Grouping-Based Reference Signal Transmission for Massive MIMO
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Solution Overview
Problem
In wireless communication systems, especially in massive MIMO schemes, pilot contamination due to non-orthogonal reference signals limits link performance, and as the number of antennas increases, the reference signal overhead becomes a significant issue, particularly in multi-cell environments where the number of orthogonal sequences is insufficient to support the growing number of UEs.
Innovation Solution
The proposed solution involves UE grouping-based reference signal transmission, where UEs within the same group use orthogonal sequences, allowing for synchronized transmission and reduced overhead, and dynamic allocation of sequences based on channel conditions and data requirements to minimize pilot contamination and enhance channel estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of antennas is increased to support more UEs in massive MIMO, then the system capacity is improved, but the reference signal overhead increases significantly
Solution Approach 1:
The patent segments UEs into different groups, where each group is assigned a specific orthogonal sequence for reference signal transmission. This segmentation allows multiple UEs to share the same time-frequency resources while maintaining orthogonality through group-based sequence assignment, thereby reducing the overall reference signal overhead in massive MIMO systems.
Solution Approach 2:
The patent changes the parameter of sequence assignment from UE-specific to group-based. By transitioning from individual UE sequences to group-level orthogonal sequences, the system reduces the total number of required reference signals while maintaining channel estimation accuracy, thus lowering the reference signal overhead.
2Reliability
If orthogonal sequences are assigned to each UE to avoid pilot contamination, then link performance is improved, but the number of available orthogonal sequences becomes insufficient
Solution Approach 1:
The patent merges multiple UEs into groups that share the same orthogonal sequence. By combining UEs within each group and assigning them a common sequence, the system maintains orthogonality between groups while reducing the total number of sequences required, thus resolving the insufficiency of orthogonal sequences in massive MIMO deployments.
Solution Approach 2:
The patent makes orthogonal sequences universal by assigning the same sequence to multiple UEs within a group. This multi-functional approach allows a single orthogonal sequence to serve multiple UEs simultaneously, increasing the system's capacity to support more UEs without requiring a proportional increase in the number of orthogonal sequences.
3Quantity of substance
If UE grouping is implemented to reduce reference signal overhead, then overhead is reduced, but pilot contamination may increase within groups
Solution Approach 1:
The patent introduces a group dimension in addition to the individual UE dimension. By organizing UEs into groups and assigning orthogonal sequences at the group level, the system creates a new dimensional structure that reduces reference signal overhead while managing pilot contamination through the orthogonal separation between groups.
Data Source
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AI summary
Grouping based reference signal transmission scheme for massive MIMO is disclosed. UEs are grouped and each UE group receives information on a sequence used for the uplink reference signal from a base station. The information is determined to assign orthogonal sequences to UEs within a UE group considering at least one or more of a number of orthogonal sequences, a number of the UEs within the UE group, amount of information to be transmitted, channel condition between the base station and each UE, and a number of sequences assigned to each UE of the UEs.