Group Distributed PTRS for OFDM Phase Noise Mitigation
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Solution Overview
Problem
Phase noise in orthogonal frequency-division multiplexing (OFDM) systems, particularly at high carrier frequencies like millimeter-wave bands, causes common phase error (CPE) and inter-carrier interference (ICI), which existing phase tracking reference signal (PTRS) structures struggle to fully mitigate, especially for ICI.
Innovation Solution
A system and method that employs a group distributed phase tracking reference signal subcarrier structure to estimate and compensate for both CPE and ICI by iteratively canceling estimated error terms from the received signal, using a combination of phase tracking reference signal subcarriers and channel responses to form compensated signals and estimate inter-carrier interference terms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fully distributed PTRS structure is used, then CPE estimation and compensation is enabled, but ICI mitigation is not achieved
Solution Approach 1:
The patent segments the distributed PTRS structure into groups of adjacent subcarriers rather than fully distributed individual subcarriers. This segmentation allows the system to maintain CPE estimation capability while creating localized reference signal clusters that enable ICI mitigation through group-based processing and interference cancellation techniques.
Solution Approach 2:
The patent transitions from a one-dimensional fully distributed PTRS structure to a two-dimensional group-based structure where reference signals are organized in both frequency (adjacent subcarriers) and time dimensions. This dimensional change enables simultaneous CPE tracking and ICI mitigation by creating local reference signal clusters that capture both common phase variations and inter-carrier interference characteristics.
2Quantity of substance
If phase noise PSD is wide compared to subcarrier spacing, then more total power is contributed as ICI, but CPE compensation becomes less effective
Solution Approach 1:
The patent applies local quality by creating localized groups of adjacent subcarriers with PTRS within the frequency domain. Instead of treating all subcarriers uniformly, the system processes local groups separately, allowing accurate CPE estimation in each local region even when overall phase noise PSD is wide. This local processing approach maintains estimation accuracy despite wideband phase noise conditions.
Solution Approach 2:
The patent performs preliminary CPE estimation and compensation within each local group of adjacent subcarriers before proceeding to ICI mitigation. By pre-compensating CPE in localized regions where phase noise correlations are stronger, the system improves subsequent ICI cancellation effectiveness and overall detection accuracy in wideband phase noise scenarios.
Data Source
AI summary
A system and method for transmitting an orthogonal frequency-division multiplexed signal with a group distributed phase tracking reference signal subcarrier structure, and for estimating, and compensating for, both common phase error, and inter-carrier interference.