Bit-Symbol Mapping for Multi-Pulse Position Modulation in Drilling
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Solution Overview
Problem
In petroleum exploration, multi-pulse position modulation (MPPM) systems face challenges due to high memory complexity and limited computing performance in harsh downhole environments, making it difficult to establish a regular mapping relationship between bit sequences and pulse sequences, especially with increasing bit width.
Innovation Solution
A bit-symbol mapping method that maps integers to a super-triangular area of a multi-dimensional matrix, reducing memory complexity by establishing a one-to-one mapping between integers and MPPM pulse sequences, and using a lookup table to simplify the encoding process, allowing for efficient bit-to-symbol mapping even in systems with limited memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional encoding table is used to map bit sequences to MPPM pulse sequences, then the mapping relationship is established, but the memory complexity increases exponentially with bit width
Solution Approach 1:
The patent segments the encoding process into two stages: first mapping bit sequences to integers using a simple binary converter, then mapping integers to MPPM pulse sequences using a pre-generated lookup table. This segmentation reduces the memory complexity from exponential to linear by breaking down the complex mapping relationship into manageable parts.
Solution Approach 2:
The patent introduces an intermediate dimension (integer representation) between the bit sequence and MPPM pulse sequence. By converting bit sequences to integers and then to pulse sequences, the system transforms a direct complex mapping problem into a two-step process with reduced memory requirements at each stage.
2Adaptability or versatility
If the bit width is increased to expand data representation capability, then the encoding range is improved, but the storage complexity of code tables grows exponentially
Solution Approach 1:
The patent divides the encoding task into separate conversion steps: binary-to-integer conversion and integer-to-pulse-sequence conversion. This allows the system to handle larger bit widths without proportionally increasing storage complexity, as each segment uses a simplified mapping approach.
Solution Approach 2:
The patent pre-generates the integer-to-pulse-sequence lookup table during system initialization or offline processing. This preliminary action separates the computationally intensive table generation from the real-time encoding operation, allowing the encoder to function efficiently with minimal memory during actual drilling operations.
3Measurement precision
If a complex encoding method is implemented to achieve accurate bit-symbol mapping, then the mapping precision is improved, but the computing performance becomes insufficient in harsh environments
Solution Approach 1:
The patent segments the encoding process into simple, deterministic steps: binary-to-integer conversion followed by table lookup. Each segment is computationally lightweight, avoiding complex real-time calculations while maintaining precise mapping through the structured two-stage approach.
Solution Approach 2:
The patent performs the complex mapping relationship establishment in advance by pre-generating the lookup table. During real-time operation in harsh drilling environments, the system only needs to perform simple integer conversion and table lookup operations, significantly reducing computing requirements while maintaining mapping precision.
Data Source
AI summary
Disclosed is a bit-symbol mapping method using multi-pulse position modulation (MPPM), which relevant to the field of signal processing. An index of each dimension of an N-order M-dimensional matrix may be a pulse position number of a MPPM(N, M) symbol. The method includes mapping integers to a super-triangular area of the N-order M-dimensional matrix and establishing a correlation between the integers and the N-order M-dimensional matrix elements. In this way, a correspondence between a bit sequence and a MPPM(N, M) symbol is established using a correspondence between the N-order M-dimensional matrix element and an index number of each dimension of the N-order M-dimensional matrix element. A mathematical expression of the number of integers mapped to each layer in each dimension of a super-triangular area of an N-order M-dimensional matrix is used to generate a lookup table TLUT.