Wireless Device HARQ Buffer Management for SPS Data Loss
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Solution Overview
Problem
In wireless communication networks, the existing Semi-Persistent Scheduling (SPS) mechanism leads to data loss and increased latency due to the need for padding transmissions and adaptive retransmissions, especially in scenarios with short SPS intervals, where the HARQ buffer is overwritten by new data when a dynamic UL grant is received.
Innovation Solution
Implementing a method where wireless devices are configured to skip padding transmissions and use dynamic UL grants, which allow them to determine if the HARQ buffer contains data or not, transmitting accordingly using resources indicated by either the dynamic or SPS grants, thereby avoiding data loss and optimizing resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If padding transmissions are performed in SPS grants, then resource allocation is maintained, but data loss occurs when HARQ buffer is overwritten by new data
Solution Approach 1:
The wireless device checks the HARQ buffer status before transmitting new data on a dynamic UL grant. If the buffer contains data from a previous SPS transmission, the device performs a retransmission instead of overwriting with new data. This preliminary check prevents data loss by determining whether the buffer should be overwritten before the overwrite occurs.
2Reliability
If adaptive retransmissions are used in SPS, then retransmission reliability is improved, but latency increases due to additional transmission steps
Solution Approach 1:
The system dynamically adjusts the retransmission behavior based on real-time conditions. When a dynamic UL grant is received, the device checks whether the HARQ buffer contains data and whether new data is available. If the buffer has data and no new data is available, a retransmission is performed. This dynamic decision-making optimizes the balance between reliability and latency by avoiding unnecessary retransmissions while ensuring data is retransmitted when needed.
3Productivity
If short SPS intervals are configured, then resource allocation efficiency is improved, but data loss increases due to buffer overwriting
Solution Approach 1:
The wireless device implements a feedback mechanism by checking the HARQ buffer status before each dynamic UL grant transmission. This feedback loop allows the device to determine whether the buffer contains data that should be retransmitted before overwriting occurs. The check acts as a feedback signal that prevents data loss while maintaining the efficiency benefits of short SPS intervals.
Data Source
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AI summary
Embodiments herein relate to a method performed by a wireless device (10) for handling uplink, UL, communication from the wireless device (10) in a wireless communication network (1), which wireless device is configured with one or more Semi Persistent Scheduling, SPS, grants and to skip padding transmissions of SPS grant. The wireless device receives a dynamic UL grant from a radio network node indicating one or more resources for an UL transmission to the radio network node. The wireless device determines that a Hybrid Automatic Repeat Request, HARQ, buffer for transmission of a previous transmission comprises data or not, which HARQ buffer is associated with a same HARQ process as the dynamic UL grant. Furthermore, the wireless device (10) transmits the data in the HARQ buffer using one or more resources as indicated by the dynamic UL grant or as indicated by the SPS grant when determined that the HARQ buffer comprises data, and transmits new UL data using the one or more resources as indicated by the dynamic UL grant when determined that the HARQ buffer comprises no data.