Location-Based PSFCH Feedback for Groupcast Sidelink
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Solution Overview
Problem
In wireless communication systems, particularly in Evolved Universal Terrestrial Radio Access Networks (E-UTRAN) and next-generation 5G networks, there is a challenge in effectively handling device-to-device feedback for groupcast sidelink transmissions, especially in determining appropriate feedback indications for successful decoding of sidelink transmissions based on location and communication range.
Innovation Solution
A method where a second User Equipment (UE) determines a Physical Sidelink Feedback Channel (PSFCH) resource for transmitting acknowledgement (ACK) or non-acknowledgement (NACK) indications based on the availability of location information and successful decoding of groupcast sidelink transmissions, ensuring feedback is only sent if the UE is within the communication range or if location information is available.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a second UE transmits NACK indication on PSFCH resource for groupcast sidelink transmission, then communication reliability is improved, but resource usage efficiency deteriorates when the UE is outside communication range
Solution Approach 1:
The patent applies local quality by making the feedback transmission behavior location-dependent. The second UE determines whether to transmit NACK based on its location relative to the first UE and the communication range. When location information is available and the UE is outside the communication range, feedback transmission is suppressed. This creates a spatially differentiated feedback mechanism that adapts to local conditions rather than applying a uniform feedback policy to all UEs.
Solution Approach 2:
The patent inverts the conventional feedback approach by suppressing feedback transmission under specific conditions rather than always transmitting. Instead of the traditional rule where NACK is always sent for unsuccessful decoding, the patent inverts this by not sending NACK when location information indicates the UE is outside communication range. This inversion reduces unnecessary feedback transmissions and improves resource efficiency.
2Loss of energy
If location information is used to determine feedback transmission, then resource usage is optimized, but device complexity increases
Solution Approach 1:
The patent applies self-service by enabling the second UE to autonomously determine whether to transmit feedback based on its own location information and the received first SCI. The UE independently evaluates its position relative to the communication range and makes the decision without requiring additional network coordination or complex external assistance. This self-service approach optimizes resource usage while keeping the implementation relatively simple.
Data Source
AI summary
In an example, a second UE receives a first SCI and a second SCI from a first UE in a first slot. A groupcast sidelink transmission is scheduled by the first SCI and the second SCI. The second SCI indicates a location indication, associated with a location of the first UE, and a communication range. A PSFCH resource is determined based upon the first SCI. The second UE doesn't transmit a NACK indication on the PSFCH resource if location information of the second UE is available, the groupcast sidelink transmission isn't successfully decoded, and the second UE is outside the communication range. The second UE transmits the NACK indication on the PSFCH resource if the location information isn't available and the groupcast sidelink transmission isn't successfully decoded, or if the location information is available, the groupcast sidelink transmission isn't successfully decoded, and the second UE is within the communication range.