Aperiodic SRS Triggering in TDD-FDD Carrier Aggregation
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Solution Overview
Problem
Conventional uplink signal transmission in wireless communication systems does not effectively consider environments with multiple serving cells using different duplex schemes, such as TDD and FDD, which can limit channel estimation and throughput.
Innovation Solution
A method for transmitting a sounding reference signal (SRS) by a wireless device configured with multiple serving cells, including a TDD and FDD cell, where the device receives downlink control information to determine if an aperiodic SRS request is included, and transmits the SRS through the appropriate secondary cell based on the duplex scheme of the primary and secondary cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SRS transmission is performed in all serving cells, then channel estimation accuracy improves, but resource waste increases
Solution Approach 1:
The patent applies local quality by differentiating SRS transmission requirements for primary and secondary cells based on their specific duplex schemes. Instead of uniform SRS transmission across all cells, the system selectively triggers SRS only in cells where it provides necessary channel state information, optimizing the balance between measurement precision and resource efficiency.
Solution Approach 2:
The patent implements partial action by triggering SRS transmission only in specific serving cells (primary or secondary) based on duplex scheme requirements and channel estimation needs. The aperiodic SRS request in downlink control information selectively activates SRS transmission only where necessary, avoiding excessive SRS transmissions in all cells while maintaining sufficient channel estimation accuracy.
2Productivity
If SRS transmission is restricted to specific cells, then resource efficiency improves, but channel estimation accuracy deteriorates
Solution Approach 1:
The patent changes the parameter of SRS transmission triggering based on cell type (primary/secondary) and duplex scheme (TDD/FDD). By dynamically adjusting whether an aperiodic SRS request triggers transmission in a specific cell based on these parameters, the system optimizes channel estimation accuracy while improving resource efficiency compared to blanket SRS transmission.
Solution Approach 2:
The patent introduces dynamic SRS transmission control through aperiodic triggering mechanisms. The base station dynamically decides which cell should transmit SRS based on current channel conditions and scheduling requirements, allowing flexible adaptation between channel estimation accuracy and resource efficiency rather than using fixed transmission patterns.
3Adaptability or versatility
If aperiodic SRS request is always included in downlink control information, then SRS transmission flexibility improves, but downlink control information overhead increases
Solution Approach 1:
The patent extracts the aperiodic SRS request from being a mandatory constant field in all downlink control information. Instead, it is selectively included only when SRS transmission is actually needed for a specific serving cell, reducing downlink control information overhead while maintaining the flexibility benefits when required.
Data Source
AI summary
A method is provided for receiving a sounding reference signal (SRS) in a wireless communication system. A base station transmits downlink control information to a user equipment at a first serving cell of the plurality of serving cells. The downlink control information includes a carrier indicator and a downlink assignment. When the downlink control information includes an aperiodic SRS request that indicates a triggering of an SRS transmission, the base station receives an SRS from the user equipment at the second serving cell. If the first serving cell is a frequency division duplex (FDD) and the second serving cell is a time division duplex (TDD) cell, the downlink control information includes the aperiodic SRS request. If the first serving cell is the TDD cell and the second serving cell is the FDD cell, the downlink control information does not include the aperiodic SRS request.