NB-IoT AM RLC Feedback for Low-Latency NTN Transmission
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Solution Overview
Problem
In IoT NTN scenarios, HARQ feedback significantly increases transmission delays and power consumption due to large round-trip delays, while RLC feedback mechanisms are weaker and less frequent, leading to deteriorated data transmission latency and reliability.
Innovation Solution
Enhanced AM RLC configurations for NB-IoT devices in NTN, including fast polling and status reporting, with shortened window sizes, condition-based triggers, and timer-based triggers, and autonomous status reporting using semi-persistent scheduling resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ feedback is enabled in NTN scenarios, then data transmission reliability is improved, but transmission delay and power consumption increase significantly
Solution Approach 1:
The patent extracts and removes the HARQ feedback mechanism from the NTN communication system, recognizing that the large round-trip delay in satellite-based networks makes HARQ feedback ineffective for improving reliability. Instead, the solution focuses on enhancing RLC-level mechanisms (polling and status reporting) to achieve reliable data transmission without the detrimental delays introduced by HARQ.
2Speed
If HARQ feedback is disabled to reduce transmission delay, then transmission speed is improved, but data transmission reliability deteriorates
Solution Approach 1:
The patent implements enhanced feedback mechanisms at the RLC layer, specifically improving the polling and status reporting processes. The transmitting end actively polls the receiving end for acknowledgment status, and the receiving end provides timely status reports, creating a feedback loop that ensures reliable data transmission without relying on HARQ feedback.
3Loss of time
If RLC polling frequency is increased to improve feedback responsiveness, then data transmission latency is reduced, but network resource consumption increases
Solution Approach 1:
The patent implements dynamic polling mechanisms where the polling frequency and intensity are adjusted based on transmission conditions. The transmitting end modifies polling behavior according to the current state of data transmission, acknowledgment status, and network conditions, thereby optimizing the balance between feedback responsiveness and resource consumption.
Data Source
AI summary
Apparatus and methods are provided for enhanced AM RLC for NB-IoT UE in the NTN. In one novel aspect, the UE is configured with HARQ disabled, and configured with fast polling and/or fast status report for AM RLC enhancement. In one embodiment, the UE is configured with shortened AM window size, and wherein the shortened window size is smaller than an AM window size for an NB-IoT device. In other embodiments, the fast polling is triggered based on PDU threshold or byte threshold, or triggered based on an NTN polling timer, or triggered based on a combination of an NTN polling timer and one or more threshold triggers. In one embodiment, UE is configured to autonomously send a status report when a reception failure of an RLC PDU is detected, and wherein the status report is sent by a semi-persistent scheduling (SPS) uplink resource.