DCI Scheduling for Multi-TTI PUSCH in Unlicensed Spectrum
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing multi-transmission time interval (TTI) physical uplink shared channel (PUSCH) transmissions, particularly in unlicensed spectrum, due to limitations in downlink control information (DCI) overhead and scheduling flexibility, which affects bandwidth, latency, and data rates.
Innovation Solution
The implementation of enhanced DCI enhancements for dynamic switching between single-TTI and multi-TTI scheduling, including mini-slot based resource allocation, SRS multiplexing, and CBG-based transmission, to optimize PUSCH transmission in unlicensed spectrum, ensuring continuous time resources and efficient resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-TTI scheduling is implemented to improve resource allocation efficiency, then bandwidth utilization and data rates improve, but DCI overhead and scheduling complexity increase
Solution Approach 1:
The patent segments the scheduling information by separating multi-TTI scheduling indications from single-TTI scheduling. The DCI format is divided into specific fields: a multi-TTI indicator field that signals whether multi-TTI scheduling is active, a time resource allocation field that specifies the duration and timing, and a frequency resource allocation field. This segmentation allows the system to implement multi-TTI scheduling only when needed, reducing overall DCI overhead while maintaining high bandwidth utilization when multi-TTI mode is activated.
Solution Approach 2:
The patent implements dynamic switching between single-TTI and multi-TTI scheduling modes based on channel conditions and traffic requirements. The gNB can dynamically adjust the multi-TTI indicator in DCI messages to switch scheduling modes on-the-fly. This dynamic approach allows the system to optimize bandwidth utilization by using multi-TTI scheduling when channel conditions are favorable and traffic demands long-duration allocations, while falling back to single-TTI scheduling when conditions require more flexible, shorter allocations, thus managing DCI overhead efficiently.
2Adaptability or versatility
If dynamic switching between single-TTI and multi-TTI scheduling is implemented, then scheduling flexibility improves, but DCI message complexity increases
Solution Approach 1:
The patent designs a universal DCI format that can handle both single-TTI and multi-TTI scheduling through the inclusion of a multi-TTI indicator field. This single DCI structure serves multiple functions: when the indicator is set to single-TTI mode, the time resource allocation field specifies a single slot; when set to multi-TTI mode, the same field specifies multiple slots with their respective durations. This multi-functional design allows the system to maintain scheduling flexibility across different modes without requiring separate DCI formats, thereby managing complexity effectively.
Solution Approach 2:
The patent utilizes parameter changes within the DCI structure to enable dynamic mode switching. The multi-TTI indicator field acts as a control parameter that, when changed, alters the interpretation of other DCI fields. Specifically, the time resource allocation parameter can represent either a single slot index or a sequence of multiple slot indices depending on the indicator value. This parameter-based control mechanism provides scheduling flexibility while avoiding the need for complex conditional logic in DCI processing.
3Loss of time
If mini-slot based resource allocation is used, then latency is reduced, but resource allocation complexity increases
Solution Approach 1:
The patent applies segmentation to the time domain by introducing mini-slots as finer-grained time units within slots. Each slot is divided into multiple mini-slots, allowing resource allocations to start at mini-slot boundaries rather than slot boundaries. The time resource allocation field in DCI can specify starting mini-slot indices and durations in mini-slots, enabling precise control over transmission timing. This segmentation reduces latency by allowing transmissions to begin immediately at the next mini-slot boundary rather than waiting for slot boundaries, while the structured mini-slot framework keeps resource allocation complexity manageable through regular intervals.
4Measurement precision
If SRS multiplexing is implemented to improve uplink channel estimation, then channel estimation accuracy improves, but signal interference increases
Solution Approach 1:
The patent merges SRS (Sounding Reference Signal) transmissions with PUSCH (Physical Uplink Shared Channel) data transmissions by allowing them to occupy the same time-frequency resources through multiplexing. The SRS signals are transmitted in the same uplink slots as PUSCH, with specific resource element mappings that enable both signals to coexist. This merging approach improves channel estimation accuracy by obtaining fresh channel state information from SRS while simultaneously transmitting data, reducing the need for separate estimation transmissions that would increase overall interference and resource consumption.
Solution Approach 2:
The patent applies local quality differentiation by assigning different cyclic shifts and frequency offsets to SRS and PUSCH signals within the same time-frequency resources. The SRS transmission uses specific localized resource elements with distinct signal characteristics (different cyclic shifts of base sequences) that allow the receiver to separately process and estimate channels for each signal type. This local differentiation enables accurate channel estimation for both SRS and PUSCH without requiring full orthogonal separation, thereby reducing overall signal interference while maintaining measurement precision.
Data Source
AI summary
Methods, systems, and storage media are described for multi-transmission time interval (TTI) physical uplink shared channel (PUSCH) transmissions. In particular, some embodiments relate to downlink control information (DCI) enhancements to support dynamic switching between single-TTI scheduling and multi-TTI scheduling. Other embodiments may be described and/or claimed.