LBT Gap Signaling for Multi-TTI Grants
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing spectrum sharing, particularly in shared spectra, where listen-before-talk (LBT) procedures can lead to delays and blocked transmissions due to the need for continuous channel checks, especially with multi-transmission time interval (TTI) allocations.
Innovation Solution
Implementing mechanisms for signaling listen-before-talk (LBT) mode and transmission gaps within multi-TTI or back-to-back UL grants, allowing base stations to configure gap periods within scheduled allocations, enabling other nodes to access the spectrum and adapt to channel variations while minimizing signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If multiple contiguous TTI allocations are used to reduce LBT overhead, then LBT overhead is reduced, but other nodes are delayed from accessing the spectrum and preconfigured scheduled transmissions are blocked
Solution Approach 1:
The patent divides the contiguous TTI allocation into multiple segments with gap periods inserted between them. Instead of allocating TTIs continuously (TTI1, TTI2, TTI3, TTI4), the allocation is segmented to include gaps (TTI1, gap, TTI2, gap, TTI3, gap, TTI4). This segmentation allows other nodes to access the spectrum during gap periods while maintaining reduced LBT overhead compared to fully continuous allocations.
Solution Approach 2:
The patent implements periodic gap periods within the TTI allocation sequence. These gap periods occur at regular intervals during the multi-TTI allocation, creating a periodic pattern of transmission followed by listening periods. This periodic action allows the system to maintain efficient contiguous scheduling while periodically yielding spectrum access to other nodes, thereby balancing LBT overhead reduction with spectrum sharing efficiency.
2Reliability
If LBT procedure is performed before each transmission in shared spectrum, then channel access is ensured, but transmission delays and blocked transmissions occur
Solution Approach 1:
The patent performs the LBT procedure in advance during gap periods before the actual data transmission begins. By conducting channel sensing during the gap periods between TTI segments, the system prepares for subsequent transmissions without delay. This preliminary action ensures that when transmission opportunities arise, the channel is already verified as clear, eliminating the need for additional LBT procedures before each TTI and thus reducing transmission delays.
Solution Approach 2:
The patent maintains continuous transmission during allocated TTI periods by performing LBT only during gap periods rather than before each TTI. Once the channel is clear during a gap period, transmissions continue continuously through the subsequent TTI segments without interruption or repeated LBT procedures. This continuity of useful action minimizes transmission delays while maintaining reliable channel access through periodic LBT during gaps.
3Productivity
If gap periods are introduced within multi-TTI allocations, then other nodes can access the spectrum, but signaling overhead increases
Solution Approach 1:
The patent modifies the allocation parameters by introducing gap periods with specific duration and positioning within the TTI sequence. By carefully controlling the length and placement of these gap periods, the system enables spectrum access for other nodes while minimizing the impact on overall transmission efficiency. The gap periods are parameterized to be just long enough to allow other nodes to access the spectrum but short enough to maintain high productivity, thereby reducing the need for extensive signaling about allocation details.
Solution Approach 2:
The gap periods serve multiple functions simultaneously: they allow other nodes to access the spectrum, provide opportunities for LBT procedures, and create flexibility in resource allocation. By making the gap periods multi-functional, the system reduces signaling overhead because a single structural element (the gap) accomplishes multiple objectives that would otherwise require separate signaling mechanisms.
Data Source
AI summary
Wireless communications systems, apparatuses, and methods are provided. A method of wireless communication may include communicating, by a first wireless communication device with a second wireless communication device, a first scheduling grant indicating a gap period within a first scheduled period and communicating, by the first wireless communication device with the second wireless communication device during the first scheduled period, a first communication signal including a first silence period corresponding to the gap period.