Phase Error Estimation in 5G Wireless Systems
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Solution Overview
Problem
Existing wireless communication systems based on OFDM struggle to effectively estimate and correct phase errors, especially in millimeter wave communication systems where phase errors rapidly change, leading to performance degradation due to inter-carrier interference.
Innovation Solution
A method and apparatus for estimating and correcting phase errors within a symbol using a time-domain signal, where a correlation-based approach is employed to filter and correct phase errors, utilizing a reference signal sent by the transmitter and processed by the receiver to reduce inter-carrier interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If phase error correction is performed using a cyclic prefix on a per-symbol basis, then the complexity of phase error estimation is reduced, but the precision of phase error estimation deteriorates when phase error rapidly changes within a symbol
Solution Approach 1:
The patent segments the phase error estimation process into two distinct components: (1) common phase error (CPE) estimation affecting all OFDM subcarriers using a reference signal, and (2) inter-carrier interference (ICI) reduction using cyclic prefix-based phase error estimation. This segmentation allows each component to be optimized independently - CPE estimation achieves high precision through reference signal correlation, while ICI reduction maintains low complexity through cyclic prefix processing.
Solution Approach 2:
The patent changes the estimation granularity parameter from coarse (per-symbol basis only) to fine (within-symbol estimation). By introducing within-symbol phase error estimation using correlation of time-domain signals, the system achieves higher precision phase error tracking without excessively increasing complexity, as the estimation is performed only on relevant signal portions.
2Speed
If phase error estimation is performed on a per-symbol basis, then the processing speed is improved, but the reliability of phase error correction deteriorates in millimeter wave communication systems with severe phase errors
Solution Approach 1:
The patent applies preliminary action by performing common phase error estimation using reference signals before the main data reception process. The reference signal-based CPE estimation is executed in advance to establish a baseline phase correction, which then complements the per-symbol ICI reduction. This preliminary estimation ensures that severe phase errors are addressed before they degrade the main signal processing.
Solution Approach 2:
The patent introduces an intermediary reference signal mechanism that mediates between the need for high-speed per-symbol processing and the need for reliable phase error correction. The reference signal serves as an intermediary carrier that enables precise CPE estimation without burdening the main data signal processing, thereby maintaining processing speed while improving reliability through the additional estimation layer.
3Measurement precision
If correlation-based phase error estimation is performed using time-domain signals, then the precision of phase error estimation is improved within a symbol, but the complexity of signal processing increases
Solution Approach 1:
The patent extracts only the necessary components for phase error estimation from the full time-domain signal. Instead of processing the entire received signal, the system extracts correlation information from specific portions of the time-domain signal that contain phase error characteristics. This extraction approach achieves high precision phase error estimation while minimizing processing complexity by focusing computational resources on the most informative signal portions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly improves reception performance by accurately estimating and correcting phase errors within a symbol, reducing the influence of inter-carrier interference and enhancing overall system performance, as demonstrated by a 7 dB performance gain in millimeter wave communication systems.
Implementation Method 1
filtering the received time-domain signal
Implementation Method 2
estimating the phase error using the filtered time-domain signal, wherein a correlation regarding the time-domain signal is used for phase error estimation
Data Source
AI summary
Provided are a method and apparatus for estimating and correcting the phase error in 5G or pre-5G communication systems providing much higher data rates compared to existing 4G communication systems including LTE systems. The existing phase error estimation scheme using a cyclic prefix in the time domain may fail to prevent performance degradation due to inter-carrier interference. In the present invention, it is possible to enhance reception performance of the receiver by estimating and correcting the phase error multiple times within a symbol using a time domain signal and by reducing the influence of inter-carrier interference.