Narrowband Reference Signal Design Avoiding LTE CRS Collision
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Solution Overview
Problem
The existing NarrowBand-Cellular Internet Of Things (NB-IOT) system lacks an effective solution for determining which reference signal (RS) to use for transmitting NB-IOT physical channel data, such as physical broadcast channel (PBCH), physical downlink shared channel (PDSCH), and physical downlink control channel (PDCCH) data, affecting data transmission performance and overhead balance.
Innovation Solution
The method involves transmitting physical downlink channel data using a first-type RS, a second-type RS, or a third-type RS, ensuring a balance between data transmission performance and RS overheads, by determining the type of RS through predefined configuration, coverage level, aggregation level, or signaling indication, and utilizing specific patterns that do not overlap or are subsets of LTE system CRS patterns, or their superpositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LTE CRS patterns are used for NB-IOT reference signals, then compatibility with LTE system is improved, but collision with NB-IOT data transmission occurs
Solution Approach 1:
The reference signal pattern is segmented into three distinct types (first-type, second-type, third-type) with different configurations. The first-type RS uses a pattern that avoids LTE CRS symbols, the second-type uses a subset of LTE CRS symbols, and the third-type uses superposition. This segmentation allows selective application based on operational mode and collision scenarios.
Solution Approach 2:
The reference signal configuration is made dynamic by allowing selection among three different types based on operational conditions. The network can dynamically choose which type of RS to use depending on the operation mode (stand-alone, guard band, or in-band) and collision status with LTE CRS, enabling adaptive optimization of both compatibility and transmission reliability.
2Reliability
If reference signal overhead is increased to improve data transmission performance, then data transmission performance is improved, but system overhead increases
Solution Approach 1:
Different reference signal configurations are applied locally based on specific operational needs. The first-type RS with reduced overhead is used when LTE CRS collision occurs, while the second-type or third-type RS with higher overhead are used when better performance is needed and collision is not an issue. This local quality approach optimizes the trade-off between performance and overhead for each specific scenario.
Solution Approach 2:
The reference signal parameters (pattern, density, configuration) are changed based on operational mode and performance requirements. By adjusting the RS type parameter, the system can switch between low-overhead first-type RS and higher-performance second/third-type RS, dynamically optimizing the overhead-performance trade-off for different NB-IOT deployment scenarios.
Data Source
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AI summary
The present invention provides a data transmission method and apparatus. The method includes: transmitting physical downlink channel data according to a first-type reference signal (RS) or a second-type RS or a third-type RS. The method of the present invention ensures a balance between data transmission performance and RS overheads for different NarrowBand-Internet Of Things (NB-IOT) physical downlink channel data, thereby resolving the problem in the related art of not knowing which RS is to be used to transmit NB-IOT physical channel data.