Terminal Uplink Scheduling in Mixed LTE-5G Carrier Aggregation
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Solution Overview
Problem
In carrier aggregation scenarios involving LTE and 5G cells with different subframe time intervals, terminals face challenges in determining the appropriate timing for reporting buffer size and power headroom to the base station, leading to inaccurate resource allocation and scheduling issues.
Innovation Solution
The system introduces a mechanism where the base station provides indications to the terminal on which subframes of the 5G cell to consider for buffer size and power headroom calculations, allowing the terminal to transmit this information accurately to the base station using the physical uplink shared channel of the LTE cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carrier aggregation is performed with LTE PCell and 5G SCell having different TTI lengths, then communication speed and capacity are improved, but the terminal cannot determine the appropriate timing for calculating and reporting buffer size and power headroom
Solution Approach 1:
The base station performs preliminary action by indicating to the terminal which specific subframe of the SCell corresponds to the PCell subframe before the terminal calculates and reports buffer size and power headroom. This advance indication resolves the timing ambiguity caused by different TTI lengths, allowing the terminal to prepare and report accurate uplink scheduling information without complex real-time determination logic.
2Measurement precision
If the terminal reports buffer size and power headroom based on multiple subframes of SCell, then more accurate resource allocation information is provided, but the base station cannot determine which specific subframe the report corresponds to
Solution Approach 1:
The base station acts as an intermediary by providing a reference indication that links the PCell subframe timing to the corresponding SCell subframe. This intermediary reference resolves the timing information loss, enabling the terminal to accurately report buffer size and power headroom for the correct subframe while the base station can correctly interpret the reported information.
3Quantity of substance
If the terminal calculates buffer size and power headroom for all SCell subframes, then complete information is available for scheduling, but the reporting overhead and processing load increase significantly
Solution Approach 1:
The system extracts only the necessary information by having the base station indicate which specific SCell subframe corresponds to the PCell subframe. The terminal then calculates and reports buffer size and power headroom only for that specific subframe rather than all subframes, reducing processing energy while maintaining the completeness of scheduling-relevant information.
Data Source
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AI summary
The present disclosure pertains a terminal (1) which communicates with a base station (2) in a mobile communication system which supports carrier aggregation provided by a first cell and a second cell which uses a second predetermined time interval that is less than a first predetermined time interval of the first cell. The terminal (1) comprising: a calculation unit (13, 14) configured to calculate reporting information to be transmitted in a certain time interval of the first predetermined time interval to the base station (2) based on a specified time interval of the second predetermined time interval wherein information related to the specified time interval of the second predetermined time interval is defined beforehand; and a reporting unit (11) configured to report the reporting information calculated by the calculation unit (13) to the base station (2); wherein the reporting information is at least one of a buffer status report, BSR and a power headroom report, PHR.