FDD HARQ Mini-Slot Scheduling for Lower Wireless Latency
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Solution Overview
Problem
TDD configured wireless communication systems experience increased latency due to HARQ feedback being transmitted in slots subsequent to the information reception, which can be mitigated by implementing FDD HARQ with mini-slots to improve latency and performance.
Innovation Solution
Adopting a HARQ scheme in TDD configured systems that utilizes mini-slots for HARQ feedback, allowing for time-aligned uplink and downlink communications, and utilizing unused portions of slots for multiplexing mini-slots to reduce latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ feedback is transmitted in slots subsequent to information reception in TDD configured systems, then system stability is maintained, but latency increases
Solution Approach 1:
The patent segments the slot structure by introducing mini-slots within slots, allowing HARQ feedback to be transmitted in dedicated mini-slot portions rather than waiting for the next complete slot. This segmentation enables finer-grained timing control, reducing latency while maintaining the overall slot-based TDD structure for system stability.
Solution Approach 2:
The patent adds a temporal dimension by creating multiple mini-slots within a single slot, allowing HARQ feedback to occur in the same slot or subsequent slots rather than strictly in the next slot. This dimensional expansion provides flexibility in timing alignment between uplink and downlink communications.
2Loss of time
If mini-slots are implemented for HARQ feedback, then latency is reduced, but device complexity increases
Solution Approach 1:
The patent designs the mini-slot structure to serve multiple functions: it enables HARQ feedback transmission, supports time-aligned uplink and downlink communications, and provides flexible resource allocation. This multi-functionality reduces the need for separate mechanisms, thereby limiting the increase in device complexity while achieving latency reduction.
Solution Approach 2:
The patent introduces dynamic mini-slot configurations that can be adaptively adjusted based on traffic conditions and QoS requirements. This dynamic approach allows the system to optimize latency performance without permanently increasing complexity, as the mini-slot structure can be activated or deactivated as needed.
3Productivity
If time-aligned uplink and downlink communications are implemented, then spectral efficiency is improved, but scheduling complexity increases
Solution Approach 1:
The patent implements preliminary time alignment between uplink and downlink slots through configured mini-slot structures. By pre-defining the timing relationships and mini-slot positions, the system achieves time-aligned communications that improve spectral efficiency while reducing real-time scheduling complexity, as much of the alignment is determined in advance.
Data Source
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AI summary
Methods, systems, and devices for wireless communication are described. A transmitting device may identify a duration of a slot used for communications with a receiving device. The transmitting device may determine that the communications with the receiving device comprises frequency division duplexing (FDD) communications. The transmitting device may transmit communications to the receiving device during a first portion of the slot, a duration of the first portion being less than the duration of the slot and the duration of the first portion is based at least in part on the determination that the communications comprise FDD communications. The transmitting device may select, based at least in part on the determination that the communications comprise FDD communications and that the communications are transmitted during the first portion of the slot, a hybrid automatic repeat request (HARQ) scheme to use during the communications.