Dynamic Time Interleaving for High-Bit-Rate Fading Channels
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Solution Overview
Problem
Existing single-carrier digital communication systems face limitations in decorrelating data symbols due to high bit rates and slow variations in the transmission medium, leading to performance degradation and increased error rates, particularly in multipath environments.
Innovation Solution
A dynamic time interleaving method for single-carrier transmitters, where the interleaving law varies over time to reduce coherence time and improve data decorrelation, using a turbo structure algorithm to generate multiple interleaving laws based on iteration and parameters, optimizing data spread and system constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If static interleaving is used for high bit rate transmission, then transmission speed is improved, but time correlation and fast fading effects increase leading to performance degradation
Solution Approach 1:
The patent applies dynamics by transitioning from static interleaving to dynamic interleaving where the interleaving pattern changes over time. The interleaver uses time-varying permutation patterns that adapt to the channel conditions, allowing the system to maintain high bit rates while reducing time correlation effects. This is achieved by modifying the interleaving function to include time-dependent parameters that change the data spreading pattern dynamically.
Solution Approach 2:
The patent changes the parameter of interleaving pattern from fixed to time-varying. By introducing time-dependent parameters in the interleaving function, the system can adjust the data spreading characteristics dynamically. This parameter change allows the interleaver to optimize performance for different channel conditions while maintaining high transmission rates, directly addressing the contradiction between speed and reliability.
2Reliability
If interleaving depth is increased to reduce time correlation, then decorrelation is improved, but latency increases limiting available bit rate
Solution Approach 1:
The dynamic interleaving approach allows the system to achieve effective decorrelation with smaller interleaving depths by changing the pattern over time. Instead of using a large fixed interleaving depth that introduces high latency, the system uses smaller depths with time-varying patterns that collectively achieve the same decorrelation effect, thereby reducing latency while maintaining reliability.
Solution Approach 2:
The patent employs periodic changes in the interleaving pattern to achieve decorrelation. By periodically varying the interleaving permutation, the system effectively spreads data over time without requiring large buffer depths. This periodic action achieves the decorrelation benefit of deep interleaving while maintaining lower latency through smaller buffer sizes.
3Ease of manufacture
If static interleaving law is used for a given transmission mode, then implementation is simplified, but adaptability to varying channel conditions deteriorates
Solution Approach 1:
The patent introduces dynamics into the interleaving law by making it time-varying while maintaining a structured approach that preserves implementation feasibility. The dynamic interleaver uses systematic rules for generating time-varying patterns, balancing adaptability with implementation complexity. This allows the system to adapt to varying channel conditions without requiring completely complex implementation.
Solution Approach 2:
The patent changes the interleaving law parameters dynamically based on channel conditions while maintaining a systematic structure. By using parameterized families of interleaving patterns that can be adjusted through parameter changes rather than complete redesign, the system achieves adaptability to different channel conditions while preserving implementation simplicity through structured parameter management.
Data Source
AI summary
The present invention relates to a time interleaving method (1) and a time interleaver (ETS) for data. The data is intended to be transmitted sequentially by a baseband carrier of a single-carrier transmitter (EM). The method consists in interleaving a block of successive data items according to a particular interleaving law variable in time for a given transmission mode of the transmitter.