Dwell-Time Channel Contention for Millimeter-Wave LBT
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Solution Overview
Problem
In wireless communications systems operating in millimeter wave frequencies, signal attenuation leads to potential interference from devices not detecting energy during listen before talk procedures, causing interference with intended communications.
Innovation Solution
Implementing a dwell time based channel contention mechanism where devices perform a listen before talk procedure for a minimum dwell time corresponding to the periodicity of reservation signals, allowing transmission gaps without re-performing LBT, and scheduling receiving devices for efficient resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If devices perform LBT procedure with extended monitoring time to detect interfering devices in mmW bands, then interference detection capability is improved, but channel access delay increases
Solution Approach 1:
The system performs preliminary channel sensing during the minimum dwell time period, which corresponds to the periodicity of reservation signals. This preliminary action allows devices to detect potential interferers in advance before attempting channel access, reducing the need for extended monitoring after channel acquisition.
Solution Approach 2:
The patent utilizes periodic reservation signals transmitted at regular intervals corresponding to the minimum dwell time. Devices perform LBT procedures synchronized with these periodic signals, allowing them to detect interferers at specific intervals rather than requiring continuous monitoring, thus balancing detection capability with access delay.
2Productivity
If devices transmit continuously without transmission gaps to maximize resource utilization, then productivity is improved, but interference to other devices increases
Solution Approach 1:
The patent introduces periodic transmission gaps aligned with the minimum dwell time period and reservation signal transmissions. During these gaps, devices refrain from transmitting, allowing other devices to perform LBT procedures and detect the channel as clear. This periodic interruption reduces interference while maintaining overall resource utilization efficiency.
Solution Approach 2:
The system maintains continuous useful action by allowing devices to resume transmissions immediately after the transmission gap without requiring a full re-performing of LBT procedures. The channel occupancy is maintained across gaps, ensuring continuous resource utilization while periodically reducing interference.
3Reliability
If devices re-perform LBT procedure after transmission gaps to ensure channel availability, then channel access reliability is improved, but transmission efficiency decreases
Solution Approach 1:
Devices perform preliminary LBT procedures before entering transmission gaps and maintain channel occupancy status. This preliminary action allows them to resume transmissions after gaps without requiring complete re-performing of LBT, thus maintaining reliability while improving efficiency.
Solution Approach 2:
The patent implements dynamic LBT behavior where devices adapt their LBT procedure execution based on transmission state. Full LBT is performed at channel acquisition, abbreviated or skipped LBT is used after transmission gaps within the same channel occupancy period, providing flexible and efficient channel access management.
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AI summary
Methods, systems, and devices for wireless communications are described in which a transmitting device using shared radio frequency spectrum may perform a listen before talk (LBT) procedure for at least a minimum dwell time and, upon successful completion of the LBT procedure, may occupy the spectrum for up to a duration of a channel occupancy time (COT). The transmitting device may discontinue transmitting during the COT for a gap period, and resume transmitting subsequent to the gap period without performing another LBT procedure. The minimum dwell time may be based on a periodicity of a channel reservation signal transmitted by one or more other devices using the shared radio frequency spectrum. In some cases, the transmitting device may schedule one or more receiving devices with resources for transmissions during the COT, and the receiving devices may perform a LBT that is non-adjacent with an associated transmission.