MU-MIMO Uplink Power Control via Channel Orthogonality
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Solution Overview
Problem
Uplink MU-MIMO transmissions in LTE networks face challenges in optimizing power control to minimize intra-cell and inter-cell interference, which affects system throughput and user quality of service due to non-orthogonal channels between user equipment (UEs) and radio base stations.
Innovation Solution
A method and radio base station design that determine power adjustment values for each UE based on single-user SINR, channel orthogonality, and MU-SINR targets to optimize transmission power, thereby minimizing interference and maximizing system throughput while maintaining quality of service.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transmission power is increased to maximize system throughput in MU-MIMO, then system throughput is improved, but inter-cell interference increases which reduces the potential gain
Solution Approach 1:
The patent changes the power control parameters by introducing individual power adjustment factors (α1, α2) for each UE in the MU-MIMO pair. These factors are optimized based on channel conditions, orthogonality metrics, and interference levels, allowing the system to achieve high throughput while controlling inter-cell interference through precise parameter tuning rather than uniform power increases.
Solution Approach 2:
The power adjustment factors are made dynamic and adaptive, changing based on real-time channel conditions, orthogonality between UEs, and interference measurements. This allows the system to optimize throughput while managing interference dynamically rather than using static power levels.
2Productivity
If power control optimization is implemented for MU-MIMO transmissions, then system gain and quality of service are improved, but calculation complexity increases
Solution Approach 1:
The patent performs preliminary calculations of channel orthogonality metrics and interference conditions before finalizing power adjustment factors. By pre-computing these parameters based on available channel state information, the system reduces the complexity of real-time optimization while still achieving high system gain through informed power control decisions.
3Object-generated harmful factors
If joint power adjustment for multiple UEs is performed, then interference is minimized and throughput is maximized, but computational requirements increase
Solution Approach 1:
The patent segments the power control problem into individual adjustment factors for each UE (α1, α2, etc.) rather than optimizing all power levels simultaneously as a single complex problem. This segmentation allows for more manageable computational requirements while still achieving joint optimization effects through the interdependence of the individual factors in the throughput and interference equations.
Data Source
AI summary
A method of power control for multi-user multi-input multi-output (MU-MIMO) transmissions between a pair of mobile terminals and a radio base station. The method comprises determining signal-to-interference-noise ratios (SINRs) for the radio channels between the mobile terminals and the radio base station, determining a channel orthogonality between the radio channels, and jointly determining, based on the SINRs and the channel orthogonality, power adjustment values for the mobile terminals. The present invention makes use of an understanding that the system gain resulting from MU-MIMO transmissions may be improved by optimizing the transmission power of the co-scheduled mobile terminals. For instance, the power adjustment values may be determined so as to attain certain SINR targets. Alternatively, the power adjustment values may be determined so as to maximize the throughput while maintaining a power budget constraint. Further, a radio base station for MU-MIMO transmissions is provided.