Terminal Device Soft Buffer Alignment for LTE Carrier Aggregation
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Solution Overview
Problem
In LTE radio systems, there are discrepancies between the actual operation of base station devices and terminal devices regarding bit width of Rank Indicators (RI), rate matching of code blocks, and soft channel bit storage, leading to potential communication failures.
Innovation Solution
A terminal device configuration that includes a higher layer processing unit, control unit, reception unit, and transmission unit, which manages communication through multiple cells using carrier aggregation, and determines the number of soft channel bits and Rank Indicators based on capability parameters and transmission modes to ensure accurate communication with the base station.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carrier aggregation and MIMO functions are extended in LTE, then communication capability and data transmission efficiency are improved, but discrepancies between base station and terminal device operations occur leading to communication failures
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the soft buffer size based on the determined UE category. The base station determines the appropriate soft buffer size parameter according to the UE's capability category (e.g., category 6, 7, or 8) and configures it accordingly, ensuring that the terminal device uses the correct buffer size for its category. This resolves the discrepancy where terminal devices might assume different buffer sizes than what the base station intends, thereby improving communication reliability while maintaining high data transmission efficiency through carrier aggregation and MIMO.
2Adaptability or versatility
If terminal devices assume different operational parameters than base station actual operations, then device complexity and adaptability are improved, but communication accuracy and reliability deteriorate
Solution Approach 1:
The patent implements feedback mechanisms where the base station determines the UE category based on capability information exchanged between the base station and terminal device. The base station then notifies the terminal device of the determined category, which includes the soft buffer size parameter. This feedback loop ensures that both the base station and terminal device operate with consistent parameters, resolving the issue of mismatched assumptions while preserving device adaptability through category-based configuration.
Solution Approach 2:
The patent applies preliminary action by determining the UE category and configuring the soft buffer size before actual data transmission begins. The capability exchange and category determination occur during the connection setup phase, ensuring that both the base station and terminal device have aligned operational parameters before communication starts. This prevents communication failures due to parameter mismatches during data transmission.
3Ease of operation
If soft buffer size is not properly aligned between base station and terminal device, then ease of operation is improved, but data transmission reliability and accuracy worsen
Solution Approach 1:
The patent resolves the contradiction by automatically adjusting the soft buffer size parameter based on the determined UE category. The base station determines the appropriate buffer size according to the terminal device's category (e.g., category 6 with 36×10^4 bits, category 7 with 72×10^4 bits, or category 8 with 144×10^4 bits) and configures it through RRC signaling. This automatic parameter adjustment maintains ease of operation while ensuring data transmission reliability through proper buffer size alignment between base station and terminal device.
Data Source
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AI summary
Provided is a terminal device configured to transmit an RI for PDSCH transmission, to receive first information used for determining a first maximum number of layers being a first maximum number assumed for determining the bit width for the RI, to receive a transport block on the PDSCH, and to decode a code block of the transport block. Here, in a case that the decoding of the coded block fails, at least soft channel bits corresponding to a range of prescribed soft channel bits are stored, and the prescribed soft channel bits are based on the first information used for determining the aforementioned first maximum number of layers.