Iterative Precoder Power Allocation for Distributed Mmimo
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Solution Overview
Problem
Massive multiple-input multiple-output (mMIMO) systems face challenges in achieving homogeneous power profiles in downlink transmissions, leading to reduced communication range due to heterogeneous power profiles, especially in distributed mMIMO setups, where traditional zero-forcing precoding methods are complex and suboptimal.
Innovation Solution
A low-complexity iterative precoding method that updates power allocation weights for access point antennas based on channel estimates, using a precoder computed from previous weights, until a stopping criterion is reached, to achieve a more balanced power distribution and optimize communication range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional zero-forcing precoding schemes are used in distributed mMIMO, then interference between users is suppressed, but the power profiles become highly heterogeneous causing reduced communication range
Solution Approach 1:
The patent modifies the traditional zero-forcing precoder by introducing power allocation weights that adjust the power distribution across transmit chains. This parameter change transforms the homogeneous power constraint into a flexible power allocation mechanism, allowing each transmit chain to operate at its optimal power level while maintaining interference suppression performance.
Solution Approach 2:
The patent implements an iterative algorithm that dynamically adjusts power allocation weights based on channel conditions and power profile heterogeneity. This dynamic approach allows the system to adaptively balance interference suppression and communication range, rather than using a fixed power allocation scheme.
2Length of moving object
If high complexity zero-forcing precoding algorithms using second-order cone programming are used, then homogeneous power profiles are achieved and communication range is maintained, but computational complexity becomes prohibitive for practical implementation
Solution Approach 1:
The patent replaces the computationally expensive second-order cone programming approach with a simpler iterative algorithm that uses basic matrix operations and power allocation updates. This 'cheaper' computational approach achieves similar homogeneous power profile results without the prohibitive complexity of SOCP.
Solution Approach 2:
The patent breaks down the complex precoder design into iterative steps: computing initial precoder, evaluating power profiles, updating power allocation weights, and recalculating precoder. This segmentation of the design process into manageable iterations reduces overall computational complexity while maintaining performance.
3Reliability
If common power backoff is applied to all transmit chains to comply with maximum power constraints, then power constraints are satisfied, but communication range is reduced proportionally to the heterogeneity in power profile
Solution Approach 1:
The patent applies different power allocation weights to different transmit chains based on their individual power profiles and channel conditions. Instead of a uniform power backoff, each transmit chain receives a tailored power allocation that complies with its maximum power constraint while minimizing the impact on communication range.
Data Source
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AI summary
An apparatus is disclosed, which may comprise: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform: receiving downlink channel estimates between a plurality of access point (AP) antennas of one or more APs and a plurality of user equipment (UE) antennas of one or more UEs; iteratively updating a set of power allocation weights for the AP antennas using weights extracted from a precoder; computing the precoder based on the received channel estimates and a previous set of power allocation weights; performing the iterative updates until a stopping criterion is reached; and outputting data representative of a precoder computed from the received channel estimates and the updated set of power allocation weights.