Conversion of the Spatio-Temporal Correlation from Uplink to Downlink in FDD Systems

In FDD systems, uplink spatio-temporal correlation knowledge can be obtained via uplink measurements and time-averaging. Many algorithms however require the knowledge of the downlink correlation, such as base-station transmit beam-forming in the case of spatial correlation and user SNR prediction algorithms in the case of temporal correlation. This paper presents two possible algorithms for the conversion of the uplink spatio-temporal correlation to its downlink counterpart and compares their performance in terms of the link-level conversion error.