Codebook MU-MIMO Precoder Generation
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Solution Overview
Problem
Existing MU-MIMO systems face challenges in reducing inter-wireless device interference and achieving high throughput due to the need for accurate and complete channel state information, which incurs significant overhead and is prone to inaccuracies.
Innovation Solution
The method employs partial channel state information to create new or modified precoders that minimize interference among wireless devices in MU-MIMO groups, using codebook-based feedback to calculate precoders with lower dimensional matrices, thereby reducing computational complexity and overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complete channel state information is obtained and Zero-Forcing precoding is employed to cancel inter-layer interference, then interference cancellation performance is improved, but uplink overhead increases significantly
Solution Approach 1:
The patent extracts only the necessary precoding information from complete channel state information by utilizing codebook-based feedback. Instead of transmitting full CSI, the system extracts precoding matrix indicators (PMI) that are sufficient for MU-MIMO operations, thereby reducing uplink overhead while maintaining interference cancellation capability through codebook-based precoder selection
Solution Approach 2:
The patent applies partial action by using codebook-based feedback which provides partial channel state information rather than complete CSI. This partial information is sufficient for determining precoders in MU-MIMO systems, achieving acceptable interference cancellation performance without the overhead of complete CSI acquisition
2Device complexity
If precoder feedback from SU-MIMO is used in existing systems with MU-MIMO transmission, then implementation complexity is reduced, but significant inter-wireless device interference is created
Solution Approach 1:
The patent introduces codebook-based precoding as an intermediary mechanism between SU-MIMO feedback and MU-MIMO transmission. The codebook serves as a mediator that transforms SU-MIMO precoder feedback into MU-MIMO suitable precoders, enabling the system to leverage simple SU-MIMO feedback while avoiding direct interference issues through codebook-based precoder selection and application
Solution Approach 2:
The patent changes the parameter representation by transforming precoder feedback from SU-MIMO context to MU-MIMO context through codebook indexing. By changing how precoder information is represented and interpreted (using PMI and codebook indices), the system maintains low complexity while adapting to multi-user scenarios and reducing interference
3Quantity of substance
If uplink channel measurements are used for determining downlink precoders, then system overhead is reduced, but accuracy deteriorates due to uplink/downlink radio frequency path inaccuracies
Solution Approach 1:
The patent uses codebook-based feedback as a copy or representation of channel state information that is sufficient for precoding purposes. Instead of relying on imperfect uplink-downlink reciprocity, the system creates a coded representation (PMI) that captures essential channel characteristics needed for MU-MIMO precoding, achieving both low overhead and adequate accuracy
Data Source
AI summary
A network node configured to communicate with a plurality of wireless devices is provided. The network node includes processing circuitry configured to: receive partial Channel State Information, CSI, from each of the plurality of wireless devices; determine a first plurality of precoders based at least in part on the partial CSI received from each of the plurality of wireless devices where each precoder of the first plurality of precoders is associated with a respective one of the plurality of wireless devices; determine a second plurality of precoders based at least in part on the first plurality of precoders; and optionally cause multiple-user multiple-input multiple-output, MU-MIMO, transmission to the plurality of wireless devices based at least in part on the plurality of second precoders.