Terminal Beam Sweeping for 5G Channel Reciprocity
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Solution Overview
Problem
In 5G communication systems, imperfect channel reciprocity between uplink and downlink due to independently connected RF chains and phase shifters in antenna arrays leads to performance degradation, reducing the effectiveness of beamforming and increasing path loss, which limits the service area and interferes with signal transmission.
Innovation Solution
A method for determining optimal transmission and reception beams by sweeping multiple beams, measuring reference signals, estimating downlink channel gain, generating a channel-related matrix, and reconfiguring channels to compensate for imperfect reciprocity, allowing for improved beam alignment and communication performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If beamforming technology is applied using multiple antennas to increase reaching distance and reduce interference, then service area and communication performance are improved, but device complexity increases due to independently connected RF chains and phase shifters
Solution Approach 1:
The patent divides the beam management process into separate uplink and downlink beam determination operations. The terminal independently determines uplink transmission beams and downlink reception beams through separate beam sweeping and measurement procedures, allowing complex beamforming to be managed in segmented, independent stages rather than requiring coordinated complex system-wide management.
Solution Approach 2:
The patent performs preliminary beam sweeping and reference signal measurement before actual data transmission. The terminal pre-determines optimal uplink and downlink beams by sweeping through candidate beams and measuring reference signals, storing these beam configurations for subsequent communication. This preliminary beam establishment reduces the complexity of real-time beam management during active transmission.
2Device complexity
If channel reciprocity is assumed between uplink and downlink to simplify beam determination, then device complexity is reduced, but measurement precision deteriorates due to imperfect reciprocity caused by independently connected RF chains and phase shifters
Solution Approach 1:
Instead of assuming downlink channel characteristics based on uplink measurements (traditional reciprocity approach), the patent inverts the approach by independently measuring and determining downlink reception beams through separate downlink reference signal measurements. This inversion eliminates reliance on imperfect reciprocity assumptions while maintaining independent uplink and downlink beam optimization.
Solution Approach 2:
The patent implements feedback mechanisms where the terminal measures downlink reference signals using swept reception beams and provides measurement results back to determine optimal downlink beams. This feedback-based approach allows the system to adapt to actual channel conditions rather than relying on theoretical reciprocity, improving measurement precision despite device complexity.
3Reliability
If beam sweeping operation is performed to determine optimal transmission and reception beams, then communication performance is improved, but loss of time increases due to sequential beam measurement and determination processes
Solution Approach 1:
The patent merges uplink and downlink beam sweeping operations into a coordinated procedure. The terminal performs uplink beam sweeping for transmission beam determination and downlink beam sweeping for reception beam determination in an integrated manner, utilizing the same time resources and processing capabilities for both directions, thereby reducing total beam determination time while maintaining optimal beam selection.
Solution Approach 2:
The patent implements periodic beam sweeping where the terminal systematically cycles through candidate beams at regular intervals, measuring reference signals and updating beam determinations in periodic cycles. This structured periodic approach allows efficient utilization of time resources, ensuring comprehensive beam evaluation while minimizing idle time and optimizing the trade-off between thoroughness and speed.
Data Source
AI summary
A method of operating a communication device includes: sweeping a plurality of first reception beams; measuring reference signals, received from another communication device, based on the plurality of first reception beams; estimating a downlink channel gain based on the measured reference signals and reception array response information corresponding to reception antenna characteristics of the communication device; generating a downlink channel related matrix based on the downlink channel gain and the reception array response information; determining a second reception beam based on the downlink channel related matrix; determining a transmission beam based on at least one of the downlink channel gain, the downlink channel related matrix, and the second reception beam; and performing communication with the other communication device using the second reception beam and the transmission beam.