Channel Quality Reporting in LTE-M and NB-IoT Connected Mode
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Solution Overview
Problem
Current technologies face challenges in channel state information (CSI) reporting for connected mode user equipment (UEs) in LTE-MTC and NB-IoT, particularly for UEs configured with CEModeB, where aperiodic and periodic CSI reporting is not supported.
Innovation Solution
The proposed solution involves signaling and configuration methods that enable UEs, including those in CEModeB, to report channel quality in connected mode by determining when aperiodic channel quality reporting is triggered and transmitting a downlink channel quality report to the network node, represented by the number of repetitions used to receive a channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aperiodic CSI reporting is not supported for CEModeB UEs, then device complexity is reduced, but downlink transmission efficiency deteriorates due to lack of channel quality feedback
Solution Approach 1:
The patent changes the reporting parameter from traditional CSI metrics to a simplified indicator based on the number of repetitions required to decode downlink channels. This parameter transformation enables CEModeB UEs to provide channel quality feedback without implementing complex CSI measurement and reporting mechanisms, thereby improving downlink transmission efficiency while maintaining low device complexity
Solution Approach 2:
The patent introduces a lightweight, simplified reporting mechanism that uses minimal uplink resources (NPUSCH format 3) to transmit channel quality indicators. This disposable-like approach allows the UE to provide necessary feedback without establishing complex persistent reporting structures, resolving the contradiction between transmission efficiency and device complexity
2Productivity
If channel quality reporting is implemented for CEModeB UEs, then downlink transmission efficiency is improved, but signaling overhead increases
Solution Approach 1:
The patent extracts only the essential channel quality information needed for downlink adaptation by having the UE report the number of repetitions required to achieve successful decoding. This extraction approach provides the network with sufficient channel quality feedback to adjust transmission parameters while avoiding the overhead of comprehensive CSI reporting, thus improving transmission efficiency without excessive signaling
Solution Approach 2:
The patent makes the existing NPUSCH format 3 serve multiple functions by utilizing it for both uplink data transmission and channel quality reporting. This multi-functionality allows the system to obtain channel quality feedback without allocating additional dedicated signaling resources, thereby improving downlink transmission efficiency while minimizing signaling overhead
3Measurement precision
If measurements are performed with sufficient time for accuracy, then measurement precision is improved, but time consumption increases
Solution Approach 1:
The patent enables the UE to perform channel quality measurements using its existing downlink reception and decoding processes. The UE naturally accumulates measurement data while receiving and attempting to decode repeated downlink transmissions, then reports the number of repetitions needed for successful decoding. This self-service approach provides accurate channel quality measurements without requiring separate measurement procedures, thus improving measurement precision while minimizing additional time consumption
Data Source
AI summary
According to some embodiments, a method performed by a wireless device operating in connected mode for reporting channel quality comprise: determining that aperiodic channel quality reporting has been triggered for the wireless device and transmitting a downlink channel quality report to a network node. A channel quality in the report is represented by a number of repetitions used to receive a channel. In particular embodiments, the number of repetitions comprises a number of repetitions used to receive a machine type communication (MTC) physical downlink control channel (MPDCCH) or a narrowband Internet-of-things (NB-IoT) physical downlink control channel (NPDCCH).