Scrambling Code Rotation via Phase Offset Lookup Tables
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Solution Overview
Problem
Existing scrambling code generators in wireless communication systems, such as WCDMA, face inefficiencies in single-bit rotation performance, excessive matrix storage resource consumption, and inflexibility in matrix multiplication, particularly in scenarios requiring discontinuous phase offsets and high time performance for interference cancellation.
Innovation Solution
A method and apparatus that transform input phase offsets into binary numbers, generate access addresses for rotation coefficients, and use these coefficients to map and rotate scrambling code sequences, reducing the need for extensive matrix multiplication and storage, allowing for flexible and efficient scrambling code generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the scrambling code generator is controlled to generate bit by bit for N-bit offset, then the generator can handle discontinuous offsets, but it takes a lot of time and the generator is occupied for a long time
Solution Approach 1:
The invention pre-calculates and stores transformation matrices for different phase offset values in a lookup table. When a phase offset is needed, the system directly retrieves the pre-computed matrix instead of generating it in real-time, significantly reducing the time overhead while maintaining support for discontinuous offsets.
Solution Approach 2:
The system pre-generates transformation matrices for various phase offset scenarios and stores them in advance. This allows the scrambling code generator to quickly retrieve ready-made matrices rather than computing them on-the-fly, thereby reducing occupation time while preserving adaptability to discontinuous offsets.
2Adaptability or versatility
If matrix multiplication method is used to generate transformation matrices, then phase offset can be achieved, but a large number of transformation matrix coefficients need to be stored requiring a lot of storage space
Solution Approach 1:
The invention extracts and stores only the essential transformation matrices needed for common phase offset scenarios in a lookup table. By selecting and storing only the most frequently needed matrices rather than all possible matrices, the system achieves phase offset capability while minimizing storage space requirements.
3Reliability
If the protocol scrambling code generator is used for interference cancellation, then signal protection is achieved, but the minimum scrambling code offset is 512 chips and it takes a long time to generate the scrambling code
Solution Approach 1:
The system pre-computes and stores transformation matrices for various phase offsets, enabling rapid retrieval during interference cancellation operations. This eliminates the need to wait for the protocol generator to produce the next available scrambling code, significantly improving time performance while maintaining signal protection through proper scrambling.
Solution Approach 2:
The invention introduces a lookup table as an intermediary between the scrambling code requirement and the protocol generator. The lookup table provides immediate access to pre-computed transformation matrices, acting as a buffer that decouples the time-critical interference cancellation from the slower protocol generator, thereby improving productivity without sacrificing reliability.
Data Source
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AI summary
Provided are a scrambling code generation method, apparatus and a scrambling code processing apparatus, and the method comprises: transforming an input phase offset into a binary number, generating an access address of a rotation coefficient according to a position of a significant bit with the maximum weight in the binary number, selecting a corresponding rotation coefficient from a rotation coefficient table according to the access address; mapping a k-bit initial scrambling code sequence onto a 2K-bit scrambling code sequence, calculating the mapped scrambling code sequence with the rotation coefficient to obtain a rotated scrambling code sequence; updating the significant bit with the maximum weight to zero; if the updated phase offset is zero, outputting the rotated scrambling code sequence, and if the updated phase offset is not zero, taking the updated phase offset as the current input phase offset and taking the rotated scrambling code sequence as the initial scrambling code sequence, then repeating the abovementioned procedures. This solution improves performance and flexibility, and has a relatively low cost.