OFDM Symbol Interleaving With Single Memory Across DVB-T2 Modes
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Solution Overview
Problem
The Digital Video Broadcasting-Terrestrial (DVB-T) and DVB-H standards face challenges in providing an efficient implementation of an interleaver for various modes, such as the 16k mode, that offers good performance while minimizing implementation costs, especially with the introduction of new modes like 1k, 16k, and 32k in DVB-T2, which require effective symbol interleaving.
Innovation Solution
A symbol interleaver is designed using a permutation code and generator polynomial, verified by simulation analysis, to optimally map data symbols onto OFDM sub-carrier signals, utilizing a single interleaver memory for both odd and even symbols by generating appropriate write and read addresses, and an address generator that includes a linear feedback shift register and permutation circuit to ensure efficient interleaving across different modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate interleaver memories are provided for each mode (1k, 2k, 4k, 8k, 16k, 32k), then each mode achieves optimal interleaving performance, but the device complexity and implementation cost increase significantly
Solution Approach 1:
A single interleaver memory is designed to serve multiple DVB-T2 modes (1k, 2k, 4k, 8k, 16k, 32k) by dynamically configuring its operation through mode selection signals. The memory structure and address generation logic are made adaptable to different modes, allowing one memory unit to replace what would traditionally require six separate memory units, thereby reducing device complexity while maintaining interleaving performance across all modes
Solution Approach 2:
The interleaver memory is made dynamically configurable through mode selection signals that adjust the memory's addressing and operation characteristics based on the active DVB-T2 mode. The address generation logic dynamically adapts to different mode requirements, enabling the same physical memory to be optimally utilized for different interleaving scenarios without requiring dedicated hardware for each mode
2Device complexity
If a single interleaver memory is shared across all DVB-T2 modes, then device complexity is reduced, but achieving optimal interleaving performance for each mode becomes more difficult
Solution Approach 1:
The interleaver memory's operational parameters (addressing scheme, memory depth, access patterns) are dynamically changed based on the active DVB-T2 mode through mode selection signals. This allows the same physical memory to be reconfigured for optimal performance in each mode by adjusting control parameters rather than requiring dedicated hardware, thereby maintaining reliability across modes while using a single memory unit
Solution Approach 2:
Different portions or configurations of the single interleaver memory are optimized for different modes through selective activation and addressing. The memory structure is designed with local optimizations that can be selectively engaged based on the active mode, ensuring that each mode receives the appropriate interleaving treatment from the shared resource
3Reliability
If mode-specific interleaver implementations are provided for each DVB-T2 mode, then optimal performance is achieved for each mode, but the ease of manufacture and implementation cost increase
Solution Approach 1:
A universal interleaver memory design is created that can be manufactured as a single standardized component serving all DVB-T2 modes. This single multi-functional memory unit replaces what would require six separate mode-specific memory units, significantly reducing manufacturing complexity, component inventory requirements, and implementation cost while maintaining the ability to achieve optimal interleaving performance for each mode through software or control logic configuration
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 Orthogonal Frequency Division Multiplexed OFDM symbols into an output data stream, the predetermined number of sub-carrier signals being determined in accordance with one of a plurality of operating modes and the data symbols being divided into first sets of data symbols and second sets of 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 or more 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 data symbols from both the first and second sets in accordance with the odd interleaving process from 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.