiver to receive, from a transmitter a radio signal via a radio time-variant frequency MIMO channel, the radio signal including downlink reference signals according to a reference signal configuration, and downlink signals including the reference signal configuration, and a processor. The processor estimates the CSI using measurements on the downlink reference signals of the radio channel according to the reference signal configuration over one or more time instants/slots, constructs a frequency-domain channel tensor using the CSI estimate, performs a higher-order principal component analysis, HO-PCA, on the channel tensor, identifies a plurality of dominant principal components of the channel tensor, thereby obtaining a compressed channel tensor, and reports to the transmitter the explicit CSI including the dominant principal components of the channel tensor.

Abstract: There are disclosed techniques (e.g., apparatus, methods) for estimating an impulse response of a linear system. An apparatus is configured to generate a transmit signal on the basis of a first sequence. The apparatus is configured to obtain a receive signal and to multiply the receive signal with a second sequence, to obtain a modified receive signal, wherein the second sequence is different from the first sequence. The apparatus is configured to analog-to-digital, ADC, convert an integration result in order to obtain a sample value, the integration result being based on an integration of the modified receive signal over a period of time. The apparatus is configured to obtain an estimate of the impulse response on the basis of a plurality of sample values.

Abstract: A communication device for providing an explicit channel state information, CSI, feedback in a wireless communication system includes a transceiver to receive, from a transmitter a radio signal via a radio time-variant frequency MIMO channel, the radio signal including downlink reference signals according to a reference signal configuration, and downlink signals including the reference signal configuration, and a processor. The processor estimates the CSI using measurements on the downlink reference signals of the radio channel according to the reference signal configuration over one or more time instants/slots, constructs a frequency-domain channel tensor using the CSI estimate, performs a higher-order principal component analysis, HO-PCA, on the channel tensor, identifies a plurality of dominant principal components of the channel tensor, thereby obtaining a compressed channel tensor, and reports to the transmitter the explicit CSI including the dominant principal components of the channel tensor.