SC-FDMA Resource Allocation with Cell-Specific Mirroring
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Solution Overview
Problem
In SC-FDMA wireless communication systems, existing frequency selective scheduling and frequency hopping methods fail to effectively randomize interference between neighbor cells, leading to reception quality degradation due to fixed hopping patterns and limited interference randomization, especially for UEs with fast-changing channel status.
Innovation Solution
Implementing a method that allows different mirroring on/off patterns for each cell, using PN sequences or orthogonal codes to determine mirroring status at each hopping time, thereby randomizing interference and minimizing RU collisions between cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If frequency selective scheduling is used to allocate frequency bands with good channel status to UEs, then system performance is maximized with limited resources, but for UEs with fast-changing channel status, the allocated frequency band may not ensure good channel status when data transmission occurs
Solution Approach 1:
The patent implements dynamic frequency hopping patterns that adapt to channel conditions. Instead of fixed frequency allocations, the system dynamically changes the frequency resources allocated to UEs across different time slots, allowing the allocation to respond to fast-changing channel status while maintaining overall system efficiency
Solution Approach 2:
The system changes the frequency parameter dynamically through frequency hopping. By varying the frequency allocation parameters across time slots according to predefined hopping patterns, the system ensures that UEs with fast-changing channel status can maintain reliable connections despite channel variations
2Reliability
If frequency hopping is implemented to randomize channel quality and interference, then diversity is achieved, but when RUs hop to non-successive positions, the single carrier property is violated and data transmission fails
Solution Approach 1:
The patent employs asymmetric frequency hopping patterns where the hopping behavior differs between cells. By using different mirroring on/off patterns in different cells, the system achieves interference randomization while maintaining the single carrier property within each cell. The asymmetry in hopping patterns between cells prevents collision while preserving the successive RU structure required for single carrier transmission
Solution Approach 2:
The system segments the frequency hopping operation into two parts: intra-cell hopping that maintains successive RUs for single carrier property, and inter-cell differentiation through different mirroring patterns that achieves interference randomization. This segmentation allows both requirements to be satisfied simultaneously
3Reliability
If fixed mirroring patterns are used for frequency hopping to achieve frequency diversity, then successive RUs can hop maintaining single carrier property, but interference randomization between neighbor cells is limited due to identical hopping patterns
Solution Approach 1:
The patent applies different mirroring on/off patterns in different cells, creating local variations in frequency hopping behavior. Each cell has its own unique pattern configuration, which maintains the frequency diversity benefit of mirroring while introducing local differences that randomize interference between cells. This local differentiation resolves the contradiction between maintaining frequency diversity and reducing inter-cell interference
4Quantity of substance
If frequency resources are continuously allocated to UEs for VoIP-like services, then small amount of frequency resources are needed continuously, but signaling overhead becomes substantial with frequency selective scheduling
Solution Approach 1:
The system implements self-service frequency allocation through predetermined frequency hopping patterns. Instead of requiring continuous signaling for frequency selective scheduling, UEs autonomously determine their frequency resources based on pre-configured hopping patterns and cell-specific parameters, dramatically reducing signaling overhead while maintaining continuous resource allocation for VoIP-like services
Data Source
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AI summary
An apparatus and method for allocating resources in an Single Carrier-Frequency Division Multiple Access (SC-FDMA) communication system are provided, in which a Node B determines on a cell basis whether to turn or off inter-subband hopping and whether to turn on or off mirroring for a resource unit for the UE on a frequency axis along which at least two subbands are defined, at set hopping times, selects a resource unit by selectively performing inter-subband hopping and mirroring on the resource unit for the UE according to the determination, and allocates the selected resource unit to the UE.