Uplink Beamforming Calibration in Multi-Antenna Wireless Systems
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Solution Overview
Problem
Conventional multi-antenna communication systems face challenges in maintaining optimal uplink beamforming due to fluctuating signal levels, additive interference, and multipath fading, which affect signal quality and interference rejection.
Innovation Solution
A method and system for uplink beamforming calibration in a multi-antenna wireless communication system, where a wireless transceiver determines the desired time-varying transmit phase relationship between antennas based on received RF signals, adjusts transmit power and phase, and dynamically selects antennas to optimize channel characteristics and interference mitigation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple antennas are used for uplink beamforming, then interference rejection and link quality are improved, but phase inconsistency between antennas degrades beamforming performance
Solution Approach 1:
The patent performs preliminary phase calibration by transmitting calibration signals through each antenna path and measuring the phase differences before actual beamforming operations. This preliminary measurement allows the system to pre-compensate for phase inconsistencies in the RF signal paths, ensuring phase consistency is established before data transmission begins.
Solution Approach 2:
The system implements a feedback mechanism where the base station measures the phase differences of calibration signals received from each antenna and sends calibration commands back to the wireless terminal. The terminal adjusts its transmit phases based on this feedback to achieve coherent combining at the base station, thereby maintaining phase consistency dynamically.
2Measurement precision
If phase calibration is performed frequently to maintain accuracy, then beamforming performance is improved, but system overhead and complexity increase
Solution Approach 1:
The patent implements periodic phase calibration where calibration signals are transmitted at regular intervals rather than continuously. This periodic approach maintains phase calibration accuracy while reducing the overhead compared to continuous calibration, as the system can maintain calibrated states between calibration periods in stable channel conditions.
Solution Approach 2:
The system dynamically adjusts calibration parameters such as calibration signal frequency, power levels, and interval periods based on channel conditions and beamforming requirements. By changing these parameters adaptively, the system optimizes the balance between calibration accuracy and system overhead, performing more frequent calibration only when channel conditions deteriorate or beamforming precision requirements increase.
Data Source
AI summary
A wireless transceiver, comprising a transmitter, a receiver and a plurality of antennas, determines transmit phase relationship between at least two of antennas based on radio frequency (RF) signals received via the at least two antennas from one or more antennas of a base station. RF signals are transmitted via the at least two antennas utilizing the determined transmit phase relationship. The receiver is calibrated based on receiver performance determined from the received RF signals for subsequent reception of RF signals. The transmit phase relationship is dynamically adjusted based on the transmit RF measurements and the determined receiver performance. Transmit channel qualities are determined for each transmit antenna based on the transmit RF measurements and the dynamically adjusted transmit phase relationship. Transmit antennas are dynamically selected based on the adjusted transmit phase relationship, the characterized transmit channel qualities and the determined receiver performance for subsequent transmission to the base station.