Dynamic Reference Signal Selection for Wireless Fallback Transmission
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Solution Overview
Problem
In a distributed antenna system based on the LTE-A system, existing methods for fallback transmission in normal and MBSFN subframes are inefficient, leading to suboptimal resource utilization and interference issues due to fixed transmission modes and scrambling sequences.
Innovation Solution
The solution involves dynamically selecting between Cell-specific Reference Signal (CRS) and DeModulation Reference Signal (DMRS) for fallback transmission based on subframe types, and using different DMRS scrambling sequences for each antenna position or terminal, allowing for adaptive resource allocation and interference randomization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed transmission modes and scrambling sequences are used for fallback transmission, then device complexity is reduced, but resource utilization efficiency deteriorates and interference issues arise
Solution Approach 1:
The patent implements dynamic selection between CRS-based and DMRS-based fallback transmission modes based on subframe type. The system transitions from fixed transmission modes to adaptive mode selection, where the base station determines the appropriate reference signal type according to whether the subframe is a normal subframe or MBSFN subframe, thereby improving resource utilization while maintaining manageable complexity through rule-based adaptation
Solution Approach 2:
The patent changes the scrambling sequence initialization parameters based on antenna position and terminal identification. Instead of using a fixed scrambling sequence, the system initializes the scrambling sequence with different values (e.g., nSCID parameter) according to the antenna port and terminal ID, which randomizes interference while keeping the overall system complexity controlled through parameter variation rather than structural changes
2Reliability
If CRS-based fallback transmission is used in normal subframes, then reception stability is improved, but resource utilization efficiency deteriorates
Solution Approach 1:
The patent segments the fallback transmission method into two distinct paths: CRS-based fallback for normal subframes and DMRS-based fallback for MBSFN subframes. This segmentation allows the system to apply the most appropriate reference signal type for each subframe category, maintaining reception stability where needed (CRS in normal subframes) while improving resource utilization in MBSFN subframes where DMRS is more efficient
Solution Approach 2:
The patent applies different transmission qualities and methods to different subframe types. Instead of uniformly applying CRS-based transmission across all subframes, the system locally adapts the transmission mode according to the specific subframe type (normal or MBSFN), optimizing resource utilization for each local context while maintaining overall reception stability
3Device complexity
If the same scrambling sequence is used for all antennas, then device complexity is reduced, but interference randomization capability deteriorates
Solution Approach 1:
The patent varies the scrambling sequence initialization parameter nSCID based on antenna port and terminal ID. This parameter change approach allows different antennas and terminals to use different scrambling sequences, achieving interference randomization without complex structural changes. The system maintains simplicity by using a standardized scrambling mechanism with variable initialization parameters rather than implementing entirely different scrambling algorithms for each antenna
Data Source
AI summary
The present invention relates to a method for transmitting data from a base station to a terminal in a wireless communication system, wherein the method includes the steps of: determining a terminal for transmitting downlink data; when the downlink data is transmitted, confirming the kind of subframe in which the downlink data is transmitted; when the subframe is a normal subframe, transmitting the downlink data on the basis of a cell specific reference signal (CRS) or a demodulation reference signal (DMRS); and, when the subframe is a multimedia broadcast multicast service signal frequency network (MBSFN) subframe, transmitting the downlink data on the basis of the DMRS.