Resource Mapping for Bursty Interference in LTE
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Solution Overview
Problem
Wireless communication systems, particularly in LTE/LTE-Advanced networks, face interference challenges due to bursty interference from unlicensed spectrum signals, which can lead to re-transmissions and degrade performance.
Innovation Solution
The solution involves spreading modulated symbols across a larger time-frequency transmission grid, using two-dimensional interleaving, and implementing code block-level re-mapping for re-transmissions, along with layered coding to enhance decoding efficiency and reduce interference impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If code blocks are transmitted sequentially in traditional LTE resource mapping, then the transmission structure is simple and easy to implement, but bursty interference from unlicensed spectrum signals causes re-transmissions and degrades performance
Solution Approach 1:
The patent applies two-dimensional interleaving that distributes code block bits across both time and frequency dimensions rather than sequential time-only transmission. This dimensional transformation allows the system to achieve frequency diversity and time diversity simultaneously, reducing the impact of bursty interference while maintaining acceptable implementation complexity through structured mapping patterns.
Solution Approach 2:
The patent segments the transmission resource mapping into distinct interleaving patterns for different code blocks within a transport block. Each code block is independently interleaved across time-frequency resources, allowing selective recovery even when some segments are corrupted by interference. This segmentation approach improves reliability without requiring complete re-transmission of the entire transport block.
2Reliability
If two-dimensional interleaving is applied to spread code blocks across time-frequency resources, then robustness against bursty interference is improved, but the processing complexity and computational overhead increase
Solution Approach 1:
The patent employs configurable interleaving parameters including interleaver size, shift amounts, and mapping patterns that can be adjusted based on channel conditions and interference characteristics. These parameter changes allow the system to optimize the balance between interference robustness and processing complexity, adapting the two-dimensional interleaving intensity to match the actual threat level from bursty interference.
Solution Approach 2:
The patent applies different interleaving strategies and parameters to different code blocks or different portions of the transmission based on local channel conditions and interference patterns. This localized approach allows regions most susceptible to bursty interference to receive enhanced protection through more aggressive interleaving, while other regions use simpler mapping, thereby optimizing overall system performance without uniformly increasing complexity everywhere.
3Adaptability or versatility
If code block transmission sequences are fixed, then the scheduling and resource allocation are simple, but the system cannot adapt to varying interference conditions and re-transmission rates
Solution Approach 1:
The patent implements dynamic code block transmission sequencing where the interleaving patterns and transmission order are adjusted in real-time based on observed interference conditions, channel quality, and re-transmission statistics. This dynamic adaptation allows the system to respond to varying interference environments by changing the mapping sequences, thereby improving adaptability while managing complexity through algorithmic optimization and pre-computed mapping tables.
Data Source
AI summary
Resource mapping and coding schemes to handle bursty interference are disclosed that provide for spreading the modulated symbols for one or more transmission code words over more symbols in the time-frequency transmission stream. Certain aspects allow for the modulated symbols to be based on bits from more than one code word. Other aspects also provide for re-mapping code word transmission sequences for re-transmissions based on the number of re-transmissions requested by the receiver. Additional aspects provide for layered coding that uses a lower fixed-size constellation to encode/decode transmissions in a layered manner in order to achieve a larger-size constellation encoding. The layered encoding process allows the transmitter and receiver to use different coding rates for each coding layer. The layered encoding process also allows interference from neighboring cells to be canceled without knowledge of the actual constellation used to code the interfering neighboring signal.