TDD-SDL Carrier Aggregation Feedback Timing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing 3GPP LTE protocol lacks a downlink data channel retransmission method for TDD+SDL carrier aggregation mode, where a primary carrier operates in TDD mode and secondary carriers use SDL mode, making it difficult to efficiently feed back answer information in this configuration.
Innovation Solution
An answer information feedback method is provided that determines the downlink subframe for secondary carriers in SDL mode corresponding to the uplink subframe of the primary carrier in TDD mode, using a predetermined downlink retransmission timing mode, allowing answer information to be transmitted to the network side using the uplink subframe of the primary carrier, even when the secondary carriers are separated by at least four subframes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a predetermined downlink retransmission timing mode is used for TDD+SDL carrier aggregation, then answer information feedback efficiency is improved, but the system complexity increases due to the need to handle different duplexing modes
Solution Approach 1:
The patent applies universality by creating a downlink retransmission timing mode that works for both TDD and SDL carriers simultaneously. The terminal determines corresponding downlink subframes using a unified timing relationship that accommodates the mixed duplexing mode, allowing the system to handle TDD+SDL carrier aggregation with a single standardized approach rather than separate mechanisms for each carrier type.
2Quantity of substance
If all downlink subframes of secondary carriers are used for data transmission, then data transmission capacity is improved, but the reliability of answer information feedback deteriorates due to potential timing conflicts
Solution Approach 1:
The patent applies preliminary action by establishing predetermined downlink retransmission timing modes before actual data transmission occurs. The terminal and network side agree in advance on the timing relationships between uplink subframes and corresponding downlink subframes, allowing all downlink subframes to be utilized for data transmission while ensuring that answer information can be reliably fed back at predetermined intervals without timing conflicts.
3Productivity
If the uplink subframe of primary carrier is used to transmit answer information for secondary carriers, then resource utilization is improved, but the difficulty of detecting and measuring timing relationships increases
Solution Approach 1:
The patent applies parameter changes by defining specific timing parameters (K1, K2, K3 values) that determine the relationship between uplink subframes and downlink subframes. These parameters are configured based on the TDD uplink-downlink configuration and SDL carrier characteristics, allowing the system to optimize resource utilization while providing clear, measurable timing relationships that reduce detection difficulty through standardized parameter sets.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An answer information feedback method includes steps of: with respect to a current uplink subframe of a primary carrier in a TDD mode, determining, by a terminal, a downlink subframe of a secondary carrier in an SDL mode and corresponding to the current uplink subframe in answer information feedback as a to-be-fed-back downlink subframe, the to-be-fed-back downlink subframe being determined from designated downlink subframes of the secondary carrier in accordance with a downlink retransmission timing mode for a DL-reference UL/DL configuration of the secondary carrier, the designated downlink subframes including downlink subframes except a downlink subframe having a location identical to an uplink subframe indicated by the DL-reference UL/DL configuration, the DL-reference UL/DL configuration being identical to a timeslot configuration of the primary carrier; and transmitting answer information for the to-be-fed-back downlink subframe to a network side using the current uplink subframe.