Transmit Diversity on a Control Channel without Additional Reference Signals
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Accused Products
Abstract
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
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Citations
54 Claims
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1-29. -29. (canceled)
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30. A method comprising:
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providing antenna port sharing among N antenna ports used for localized control channels and M antenna ports used for distributed control channels by selecting a first precoding vector based on channel state information (CSI) related to a user equipment (UE); mapping a first control channel precoded with the first precoding vector for the UE to a localized evolved or enhanced control channel element (E-CCE); assigning the first control channel to a first antenna port selected from the set of antenna ports used for localized control channels; selecting the first antenna port and the first precoding vector for a second control channel; selecting a second antenna port from the set of antenna ports used for distributed control channels for the second control channel; selecting a second precoding vector for the second control channel; and mapping the second control channel precoded with the selected first precoding vector and the selected second precoding vector to a distributed E-CCE that shares a same physical resource block (PRB) pair with the localized E-CCE; and transmitting the first control channel and the second control channel to a set of UEs, where N and M are positive integers. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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43. An apparatus for communication, comprising:
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a processor; and a memory including computer program code, where the memory and computer program code are configured to, with the processor, cause the apparatus at least to provide antenna port sharing among N antenna ports used for localized control channels and M antenna ports used for distributed control channels by operations that comprise selecting a first precoding vector based on channel state information (CSI) related to a user equipment (UE);
mapping a first control channel precoded with the first precoding vector for the UE to a localized evolved or enhanced control channel element (E-CCE);
assigning the first control channel to a first antenna port selected from the set of antenna ports used for localized control channels;
selecting the first antenna port and the first precoding vector for a second control channel;
selecting a second antenna port from the set of antenna ports used for distributed control channels for the second control channel;
selecting a second precoding vector for the second control channel; and
mapping the second control channel precoded with the selected first precoding vector and the selected second precoding vector to a distributed E-CCE that shares a same physical resource block (PRB) pair with the localized E-CCE; and
transmitting the first control channel and the second control channel to a set of UEs, where N and M are positive integers. - View Dependent Claims (44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54)
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Specification