LTE Preamble Sequence Generation Using Cyclic Shift Step Length
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In the LTE system, the cyclic shift step length restricts the value of cyclic shift in the unrestricted set, limiting the generation of preamble sequences, especially in scenarios with large cells where a single root sequence can only generate one preamble sequence.
Innovation Solution
Setting the cyclic shift step length NCS to 0 when a root sequence can only generate one preamble sequence, and using the formula Cv=v·NCS for multiple preamble sequences, where v=0, 1, 2, ..., └NZC/NCS┘−1, to generate 64 unique preamble sequences without cyclic shift restriction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cyclic shift step length NCS is used to generate preamble sequences in unrestricted set, then multiple preamble sequences can be generated from a root sequence, but the cyclic shift values are restricted by NCS which limits sequence generation in large cells
Solution Approach 1:
The patent changes the parameter of cyclic shift step length from a restricted non-zero value to 0, and modifies the cyclic shift calculation from Cv=v·NCS to Cv=v·NZC (where NZC is the sequence length). This parameter change allows generation of multiple distinct preamble sequences even when NCS would normally restrict to a single sequence, thereby resolving the contradiction between quantity of sequences and coverage adaptability
2Reliability
If cyclic shift restriction is applied for high speed scenarios, then frequency offset overlap is avoided, but the number of available preamble sequences is reduced
Solution Approach 1:
The patent segments the cyclic shift generation into two distinct modes: restricted set for high-speed scenarios and unrestricted set for normal scenarios. By maintaining separate generation rules for each set, the system can apply cyclic shift restrictions only where needed (high-speed) while allowing full sequence generation capability in normal conditions, thus resolving the contradiction between reliability and quantity
Data Source
AI summary
A method for generating a preamble sequence and determining a cyclic shift. The method includes: when set a piece of root sequence can only generate one preamble sequence and there is no cyclic shift restriction, setting the cyclic shift step length NCS to be equal to 0 and the corresponding cyclic shift amount Cv=0, at this time the root sequence is directly used as the preamble sequence; when set a piece of root sequence can generate a plurality of preamble sequences and there is no cyclic shift restriction, the cyclic shift step length NCS being not equal to 0, at this time the cyclic shift amount Cv=v·NCS, wherein v=0, 1, 2, . . . , └NZC/NCS┘−1. This method is applied to the situation that a root sequence generates a preamble sequence, and the method for generating the preamble sequence is simple and easy to operate.