NOMA User Scheduling via Throughput Ratio Metric
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In Non-Orthogonal Multiple Access (NOMA) systems, existing user scheduling algorithms like Proportional Fairness (PF) scheduler struggle to balance total user throughput and long-term user fairness, leading to issues such as users being denied transmission rates when their average throughput is high, and failing to account for channel gain differences that enhance overall throughput.
Innovation Solution
A system and method for attributing users to sub-bands based on a performance metric that maximizes the ratio of total achievable throughput to known throughput over a preceding period, using a Flexible Throughput vs Fairness Maximisation Metric (FTFMM) to select pairs of users for assignment, which balances throughput and fairness by weighting factors to prioritize either NOMA throughput or fairness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Proportional Fairness (PF) scheduler is used for user scheduling in NOMA systems, then user fairness is improved, but total user throughput deteriorates due to users being denied transmission rates when their average throughput is high
Solution Approach 1:
The patent modifies the PF scheduling metric by introducing a new parameter γ (gamma) that weights the relationship between current achievable throughput and historical average throughput. By adjusting γ dynamically or optimizing it, the system can shift between fairness-oriented and throughput-oriented scheduling behavior, resolving the contradiction between user fairness and total throughput.
Solution Approach 2:
The scheduling metric becomes dynamic by incorporating time-varying components: the achievable throughput Rs,k(t) changes with channel conditions, and the historical throughput Tk(t) evolves over the averaging window. This dynamic metric allows the system to adapt to changing conditions and balance fairness and throughput based on real-time system state.
2Reliability
If PF scheduler prioritizes users with low average throughput, then user fairness is improved, but system capacity deteriorates due to suboptimal user selection for NOMA
Solution Approach 1:
The patent introduces a modified scheduling metric that changes the selection criterion from purely fairness-based to a hybrid metric incorporating both fairness and NOMA-specific parameters. The parameter γ controls the balance, allowing the system to select users that satisfy both fairness requirements and NOMA optimization conditions (such as channel gain differences).
Solution Approach 2:
The scheduling metric becomes a composite of multiple components: the achievable throughput Rs,k(t), the historical average throughput Tk(t), and the weighting factor γ. This composite metric integrates multiple objectives (fairness, throughput, NOMA optimization) into a single unified criterion for user selection.
3Ease of manufacture
If conventional PF scheduling is used, then implementation simplicity is maintained, but performance optimization deteriorates due to failure to account for channel gain differences in NOMA
Solution Approach 1:
The patent extends the conventional PF metric by adding a scaling factor γ and incorporating achievable throughput calculations specific to NOMA. While the basic structure remains similar to conventional PF, the added parameters and calculations optimize throughput by accounting for NOMA characteristics such as superposition coding and successive interference cancellation.
Data Source
AI summary
A method of determining a performance metric for a selection of a first user and a second user among a set of candidate users for attribution to a sub-band in a multiple access communications system based on Non-Orthogonal Multiple Access (NOMA), is provided wherein the first user (k1) and the second user (k2) are selected as the pair of candidate users corresponding to an extremum of the ratio between a first term reflecting the total throughput achievable by any pair of the candidate users assigned to the sub-band (s) under consideration, and a second term reflecting the known throughput achieved by that same pair of candidate users over a predetermined preceding period. Implementations include a method of determining a performance metric is presented for attributing users to one or more of a plurality of sub-bands in a multiple access communications system, wherein in an initial assignment phase for a specific sub-band, a first user is selected for that band on the basis of one or more criteria such as user priority. Then a second sub-band user maximizing or minimizing the performance metric.