Patent ID: 9236998
Filing Date: 2016-01-12
CPC Classification: H04B,H04L,H04W

Claim Text:
1. A communication device having a receive path comprising: a number M antennas and respective radio modules, wherein the M antennas and respective radio modules support N×N multiple-input multiple-output (MIMO) transmissions and receptions, wherein M≧N; a processor operable in a baseband domain and configured to perform a self-calibration procedure by which a correction factor is computed for a channel reciprocity level, determined by said self-calibration procedure; a plurality of switches and receive paths in each one of said radio modules, said switches configured to select a receive path for regular MIMO operation or a plurality of receive paths during said self-calibration procedure, wherein at least one of said plurality of receive paths includes a path loss element between the respective antenna and a low noise amplifier (LNA); and a digital attenuator configured to adjust calibration signals in the baseband domain, wherein the M antennas are configured to alternate transmitting and receiving periods on a single channel according to a time division duplex (TDD) communication protocol, wherein the M antennas are configured to define phases employed in MIMO transmission and selected using information measured at the communication device during the receiving periods based on the channel reciprocity level, wherein the digital attenuator is further configured to digitally attenuate the calibration signals by an amount that is sufficient to prevent the LNA in one of the plurality of receive paths that is undergoing calibration from saturating, wherein the communication device is further operable to perform the self-calibration procedure in which a first antenna/radio pair (i and j), (i) acts as a transmitter and the other antenna/radio (j) acts as the receiver during the self-calibration procedure, the self-calibration procedure comprising: