SCMA Resource Allocation via Device Grouping and Filtering
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Solution Overview
Problem
In sparse code multiple access (SCMA) systems, the synchronization of devices is typically required for correct signal reception at the base station, leading to significant signaling overhead, especially as the number of devices increases, which can be costly and inefficient.
Innovation Solution
The synchronization requirement is relaxed by grouping devices based on location and mobility, allowing them to use asynchronous SCMA transmissions within allocated resource regions, and using digital filters to mitigate inter-resource region interference, which can be filtered at both the transmitter and receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If global synchronization signaling is implemented for all devices, then signal reception accuracy is improved, but signaling overhead increases significantly
Solution Approach 1:
The patent segments devices into multiple groups based on their location and mobility characteristics. Each group is assigned a specific resource region (time-frequency resources) for transmission. This segmentation allows the base station to relax global synchronization requirements while maintaining reception accuracy within each group, thereby reducing the signaling overhead required for synchronization.
Solution Approach 2:
The patent applies local quality by requiring synchronization only within each device group rather than globally across all devices. Devices in the same group share common time-frequency resources and require synchronized transmission, while devices in different groups operate independently with their own resource regions. This local synchronization approach maintains signal reception accuracy where needed while eliminating unnecessary global signaling overhead.
2Quantity of substance
If the number of supported devices is increased, then system capacity is improved, but collision probability increases
Solution Approach 1:
The patent divides the overall resource block into multiple resource regions, with each region assigned to a specific device group. This segmentation allows more devices to be supported simultaneously by distributing them across different resource regions, thereby reducing the probability of collision between devices while increasing system capacity.
Solution Approach 2:
The patent introduces an additional dimension for resource allocation by creating multiple resource regions in the time-frequency domain. Instead of all devices competing for the same resources, devices are allocated to different regions along the time and frequency dimensions. This dimensional expansion allows more devices to be supported while maintaining reliable transmission by reducing resource contention and collision probability.
3Loss of information
If asynchronous transmissions are allowed, then signaling overhead is reduced, but inter-resource region interference increases
Solution Approach 1:
The patent introduces digital filters as intermediaries to mitigate inter-resource region interference caused by asynchronous transmissions. These filters are applied at both the transmitter and receiver ends to suppress interference from other resource regions while allowing the desired signal to pass through. This intermediary filtering mechanism enables asynchronous transmissions to proceed with reduced interference, thereby lowering signaling overhead while maintaining transmission quality.
Data Source
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AI summary
An embodiment method of resource allocation for sparse code multiple access (SCMA) transmissions includes partitioning a resource block into a plurality of resource regions. The method also includes assigning the plurality of resource regions to respective device groups. The resource region assignments are then signaled to devices of the respective device groups. The method also includes receiving SCMA signals from the devices of the respective device groups. The SCMA signals from one group of the respective device groups are asynchronous with respect to the SCMA signals from another group of the respective device groups.