Base station, user equipment, and method for determining precoding matrix
AssigneeNtt Docomo, Inc.
InventorsYuichi Kakishima, Satoshi Nagata, Chongning Na, Xiaolin Hou, Huiling Jiang
Life of this patent
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Abstract
A base station that communicates with a user equipment using multiple antenna ports includes an uplink channel estimation unit that estimates uplink channel states, a downlink channel estimation unit that estimates downlink channel states based on the estimated uplink channel states and channel reciprocity of uplink and downlink, a receiver unit that receives from the user equipment CSI feedback information, and a precoder generating unit that determines a precoding matrix of downlink based on Channel State Information (CSI) indicating the estimated downlink channel states and on the CSI feedback information.
Claims17
A base station that communicates with a user equipment using multiple antenna ports, the base station comprising:
- an uplink channel estimation unit that estimates uplink channel states;
- a downlink channel estimation unit that estimates downlink channel states based on the estimated uplink channel states and channel reciprocity of uplink and downlink;
- a receiver unit that receives from the user equipment CSI feedback information;
- and
- a precoder generating unit that determines a precoding matrix of downlink based on Channel State Information (CSI) indicating the estimated downlink channel states and on the CSI feedback information.
A user equipment that communicates with a base station, the user equipment comprising:
- a channel estimation unit that estimates downlink channel states based on reference signals for estimating downlink channel states transmitted from multiple antenna ports of the base station;
- a CSI feedback information generating unit that generates CSI feedback information based on the estimated downlink channel states;
- and
- a transceiver unit that transmits to the base station the CSI feedback information and reference signals for estimating uplink channel states,
- wherein the CSI feedback information includes at least one of Rank Indicator (RI), Precoding Matrix Indicator (PMI), Channel Quality Indicator (CQI), and Beam Index (BI), and wherein
- the CSI feedback information generating unit generates CSI feedback information subject to the feedback mode that includes the PMI, and
- the transceiver unit transmits to the base station the CSI feedback information excluding the PMI.
A method for determining a precoding matrix in a three-dimensional (3D) Multiple Input Multiple Output (MIMO) system, the method comprising:
- estimating, with a base station, uplink channel states,
- estimating, with the base station, downlink channel states based on the estimated uplink channel states and channel reciprocity of uplink and downlink;
- transmitting, with a user equipment, CSI feedback information to the base station;
- and
- determining, with the base station, a precoding matrix of downlink based on CSI indicating the estimated downlink channel states and the CSI feedback information from the user equipment.
Dependencies are inferred from the claim text.