ISDB-T Time Deinterleaver Architecture With Reduced Memory Pointers
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Solution Overview
Problem
OFDM-based communication systems, such as ISDB-T, face challenges in reducing the complexity and area of deinterleaver designs due to large memory requirements, leading to increased power consumption and complexity from numerous memory pointers implemented as flip-flops.
Innovation Solution
The proposed solution involves a deinterleaver apparatus with a practical OFDM symbol counter of 25 to 30 bits, a divider for calculating intra-buffer offsets, and lookup tables for obtaining delay buffer sizes and buffer base addresses, implemented using ROM or dynamic arithmetic calculations, which reduces the need for large RAM-based designs and flip-flops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RAM-based deinterleaver design with large memory pointers is used, then deinterleaving functionality is achieved, but chip area and power consumption increase
Solution Approach 1:
The patent segments the deinterleaver design into multiple components: a smaller RAM with reduced pointers, lookup tables for buffer base addresses, and arithmetic logic for calculating intra-buffer offsets. This segmentation allows the system to achieve the same deinterleaving functionality with significantly reduced chip area by distributing the computational burden across multiple specialized components rather than relying on a single large RAM structure.
Solution Approach 2:
The patent introduces lookup tables as intermediary structures that store pre-computed buffer base addresses. These lookup tables act as mediators between the main RAM and the deinterleaving logic, allowing the system to access buffer information efficiently without requiring large pointers in the main RAM, thereby reducing the overall chip area while maintaining functionality.
2Reliability
If large number of memory pointers are implemented as flip-flops, then deinterleaver functionality is maintained, but power consumption increases
Solution Approach 1:
The patent segments the pointer functionality into two parts: a smaller set of actual memory pointers implemented as flip-flops, and virtual pointers generated through arithmetic calculations using lookup tables. This segmentation reduces the number of physical flip-flops required, directly lowering power consumption while maintaining the ability to address all necessary buffer locations through the combination of real and virtual pointers.
Solution Approach 2:
The patent creates virtual copies of pointer information by storing buffer base addresses in lookup tables. Instead of implementing physical pointers for all possible buffer locations, the system uses these table-based copies to generate the necessary addressing information, significantly reducing the number of active flip-flops and their associated power consumption.
3Duration of action of moving object
If practical OFDM symbol counter with 25 to 30 bits is used, then uninterrupted television viewing time is maintained, but counter complexity increases
Solution Approach 1:
The patent implements a practical OFDM symbol counter with 25 to 30 bits, which provides sufficient counting capacity for uninterrupted television viewing times without implementing the full theoretical maximum bit width. This partial action approach achieves the required duration coverage for typical viewing scenarios while keeping the counter complexity and resource requirements at manageable levels.
4Productivity
If lookup tables are implemented using ROM, then buffer base addresses are obtained efficiently, but memory usage increases
Solution Approach 1:
The patent segments the memory structure by implementing lookup tables as separate ROM components dedicated to storing buffer base addresses. This segmentation allows the system to use efficient ROM-based address retrieval for the specific lookup table data while keeping the main RAM usage minimized, as the ROM structures are optimized for their specific addressing function rather than general-purpose storage.
Data Source
AI summary
A method and apparatus for de-interleaving interleaved data in a deinterleaver memory in an Orthogonal Frequency Division Multiplexing (OFDM) based Integrated Services Digital Broadcasting Terrestrial (ISDB-T) receiver. In different embodiments, the apparatus comprises of a OFDM symbol counter along with a divider or a buffer pointer RAM with circular pointer logic, a first lookup table to obtain delay buffer size and interleaving lengths for a given OFDM transmission layer, and a second lookup table to obtain buffer base address and interleaving lengths for a given OFDM transmission layer.