Wireless Receiver Distortion Cancellation Using Dual Channel Estimates

Solution Overview

Problem

Wireless devices face distortion issues due to increased output power causing clipping, leading to elevated in-band noise and inaccurate symbol estimation, which can result in undecodable data and increased power consumption.

Innovation Solution

A wireless device system that determines multiple channel estimates based on non-precoded and precoded signals to accurately estimate distortion, allowing for a distortion reduction operation to generate a reduced-distortion signal, thereby improving symbol estimation and reducing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the transmitter is configured to reduce input backoff to increase output power, then the communication range is improved, but the transmitter clips the output signal causing wide band distortion and elevated in-band noise

Engineering Contradiction:

Improveoutput powerVSAvoiddistortion

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The receiver performs preliminary channel estimation using a non-precoded signal before processing the precoded signal. This preliminary channel estimate is used to predict and remove distortion from the precoded signal, preventing distortion from degrading the received signal quality before detection occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system transmits both non-precoded and precoded signals, where the non-precoded signal appears to be redundant but actually serves as a reference for estimating channel characteristics and predicting distortion. This transforms what could be seen as wasted transmission resources into a beneficial tool for distortion cancellation.

Inventive Principle:

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

2Object-affected harmful factors

If the receiver performs iterative distortion estimation and removal, then distortion is reduced, but power consumption increases and symbol estimation accuracy may still be insufficient for high distortion levels

Engineering Contradiction:

ImprovedistortionVSAvoidpower consumption

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The receiver performs preliminary channel estimation using a non-precoded signal before processing the precoded signal. This preliminary channel estimate is used to predict and remove distortion from the precoded signal, preventing distortion from degrading the received signal quality before detection occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The non-precoded signal serves as an intermediary reference that enables the receiver to estimate channel characteristics without being affected by precoding operations. This intermediary signal allows for accurate distortion prediction that would be difficult to obtain from the precoded signal alone.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If linear detectors are used for symbol estimation under high distortion conditions, then the detection process is simple, but symbol estimation accuracy is insufficient leading to undecodable data

Engineering Contradiction:

Improvedetection simplicityVSAvoidsymbol estimation accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The receiver performs preliminary channel estimation using a non-precoded signal before processing the precoded signal. This preliminary channel estimate is used to predict and remove distortion from the precoded signal, preventing distortion from degrading the received signal quality before detection occurs.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9973225B1Receiver providing reduced distortion in a wireless device

Publication Date: 2018.05.15 QUALCOMM INC

AI summary

A device includes one or more antennas configured to receive a first signal and a second signal from a second device. The first signal includes a non-precoded signal. The device further includes a receiver coupled to the one or more antennas. The receiver is configured to determine a first channel estimate based on the first signal and determine a second channel estimate based on the second signal. The receiver is also configured to determine an estimated distortion based at least in part on the first channel estimate and the second channel estimate. The receiver is further configured to perform a distortion reduction operation on the second signal based on the estimated distortion to generate a reduced-distortion signal.