Multi-sTTI Scheduling for URLLC Data Channel Reliability
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Solution Overview
Problem
Current LTE/LTE-Advanced systems face challenges in providing ultra-reliable and low-latency communication services due to high latency and data throughput limitations, particularly in achieving the required Block Error Rate (BLER) of 10^-5 for data channel transmission and reception.
Innovation Solution
A multi-TTI-based scheduling method is introduced, where repetitive transmission information is used to manage the number of transmissions for uplink and downlink data channels based on slots or sub-slots, enhancing reliability and latency performance by configuring non-slot-based sTTI structures and setting redundancy versions for data channel transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If typical TTI frame structure is used, then system compatibility is maintained, but latency and data throughput are insufficient for URLLC requirements
Solution Approach 1:
The patent divides the traditional TTI frame structure into shorter time intervals by introducing sTTI (short TTI) with durations of 2, 3, or 7 OFDM symbols instead of the full 14 symbols. This segmentation allows data transmission to occur in smaller, faster time units, reducing latency while maintaining compatibility with the overall LTE frame structure through multi-TTI scheduling
Solution Approach 2:
The patent implements dynamic TTI length adjustment by allowing the system to flexibly switch between different sTTI lengths (2, 3, or 7 symbols) based on traffic requirements and channel conditions. This dynamic adaptation enables the system to optimize latency and throughput for URLLC services while preserving backward compatibility with legacy LTE operations
2Reliability
If single TTI transmission is used, then transmission speed is fast, but transmission reliability does not meet BLER=10^-5 requirement
Solution Approach 1:
The patent combines multiple sTTI transmissions to form a multi-TTI scheduling framework where data can be transmitted across several short time intervals. This merging approach accumulates transmission reliability through repeated transmissions while keeping individual sTTI durations short, achieving BLER=10^-5 without requiring complex retransmission protocols
Solution Approach 2:
The patent employs periodic repetitive transmissions within the multi-TTI scheduling framework, where the same data is transmitted repeatedly across multiple sTTI instances. This periodic action increases the probability of successful reception by providing multiple opportunities for correct decoding, thereby achieving the required reliability without significantly increasing scheduling complexity
3Productivity
If sTTI frame structure is introduced, then latency and throughput are improved, but system complexity increases
Solution Approach 1:
The patent designs the sTTI frame structure to serve multiple functions: it enables low-latency URLLC transmission, maintains backward compatibility with legacy LTE through multi-TTI scheduling, and supports flexible resource allocation. By making the frame structure multi-functional, the system achieves high throughput and low latency without proportionally increasing complexity
Solution Approach 2:
The patent changes key frame structure parameters by introducing variable sTTI lengths (2, 3, or 7 OFDM symbols) and flexible slot configurations. These parameter changes allow the system to optimize for different service requirements while maintaining a manageable level of complexity through standardized configuration options and inheritance from legacy LTE structures
Data Source
AI summary
Provided is a method of scheduling for improving the performance of data channel detection in order to provide URLLC services in the 3GPP LTE/LTE-A system. In particular, a method of a UE may be provided for transmitting an uplink data channel or receiving a downlink data channel. The method may include receiving repetitive transmission information for the uplink data channel or the downlink data channel from a base station, and receiving the downlink data channel from the base station or transmitting the uplink data channel to the base station, based on the repetitive transmission information. The repetitive transmission information indicates a number of repetitive transmissions for the uplink data channel or the downlink data channel, and the repetitive transmission is performed based on on a unit of a slot or a unit of a sub-slot.