Common Precoder for MIMO Antenna Power Imbalance
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Solution Overview
Problem
In MIMO systems, especially in distributed antenna configurations, power imbalances and timing differences between antennas lead to inefficient use of power amplifiers and reduced performance due to the orthogonality between SISO and MIMO signals, resulting in suboptimal precoder weights and decreased spectral efficiency.
Innovation Solution
A common precoder is introduced that performs an inverse operation to the MIMO precoder, ensuring streams are mapped to individual antennas, thereby minimizing the impact of timing and power offsets, and ensuring full utilization of power amplifiers by interleaving physical antennas and using a specific codebook restriction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If streams are mapped to orthogonal precoders at the transmitter to simplify transmission, then device complexity is reduced, but the receiver experiences mixed streams requiring complex separation operations that degrade performance
Solution Approach 1:
The patent applies precoding at the receiver side rather than at the transmitter. The receiver uses precoder weights to separate the mixed streams before detection, inverting the conventional approach. This allows the transmitter to use simple orthogonal mapping while the receiver performs the separation function through precoding operations on the received signal.
2Adaptability or versatility
If distributed antennas are deployed to improve coverage in indoor environments, then adaptability is improved, but power imbalances and timing differences between antennas reduce MIMO performance
Solution Approach 1:
The patent changes the parameter of precoding location from transmitter to receiver. By performing precoding at the receiver, the system can compensate for power imbalances and timing differences in distributed antenna configurations. The receiver precoder weights are adapted to the actual channel conditions, allowing optimal performance even when transmit powers differ between antennas.
3Ease of operation
If a common precoder is used for both SISO and MIMO transmissions to simplify implementation, then ease of operation is improved, but power amplifier utilization becomes inefficient due to orthogonality requirements
Solution Approach 1:
The patent segments the precoding function into two parts: a common precoder for SISO transmissions and a separate MIMO precoder for MIMO transmissions. The common precoder handles legacy SISO users and pilot transmissions, while the MIMO precoder specifically handles MIMO data streams. This segmentation allows each precoder to be optimized for its specific function, improving power amplifier utilization for MIMO while maintaining simplicity for SISO.
Data Source
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AI summary
An antenna device and method for precoding data in a MIMO system. The antenna device comprises a plurality of physical antennas in a distributed antenna system and a MIMO precoder. The MIMO precoder has a plurality of inputs for a plurality of data streams and a plurality of outputs for the plurality of data streams. A second precoder is disposed in series with the MIMO precoder. The second precoder maps a data stream to an output associated with a physical antenna port associated with at least one of the plurality of physical antennas.