Buffer Status Reporting via Preconfigured Uplink Resources in NTNs
Solution Overview
Problem
In non-terrestrial networks (NTNs), the large distances between user equipment (UE) and serving nodes result in significant propagation delays, leading to high latency and inefficiencies in buffer status report (BSR) transmissions due to the need for multiple messages and grants, which are exacerbated by the mobility of high-altitude vehicles like non-geostationary satellites.
Innovation Solution
UEs in NTNs can preempt scheduling requests and utilize dedicated periodic uplink resources, transmit BSRs via RACH preambles, or employ two-step RACH procedures to efficiently convey buffer status without additional scheduling requests, and base stations can allocate dynamic or range-based uplink grants to reduce latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If traditional BSR transmission procedures are used in NTNs, then buffer status information can be reported, but latency is significantly increased due to multiple message exchanges and propagation delays
Solution Approach 1:
The system pre-configures uplink resources and BSR transmission parameters before data arrives at the UE. The base station provides ahead-of-time configurations including uplink grant parameters, BSR trigger conditions, and resource allocations, allowing the UE to immediately transmit BSRs when data arrives without waiting for scheduling requests or additional grants, thereby eliminating multiple message exchange delays
Solution Approach 2:
The patent extracts and eliminates unnecessary signaling steps from the traditional BSR transmission procedure. By using pre-configured resources and allowing direct BSR transmission on uplink data channels, the system removes the need for scheduling requests, uplink grant allocations, and separate BSR transmission steps, keeping only the essential buffer status reporting function
2Ease of operation
If multiple scheduling requests and grants are used for BSR transmissions, then resource allocation can be managed, but the number of message exchanges increases latency
Solution Approach 1:
The base station performs resource allocation and configuration in advance, providing the UE with pre-configured uplink resources, BSR trigger conditions, and transmission parameters before data arrives. This preliminary setup eliminates the need for multiple interactive scheduling requests and grants during actual BSR transmission
Solution Approach 2:
The UE is empowered to autonomously determine when and how to transmit BSRs based on pre-configured trigger conditions and parameters. When data arrives or buffer status changes, the UE self-initiates BSR transmission on appropriate uplink channels without requiring base station scheduling requests or grants, making the system self-serve the resource allocation function
3Productivity
If dedicated periodic uplink resources are allocated for BSR transmissions, then transmission efficiency improves, but resource allocation complexity increases
Solution Approach 1:
The pre-configured uplink resources are designed to serve multiple purposes: they can carry BSR transmissions, regular uplink data, and support various BSR trigger conditions. This multi-functional resource allocation simplifies the overall system by using a single resource configuration framework for different transmission needs rather than separate dedicated resources for each function
Data Source
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AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may transmit buffer status information using configured periodic uplink resources. For example, a base station may configure dedicated periodic uplink resources, periodic random access resources, or periodic uplink grants to enable the UE to transmit the buffer status information. In some cases, the periodic random access resources may enable the UE to transmit a first message of a four-step or two-step random access procedure to indicate the buffer status information. Additionally or alternatively, the base station may configure a type of scheduling request for the UE to transmit that can indicate whether a buffer size falls within a range, where the base station then can more accurately allocate uplink resources in an uplink grant for the UE to transmit the uplink data based on receiving this type of scheduling request.