Massive MIMO DPD Coefficient Allocation by Antenna Channel Gain
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Solution Overview
Problem
Massive MIMO systems face challenges in achieving optimal performance due to high complexity and power consumption of digital predistortion (DPD) techniques, especially with large numbers of antennas, where non-linear amplifier distortions and unequal channel contributions across antennas complicate DPD implementation.
Innovation Solution
A method for determining the size of DPDs in a massive MIMO system by allocating coefficients based on channel gain estimates using a utility function, allowing adaptive optimization of DPD sizes per antenna to balance complexity and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MIMO DPD scheme is adopted to mitigate non-linear distortions in massive MIMO systems, then system performance is improved, but implementation complexity increases significantly
Solution Approach 1:
The patent divides the MIMO DPD system into independent per-antenna DPD units, where each antenna has its own DPD instance. This segmentation reduces the overall complexity by avoiding the need for a full MIMO DPD matrix operations, while still providing distortion mitigation for each antenna individually. The complexity scales linearly with the number of antennas rather than quadratically.
Solution Approach 2:
The patent applies different DPD configurations to different antennas based on their individual channel conditions. Each antenna's DPD is optimized locally according to its specific channel gain and distortion characteristics, rather than applying a uniform global DPD approach. This allows for more efficient resource allocation and reduced overall complexity.
2Device complexity
If per-antenna DPDs are deployed to reduce complexity in massive MIMO systems, then implementation complexity is reduced, but system performance deteriorates due to unequal channel contributions
Solution Approach 1:
The patent introduces dynamic adaptation of DPD parameters for each antenna based on real-time channel conditions. The DPD coefficients and configurations are adjusted dynamically according to the channel gain estimates, allowing the system to optimize performance for each antenna individually while maintaining manageable complexity. This dynamic approach enables per-antenna DPDs to achieve performance closer to full MIMO DPD.
Solution Approach 2:
The patent changes the parameters of each antenna's DPD based on its specific channel characteristics. By adapting DPD parameters such as model order, memory depth, and coefficient values according to individual antenna channel gains, the system achieves better overall performance without requiring a full MIMO DPD approach, thus maintaining lower complexity.
3Productivity
If the number of antennas at the access node is increased to improve spectral efficiency, then spectral efficiency is improved, but RF chain power consumption increases
Solution Approach 1:
The patent segments the power consumption management by antenna, allowing independent optimization of each RF chain and DPD unit. By dividing the system into independent per-antenna units, the network can selectively activate or adjust DPD for individual antennas based on their channel conditions and power consumption characteristics, rather than uniformly powering all RF chains at maximum capacity.
Solution Approach 2:
The patent dynamically adjusts DPD parameters and RF chain configurations based on channel conditions to optimize power consumption. When channel conditions are good, the system can reduce DPD complexity or disable certain RF chains, thereby reducing power consumption while maintaining spectral efficiency. This parameter adaptation allows the system to scale antenna usage according to power availability.
4Ease of operation
If DPD coefficients are uniformly allocated across all antennas, then implementation is simplified, but energy efficiency deteriorates due to unequal channel contributions
Solution Approach 1:
The patent implements non-uniform DPD coefficient allocation where each antenna receives coefficients tailored to its specific channel conditions. Antennas with stronger channel gains receive more DPD resources, while antennas with weaker gains receive fewer resources. This local quality approach optimizes energy efficiency by concentrating DPD resources where they provide the most benefit, rather than uniformly distributing them across all antennas.
Solution Approach 2:
The patent changes the allocation parameters of DPD coefficients based on measured channel gains for each antenna. The system dynamically adjusts the number of DPD coefficients, model complexity, and computational resources allocated to each antenna according to its channel conditions, achieving optimal energy efficiency while maintaining implementation feasibility through automated parameter adjustment.
Data Source
AI summary
There are provided mechanisms for DPD size determination of an access node. The access node is configured for operation in a digital massive MIMO system. The access node includes a plurality of antennas, one radio chain per antenna, and one DPD per radio chain. A method is performed by the access node. The method includes obtaining channel gain estimates per each of the plurality of antennas. The method includes determining the size, in terms of number of coefficients, of each DPD according to a utility function that depends on the channel gain estimates per antenna. The method includes allocating the determined number of coefficients to each DPD.