Uplink Signal Allocation in Short TTI Systems
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Solution Overview
Problem
Existing LTE systems lack effective control mechanisms for transmitting uplink data and demodulation reference signals using short TTIs, leading to potential communication quality issues due to non-contiguous allocation in time direction, which can result in power limitations and improper demodulation.
Innovation Solution
A user terminal with a transmission section and control section that allocates uplink signals and reference signals using predetermined patterns, ensuring the reference signal is either in the same sTTI as the uplink signal or in the preceding sTTI, to maintain proper UL transmission control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If uplink data and demodulation reference signal are allocated in different sTTIs, then resource utilization flexibility is improved, but demodulation reliability deteriorates due to non-contiguous allocation
Solution Approach 1:
The demodulation reference signal is allocated in advance in a preceding sTTI before the uplink data transmission. This preliminary allocation ensures that the reference signal is available for demodulation while maintaining contiguous time-domain allocation, resolving the contradiction between flexibility and reliability.
2Loss of time
If short TTI is used for uplink transmission, then transmission latency is reduced, but transmission control complexity increases due to lack of existing rules
Solution Approach 1:
The invention changes the time-domain allocation parameter by defining specific patterns for sTTI resource allocation. These patterns establish clear rules for allocating uplink data and reference signals within short TTIs, reducing control complexity while maintaining low latency transmission.
3Adaptability or versatility
If multiple allocation patterns are provided for UL signal and reference signal, then adaptability is improved, but system complexity increases
Solution Approach 1:
The invention segments the allocation into distinct patterns: one pattern where the reference signal and uplink data are in the same sTTI, and another pattern where the reference signal is in a preceding sTTI. This segmentation provides adaptability while keeping each pattern simple and manageable.
Data Source
AI summary
Even in the case of transmitting the uplink data and the demodulation reference signal using the short TTI, in order to appropriately control the UL transmission, according to one aspect of the present invention, a user terminal transmits a UL signal and a reference signal by using a predetermined sTTI among multiple sTTIs included in a slot, and controls the allocation of the UL signal and the reference signal based on a predetermined allocation pattern among multiple allocation patterns showing allocations of UL signals and reference signals. In these multiple allocation patterns, a UL signal and a reference signal are included in the same slot, and the reference signal is allocated to the same sTTI where the UL signal is allocated, or to an sTTI preceding the sTTI the UL signal is allocated.