Calibrating Phase Distortion in LTE Transceiver Chains
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Phase hardware-induced distortion in LTE communications systems prevents accurate determination of downlink channel state information (DL-CSI), leading to increased co-channel interference in MU-MIMO systems.
Innovation Solution
The method involves estimating phase differences between downlink and uplink channels, determining relative phase distortion induced by transceiver chains, and using this information to calibrate and compensate for hardware-induced phase distortion, thereby improving the accuracy of DL-CSI estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MU-MIMO beamforming is implemented to enhance communication capabilities, then spectral efficiency and network coverage are improved, but co-channel interference increases and DL-CSI accuracy deteriorates due to phase hardware-induced distortion
Solution Approach 1:
The patent implements a feedback mechanism where the UE measures downlink channel phase differences and feeds back estimates to the eNB. The eNB then determines uplink phase differences and calculates relative phase distortion, using this feedback loop to continuously calibrate and compensate for hardware-induced phase distortion, thereby reducing co-channel interference while maintaining MU-MIMO beamforming performance
Solution Approach 2:
The patent introduces phase difference estimation and relative phase distortion calculation as intermediary processes between the transceiver chains and the beamforming operation. By measuring phase differences in both downlink and uplink channels and computing the relative distortion, the system creates an intermediary calibration mechanism that enables accurate DL-CSI determination despite hardware impairments
2Measurement precision
If phase calibration is performed to improve DL-CSI accuracy, then co-channel interference is reduced, but system complexity and calibration overhead increase
Solution Approach 1:
The patent makes the phase calibration process universal by using the same uplink and downlink channel measurements for both standard beamforming operation and phase distortion calibration. The phase difference measurements serve dual purposes: enabling normal MU-MIMO communication and providing the data needed for calibration, thereby avoiding additional dedicated calibration procedures and reducing overall system complexity
Data Source
AI summary
Methods and systems are described for calibrating phase hardware-induced distortion in a cellular communications system. In one aspect, an estimate of a phase difference at a user equipment (UE) between downlink channels including signals sent over two or more BS transmitter chains is obtained. A phase difference between uplink channels including signals received over two or more BS receiver chains is determined. A relative phase distortion induced by two or more BS transceiver chains is determined based on the received estimate of phase difference between downlink channels and the determined phase difference between uplink channels.