Selective CRS Muting for Downlink Interference Reduction
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Solution Overview
Problem
In LTE wireless communication networks, the pervasive transmission of Cell Specific Reference Signals (CRS) across all downlink resource blocks can cause interference with user data, reducing achievable downlink user data rates and overall network performance, especially in situations where CRS transmission is not strictly necessary.
Innovation Solution
Implementing a method to selectively mute CRS transmission in specific subsets of downlink resource blocks based on conditions such as signal-to-interference-plus-noise ratio (SINR) and transmission modes, allowing neighboring base stations to coordinate and optimize interference reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Cell Specific Reference Signals (CRS) are transmitted pervasively across all downlink resource blocks, then coverage detection and channel estimation are ensured, but downlink interference increases and user data rates decrease
Solution Approach 1:
The patent applies local quality by making CRS transmission selective rather than uniform across all resource blocks. Base stations transmit CRS only in specific resource blocks where it is necessary for coverage detection and channel estimation, while omitting it in other resource blocks to reduce interference. This localized approach allows different parts of the downlink spectrum to have different transmission characteristics optimized for their specific function.
Solution Approach 2:
The patent segments the downlink resource blocks into multiple groups, with each group having independent CRS transmission control. This segmentation allows the network to selectively enable or disable CRS in specific resource block groups based on interference conditions, user equipment requirements, and transmission modes, thereby resolving the contradiction between reliable coverage detection and minimizing data rate degradation.
2Measurement precision
If CRS transmission is maintained across all resource blocks, then channel estimation reliability is preserved, but interference with user data increases
Solution Approach 1:
The patent implements partial action by transmitting CRS only in the minimum necessary resource blocks to maintain adequate channel estimation accuracy, rather than across all resource blocks. The system identifies and transmits CRS selectively in resource blocks where user equipment requires channel estimation for demodulation, while omitting CRS in resource blocks where interference would harm user data but channel estimation is not critical.
3Adaptability or versatility
If CRS is transmitted in all downlink resource blocks by default, then transmission compatibility is ensured, but resource allocation efficiency decreases
Solution Approach 1:
The patent introduces dynamic CRS transmission control where the base station adapts CRS transmission patterns based on real-time transmission modes, interference conditions, and resource block utilization. The system dynamically determines which resource blocks require CRS transmission and adjusts the transmission pattern accordingly, rather than using a static default transmission approach. This dynamic adaptation improves resource allocation efficiency while maintaining compatibility with different transmission modes.
Data Source
AI summary
Disclosed is a method and system for selectively muting default downlink transmission of particular reference signals in order to reduce interference experienced by user equipment devices (UEs) receiving user data. In scheduling transmission of a downlink resource block (RB), a base station may select a particular transmission mode (TM) that does not require transmission of the particular reference signal. The base station may also determine that no condition exists that requires default transmission of the particular reference signal during a time interval allocated for transmission of the RB and on sub-carrier frequencies allocated to the RB. With particular TM selected and the absence of other requirements for default transmission of the particular reference signal, the base station can then mute transmission of the particular reference signal during transmission of the downlink RB. The base station may also coordinate scheduling with a neighboring base station to achieve further interference reduction.