OFDM Symbol Interleaver with Dynamic Permutation for Odd DVB Modes

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Solution Overview

Problem

Existing OFDM systems, such as DVB-T and DVB-H, face challenges in error correction due to correlated fading in terrestrial broadcast channels, which can be mitigated by effectively interleaving data symbols across sub-carrier signals, but current interleaving schemes are not optimal, especially for odd OFDM symbols.

Innovation Solution

A data processing apparatus with a symbol interleaver that uses a linear feedback shift register and permutation circuit to generate pseudo-random bit sequences and change permutation codes for each OFDM symbol, ensuring that data symbols are optimally mapped across sub-carriers, particularly utilizing an odd interleaving process to improve error correction efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fixed permutation code is used for interleaving data symbols onto sub-carrier signals, then the interleaving process is simple and deterministic, but successive data bits may be mapped to the same sub-carrier, reducing error correction performance

Engineering Contradiction:

Improveerror correction performanceVSAvoidinterleaving scheme complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies dynamics by changing the permutation code from one OFDM symbol to another, transforming the static interleaving scheme into a dynamic one. This ensures that successive data bits are not consistently mapped to the same sub-carrier, thereby improving error correction performance while managing complexity through systematic code variation

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements periodic action by cycling through different permutation codes for successive OFDM symbols. This periodic variation in permutation codes ensures diverse mapping patterns over time, preventing systematic mapping errors while maintaining a structured and manageable interleaving process

Inventive Principle:

Principle #19Periodic action

2Reliability

If separate interleaving processes are used for even and odd OFDM symbols, then optimal interleaving can be achieved for each symbol type, but device complexity and processing overhead increase

Engineering Contradiction:

Improveinterleaving effectivenessVSAvoidinterleaving process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies universality by designing a single interleaving apparatus that can handle both even and odd OFDM symbols through a unified mechanism. The same interleaver structure processes all symbols, with the permutation code variation providing the necessary differentiation, thereby reducing complexity while maintaining effectiveness

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent implements parameter changes by varying the permutation code parameter across different OFDM symbols rather than maintaining separate interleaving processes. This parameter-based differentiation allows a single apparatus to adapt its behavior for even and odd symbols, reducing structural complexity while preserving optimal interleaving performance

Inventive Principle:

Principle #35Parameter changes

3Reliability

If data symbols are mapped sequentially onto sub-carrier signals, then the mapping process is simple and fast, but error correction coding performance deteriorates due to correlated fading effects

Engineering Contradiction:

Improveerror correction coding performanceVSAvoidsymbol mapping speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent introduces an intermediary element (the permutation circuit with variable permutation codes) between the sequential data symbols and the sub-carrier signals. This intermediary shuffles the mapping order dynamically, breaking the correlation caused by sequential mapping while maintaining efficient processing through a structured intermediate transformation step

Inventive Principle:

Principle #24Intermediary (Mediator)

4Quantity of substance

If the same interleaver memory is used for both even and odd OFDM symbols, then memory usage is optimized, but interference between symbol types may occur without proper differentiation

Engineering Contradiction:

Improvememory usage efficiencyVSAvoidsymbol processing integrity

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent implements continuity by using the same interleaver memory for both even and odd OFDM symbols without interruption or switching. The variable permutation codes ensure continuous and differentiated processing within the unified memory structure, maintaining both memory efficiency and symbol processing integrity through uninterrupted operation

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS8199802B28K mode interleaver with odd interleaving only and per OFDM symbol permutation code change in a digital video broadcasting (DVB) standard

Publication Date: 2012.06.12 SONY GROUP CORP

AI summary

A data processing apparatus maps input symbols to be communicated onto a predetermined number of sub-carrier signals of an Orthogonal Frequency Division Multiplexed (OFDM) symbol. The data processor includes an interleaver memory which reads-in the predetermined number of data symbols for mapping onto the OFDM sub-carrier signals. The interleaver memory reads-out the data symbols on to the OFDM sub-carriers to effect the mapping, the read-out being in a different order than the read-in, the order being determined from a set of addresses, with the effect that the data symbols are interleaved on to the sub-carrier signals. The set of addresses are generated from an address generator which comprises a linear feedback shift register and a permutation circuit.