Aperiodic SRS Subframe Positioning in Carrier Aggregation
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Solution Overview
Problem
Current multicarrier communication systems face challenges in efficiently managing carrier aggregation and spectrum utilization, particularly in meeting increasing data traffic demands and providing seamless mobility with high data rates, especially in scenarios where licensed spectrum is insufficient.
Innovation Solution
The implementation of carrier aggregation techniques, including licensed assisted access (LAA) and advanced modulation schemes like OFDM, along with adaptive energy detection thresholds for clear channel assessment, enables efficient use of both licensed and unlicensed spectra, optimizing network efficiency and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carrier aggregation and spectrum sharing techniques are implemented to increase network capacity, then network capacity and data rates are improved, but system complexity and interference management difficulty increase
Solution Approach 1:
The patent segments the uplink transmission by separating sounding reference signals (SRS) from data transmissions in different subframes. This segmentation allows the system to manage different types of signals independently, reducing interference and simplifying the management of complex carrier aggregation scenarios while maintaining high network capacity.
Solution Approach 2:
The patent performs channel sounding in advance before actual data transmissions. By transmitting SRS signals in specific subframes before data-bearing subframes, the system pre-acquires channel state information, which simplifies subsequent data transmission management and reduces the complexity of real-time interference management in carrier aggregation systems.
2Measurement precision
If sounding reference signals are transmitted in every scheduled subframe to maintain accurate channel state information, then channel estimation accuracy is improved, but uplink overhead and resource consumption increase
Solution Approach 1:
The patent implements periodic transmission of sounding reference signals at specific intervals rather than in every subframe. The network configures periodic SRS resources, allowing channel state information to be updated at regular intervals, which maintains adequate estimation accuracy while significantly reducing uplink overhead compared to continuous SRS transmission.
Solution Approach 2:
The patent performs channel sounding in advance before actual data transmissions. By transmitting SRS signals in specific subframes before data-bearing subframes, the system pre-acquires channel state information, reducing the need for frequent SRS transmissions and thereby lowering uplink overhead while maintaining adequate channel estimation accuracy.
3Adaptability or versatility
If multiple cells are aggregated to provide seamless mobility and high data rates, then user experience and network flexibility are improved, but interference management and synchronization difficulty increase
Solution Approach 1:
The patent segments different cell groups (master cell group and secondary cell group) with separate timing advance groups. This segmentation allows independent timing management for different cells, reducing timing misalignment and interference between aggregated cells, thereby enabling flexible carrier aggregation while managing interference effectively.
Solution Approach 2:
The patent introduces timing advance commands as an intermediary mechanism to coordinate uplink transmissions from user equipment to multiple aggregated cells. The network sends timing advance adjustments to synchronize uplink signals across different cells, acting as a mediator that enables flexible carrier aggregation while managing interference and timing alignment.
Data Source
AI summary
A wireless device receives a radio resource control message comprising an aperiodic sounding reference signal (SRS) subframe parameter. A downlink control information is received. The downlink control information indicates uplink resources in a plurality of scheduled consecutive subframes for transmission of transport blocks by the wireless device and triggers an SRS transmission in a subframe of the plurality of scheduled consecutive subframes. The SRS is transmitted in the subframe. A position of the subframe in the plurality of scheduled consecutive subframes is determined based on the aperiodic SRS subframe parameter.