OFDM Symbol Interleaver Addressing for DVB-T2 16k Mode
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Solution Overview
Problem
The existing DVB-T and DVB-H standards lack an efficient symbol interleaver for the 16k mode, which is necessary for providing a more sparse deployment of DVB transmitters in a single frequency network, requiring improved error correction coding performance due to correlated fading in terrestrial broadcast channels.
Innovation Solution
A data processing apparatus with a linear feedback shift register and permutation circuit generates addresses for interleaving data symbols onto OFDM sub-carrier signals, using a specific generator polynomial and permutation order to optimize symbol separation and error correction, enabling flexible implementation across different modes like 2k, 4k, 8k, and 16k.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a symbol interleaver is implemented for the 16k mode to provide sparse deployment of DVB transmitters, then error correction coding performance is improved, but device complexity increases due to the need for additional addressing and permutation circuits
Solution Approach 1:
The address generator is designed to be mode-agnostic, capable of generating addresses for any OFDM mode (2k, 4k, 8k, 16k) by simply changing the maximum address value parameter. The same LFSR structure and permutation circuit serve all modes, eliminating the need for separate interleaver implementations for each mode while maintaining optimal error correction performance.
Solution Approach 2:
The invention changes the parameter N (maximum address value) to adapt the interleaver to different OFDM modes. By modifying this single parameter, the system can operate in 2k mode (N=2048), 4k mode (N=4096), 8k mode (N=8192), or 16k mode (N=16384) without structural modifications, thus improving reliability for sparse deployment while controlling device complexity through parameterization rather than structural multiplication.
2Area of stationary object
If the number of sub-carrier signals is increased to approximately sixteen thousand for sparser transmitter deployment, then coverage area is improved, but the difficulty of generating and managing addresses for symbol mapping increases
Solution Approach 1:
The invention replaces manual or complex computational address generation with a deterministic LFSR-based pseudo-random sequence generator. The address generation is achieved through bitwise operations and linear feedback shifts rather than complex algorithms, making it computationally efficient and easily implementable in hardware or software for 16k mode while maintaining uniform symbol distribution across the expanded coverage area.
Solution Approach 2:
The permutation circuit acts as an intermediary between the LFSR output and the final address. It transforms the LFSR-generated sequence into uniformly distributed addresses suitable for 16k mode by applying a specific permutation pattern, thereby simplifying the overall address generation process while ensuring optimal symbol separation for error correction in sparse transmitter deployments.
Data Source
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AI summary
A data processing apparatus maps data symbols received from a predetermined number of sub-carrier signals of an Orthogonal Frequency Division Multiplexed (OFDM) symbol into an output data stream. 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. A generator polynomial for the linear feedback shift register of Riʹ12=Ri-1ʹ0⊕Ri-1ʹ1⊕Ri-1ʹ4⊕Ri-1ʹ5⊕Ri-1ʹ9⊕Ri-1ʹ11 is provided with a permutation order which has been established by simulation analysis to optimise communication performance via typical radio channels, of an OFDM modulated system such as a Digital Video Broadcasting (DVB) standard such as DVB-Terrestrial2 (DVB-T2).