Relay Node Early BSR Triggering for Uplink Latency Reduction
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Solution Overview
Problem
The standard uplink scheduling procedure in relay-based wireless communication networks introduces significant latency, which is not adequately addressed by existing mechanisms, particularly in scenarios with small data transmissions and timely information availability at relay nodes.
Innovation Solution
Implementing an early buffer status report (BSR) triggering mechanism at the relay node to inform the donor base station about the scheduled status of UEs, allowing for reduced latency by proactively sending BSRs before receiving uplink data from UEs and providing timely information for resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the standard uplink scheduling procedure is applied to the relay-node-to-DeNB link, then the scheduling mechanism reuses existing LTE protocols, but the user plane delay becomes significant (about 20 ms)
Solution Approach 1:
The relay node triggers a Buffer Status Report (BSR) procedure immediately upon receiving a Scheduling Request (SR) from a UE, before actually receiving the uplink data from the UE. This preliminary action allows the donor eNB to prepare scheduling decisions in advance, reducing the overall latency in the uplink path from UE through relay to donor eNB.
2Measurement precision
If the relay node waits to trigger BSR after receiving UL data from UE, then the BSR contains accurate buffer information, but the access delay increases
Solution Approach 1:
The relay node sends the BSR to the donor eNB before the uplink data from the UE has been fully received and processed. This preliminary triggering of the BSR allows the scheduling information to be prepared in advance, reducing the overall access delay while the BSR is triggered based on the scheduling request indication that data is expected.
Solution Approach 2:
The system preemptively triggers the BSR procedure in anticipation of upcoming uplink data, counteracting the potential delay that would occur if waiting for actual data receipt. This preliminary anti-action ensures that scheduling resources are ready before the data arrives, preventing latency accumulation in the relay path.
3Loss of time
If early BSR triggering is implemented at the relay node, then latency is reduced, but the BSR may be sent before the relay has complete information about the UL data
Solution Approach 1:
The relay node triggers the BSR based on the indication from the UE's scheduling request that data is about to be transmitted or has been transmitted. This preliminary triggering occurs at the optimal moment when the relay node has sufficient information to initiate the scheduling process without waiting for complete data reception, thus reducing latency while maintaining adequate information for scheduling decisions.
Data Source
AI summary
In one or more embodiments, the present invention provides a method and apparatus for "early" triggering of a BSR in a relay node ( 16). Doing so is advantageous, for example, in reducing the overall time between a UE's transmission of data to a relay node ( 16) on an access link (22) and the corresponding transmission of that data from the relay node (16) to a donor base station (20) on a backhaul link (24). Of course, that example is non-limiting. More broadly, in at least one embodiment, the present invention provides for triggering a BSR in the relay node (16) right after learning that there is at least one UE (12) connected to the relay node ( 16) that wants to transmit UL data. Further, one or more embodiments provide a simple method and apparatus for using a relay node BSR to inform a donor base station (20) about the scheduled status of UEs supported by the relay node (16).