Ranging Pseudo Noise Code Generator Using Modular Shift Register
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Solution Overview
Problem
Existing apparatuses for generating ranging PN codes in wireless portable Internet systems with OFDMA schemes require significant time and memory to produce desired results, especially when dealing with high offset values and varying cell ID numbers.
Innovation Solution
A modular shift register generator (MSRG) based system that uses a constant initial value and generates ranging PN codes using a cell ID number search unit, a ranging pseudo noise code mask value generator, and a ranging pseudo noise code generator, which performs modulo-2 addition with a detected cell ID number and system parameters to produce codes with appropriate offset values for ranging modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple shift register generator (SSRG) scheme is used to generate ranging PN codes, then the device complexity is reduced, but the processing time increases significantly when offset values are high
Solution Approach 1:
The patent pre-calculates and stores mask values for different offset values in a lookup table during system initialization. When ranging PN codes need to be generated, the system simply retrieves the pre-computed mask value corresponding to the required offset, performs a fast XOR operation with the base sequence, and obtains the result immediately. This eliminates the time-consuming iterative generation process of traditional SSRG while maintaining simplicity.
2Productivity
If every possible state value is stored to generate ranging PN codes for all base stations, then the generation speed is improved, but the memory requirements increase significantly
Solution Approach 1:
The patent generates a single base ranging PN sequence that can serve all base stations. By introducing offset-specific mask values that are applied through XOR operations, the same base sequence can generate different ranging PN codes for different offsets and base stations. This universal approach eliminates the need to store separate sequences for each base station while maintaining the ability to quickly generate the required codes.
Solution Approach 2:
Instead of storing multiple complete sequences, the system stores compact mask values (much smaller in size) that represent the differences or modifications needed for different offsets. By changing the parameter representation from full sequences to compact mask values, the system achieves fast generation speed with minimal memory consumption.
3Adaptability or versatility
If different initialization codes are applied for different cells using cell ID numbers, then the adaptability to different base stations is improved, but the device complexity and processing time increase
Solution Approach 1:
The patent extracts the cell-specific information into separate mask values that are applied to a universal base sequence. Instead of embedding cell ID handling logic within the sequence generation process itself, the system separates the common base sequence generation from the cell-specific customization, achieving adaptability through a simple, low-complexity mask application step.
Data Source
AI summary
Disclosed is an apparatus for generating a ranging pseudo noise code used for a terminal of a portable internet system of an OFDM access scheme. The apparatus for generating ranging pseudo noise code detects a cell ID number using a preamble signal transmitted from a base station covering the terminal, detects a ranging pseudo noise code mask value using the detected cell ID number and system parameters input from the base station, and generates a ranging pseudo noise code using the detected cell ID number and the ranging pseudo noise code mask value. With the above structure, a constant initial value can be used irregardless of the cell ID number of the base station, and a desired ranging pseudo noise code can be generated as fast as possible so as to have a desired offset.