SR Resource Management for sTTI Latency
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Solution Overview
Problem
Current mobile communication systems face challenges in ensuring low latency and high reliability for Critical Machine-Type Communication (CMTC) scenarios, particularly in factory automation, motion control, and smart energy grids, due to unsatisfactory performance in scheduling request (SR) and buffer status report (BSR) management in short Transmission Time Interval (sTTI) scenarios, leading to prolonged signaling latency and potential misunderstandings between User Equipment (UE) and Base Station (BS).
Innovation Solution
A resource management method is introduced where SRs are triggered by buffer status changes and sent on specific uplink control channels based on data criticality, with delay-critical data using short TTI channels and non-critical data using legacy TTI channels, and resource grants are managed to ensure timely and accurate communication, including predefined maximum SR transmissions and prohibition periods to prevent miscommunication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If SR is sent on legacy TTI control channel for non-delay-critical data, then resource management is simplified, but latency increases for delay-critical services
Solution Approach 1:
The patent segments the uplink control channel resources into two distinct types: legacy TTI control channels for non-delay-critical data and short TTI control channels for delay-critical data. This segmentation allows the system to handle different traffic types with appropriate latency requirements separately, resolving the contradiction between simplified resource management and low latency performance.
Solution Approach 2:
The patent applies local quality by assigning different channel characteristics to different data types. Short TTI control channels provide faster response characteristics specifically for delay-critical services, while legacy channels handle non-critical traffic. This localized optimization resolves the contradiction by providing high performance where needed without complicating the entire system.
2Reliability
If multiple SR transmissions are allowed for reliability, then transmission reliability improves, but signaling latency increases
Solution Approach 1:
The patent introduces dynamic SR transmission mechanisms where the UE can adaptively determine the number of SR transmissions based on whether an uplink grant is received. The counter-based approach allows the system to balance reliability and latency dynamically - increasing transmissions only when necessary for reliability while avoiding unnecessary delays when grants are received promptly.
Solution Approach 2:
The patent implements feedback mechanisms where the base station's uplink grant responses are used to control further SR transmissions. The UE monitors received grants and adjusts its SR transmission behavior accordingly, providing feedback-driven control that balances reliability requirements with latency constraints.
3Loss of time
If SR transmission opportunities are increased for delay-critical data, then latency guarantee improves, but system complexity increases
Solution Approach 1:
The patent segments SR transmission opportunities into short TTI and legacy TTI channels based on data criticality. This segmentation provides multiple transmission opportunities for delay-critical data through the short TTI channel while maintaining simpler legacy channel behavior for non-critical data, thus improving latency guarantee without uniformly increasing system complexity.
Solution Approach 2:
The patent changes key parameters such as TTI length and channel timing characteristics to create faster SR transmission opportunities for delay-critical data. By modifying these parameters specifically for the short TTI channel rather than the entire system, the patent improves latency guarantee while containing the increase in system complexity to a localized scope.
Data Source
AI summary
According to the present disclosure, behaviors of User Equipment (UE) and base station (BS) pertinent to Scheduling Request (SR) and/or Buffer Status Report (BSR) as well as resource management in short Transmission Time Interval (sTTI) relevant scenarios are discussed. UE may firstly determine if the SR is triggered by a buffer status change of a delay-critical data which needs a sTTI. If so, UE will send the SR to BS on a first type of uplink control channel designed for sTTI. Otherwise, UE will send the SR to the base station on a second type of uplink control channel designed for legacy TTI.