Scheduling Request Resources in Random Access Channel for Low Latency
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing scheduling requests (SR) with existing techniques, particularly in low latency scenarios where reduced transmission time intervals (TTIs) are necessary to minimize latency and enhance resource allocation for multiple-access systems like LTE and NR.
Innovation Solution
The proposed solution involves allocating SR resources within random access channel resources, utilizing shortened TTIs such as two-symbol or three-symbol TTIs, where the three-symbol TTI may include a reference signal transmission, allowing for efficient conversion of random access resources between different TTI durations to optimize resource utilization and reduce latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional scheduling request resources are used in legacy LTE TTIs, then resource allocation is straightforward, but latency is high and resource allocation efficiency is poor for low latency users
Solution Approach 1:
The patent combines scheduling request resources with random access channel resources, allowing UEs to transmit SRs using PRACH resources. This merging eliminates the need for separate SR resources in sTTI, reducing latency while utilizing existing infrastructure designed for low-latency random access procedures
Solution Approach 2:
The patent makes random access resources serve dual purposes: traditional random access functionality and scheduling request transmission. By configuring subsets of PRACH resources for SR transmission, the system achieves multi-functionality without requiring dedicated SR resources, thereby reducing latency for low-latency users
2Loss of time
If shortened TTIs are introduced to reduce latency, then low latency communications are achieved, but resource allocation becomes more complex and resource conversion between different TTI durations is required
Solution Approach 1:
The patent segments random access resources into different subsets allocated to different UEs based on their TTI requirements. This segmentation allows sTTI users to access specific PRACH resources configured for low latency, while legacy users continue using traditional resources, enabling simultaneous support of multiple TTI durations without interference
Solution Approach 2:
The patent implements dynamic resource allocation where the base station configures and can reconfigure PRACH resources for SR transmission based on current system conditions and UE requirements. This dynamic approach allows the system to adapt resource allocation to changing latency requirements and traffic patterns
3Loss of time
If SR resources are allocated in sTTI with shorter duration, then latency is reduced, but the number of available resources is limited and resource conversion between different TTI durations is needed
Solution Approach 1:
The patent performs preliminary configuration of PRACH resources for SR transmission before actual SR traffic arrives. The base station pre-allocates specific PRACH resources and subsets for potential SR transmissions, so when low-latency SR traffic arrives, UEs can immediately use the pre-configured resources without waiting for resource allocation decisions, thereby minimizing latency
Data Source
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AI summary
Methods, systems, and devices for wireless communication are described that provide scheduling request (SR) resources that may be used by a user equipment (UE) to request uplink resources. SR resources may be allocated within random access channel resources, and a UE may use the SR resources to transmit a SR. The random access resources may be allocated in a first duration transmission time interval (TTI) that has a duration that is shorter than a second duration TTI. The SR resources may be a subset of random access preambles associated with the random access resources.