Conditional Zero Padding for Wireless Data Transmission
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Solution Overview
Problem
Channel delay spread in wireless communication systems can cause Inter-Symbol Interference (ISI) due to signals taking multiple paths, making it difficult to recover data at the receiver, especially when cyclic prefixes are insufficient.
Innovation Solution
The implementation of conditional zero padding, where symbols are preceded by a cyclic prefix of fixed length, with additional zero tail or zero head padding applied if necessary to ensure the padding length, along with the cyclic prefix, is greater than or equal to the channel delay spread, to avoid ISI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cyclic prefix is used to prevent ISI, then data recovery reliability is improved, but when channel delay spread exceeds cyclic prefix length, ISI still occurs and data recovery fails
Solution Approach 1:
The patent introduces conditional zero padding that dynamically adjusts the transmission structure based on channel conditions. When channel delay spread exceeds cyclic prefix length, zero padding is added to extend the protective duration, making the system adaptive to varying channel characteristics while maintaining data recovery reliability.
Solution Approach 2:
The patent changes the time-domain parameters of the transmitted signal by adding zero padding extensions. This modifies the effective protection length parameter to match the channel delay spread characteristics, resolving the contradiction between fixed cyclic prefix length and variable channel conditions.
2Reliability
If zero padding is always added to prevent ISI, then data recovery reliability is improved, but transmission overhead increases and productivity decreases
Solution Approach 1:
The patent applies zero padding selectively rather than universally. Zero padding is added only when channel delay spread exceeds cyclic prefix length, providing just enough protection to prevent ISI without unnecessarily reducing transmission efficiency in channels where cyclic prefix is sufficient.
Solution Approach 2:
The system dynamically determines whether zero padding is needed based on channel conditions, adjusting the transmission structure in real-time to balance reliability and transmission efficiency according to actual channel delay spread characteristics.
3Object-affected harmful factors
If longer padding is used to cover larger channel delay spread, then ISI prevention is improved, but transmission overhead increases and productivity decreases
Solution Approach 1:
The patent applies the minimum necessary zero padding length required to cover the channel delay spread when needed, rather than using fixed excessive padding. This provides adequate ISI prevention while minimizing the impact on transmission efficiency.
Data Source
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Figure 3A~3B
AI summary
An apparatus and method for transmitting data with conditional zero padding is provided. In accordance with an embodiment of the disclosure, a transmitter transmits data to a receiver by transmitting symbols such that each symbol is preceded by a cyclic prefix of a fixed length and the symbol conditionally includes enough zero padding to avoid ISI (Inter-Symbol Interference) between consecutive symbols. In some implementations, if the fixed length for cyclic prefixes is long enough to avoid ISI between consecutive symbols, then the symbols may omit zero padding. Otherwise, the symbols may include enough zero padding to avoid ISI between consecutive symbols. The zero padding may be zero tail or zero head.