OFDM Symbol Interleaving With Single-Memory Odd-Only Addressing
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Solution Overview
Problem
The Digital Video Broadcasting standards, such as DVB-T and DVB-H, face challenges in providing an efficient implementation of symbol interleavers across various modes while maintaining performance and reducing implementation costs, particularly in the DVB-T2 standard which requires efficient mapping of data symbols onto OFDM sub-carrier signals.
Innovation Solution
A data processing apparatus that employs an odd interleaving process for both odd and even OFDM symbols, using a single interleaver memory, and switches to odd-only interleaving when the number of sub-carriers is half or less than half of the maximum, optimizing memory usage and interleaving efficiency across different modes like 2k, 4k, 8k, 16k, and 32k modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate odd and even interleaving processes are used for different OFDM symbols, then interleaving performance is improved, but device complexity and implementation cost increase
Solution Approach 1:
The patent applies universality by designing a single interleaver structure that can perform both odd and even interleaving functions. The same interleaver memory and address generator are used for both odd and even OFDM symbols, with the only difference being the address generation pattern. This eliminates the need for separate interleavers for odd and even symbols, reducing device complexity while maintaining interleaving performance through appropriate address sequencing.
Solution Approach 2:
The patent merges the odd and even interleaving processes into a single unified interleaver. Instead of having separate interleavers for odd and even OFDM symbols, the invention combines both functions into one interleaver that uses different address generation patterns (sequential addressing for odd symbols, permuted addressing for even symbols) to achieve the same interleaving effect, thereby reducing implementation cost and complexity.
2Ease of manufacture
If a single interleaver memory is used for both odd and even OFDM symbols, then implementation cost is reduced, but memory access conflicts may occur
Solution Approach 1:
The patent applies preliminary action by pre-defining two distinct address generation patterns: one for odd OFDM symbols (sequential addressing) and one for even OFDM symbols (permuted addressing). The address generator is configured in advance with these patterns, allowing the single interleaver memory to be accessed without conflicts by simply switching between pre-planned addressing schemes based on whether the current symbol is odd or even.
Solution Approach 2:
The patent introduces dynamics by making the address generation pattern adaptable based on the OFDM symbol type. The address generator dynamically switches between sequential addressing mode (for odd symbols) and permuted addressing mode (for even symbols), allowing the single interleaver memory to serve both purposes efficiently without access conflicts, thus reducing implementation cost while managing memory access complexity.
Data Source
AI summary
A data processing apparatus is arranged to map input data symbols to be communicated onto a predetermined number of sub-carrier signals of Orthogonal Frequency Division Multiplexed OFDM symbols. The predetermined number of sub-carrier signals is determined in accordance with one of a plurality of operating modes and the input data symbols are divided into first sets of input data symbols and second sets of input data symbols. The data processing apparatus comprises an interleaver operable to perform an odd interleaving process which interleaves the first sets of input data symbols on to the sub-carrier signals of first OFDM symbols and an even interleaving process which interleaves the second sets of input data symbols on to the sub-carrier signals of second OFDM symbols.