OFDM Interleaver Permutation for 0.5k to 32k Mode Adaptation
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Solution Overview
Problem
The existing DVB-T and DVB-H standards lack a 0.5k mode interleaver, which is necessary for more frequent channel estimation updates to accurately track time variations due to Doppler and other effects, and existing error correction coding schemes perform suboptimally in correlated fading environments.
Innovation Solution
A data processing apparatus that maps input symbols onto OFDM sub-carrier signals using a linear feedback shift register and permutation circuit to generate pseudo-random bit sequences and addresses, allowing for flexible implementation across various modes, including 0.5k, 1k, 2k, 4k, 8k, 16k, and 32k, by adjusting the generator polynomial and permutation order.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing DVB-T and DVB-H standards are used with fixed interleaver configurations for 2k, 8k modes, then implementation is standardized and reliable, but adaptability to different modes (including 0.5k mode) is insufficient
Solution Approach 1:
The patent implements a universal interleaver architecture that can operate across multiple DVB-T2 modes (0.5k, 1k, 2k, 4k, 8k, 16k, 32k) by dynamically configuring the generator polynomial and permutation order based on the selected mode. This multi-functional design eliminates the need for separate interleaver implementations for each mode while maintaining optimal performance characteristics for each specific mode.
Solution Approach 2:
The patent changes key parameters (generator polynomial coefficients and permutation order) based on the operating mode to optimize interleaver performance. By selecting different generator polynomials and permutation sequences for different modes, the system adapts its behavior to match the specific requirements of each mode without requiring structural modifications to the interleaver architecture.
2Reliability
If symbol interleaving is implemented to improve channel estimation and track time variations, then reliability in correlated fading environments improves, but device complexity increases due to additional processing requirements
Solution Approach 1:
The patent replaces complex adaptive processing mechanisms with a predetermined, static interleaving pattern generated by a linear feedback shift register. Instead of implementing dynamic adaptation logic that would increase processing complexity, the system uses the inherent randomness and long-period properties of the LFSR-generated sequence to achieve reliable symbol separation and channel estimation across varying channel conditions.
Solution Approach 2:
The interleaver sequence is generated autonomously by the linear feedback shift register using a predetermined generator polynomial, without requiring external control signals or adaptive processing. The system self-configures the interleaving pattern based on the mode selection, reducing the processing burden while maintaining reliability through the mathematical properties of the LFSR sequence.
Data Source
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.