Reduced CRS Bandwidth Mode for Empty Cell Interference
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Solution Overview
Problem
Cells without active UE connections in cellular networks continue to consume power due to broadcasting Cell Reference Symbols (CRS), causing interference and degrading DL throughput in neighboring cells, while reducing CRS power reduces cell size and channel estimation quality.
Innovation Solution
Implementing a reduced CRS bandwidth mode in cells not actively serving UEs, where CRS transmission is reduced in relation to the normal mode, specifically by applying this mode in subframes except those with system information, paging, or random access response messages, to minimize interference and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If CRS transmission is maintained in cells without active UEs, then channel estimation quality is preserved, but power consumption increases and interference to neighboring cells occurs
Solution Approach 1:
The patent implements periodic CRS transmission by configuring empty cells to transmit CRS only in specific subframes (e.g., every 4th or 8th subframe) rather than continuously. This periodic transmission pattern maintains adequate CRS visibility for channel estimation in neighboring cells while significantly reducing power consumption and interference from empty cells.
Solution Approach 2:
The patent applies different CRS transmission characteristics to different cells based on their operational status. Empty cells transmit CRS with reduced frequency and power compared to active cells, creating a localized quality adjustment that preserves channel estimation capability where needed while minimizing waste in cells without active UEs.
2Area of stationary object
If CRS transmission is maintained in cells without active UEs, then cell coverage is preserved, but interference to neighboring cells increases
Solution Approach 1:
By transmitting CRS periodically rather than continuously, the patent reduces the cumulative interference generated by empty cells to neighboring cells while maintaining sufficient CRS presence to preserve cell coverage and enable proper channel estimation and cell identification for UEs in range.
Solution Approach 2:
The patent changes transmission parameters (CRS power level, transmission frequency/subframe configuration) for empty cells compared to active cells. This parameter adjustment reduces interference generation from empty cells while maintaining adequate CRS visibility for cell coverage and channel estimation functions.
3Use of energy by moving object
If CRS bandwidth is reduced in empty cells, then power consumption and interference are reduced, but channel estimation quality deteriorates
Solution Approach 1:
The patent uses periodic CRS transmission with strategic subframe configuration to maintain adequate channel estimation quality. By transmitting CRS in specific subframes that align with UE measurement opportunities and system information transmission, the patent ensures sufficient estimation accuracy while reducing overall power consumption compared to continuous transmission.
Solution Approach 2:
The patent applies partial CRS transmission in empty cells, providing just enough CRS signals to maintain acceptable channel estimation quality for UEs in range, rather than full bandwidth continuous transmission. This partial action approach reduces power consumption while preserving the essential measurement function.
Data Source
AI summary
A method performed by a network node for managing transmission of Cell Reference Symbols, CRS, wherein the network node operates one or more cells and the network node is configured to transmit the CRS in a first bandwidth mode. When the network node has identified a cell which is not actively serving any UEs, also referred to as an empty cell, the network node applies a reduced CRS bandwidth mode in the first cell in relation to the first bandwidth mode. By applying a reduced CRS bandwidth mode in the empty cell, the overall interference of the CRS from the empty cell is reduced, thereby enhancing the performance in cells actively serving UEs.