SPS Uplink Retransmission Alignment With HARQ Feedback
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Solution Overview
Problem
In wireless communication systems, semi-persistent scheduling (SPS) uplink messages often interfere with other communications due to uncoordinated retransmissions, as the timing of retransmissions may not align with reserved resources, leading to inefficiencies and increased latency.
Innovation Solution
The proposed solution coordinates retransmissions of SPS uplink messages with hybrid automatic repeat request (HARQ) feedback timing, aligning them with reserved resources, and uses incremental redundancy HARQ feedback to reduce packet loss, ensuring retransmissions occur during designated SPS communication periods and refraining from transmitting on non-designated resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If retransmissions are allowed on any available uplink resources, then packet delivery reliability is improved, but interference with other communications increases and resource coordination becomes complex
Solution Approach 1:
The patent segments uplink resources into two distinct types: SPS-dedicated resources and non-SPS resources. UEs are configured to perform retransmissions only on SPS-dedicated resources, thereby isolating retransmission traffic from other communications and eliminating interference issues while maintaining reliable packet delivery
Solution Approach 2:
The patent introduces a coordination mechanism where the network configures UEs with specific SPS-dedicated resources for retransmissions. This configuration acts as an intermediary that directs retransmission traffic to predetermined resources, ensuring automatic coordination without complex real-time scheduling while preventing interference with other communications
2Adaptability or versatility
If retransmissions occur outside SPS resources, then resource utilization flexibility is improved, but coordination complexity increases and interference occurs
Solution Approach 1:
The patent applies preliminary action by pre-configuring UEs with specific SPS-dedicated resources for retransmissions before communication begins. The network provides RRC configuration messages that define these resources in advance, allowing UEs to automatically perform retransmissions on the correct resources without real-time coordination, thus maintaining flexibility while eliminating complexity
Solution Approach 2:
Instead of allowing flexible retransmissions on any resource and then managing coordination complexity, the patent inverts the approach by restricting retransmissions to predetermined SPS-dedicated resources. This inversion simplifies the system by eliminating the need for complex coordination mechanisms while maintaining adequate resource utilization
3Speed
If HARQ feedback timing is independent of SPS periodicity, then HARQ response speed is improved, but retransmission alignment with SPS resources becomes difficult
Solution Approach 1:
The patent implements a feedback mechanism where the network monitors HARQ feedback timing and adjusts SPS resource configuration accordingly. By providing RRC configuration messages that define SPS-dedicated resources based on observed HARQ timing patterns, the system ensures that retransmissions align with SPS resources while maintaining fast HARQ response speeds, thus eliminating latency caused by misalignment
Data Source
AI summary
Methods, systems, and devices for wireless communication are described. A base station may configure a user equipment (UE) with a scheduling scheme to align the retransmission of semi-persistent scheduling (SPS) uplink messages with hybrid automatic repeat request (HARQ) feedback. Techniques for scheduling the retransmission of uplink messages on resources designated for SPS transmission, as opposed to resources not designated for SPS transmission, are also described. Aspects of the disclosure also include using incremental redundancy HARQ feedback to reduce packet loss at a receiver. In some cases, a base station receiving an uplink message may decode the message using multiple processes based on different assumptions regarding the redundancy version ID (RVID) of the uplink message.