MIMO precoding enabling spatial multiplexing, power allocation and adaptive modulation and coding
AssigneeApple Inc.
InventorsJayesh H. Kotecha, Kaibin Huang
Life of this patent
Estimating the term…
Abstract
In a closed-loop wireless communication system, a codebook-based feedback mechanism is provided to enable non-unitary precoding for multi-stream transmission, where each stream is optimized with suitable transmission power allocation and AMC. The codebook-based feedback mechanism uses a precoding codebook having a power allocation matrix which is constrained to specify that beamforming always applies full power to a predetermined beam. With this constraint, a one-bit power allocation feedback index may be used to switch between beamforming and spatial multiplexing.
Claims20
A receiver for providing feedback in a multiple input multiple output (MIMO) communication system, the receiver comprising:
- a processor configured to:
- identify a first precoding information for a precoding matrix that corresponds to estimated channel state information for a transmission channel from a transmitter to the receiver;
- quantize the first precoding information into a precoding index;
- compute a first channel quality indicator (CQI) value for a first spatial stream based on the estimated channel state information;
- compute a second channel quality indicator (CQI) value for a second spatial stream based on the estimated channel state information, wherein to compute the second CQI value the processing element is configured to:
- set the second CQI to a predetermined value to indicate the second spatial stream is chosen to be turned off when the CQI is low;
- and
- set the second CQI to a value different from the predetermined value to indicate the spatial stream is chosen to be turned on;
- and
- radio circuitry configured to send the precoding index and CQI values via a feedback channel to the transmitter.
An apparatus for providing feedback in a multiple output (MIMO) communication system, the apparatus comprising:
- a memory element configured to store information;
- and
- a processor configured to use at least part of the information to:
- identify a first precoding information for a precoding matrix that corresponds to estimated channel state information for a transmission channel from a transmitter to a receiver;
- quantize the first precoding information into a precoding index;
- compute a first channel quality indicator (CQI) value for a first spatial stream based on the estimated channel state information;
- compute a second channel quality indicator (CQI) value for a second spatial stream based on the estimated channel state information, wherein to compute the second CQI value the processing element is configured to:
- set the second CQI to a predetermined value to indicate the second spatial stream is chosen to be turned off when the CQI is low;
- and
- set the second CQI to a value different from the predetermined value to indicate the spatial stream is chosen to be turned on;
- and
- cause the precoding index and CQI values to be transmitted via a feedback channel to the transmitter.
A non-transitory memory element storing instructions which, when executed, cause a device to:
- identify a first precoding information for a precoding matrix that corresponds to estimated channel state information for a transmission channel from a second device to the device;
- quantize the first precoding information into a precoding index;
- compute a first channel quality indicator (CQI) value for a first spatial stream based on the estimated channel state information;
- compute a second channel quality indicator (CQI) value for a second spatial stream based on the estimated channel state information, wherein to compute the second CQI value the processing element is configured to:
- set the second CQI to a predetermined value to indicate the second spatial stream is chosen to be turned off when the CQI is low;
- and
- set the second CQI to a value different from the predetermined value to indicate the spatial stream is chosen to be turned on;
- and
- transmit the precoding index and CQI values via a feedback channel to the second device.
Dependencies are inferred from the claim text.