Linear Feedback Shift Register Jump Advancement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional linear feedback shift registers (LFSRs) require multiple input cycles to advance to a desired state, which is time-consuming and power-intensive, especially when jumping to a scrambling code that is far away in the sequence.
Innovation Solution
A method and apparatus that calculate and input a control data word into the LFSR, derived from polynomial multiplication of predetermined data words stored in tables or dynamically calculated, to advance the LFSR state as if it had undergone the desired number of cycles, without actually performing those cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the LFSR is advanced by performing multiple input cycles, then the register reaches the desired state, but the process is time-consuming and power-intensive
Solution Approach 1:
The patent pre-calculates and stores advance data words in lookup tables during an initialization phase. When advancement is needed, the system retrieves pre-computed data from these tables rather than performing sequential input cycles, enabling direct jumping to target states without time-consuming step-by-step progression
Solution Approach 2:
The patent introduces an intermediary mechanism using lookup tables that map advance amounts to corresponding data words. This intermediary layer allows the system to translate the desired advancement amount into ready-to-input data sequences, eliminating the need for direct sequential cycling through all intermediate states
2Loss of time
If the LFSR is advanced by performing multiple input cycles, then the register reaches the desired state, but power consumption increases
Solution Approach 1:
The system performs power-intensive calculations during an initialization phase when power availability is sufficient, pre-computing and storing advance data words in lookup tables. During actual operation, the system only needs to retrieve data from these tables and perform minimal processing, dramatically reducing ongoing power consumption
Solution Approach 2:
The lookup tables serve as an intermediary that stores pre-computed advancement data, allowing the system to avoid repeated power-intensive sequential processing. By caching results of expensive operations, the intermediary structure enables low-power retrieval and direct application of advancement data
3Productivity
If the LFSR is advanced directly to a specific state, then the desired state is reached quickly, but the complexity of controlling the advance increases
Solution Approach 1:
The patent segments the advancement control into discrete components: lookup tables for storing advance data, a controller for managing the advancement process, and the LFSR itself. This segmentation allows each component to have well-defined functions, making the overall complex task of direct state jumping manageable through modular design
Solution Approach 2:
The lookup tables act as an intermediary that simplifies the control mechanism by pre-establishing the mapping between advance amounts and data words. This intermediary structure removes the complexity of calculating advancement sequences during operation, as the mapping is pre-computed and stored, reducing real-time control requirements
Data Source
AI summary
A technique for allowing a linear feedback shift register (LFSR), and particularly a Galois LFSR, to be advanced forward by an amount m (i.e. as if the register had undertaken m input/output cycles), without actually having to undertake m input/output cycles is described. This is useful for example in the communications domain by allowing the shift register to be able to jump to a particular scrambling code. In particular, an embodiment provides an apparatus which is able to control the advance of a LFSR by feeding into the LFSR a data word obtained from the polynomial multiplication of two predetermined data words which are looked up from one or more tables in dependence on an advance amount, being the number of steps the LFSR is to advance. The state of the LFSR after the data word has been fed into the LFSR is then the same state the LFSR would be in if it had actually been advanced by the advance amount.