C-V2X Slot Duration Adaptation for LBT Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wireless communication systems, particularly in the context of C-V2X technology operating in unlicensed frequency spectrum, face interference issues due to the listen-before-talk (LBT) procedure, which can lead to increased latency and decreased throughput as C-V2X devices unnecessarily abort transmissions upon detecting energy from other C-V2X devices, even if the next slot is available.
Innovation Solution
Configuring C-V2X devices to perform LBT operations that differentiate between interference from non-C-V2X sources like Wi-Fi and C-V2X activity, by reducing the slot duration to prevent detection during LBT sensing, thereby avoiding unnecessary transmission cancellations and optimizing network performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If C-V2X devices perform LBT operations to detect energy from other transmissions, then channel access reliability is improved, but transmission latency increases due to unnecessary aborts when detecting C-V2X activity
Solution Approach 1:
The patent segments the LBT detection process by introducing a reference signal detection mechanism that distinguishes between C-V2X and non-C-V2X transmissions. The LBT procedure is divided into: (1) energy detection phase, (2) reference signal detection phase to identify transmission type, and (3) decision phase to determine whether to abort. This segmentation allows the system to maintain reliability by detecting all transmissions while reducing latency by selectively aborting only when necessary.
Solution Approach 2:
The patent introduces reference signals as an intermediary element between the LBT energy detection and the transmission abort decision. These reference signals act as a mediator that provides additional information about the detected transmission, enabling the receiving device to distinguish between C-V2X and non-C-V2X sources. This intermediary mechanism resolves the contradiction by providing the reliability of comprehensive detection while enabling the latency reduction through intelligent discrimination.
2Productivity
If C-V2X devices use standard slot durations for transmission, then data throughput is maximized, but interference with LBT operations occurs causing unnecessary transmission cancellations
Solution Approach 1:
The patent applies dynamics by making the slot duration adjustable rather than fixed. The slot length is dynamically adapted based on the LBT operation duration and the detected interference conditions. When C-V2X activity is detected during LBT, the system dynamically shortens the slot duration to prevent overlap and unnecessary cancellations. This dynamic adjustment maintains high throughput by optimizing slot length according to real-time channel conditions while preserving transmission reliability.
Solution Approach 2:
The patent changes the temporal parameter of slot duration to resolve the contradiction between throughput and reliability. By modifying the slot length parameter based on LBT detection results and interference conditions, the system achieves both high productivity (through optimized resource utilization) and high reliability (by preventing unnecessary transmission aborts). The parameter change is implemented through flexible slot configuration that adapts to the detected channel environment.
3Reliability
If LBT sensing time interval is extended to improve detection accuracy, then channel access reliability is improved, but transmission slot duration available for data is reduced
Solution Approach 1:
The patent applies partial action by performing reference signal detection only on the necessary portion of the detected energy, rather than requiring full LBT sensing completion. When energy is detected during the LBT interval, the system performs targeted reference signal detection to identify the transmission type, then makes an immediate decision. This partial detection approach maintains channel access reliability by detecting interfering transmissions while preserving more slot duration for actual data transmission compared to completing the full LBT sensing interval.
Data Source
AI summary
Aspects for reducing interference for transmissions in unlicensed frequency bands are disclosed. An apparatus, e.g., a user equipment (UE) with information to transmit, identifies before transmitting the information in an unlicensed frequency spectrum, a specified duration of a listen-before-talk (LBT) operation in that spectrum. Based on the specified duration, the UE reduces a transmission time duration of a slot of the UE to increase a time duration of a remainder of the slot sufficient to prevent, or decrease the likelihood of, a transmission by the UE in the slot from interfering with an LBT operation by another UE.