TRANSMIT DIVERSITY ON A CONTROL CHANNEL WITHOUT ADDITIONAL REFERENCE SIGNALS

摘要

Disclosed is a method and an apparatus providing antenna port sharing and a demodulation reference signals (DMRS) based precoding scheme for a distributed enhanced physical downlink control channel (E-PDCCH) using, for example, spatial frequency block codes (SFBC)/frequency selective transmit diversity (FSTD) transmit diversity. The method exhibits the same performance as SFBC/FSTD transmit diversity using un-precoded DMRS while not prohibiting another UEs' localized E-PDCCH to be potentially multiplexed in a same physical resource block (PRB) pair. The SFBC/FSTD transmission is facilitated by mapping a subset of layers to DMRS ports used by other UEs for localized and beam formed transmission, while the precoders for the remaining layers are selected to be orthogonal to the other UEs precoders there by providing good performance while minimizing DMRS port usage. Specifically, no additional DMRS ports are needed for spatial diversity transmission