Aperiodic SRS Triggering via Modified Downlink Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current SRS mechanisms in LTE Rel-8 and Rel-9 are insufficient for LTE-A, facing challenges in balancing SRS overhead and latency, particularly in handling bursty packet arrivals and supporting advanced features like multiple transmit antennas and cooperative multi-point transmission.
Innovation Solution
Introducing aperiodic SRS transmissions facilitated by modifying downlink control messages to allocate resources and trigger SRS transmissions independently, allowing for efficient channel quality feedback without the overhead of periodic SRS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If periodic SRS transmissions are used, then channel quality feedback is obtained, but SRS overhead increases and latency increases
Solution Approach 1:
The patent transitions from periodic SRS transmissions to aperiodic (event-triggered) transmissions. The base station configures the UE with SRS transmission parameters, and the UE transmits SRS only when triggered by specific downlink control information (DCI) messages, eliminating continuous periodic transmissions and reducing overhead while maintaining timely feedback when needed.
Solution Approach 2:
The patent introduces dynamic triggering mechanisms where SRS transmission is activated or deactivated based on real-time downlink control information. The base station can dynamically adjust SRS transmission timing through DCI messages, allowing flexible adaptation to varying channel conditions and traffic patterns rather than fixed periodic schedules.
2Reliability
If periodic SRS transmissions are used, then channel quality feedback is obtained, but SRS overhead increases
Solution Approach 1:
The patent replaces continuous periodic SRS transmissions with event-triggered aperiodic transmissions. The UE transmits SRS only when specifically triggered by downlink control information, significantly reducing the quantity of SRS transmissions and associated overhead while maintaining channel quality feedback when needed.
Solution Approach 2:
The patent extracts the essential function of SRS (channel quality feedback) from the continuous periodic transmission framework. By separating the feedback function from the periodic schedule and implementing it only when triggered by relevant downlink control information, the patent reduces overhead while preserving the essential channel quality assessment capability.
3Quantity of substance
If aperiodic SRS transmissions are introduced, then SRS overhead is reduced, but control message complexity increases
Solution Approach 1:
The patent makes existing downlink control information (DCI) messages serve multiple functions: they continue to carry downlink scheduling information while also acting as triggers for aperiodic SRS transmissions. This multi-functionality approach avoids creating separate dedicated control messages, thereby limiting the increase in control message complexity while enabling aperiodic SRS.
Solution Approach 2:
The patent merges the SRS triggering function with existing downlink control information structures. By combining SRS transmission triggers with downlink scheduling DCI messages, the patent integrates multiple control functions into a single message type, avoiding the need for separate complex control mechanisms and limiting overall system complexity.
4Adaptability or versatility
If LTE Rel-8 SRS mechanisms are used, then basic channel quality feedback is provided, but support for advanced LTE-A features is insufficient
Solution Approach 1:
The patent enables dynamic adaptation of SRS transmission parameters to support advanced LTE-A features such as carrier aggregation, coordinated multi-point (CoMP) transmission, and multi-antenna operations. The base station can dynamically configure SRS transmission parameters through downlink control information to match the specific requirements of different LTE-A features, providing the flexibility needed for versatile advanced functionality.
Solution Approach 2:
The patent introduces the capability to change SRS transmission parameters (such as transmission bandwidth, subframe offset, and triggering conditions) based on the specific requirements of different LTE-A features. This parameter flexibility allows the same aperiodic SRS mechanism to adapt to various advanced features including carrier aggregation, CoMP, and MIMO operations, thereby enhancing system versatility.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A method and apparatus for facilitating an aperiodic transmission of a sounding reference signal (SRS) are disclosed. Transmission resources are allocated to the aperiodic SRS transmission. A portion of a first downlink control message is modified to produce a second downlink control message, where the first downlink control message does not trigger an aperiodic SRS transmission. The second downlink message is transmitted.