Wireless Scrambling Seed Selection for Defective Sequence Prevention
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Solution Overview
Problem
Existing wireless communication systems face inefficiencies in scrambling wireless transmissions, particularly when scrambling codes result in undesirable sequences like all-zeros or all-ones, leading to issues such as frequency domain spurs and demodulation errors.
Innovation Solution
A method is introduced to select a scrambling seed pseudo-randomly from a set of allowed scrambling seeds, ensuring that each codeword in a packet is scrambled with a sequence different from the predefined re-scrambling sequence, thereby preventing defective codewords and minimizing the impact of undesirable sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a scrambling code is randomly selected for every frame transmission, then the scrambling diversity is improved, but the risk of generating defective sequences (all-zeros, all-ones) increases
Solution Approach 1:
The system pre-identifies and excludes defective scrambling seeds from the available set before actual scrambling operations. By performing this filtering action in advance, the system ensures that only valid seeds are used for scrambling, thereby preventing defective sequences while maintaining random selection benefits.
Solution Approach 2:
The invention extracts and removes defective scrambling seeds (those producing all-zeros or all-ones sequences) from the complete set of possible scrambling seeds. This extraction process creates a refined set of allowed seeds that guarantees valid scrambling sequences while preserving the randomness needed for scrambling diversity.
2Productivity
If a predefined re-scrambling sequence is used for each codeword, then the processing efficiency is improved, but the occurrence of defective codewords increases when the scrambling sequence matches the re-scrambling sequence
Solution Approach 1:
The system takes preliminary anti-action by selecting scrambling seeds that are guaranteed not to produce sequences matching the predefined re-scrambling sequence. This preventive measure eliminates the possibility of defective codewords before they can occur, while still allowing the use of efficient predefined re-scrambling sequences for processing.
Solution Approach 2:
The invention changes the parameter space of allowable scrambling seeds by imposing an additional constraint: the selected seed must not generate a scrambling sequence identical to the predefined re-scrambling sequence. This parameter restriction prevents defective codewords while maintaining processing efficiency through the use of predefined sequences.
3Reliability
If scrambling is applied to improve PAPR and reduce frequency domain spurs, then the transmission quality is improved, but the complexity of the scrambling system increases
Solution Approach 1:
The system performs preliminary setup by pre-defining the set of allowed scrambling seeds and their corresponding scrambling sequences. This pre-computation approach simplifies the actual scrambling operation during transmission, as the system only needs to select from pre-validated options rather than generating and validating sequences in real-time.
Solution Approach 2:
The invention changes the approach from completely random seed selection to constrained selection from a pre-defined set of valid seeds. This parameter change maintains the scrambling benefits for PAPR improvement and frequency domain spur reduction while reducing system complexity through pre-validation and pre-characterization of allowed seeds.
Data Source
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AI summary
Some demonstrative embodiments include devices, systems and methods of scrambling wireless transmissions. For example, an apparatus may include a selector to select a selected scrambling seed based on a number of codewords in a packet to be transmitted; and a scrambler to scramble bits of the packet based on a periodic sequence of scrambling bits, the sequence of scrambling bits being generated according to the selected scrambling seed.