OFDM Receiver Nonlinear Distortion Compensation
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Solution Overview
Problem
Conventional methods for receiving OFDM signals struggle with nonlinear distortion, leading to inefficiencies in signal recovery due to inter-carrier interference and non-idealities introduced by transmitter and receiver front-ends.
Innovation Solution
The system employs nonlinear distortion modeling and interference estimation circuitry within the receiver to generate a model of the distortion experienced by the signal, allowing for reduced state sequence estimation and compensation, thereby improving the recovery of OFDM signals in the presence of nonlinear effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional reception methods are used for OFDM signals, then the receiver structure remains simple, but signal recovery accuracy deteriorates due to nonlinear distortion and inter-carrier interference
Solution Approach 1:
The receiver performs preliminary actions by determining a nonlinear distortion model and estimating interference before sequence estimation. The interference estimation circuitry calculates expected interference based on the distortion model and received signal, then uses this information to compensate for nonlinear effects during sequence estimation, improving accuracy without requiring completely new receiver architecture
Solution Approach 2:
The patent introduces an intermediary approach by using interference estimation as a mediator between the received signal and sequence estimation. The estimated interference acts as a compensating signal that bridges the gap between conventional reception and accurate signal recovery in the presence of nonlinear distortion
2Reliability
If nonlinear distortion modeling and interference estimation are implemented, then signal recovery accuracy improves, but device complexity increases due to additional circuitry
Solution Approach 1:
The receiver is segmented into distinct functional blocks: nonlinear distortion model determination circuitry, interference estimation circuitry, and sequence estimation circuitry. Each block performs a specific function, allowing for modular implementation and targeted optimization of reliability without requiring complete redesign of the entire receiver
3Measurement precision
If iterative processing of subcarriers is performed to compensate for interference, then bit-error rate performance improves, but processing time increases
Solution Approach 1:
The receiver employs feedback by using previously estimated subcarrier values to improve subsequent interference estimates. The sequence estimation circuitry iteratively refines its estimates by incorporating feedback from previous iterations, allowing convergence to accurate results while controlling processing time through efficient iteration management
Data Source
AI summary
An electronic receiver may comprise nonlinear distortion modeling circuitry, interference estimation circuitry, and sequence estimation circuitry. The receiver may receive an orthogonal frequency division multiplexing (OFDM) symbol in the form of an electromagnetic signal. The nonlinear distortion modeling circuitry may generate a nonlinear distortion model that models nonlinear distortion introduced to the received electromagnetic signal en route to the sequence estimation circuitry. The interference estimation circuitry may estimate inter-subcarrier interference present in the received OFDM symbol based on the generated nonlinear distortion model. The estimating of the inter-subcarrier interference may comprise applying the nonlinear distortion model to one or more candidate vectors generated by the sequence estimation circuitry. The sequence estimation circuitry may sequentially process a plurality of received virtual subcarrier values of the OFDM symbol using the estimated inter-subcarrier interference.