Uplink Power Control for LAA PUSCH with LBT
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Solution Overview
Problem
Current LTE systems face inefficiencies in uplink transmission, particularly in managing and receiving uplink transmissions across multiple serving cells, including Licensed Assisted Access (LAA) cells, due to limitations in carrier aggregation and HARQ-ACK feedback mechanisms, especially in unlicensed bands.
Innovation Solution
The implementation of advanced scheduling mechanisms for Physical Uplink Shared Channel (PUSCH) transmissions, including the use of DCI formats that indicate which SC-FDMA symbols are not transmitted, and the integration of Listen Before Talk (LBT) periods to optimize channel usage and reduce collisions, allowing for efficient uplink data transmission and reception across multiple serving cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carrier aggregation is implemented to enable simultaneous transmission in multiple serving cells, then uplink transmission capacity is improved, but system complexity and interference management difficulty increase
Solution Approach 1:
The patent segments the uplink transmission resource into multiple serving cells (component carriers) that can be independently managed. Each cell operates with its own LBT procedure and transmission parameters, allowing the system to handle multiple cells separately rather than as a monolithic complex system, thus enabling capacity improvement while controlling complexity through modular organization
Solution Approach 2:
The patent implements a universal LBT mechanism that can be applied across multiple serving cells regardless of whether they are in licensed or unlicensed bands. The base station and terminal apparatus use common DCI formats and scheduling procedures that work universally across different cell types, reducing the need for cell-specific complex management
2Reliability
If LBT procedure is introduced for unlicensed band transmission, then channel collision is reduced, but transmission delay and opportunity loss increase
Solution Approach 1:
The patent implements LBT as a preliminary action before actual uplink transmission in unlicensed bands. The terminal performs channel sensing and waits for idle conditions before transmitting PUSCH, which prevents collisions but introduces delay. The base station schedules transmissions with awareness of LBT requirements, and DCI formats include indicators to help terminals prepare in advance for potential LBT waiting periods
Solution Approach 2:
The LBT procedure operates periodically at scheduled transmission opportunities rather than continuously. The base station configures periodic scheduling intervals where LBT is performed only at these discrete points, allowing the system to balance collision avoidance with minimizing continuous sensing overhead and transmission delays
3Productivity
If DCI format indicators are used to specify non-transmitted SC-FDMA symbols, then resource allocation efficiency is improved, but signaling overhead increases
Solution Approach 1:
The patent applies local quality by providing detailed transmission indicators only where needed through DCI formats. Instead of signaling complete transmission parameters for all symbols, the system uses targeted indicators (such as indicator fields in DCI) that specify only the non-transmitted SC-FDMA symbols or resource adjustments, reducing overall signaling overhead while maintaining efficient local resource allocation where it matters most
Data Source
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AI summary
An apparatus includes: a transmitter configured to transmit a transport block on PUSCH; and a physical layer processing unit configured to calculate transmit power of the PUSCH, at least based on a number of SC-FDMA symbols NPUSCH-initialsymb for PUSCH initial transmission for the transport block, wherein the number of the SC-FDMA symbols NPUSCH-initialsymb is given at least based on NLBT and a number of SC-FDMA symbols NULsymb included in an uplink slot, and a value of NLBT is 1 in a case that a time continuous signal of a first SC-FDMA symbol included in the PUSCH is generated based on a content of a resource element corresponding to a second SC-FDMA symbol following the first SC-FDMA symbol.