Dynamic Transmission Starting Point for Unlicensed Spectrum LBT
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Solution Overview
Problem
LTE uplink performance is hampered by centralized channel access coordination and Listen-Before-Talk (LBT) regulations in unlicensed spectrum, leading to transmission delays and limited flexibility compared to asynchronous access methods like Wi-Fi, which affects data transmission to the cloud and user-centric applications.
Innovation Solution
Implementing a dynamic transmission starting point method for both downlink and uplink transmissions based on successful Listen-Before-Talk (LBT) outcomes, allowing network nodes to adjust transmission schedules and resource allocations dynamically, enabling flexible channel access on unlicensed spectrum by extending or discarding transmissions at different slot or mini-slot boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If centralized channel access coordination and LBT regulations are applied in unlicensed spectrum, then channel access reliability is improved, but transmission delay increases and flexibility is reduced
Solution Approach 1:
The patent applies dynamics by enabling flexible transmission starting points that can be adjusted based on LBT outcomes. Instead of fixed slot boundaries, the system dynamically determines when transmissions can start within a slot, allowing adaptive response to channel conditions while maintaining reliable LBT-based access.
Solution Approach 2:
The patent segments the transmission slot into multiple potential starting points. By dividing the slot structure and allowing transmissions to start at different positions within the slot based on LBT success timing, the system reduces waiting time while maintaining structured channel access coordination.
2Device complexity
If fixed slot boundary transmissions are used, then transmission scheduling simplicity is improved, but channel access flexibility is reduced
Solution Approach 1:
The system transitions from static fixed-slot transmissions to dynamic flexible starting points within slots. The eNB can indicate different starting positions to UEs based on LBT outcomes, enabling adaptive channel access while maintaining relatively simple scheduling through DCI signaling.
Solution Approach 2:
The patent changes the transmission parameter from fixed slot boundary to variable starting position within slot. By modifying the time parameter where transmissions can begin, the system achieves greater flexibility without fundamentally changing the slot structure or scheduling framework.
3Adaptability or versatility
If multiple transmission starting positions are supported, then channel access flexibility is improved, but processing complexity increases
Solution Approach 1:
The system manages multiple starting positions by changing the time parameter indication through DCI signaling. Rather than creating complex separate processing paths, the invention uses parameter indication to tell UEs when to start transmissions, keeping processing relatively simple while enabling flexibility.
Solution Approach 2:
The eNB acts as an intermediary that receives LBT outcome information and translates it into starting position indications for UEs via DCI signaling. This intermediary role simplifies the complexity by centralizing the decision-making and communication of starting positions rather than requiring distributed complex processing.
Data Source
AI summary
A radio access node or wireless device performs LBT on a channel and dynamically determines a transmission starting point on the channel, based on whether the LBT succeeds before or after a slot boundary between a slot n and a previous slot n−1. In response to determining that the LBT succeeds before the slot boundary, a transmission scheduled for the slot n is extended to start earlier, in the previous slot n−1. Otherwise, in response to determining that the LBT succeeds after the slot boundary, either a transmission scheduled for a next slot n+1 is extended to start earlier, in the slot n, or a transmission scheduled for the a second mini-slot of the slot n is extended to start earlier, in a first mini-slot of the slot n.