OFDM Signal Extension Padding Scheme for Non-Integer Bit Counts

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Solution Overview

Problem

Current padding schemes for orthogonal frequency-division multiplexing (OFDM) signal extensions in wireless data transmission systems face challenges in handling non-integer numbers of padding bits, particularly when the number of data bits per symbol is not a multiple of 4, leading to difficulties in implementing certain modulation and coding schemes.

Innovation Solution

A new padding procedure is introduced that applies special padding rules when the calculated number of data bits per symbol is not an integer, re-computing the number of coded bits and using these parameters for encoding, which includes pre-FEC and post-FEC padding modules to ensure integer values and distribute padding bits appropriately across encoders.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the number of data bits per symbol is not a multiple of 4, then certain modulation and coding schemes can be used, but the number of padding bits becomes non-integer which is difficult to implement

Engineering Contradiction:
Improvemodulation and coding scheme flexibilityVSAvoidpadding bits implementation feasibility
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by determining the number of padding bits before the encoding process. The system calculates the required padding bits based on the relationship between data bits per symbol and the chosen modulation and coding scheme, ensuring that the total number of bits (data bits + padding bits) is a multiple of 4. This pre-calculation and pre-padding approach resolves the contradiction by making the padding bit count deterministic and implementable before transmission, rather than attempting to handle non-integer padding bits during encoding.

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If a signal extension of multiples of 4μs is used to allow additional processing time, then the receiver can process longer data symbols with less processing logic overhead, but the complexity of determining padding bit distribution increases

Engineering Contradiction:
Improvereceiver processing simplicityVSAvoidpadding bit distribution calculation
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by establishing a direct mathematical relationship between the signal extension parameter (a×4μs where a=1,2,3,4) and the number of padding bits. The system changes the padding bit determination from a complex distribution problem to a straightforward calculation based on the signal extension multiplier. Specifically, the number of padding bits is determined as a function of the signal extension parameter and the data bit count, simplifying the receiver operation while maintaining systematic padding bit distribution.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3308486B1Systems, apparatuses and methods for a signal extension padding scheme
Publication Date: 2020.12.09 NXP USA INC
  • EP3308486B1 patent drawingFigure 1
  • EP3308486B1 patent drawingFigure 2
  • EP3308486B1 patent drawingFigure 3

AI summary

Systems, apparatuses and methods described herein provide a method for padding a signal extension of orthogonal frequency-division multiplexing (OFDM) symbols. A transceiver may obtain a plurality of data symbols for transmission, and determine that a number of information bits for a last symbol of the plurality of data symbols is not an integer value. A special padding rule may be applied to add padding bits to the last symbol. A number of coded bits for the last symbol may be determined when the number of information bits for the last symbol has changed, and the plurality of data symbols for data transmission may be encoded based on the determined number of coded bits for the last symbol.