Base Sequence Group Hopping for Uplink Interference Reduction
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Solution Overview
Problem
In wireless communication systems, especially 5G NR systems, the increasing number of user equipment (UEs) leads to a higher probability of collisions between grant-free transmissions, resulting in degraded performance and efficiency due to inter-cell and intra-cell interference, as UEs transmit uplink messages without scheduling grants.
Innovation Solution
The system generates a pool of distinct base sequences with low peak-to-average power ratio (PAPR) and assigns them to groups based on a hopping pattern reuse factor, allowing UEs to select base sequences for transmission, reducing collisions by using different sequences for neighboring cells and applying permutation or cyclic shifts across transmission opportunities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If UEs transmit uplink messages without scheduling grants (grant-free transmission), then transmission efficiency and latency are improved, but the probability of collision between transmissions from multiple UEs increases, leading to degraded performance
Solution Approach 1:
The patent segments the base sequences into multiple groups, where each group is assigned to a specific cell. UEs in different cells select base sequences from different groups, which segments the overall sequence space and reduces the probability of collision between UEs in neighboring cells while maintaining grant-free transmission efficiency
Solution Approach 2:
The patent applies local quality by assigning specific base sequences to specific cells based on cell identifiers. Each cell has a localized set of base sequences that UEs in that cell can use, creating a localized quality distinction that reduces inter-cell interference while allowing efficient grant-free transmission within each cell
2Loss of information
If the same base sequences are reused across neighboring cells, then signaling overhead is reduced, but inter-cell interference increases, degrading channel estimation accuracy
Solution Approach 1:
The patent segments base sequences into cell-specific groups, where each cell is assigned a distinct group of base sequences. This segmentation prevents sequence reuse across cell boundaries, eliminating inter-cell interference while requiring minimal signaling to indicate group assignment based on cell identifiers
Solution Approach 2:
The patent changes the parameter of base sequence assignment by introducing cell-specific grouping based on cell identifiers. This parameter change ensures that the same base sequences are not reused in neighboring cells, eliminating inter-cell interference while maintaining efficient signaling through implicit group assignment
3Adaptability or versatility
If a large pool of base sequences is available to all UEs, then the flexibility and adaptability of sequence selection is improved, but the probability of intra-cell collision increases, reducing transmission reliability
Solution Approach 1:
The patent segments the large pool of base sequences into multiple smaller cell-specific groups. UEs within a cell select from their cell's assigned group, which maintains flexibility within the cell while the segmentation across cells reduces overall collision probability by isolating sequence selection to smaller subsets
Solution Approach 2:
The patent adds a new dimension to base sequence selection by introducing cell-specific group assignment. Instead of a single-dimensional sequence pool, the system creates a two-dimensional structure where sequences are organized by cell groups, allowing flexible selection within each dimension while reducing collisions across dimensions
Data Source
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Figure 3A~3B
AI summary
Methods, systems, and devices for wireless communications are described. A network may generate a pool of distinct base sequences for use with uplink messages from a user equipment (UE) to a base station, where each base sequence in the pool of distinct base sequences may have a peak to average power ratio below a threshold. A base station may assign the pool of distinct base sequences into groups of base sequences based on a group size and a hopping pattern reuse factor. The base station may assign the groups of base sequences to cells and signal the group size and a hopping pattern index to UEs in the cells. A UE in a cell may identify the group of base sequences assigned to the cell based on the signaled parameters and select a base sequence for use in transmitting an uplink message to the base station.