OFDM Symbol Interleaving Across DVB-T2 Modes With Lower Memory
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Solution Overview
Problem
The Digital Video Broadcasting-Terrestrial 2 (DVB-T2) standard faces challenges in providing an efficient implementation of an interleaver for various modes that offers good performance while reducing implementation costs, particularly in supporting extended modes like 1k, 16k, and 32k, which is not adequately addressed by existing technologies.
Innovation Solution
A data processing apparatus that maps symbols from sub-carrier signals of an Orthogonal Frequency Division Multiplexed (OFDM) symbol into an output symbol stream using a symbol interleaver with a permutation code and generator polynomial, optimized for the 16k mode, which can be adapted for other modes by changing generator polynomials and permutation orders, allowing for efficient interleaving and de-interleaving across different DVB standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate interleavers are provided for each mode (2k, 8k, 4k), then good performance is achieved for each specific mode, but device complexity and implementation cost increase
Solution Approach 1:
The patent implements a universal interleaver architecture that can operate in multiple modes (2k, 8k, 4k, and extended modes) by dynamically configuring the number of sub-carriers and adjusting the permutation code and generator polynomial parameters. This single interleaver structure replaces the need for separate dedicated interleavers for each mode, thereby reducing device complexity and implementation cost while maintaining good interleaving performance across all modes through adaptive parameter selection.
2Device complexity
If a universal interleaver is used for all modes, then device complexity is reduced, but interleaving quality may deteriorate for specific modes
Solution Approach 1:
The patent employs dynamic configuration mechanisms that allow the universal interleaver to adapt its parameters based on the operating mode. The number of sub-carriers, permutation code, and generator polynomial are dynamically adjusted according to the selected mode (2k, 8k, 4k, 1k, 16k, or 32k). This dynamic adaptation ensures that the interleaver maintains optimal performance for each specific mode while utilizing a single unified structure, thereby preventing quality deterioration despite the use of a universal design.
3Adaptability or versatility
If memory size is increased to support extended modes (16k, 32k), then support for higher modes is achieved, but device complexity and cost increase
Solution Approach 1:
The patent utilizes parameter changes to support extended modes without proportionally increasing memory requirements. By modifying the permutation code, generator polynomial, and sub-carrier configuration parameters, the same memory infrastructure can accommodate different modes including extended modes (16k, 32k). This approach allows the system to scale to higher modes through software parameter adjustment rather than requiring proportional hardware memory expansion, thereby maintaining cost-effectiveness while enhancing adaptability.
Data Source
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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, such that while the input data symbols from the first set are being read from locations in the interleaver memory, input data symbols from the second set can be written to the locations just read from and when input data symbols from the second set are being read from the locations in the interleaver memory, the input data symbols from a following first set can be written to the locations just read from. Furthermore, when the number data symbols which can be carried by the sub-carriers of an OFDM symbol in one of the plurality of operating modes is half or less than half of the number of data symbols, which can be carried in an operating mode which provides the most number of data bearing sub-carrier signals per OFDM symbol, the data processing apparatus is operable to interleave the input data symbols from both first and second sets in accordance with the odd interleaving process on to the first and second OFDM symbols, and to change the permutation code which is used to form the addresses from one OFDM symbol to another.