DMRS Positioning for Uplink Control in LTE Terminals
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Solution Overview
Problem
Current LTE communication systems face inefficiencies in uplink communication, particularly in managing Transmission Time Interval (TTI) and processing time, as well as in the transmission of channel state information and HARQ-ACK through semi-persistent scheduling and DMRS positioning.
Innovation Solution
The implementation of a terminal apparatus and base station apparatus that optimize uplink communication by using advanced resource grid configurations, precoding, and DMRS patterns, allowing for efficient transmission of uplink control information and shared channels through improved TTI management and DMRS positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If semi-persistent scheduling is used for uplink transmission, then resource allocation efficiency is improved, but flexibility in TTI management deteriorates
Solution Approach 1:
The patent applies dynamics by enabling the DMRS position to be dynamically switched between first position (symbol 2) and second position (symbol 3) based on TTI duration. When TTI is shortened, the system automatically adjusts DMRS positioning to maintain orthogonality and reduce interference, thus adapting the semi-persistent scheduling to different TTI requirements while preserving resource allocation efficiency.
Solution Approach 2:
The patent changes the DMRS position parameter from fixed to variable, allowing it to take different values (first position or second position) depending on the TTI configuration. This parameter change enables the system to maintain proper orthogonality relationships and interference avoidance under varying TTI conditions, resolving the contradiction between semi-persistent scheduling efficiency and TTI management flexibility.
2Speed
If TTI is reduced for latency improvement, then communication speed is improved, but processing time complexity increases
Solution Approach 1:
The patent changes the DMRS position parameter based on TTI duration to simplify processing. By defining clear rules for DMRS positioning (first position for normal TTI, second position for shortened TTI), the patent reduces the complexity of processing time management while enabling faster communication through TTI reduction. The base station and terminal can quickly determine the appropriate DMRS position without complex calculations.
3Device complexity
If DMRS position is fixed for simplicity, then device complexity is reduced, but communication efficiency deteriorates under varying TTI conditions
Solution Approach 1:
The patent makes the DMRS position dynamic rather than fixed, allowing it to adapt to different TTI conditions. This dynamic adjustment maintains communication efficiency by ensuring proper orthogonality and interference avoidance in both normal and shortened TTI scenarios, while keeping the implementation relatively simple through predefined position options.
Solution Approach 2:
The patent changes the DMRS position parameter from a fixed value to a variable that depends on TTI duration. This parameter change enables the system to maintain high communication efficiency across different TTI configurations without requiring complex real-time optimization, as the appropriate position can be determined through simple conditional logic.
4Reliability
If orthogonal resource allocation is used for multiple UEs, then interference reduction is improved, but resource utilization efficiency deteriorates
Solution Approach 1:
The patent applies local quality by assigning different DMRS positions (first position or second position) to different UEs based on their specific TTI configurations and channel conditions. This localized optimization allows each UE to have the most appropriate DMRS position for its requirements, maintaining orthogonality and reducing interference while improving overall resource utilization efficiency compared to uniform allocation.
Data Source
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AI summary
An apparatus includes: a receiver configured to receive a PDCCH including downlink control information; and a transmitter configured to transmit a sPUSCH, based at least on detection of the PDCCH. The sum of the number of symbols to which the sPUSCH is mapped and the number of SC-FDMA symbols to which a DMRS associated with the sPUSCH is mapped is 2 and/or 3. In a case that a CRC added to the downlink control information is scrambled with a C-RNTI, the index of the SC-FDMA symbol to which the DMRS associated with the sPUSCH is mapped is given based at least on the downlink control information. In a case that the CRC added to the downlink control information is scrambled with an SPS C-RNTI, the index of the symbol to which the DMRS associated with the sPUSCH is mapped is given based at least on higher layer signaling.