Base Station Power Allocation for NOMA-MIMO Systems
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Solution Overview
Problem
In systems combining Non-Orthogonal Multiple Access (NOMA) and Single-User MIMO (SU-MIMO), it is challenging for base stations to accurately predict and allocate transmission powers to user equipment, leading to inefficiencies in downlink reception quality and capacity utilization.
Innovation Solution
A base station with a stream number determiner, precoder, transmission power determiner, and predictive index estimator allocates different transmission powers to user equipment based on channel state information, while user equipment decodes desired signals by generating and canceling interference signals, independent of base station power allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If non-orthogonal multiple access is combined with orthogonal multiple access to increase network capacity, then the quantity of users served increases, but interference between signals addressed to different user equipments increases
Solution Approach 1:
The base station performs preliminary power allocation based on predictive indices before signal transmission. By calculating predictive indices that estimate reception quality in advance, the base station can pre-determine appropriate transmission powers for different user equipments, ensuring that signals are transmitted with optimized power levels that account for potential interference conditions.
Solution Approach 2:
User equipments feed back channel state information to the base station, which uses this feedback to calculate predictive indices and adjust power allocation. The base station determines transmission powers based on the feedback from multiple user equipments, creating a closed-loop system that continuously optimizes power distribution to manage interference while maintaining network capacity.
2Reliability
If transmission power is allocated based on path loss to user equipment at cell edges, then reception quality for cell edge users improves, but transmission power consumption increases
Solution Approach 1:
The base station changes the parameter of transmission power dynamically based on predictive indices calculated from channel state information. Instead of using fixed power allocation based solely on path loss, the system adjusts transmission powers according to the calculated predictive indices, which reflect actual reception conditions. This allows optimization of power distribution to improve reception quality while avoiding excessive power consumption.
3Productivity
If multiple streams are transmitted to each user equipment using MIMO precoding, then system throughput increases, but difficulty in predicting and allocating transmission power increases
Solution Approach 1:
The base station segments the power allocation process by calculating predictive indices for each user equipment independently based on their respective channel state information. This segmentation allows the complex multi-stream MIMO power allocation problem to be broken down into manageable per-user calculations, reducing overall complexity while maintaining high system throughput.
Solution Approach 2:
The patent replaces complex mechanical power allocation mechanisms with a predictive index-based calculation system. Instead of using traditional methods that require iterative optimization and complex coordination for multi-stream MIMO power allocation, the system uses predictive indices derived from channel state information to directly determine transmission powers, simplifying the allocation process.
4Measurement precision
If user equipment performs interference cancellation by demodulating signals with highest reception power first, then decoding accuracy improves, but processing time increases
Solution Approach 1:
The base station performs preliminary power allocation based on predictive indices before signal transmission. By pre-determining transmission powers, the system reduces the complexity of interference cancellation at user equipments. Users can more quickly identify and cancel interference signals because the power relationships are already optimized, reducing processing time while maintaining decoding accuracy.
Data Source
AI summary
For each UE, a base station determines the number of streams for transmitting a data signal, performs different precoding on the data signal depending on the UE, and allocates different transmission powers to at least two UEs. The base station transmits streams addressed to the at least two UEs in a form in which these streams are non-orthogonally mixed, with transmission powers that are different for the UEs. For each of the streams addressed to these UEs, the base station estimates predictive indices for these UEs from channel state information determined by the UEs to which those streams are addressed, and, based on the predictive indices, allocates different transmission powers to those UEs such that the better the predictive index is, the lower the transmission power is.