Downlink Control Information Segmentation for Latency Reduction
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Solution Overview
Problem
The increasing number of user equipment (UEs) and data/control information to be transmitted by base stations (BSs) in wireless communication systems poses challenges due to limited resources, requiring efficient methods to reduce latency and improve throughput, especially in scenarios with high-density nodes and the need for low-latency communication.
Innovation Solution
The method involves dividing downlink control information (DCI) into first and second DCI, with the first DCI transmitted in a control region of a first time duration and the second DCI transmitted in a shorter time duration, using specific decoding candidates within a search space, allowing for efficient transmission and reception of data and control information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the BS transmits more data and control information to serve increasing numbers of UEs, then the service coverage and capacity improve, but the limited radio resources are consumed faster and latency increases
Solution Approach 1:
The patent segments downlink control information into two types: first DCI transmitted in a first TTI (e.g., 1ms) and second DCI transmitted in a second TTI (e.g., 0.5ms). This segmentation allows critical control information to be delivered faster through the shorter TTI, reducing latency for time-sensitive operations while maintaining comprehensive control through the longer TTI
Solution Approach 2:
The patent applies preliminary action by transmitting the first DCI in advance in the first TTI, which contains information about the second DCI that will be transmitted later in the second TTI. This allows the UE to prepare for upcoming data transmissions sooner, reducing overall latency while efficiently utilizing radio resources
2Reliability
If the BS uses more decoding candidates in the search space to transmit DCI, then the reliability of control information transmission improves, but the complexity of the decoding process increases
Solution Approach 1:
The patent segments the search space decoding candidates into two distinct sets: first decoding candidates for transmitting the first DCI, and second decoding candidates for transmitting the second DCI. This segmentation allows the UE to focus decoding efforts on specific candidates based on the TTI type, reducing overall decoding complexity while maintaining reliability through comprehensive coverage of all necessary candidates
Solution Approach 2:
The patent applies local quality by assigning different decoding candidate sets to different DCI types and TTI durations. The first DCI uses first decoding candidates optimized for longer TTI transmission, while the second DCI uses second decoding candidates optimized for shorter TTI transmission. This localized optimization improves decoding efficiency and reliability for each specific transmission scenario
3Loss of time
If the system uses shorter TTI duration for DCI transmission, then the latency is reduced, but the control region capacity is limited and may not accommodate all necessary control information
Solution Approach 1:
The patent segments control information transmission across two different TTI durations: the first DCI is transmitted in a first TTI (e.g., 1ms) that has sufficient control region capacity to accommodate comprehensive control information, while the second DCI is transmitted in a shorter second TTI (e.g., 0.5ms) to reduce latency for time-critical operations. This segmentation allows the system to leverage both long and short TTI advantages
4Productivity
If the BS transmits first DCI in a first TTI and second DCI in a second TTI, then the throughput is enhanced and latency is reduced, but the system complexity increases due to multiple TTI handling
Solution Approach 1:
The patent applies universality by designing a dual-TTI system where the same control region structure and decoding candidate framework are used for both first TTI and second TTI transmissions. The UE uses a unified search space concept that accommodates both TTI types, and the same DCI segmentation approach is applied across different TTI durations. This multi-functional design enables the system to handle variable TTI requirements while maintaining a consistent processing framework, reducing the effective complexity increase
Data Source
AI summary
One downlink control information DCI may be divided into first DCI and second DCI to be transmitted/received. The first DCI may be transmitted/received within a control region of a first TTI of a first time length. The first DCI may include information about the second DCI in a second TTI of a second time length shorter than the first time length. The first DCI may be transmitted/received using first decoding candidates for transmission of the first DCI among decoding candidates in the search space in the control region of the first TTI. The decoding candidates other than the first decoding candidate among the decoding candidates in the search space may be used for transmission/reception of legacy DCI.