Geometric Shift Transform for Phase-Cyclic OFDM Precoding

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Solution Overview

Problem

Conventional digital communication systems face high data rates and substantial computing power requirements for transporting modulated signals between the central and remote units, especially in pre-coded OFDM systems, which complicates frequency and time allocation and scrambling functionalities.

Innovation Solution

Implementing a phase-cyclic transform using a geometric shift table for symbol alphabet transmission, reducing data rates and computational load by storing rotated constellation lookup tables, allowing symbol code word transport and simplifying precoding calculations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sampled waveform format is used for digital signal transport between CU and RU, then signal quality and noise immunity are improved, but data rate increases up to 10 or more times the user data stream bit rate

Engineering Contradiction:

Improvesignal qualityVSAvoiddata rate

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The invention extracts only the essential information (symbol code words representing constellation points) from the complete sampled waveform, transporting only these discrete symbols between CU and RU. This eliminates redundant data while preserving the core signal information needed for reconstruction at the remote unit.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the representation parameter from continuous sampled waveform values to discrete symbol code words from a finite constellation alphabet. This parameter transformation reduces the data rate while maintaining signal integrity through the use of phase-cyclic precoding transforms.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If conventional precoding calculation methods are used in pre-coded OFDM systems, then signal processing accuracy is maintained, but computing power requirements become substantial

Engineering Contradiction:

Improvesignal processing accuracyVSAvoidcomputing power

Core Design Contradiction:

Measurement precisionVSPower

Solution Approach 1:

The invention pre-calculates and stores the phase-cyclic transform matrices at the central unit before signal transmission. By preparing these transformation matrices in advance, the system eliminates the need for complex real-time calculations at the remote unit, significantly reducing computing power requirements while maintaining processing accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention replaces complex mechanical computing operations with pre-computed mathematical transforms. The phase-cyclic precoding transforms substitute for traditional FFT-based precoding methods, reducing computational complexity through algebraic simplifications and pre-calculated lookup tables.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS12445339B2Methods and systems for digital representation of encoded communications data and simplified evaluation of precoding in systems using phase-cyclical precoding

Publication Date: 2025.10.14 WAVESTREAM CORP

AI summary

The present invention discloses the structure and operation of the “geometric shift transform” that enables the use of symbol alphabet code word representation of a user's binary data stream as the signal transport format from a central unit (modem) of a precoded OFDM system to a remote unit (the RF equipment). The invention simplifies the precoding transform (DFT) calculation, enables secure transmissions, and contemplates layer and resource block mapping operations in the central unit.