Aperiodic SRS Subframe Configuration for LTE Resource Efficiency
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Solution Overview
Problem
In 3GPP LTE communication systems, the existing periodic sounding methodology for channel state information (CSI) is inefficient as it consumes resources continuously, even when a UE has no uplink data, limiting the availability of resources for simultaneous channel sounding from multiple UE transmission antennas, which is necessary for advanced MIMO capabilities.
Innovation Solution
The introduction of aperiodic sounding methodology that allows the eNB to dynamically schedule SRS transmissions only when needed, using a bit map or state base approach to configure UE-specific A-SRS subframes within a radio frame, enabling more flexible and efficient resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If periodic sounding methodology is used to configure UE to transmit known signal at periodic intervals, then channel state information can be obtained continuously, but resource consumption increases continuously even when UE has no uplink data
Solution Approach 1:
The patent applies periodic action by transitioning from continuous periodic sounding to aperiodic sounding triggered by specific events (uplink data transmission needs). The eNB dynamically configures SRS transmission timing based on actual channel state requirements, allowing periodic measurements only when needed rather than continuously, thus reducing resource consumption while maintaining measurement precision when required
Solution Approach 2:
The patent implements dynamics by making the sounding configuration adaptive and flexible. The eNB can dynamically adjust the triggering conditions and timing of aperiodic SRS transmissions based on real-time network conditions and UE data buffer status. This dynamic configuration allows the system to optimize between measurement frequency and resource consumption on a case-by-case basis
2Reliability
If periodic sounding is configured for each UE, then channel timing alignment and power control are maintained, but resource availability for simultaneous channel sounding from multiple UE transmission antennas is limited
Solution Approach 1:
The patent applies segmentation by separating the timing alignment function from the channel sounding function. Legacy periodic sounding can be configured with longer periods (20-40 ms or longer) specifically for maintaining timing alignment and power control, while aperiodic sounding is used for obtaining frequent channel state updates when data is present. This segmentation allows different sounding mechanisms to serve different purposes simultaneously without resource conflicts
Solution Approach 2:
The patent implements preliminary action by having the eNB pre-configure UE with aperiodic sounding capability and triggering mechanisms before actual data transmission occurs. The UE is prepared with the necessary configuration parameters and triggering conditions, allowing rapid activation of aperiodic sounding when data becomes available, thus ensuring resource availability for MIMO operations without delaying timing alignment maintenance
3Productivity
If aperiodic sounding is used only when UE has uplink data to convey, then resource efficiency improves, but channel state updates may be delayed
Solution Approach 1:
The patent applies feedback by implementing a closed-loop mechanism where the eNB continuously monitors UE data buffer status and network conditions, then provides feedback by dynamically triggering aperiodic sounding when needed. The triggering conditions can include thresholds on data buffer levels, quality of service requirements, or network load conditions, ensuring that channel state updates are requested timely based on actual system state rather than following a fixed schedule
Data Source
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AI summary
A method, system and computer-usable medium for configuring UE-specific A-SRS subframes. More specifically, UE-specific Aperiodic Sounding Reference Signal (A-SRS) subframes are defined only within a radio subframe.