Per Stream Antenna Cyclic Shift Delay for Uplink MIMO
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In uplink multi-user MIMO transmissions, existing technologies face challenges in determining per antenna and per stream cyclic shift delays (CSD) to avoid unintentional beamforming and ensure proper timing alignment among multiple transmission antennas, which can lead to interference and reduced performance.
Innovation Solution
The proposed solution involves determining a first set of CSD values for legacy preambles and a second set of CSD values for non-legacy information, where CSD values differ between antennas and streams, respectively, with user CSD offsets being received via trigger messages from an access point to modify initial CSD values, thereby ensuring proper timing alignment and reducing the likelihood of unintentional beamforming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If per antenna and per stream cyclic shift delays are determined to avoid unintentional beamforming, then time diversity is enhanced and transmission reliability is improved, but device complexity and signal processing requirements increase
Solution Approach 1:
The patent segments the cyclic shift delay into two independent components: per-antenna CSD values and per-stream CSD values. This segmentation allows each component to be determined and applied separately, reducing the overall complexity while achieving the desired time diversity and preventing unintentional beamforming effects in uplink multi-user MIMO transmissions.
Solution Approach 2:
The patent applies different CSD values locally to each antenna and each stream independently. By determining specific CSD values for each antenna element and each spatial stream, the system creates local timing variations that enhance time diversity and prevent coherent combining of signals from different users, thereby improving reliability without requiring global reconfiguration.
2Reliability
If CSD values differ between antennas and streams, then unintentional beamforming is reduced and time diversity is enhanced, but manufacturing precision and calibration requirements increase
Solution Approach 1:
The patent performs preliminary determination of per-antenna and per-stream CSD values before the actual uplink transmission. By calculating and establishing these delay values in advance based on known antenna configurations and stream mappings, the system avoids the need for complex real-time calibration during operation, thereby reducing manufacturing precision requirements while still achieving the desired time diversity effects.
3Measurement precision
If per antenna and per stream CSD values are determined, then timing alignment among multiple transmission antennas is improved, but signal processing time and computational requirements increase
Solution Approach 1:
The patent segments the timing alignment process into two independent determination steps: first determining per-antenna CSD values for timing alignment, then determining per-stream CSD values for additional diversity. This segmentation allows the most critical timing alignment function to be achieved with simpler per-antenna values, reducing computational requirements and processing time while still achieving precise timing alignment.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method, an apparatus, and a computer-readable medium for wireless communication are provided. In one aspect, an apparatus includes a processor configured to determine a first set of CSD values for transmitting a first set of information on a plurality of antennas, determine a second set of CSD values for transmitting a second set of information on the plurality of antennas, and transmit the first set of information based on the first set of CSD values and the second set of information based on the second set of CSD values.