Nonlinear Compensator for Satellite HPA Interference

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Solution Overview

Problem

Conventional satellite communication systems with High Power Amplifiers (HPAs) face challenges in addressing both linear and nonlinear Inter Symbol Interference (ISI) and adjacent carrier interference (ACI), especially when multiple carriers share a single HPA, leading to reduced information quality and inefficiencies in power and bandwidth usage.

Innovation Solution

A receiver system employing adaptive Volterra filters and nonlinear combiners to compensate for linear and nonlinear ISI and ACI, using adaptive polynomial filters and Volterra series expansions to equalize and cancel interference, allowing for tight carrier spacing and efficient operation near HPA saturation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple carriers are amplified by a single HPA, then bandwidth efficiency is improved, but nonlinear interference and adjacent carrier interference increase

Engineering Contradiction:

Improvebandwidth efficiencyVSAvoidnonlinear interference

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful nonlinear interference generated by HPA into a measurable signal characteristic that can be compensated. By modeling the HPA nonlinearity using Volterra series and using the interference signal itself to generate compensation signals, the system transforms the harmful effect into a useful correction mechanism that improves overall system performance.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces an intermediary compensation signal generation mechanism that mediates between the HPA output and the receiver. The nonlinear compensator acts as an intermediary that processes the received signal and generates correction signals based on Volterra series modeling, thereby reducing the impact of nonlinear interference without requiring changes to the HPA itself.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Use of energy by moving object

If HPA operates near saturation, then power efficiency is improved, but signal distortion and interference increase

Engineering Contradiction:

Improvepower efficiencyVSAvoidsignal quality

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the receiver detects nonlinear interference characteristics and generates compensation signals that are fed back to correct the distortion. The adaptive nonlinear compensator continuously adjusts its parameters based on the received signal quality, creating a closed-loop system that maintains signal integrity even when HPA operates near saturation.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the operational parameters of the communication system by introducing adaptive compensation that allows the HPA to operate near saturation while maintaining signal quality. The system dynamically adjusts compensation parameters based on the level of nonlinear interference detected, enabling efficient power operation without sacrificing reliability.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If carrier spacing is reduced, then bandwidth efficiency is improved, but adjacent carrier interference increases

Engineering Contradiction:

Improvebandwidth efficiencyVSAvoidadjacent carrier interference

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful adjacent carrier interference into a useful signal for compensation. By modeling the interference using Volterra series and using the interfering carrier signals themselves to generate compensation, the system transforms ACI from a detrimental effect into a mechanism that enables tighter carrier spacing while maintaining signal quality.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

4Reliability

If conventional ISI compensation is applied, then linear interference is reduced, but nonlinear interference remains uncorrected

Engineering Contradiction:

Improvesignal qualityVSAvoidcompensation system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple compensation techniques into a composite solution. It integrates linear equalization with nonlinear Volterra series-based compensation, creating a composite compensation system that addresses both linear and nonlinear interference components. This composite approach provides comprehensive interference reduction while managing system complexity through modular implementation.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS8331511B2System and method for compensating for nonlinear interference cancellation in multi-carrier transmission

Publication Date: 2012.12.11 HUGHES NETWORK SYST

AI summary

An aspect of the present invention is drawn to a receiver operable to receive a first signal transmitted on a first carrier and to receive a second signal transmitted on a second carrier. The receiver includes a first filter, a second filter and a nonlinear compensator. The first filter is arranged to receive the first signal and to generate a first filtered signal. The second filter is arranged to receive the second signal and to generate a second filtered signal. The nonlinear compensator is arranged to output a first compensating signal based on the first filtered signal and the second filtered signal and to output a second compensating signal based on the first filtered signal and the second filtered signal. Further, the nonlinear compensator can reduce one of nonlinear interference within the first filtered signal and nonlinear interference between the first filtered signal and the second filtered signal.