Apparatus and method for overhead reduction of feedback in closed loop MIMO system
AssigneeSamsung Electronics Co., Ltd.
InventorsShuangfeng Han, Zhen Wang, Ho-Kyu Choi, Cheng Shan
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Abstract
A method and apparatus reduce overhead of feedback in a closed loop Multiple Input Multiple Output (MIMO) system. A controller feeds back the long-term Precoder Matrix Index (PMI) to a serving base station under direction of the serving base station when the long term PMI feedback transmission is required, generates a new codebook using the long term PMI, and determines a short term PMI from the new codebook. A feedback transmitter feeds back the short-term PMI to the serving base station.
Claims22
A feedback method of a terminal in a Multiple Input Multiple Output (MIMO) wireless communication system, the feedback method comprising:
- feeding back, by a feedback transmitter, a long term Precoder Matrix Index (PMI) to a serving base station under direction of the serving base station when the long term PMI feedback transmission is required;
- generating, by a controller, a new codebook using the long term PMI;
- determining, by the controller, a short term PMI from the new codebook;
- and
- feeding back, by the feedback transmitter, the short term PMI to the serving base station,
- wherein the long term PMI feedback transmission is required when a transmit correlation matrix is determined from a reference signal received from the serving base station and a ratio of two greatest eigenvalues in the transmit correlation matrix exceeds a threshold.
An operating method of a base station in a Multiple Input Multiple Output (MIMO) wireless communication system, comprising:
- sending, by a transmitter, a reference signal to a terminal;
- receiving, by a controller, a long term Precoder Matrix Index (PMI) from the terminal;
- generating, by the controller, a new codebook using the long term PMI;
- and
- receiving, by the controller, from the terminal a short term PMI from the new codebook, wherein receiving the long term PMI from the terminal comprises:
- receiving an Efficient Feedback Mode (EFM) request from the terminal;
- sending a response message to the terminal when the EFM request is permissible;
- and
- receiving the long term PMI from the terminal, and
- wherein the EFM request takes places when a ratio of two greatest eigenvectors of transmit correlation matrix exceeds a threshold.
An apparatus of a terminal for feedback in a Multiple Input Multiple Output (MIMO) wireless communication system, comprising:
- a feedback transmitter configured to feed back a long term Precoder Matrix Index (PMI) to a serving base station under direction of the serving base station when long term PMI feedback transmission is required;
- a controller configured to generate a new codebook using the long term PMI, and determine a short term PMI from the new codebook;
- and
- an antenna configured to receive a reference signal from the serving base station;
- the feedback transmitter further configured to feed back the short term PMI to the serving base station,
- wherein the controller is further configured to determine a transmit correlation matrix from the reference signal received from the serving base station, and determine that the long term PMI feedback transmission is required when a ratio of two greatest eigenvalues in the transmit correlation matrix exceeds a threshold.
An apparatus of a base station in a Multiple Input Multiple Output (MIMO) wireless communication system, comprising:
- a transmitter configured to send a reference signal to a terminal via an antenna;
- and
- a controller configured to receive a long term Precoder Matrix Index (PMI) from the terminal, generate a new codebook using the long term PMI, and receive from the terminal a short term PMI from the new codebook,
- wherein the controller, when receiving the long term PMI from the terminal, is configured to receive an Efficient Feedback Mode (EFM) request from the terminal, and send a response message to the terminal when the EFM request is permissible, and
- wherein the EFM request takes places when a ratio of two greatest eigenvectors of transmit correlation matrix exceeds a threshold.
Dependencies are inferred from the claim text.