LAA CSI Measurement Power Offset Compensation
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Solution Overview
Problem
In LTE systems, existing techniques for measuring and reporting channel state information (CSI) in License Assisted Access (LAA) scenarios face challenges due to varying transmit power of CRS/CSI-RS, leading to inaccurate CSI measurements, especially when Listen-Before-Talk (LBT) conditions dynamically alter channel occupancy.
Innovation Solution
The proposed solution involves techniques for accurate CSI measurement and reporting in LAA scenarios by configuring periodic and aperiodic CSI-RS transmissions within DL bursts and DRS occasions, allowing UEs to scale CSI based on indicated transmit power and perform independent CSI processes for each component carrier, ensuring accurate CSI computation and reporting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If CSI measurements are performed based on CRS or CSI-RS in LAA scenarios, then channel state information can be obtained for wireless communication, but the varying transmit power of CRS/CSI-RS due to dynamic LBT conditions leads to inaccurate CSI measurements
Solution Approach 1:
The patent introduces a power offset parameter (P_O_CSI-RS) that is configured by the network and applied by the UE to compensate for power variations in CSI-RS transmissions. This parameter change allows the UE to normalize CSI measurements across different transmit power levels, thereby maintaining measurement accuracy despite dynamic LBT conditions affecting the actual transmit power.
Solution Approach 2:
The patent implements a feedback mechanism where the network configures the UE with power offset parameters based on expected or actual transmit power levels. The UE uses this feedback information to adjust its CSI measurements, creating a closed-loop system that compensates for power variations and improves measurement reliability in dynamic LAA environments.
2Adaptability or versatility
If Listen-Before-Talk (LBT) is used to manage channel access in LAA, then channel occupancy can be dynamically adjusted, but this causes varying transmit power of reference signals leading to inaccurate CSI measurements
Solution Approach 1:
The patent applies preliminary action by configuring the UE with power offset parameters (P_O_CSI-RS) before CSI measurements are performed. The network provides this compensation information in advance, allowing the UE to pre-adjust its measurement calculations to account for expected power variations, thereby maintaining precision despite the adaptability introduced by LBT.
Solution Approach 2:
The patent changes the measurement parameter by introducing a power offset compensation factor. This parameter modification allows the UE to adjust its CSI measurement calculations dynamically, maintaining measurement precision while accommodating the channel occupancy adaptability required by LBT operations.
3Measurement precision
If CSI-RS transmissions are configured within DL bursts and DRS occasions, then accurate CSI measurement can be achieved, but this requires complex configuration and processing for periodic and aperiodic transmissions
Solution Approach 1:
The patent applies universality by using a single power offset parameter (P_O_CSI-RS) that serves multiple functions: it compensates for power variations in both periodic and aperiodic CSI-RS transmissions, works across different DL burst structures, and applies to various DRS occasion configurations. This unified approach simplifies the overall system despite the diversity of transmission scenarios.
Solution Approach 2:
The patent segments the CSI measurement process into distinct phases: configuration phase where power offset parameters are provided, measurement phase where CSI-RS is received and measured using the offset, and reporting phase where CSI is transmitted. This segmentation allows complex periodic and aperiodic transmissions to be handled through a standardized multi-step process, reducing overall processing complexity.
Data Source
AI summary
Techniques for channel state information (CSI) reporting are discussed. One example apparatus at a user equipment can derive, for one or more subframes of a license assisted access (LAA) secondary cell (SCell), one or more channel measurements based on reference signals (e.g., cell-specific reference signals (CRS) or CSI reference signals (CSI-RS)), in those subframes; generate CSI that comprises a channel quality indicator (CQI) based on an average of the one or more channel measurements from multiple subframes comprising a first subframe and a later second subframe, wherein each orthogonal frequency division multiplexing (OFDM) symbol of a second slot of the first subframe is occupied, wherein each of a first three OFDM symbols of the second subframe are occupied, and wherein each OFDM symbol between the first subframe and the second subframe is occupied; and generate a CSI report that indicates the set of CSI parameters.