Dynamic TTI Scheduling for Low-Latency Radio Communication
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Solution Overview
Problem
The existing LTE scheduling system lacks flexibility, leading to suboptimal frequency use efficiency and increased delay in communication, as it rigidly allocates time/frequency resources for downlink (DL) and uplink (UL) transmissions, limiting the potential of flexible duplex systems in next-generation mobile communication systems.
Innovation Solution
The solution involves synchronizing DL and UL transmissions to occur at the same Transmission Time Interval (TTI), allowing for dynamic control of DL/UL resources and reducing scheduling timing differences, thereby enabling more efficient use of frequency spectrum and reducing Round Trip Time (RTT) for Hybrid Automatic Repeat Request (HARQ) processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If DL and UL transmissions are scheduled at different TTIs to secure future radio resources, then resource allocation stability is improved, but communication delay increases and flexibility is reduced
Solution Approach 1:
The patent applies dynamics by making the scheduling timing flexible rather than fixed. The control section dynamically determines whether to schedule DL/UL transmissions in the same TTI or different TTIs based on current system conditions, traffic patterns, and resource availability. This dynamic approach allows the system to adapt to changing conditions, achieving low delay when needed while maintaining stability when resources require advance reservation.
Solution Approach 2:
The patent changes the timing parameter of resource allocation from a fixed offset to a variable value. By adjusting the TTI offset between DL and UL transmissions based on traffic conditions and resource status, the system can optimize between immediate transmission (same TTI) and advance resource reservation (different TTIs), thereby resolving the contradiction between delay and stability.
2Loss of time
If DL and UL transmissions are scheduled at the same TTI, then communication delay is reduced and flexibility is improved, but frequency use efficiency may deteriorate due to rigid resource allocation
Solution Approach 1:
The system dynamically adjusts scheduling decisions based on real-time conditions. When same-TTI scheduling is beneficial for low delay, the control section schedules DL and UL in the same TTI. When frequency efficiency is prioritized, it schedules in different TTIs. This dynamic adaptation allows the system to achieve low delay without permanently sacrificing frequency use efficiency.
Solution Approach 2:
The control section performs preliminary assessment of resource availability and traffic conditions before making scheduling decisions. By evaluating future resource needs and current traffic patterns, the system can determine whether same-TTI scheduling will harm frequency efficiency, and adjust accordingly by scheduling in different TTIs when necessary.
3Adaptability or versatility
If flexible duplex system dynamically changes DL/UL allocation, then adaptability is improved, but scheduling complexity increases
Solution Approach 1:
The patent segments the scheduling decision-making process into distinct functional blocks within the control section. The control section is divided into sub-functions that independently evaluate different aspects (traffic conditions, resource availability, timing requirements) and combine their results to make scheduling decisions. This segmentation manages complexity by organizing the decision process into manageable, modular components.
Solution Approach 2:
The control section serves multiple functions: it monitors traffic conditions, evaluates resource availability, determines scheduling timing, and generates allocation decisions. By consolidating these diverse functions into a single multi-functional control section, the patent achieves high adaptability without proportionally increasing overall system complexity, as the same control entity handles all scheduling-related tasks.
Data Source
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Figure 3A~3B
AI summary
There is provided a user terminal capable of realizing a low delay communication in the next generation mobile communication system, including: a reception section that receives at least one downlink control information out of first downlink control information for scheduling reception of downlink data and second downlink control information for scheduling transmission of uplink data; and a control section that controls to perform reception of the downlink data and/or transmission of the uplink data corresponding to the downlink control information at a predetermined transmission time interval (TTI), wherein the control section is configured to set the predetermined TTI to the same TTI based on the TTI that has received the downlink control information, regardless of whether the downlink control information is the first downlink control information or the second downlink control information.