Multi-Beam LBT for 60 GHz NR-U Channel Access
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Solution Overview
Problem
Current 5G NR-U systems deployed at 60 GHz face challenges in efficiently accessing the unlicensed spectrum due to the use of omnidirectional Listen Before Transmit (LBT) techniques, which do not fully leverage spatial diversity and multiplexing capabilities of multi-beam transmissions.
Innovation Solution
A transceiver configured to perform directional clear channel assessment sensing on multiple beams, determining beam busy status, initializing and managing back-off timers based on beam availability, and transmitting data only when all beams are idle or after a predetermined idle duration, thereby optimizing channel access in a multi-beam LBT environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If omnidirectional LBT is used for channel access, then the system maintains simplicity in channel access procedure, but the probability of successful channel occupation decreases and spatial reuse is not optimized
Solution Approach 1:
The patent segments the single omnidirectional LBT procedure into multiple directional LBT procedures, one for each beam. Each beam performs independent clear channel assessment in its specific direction, allowing the system to maintain procedural simplicity while improving channel occupation success probability through targeted directional sensing.
Solution Approach 2:
The patent transitions from a single-dimensional omnidirectional LBT approach to a multi-dimensional directional LBT approach by introducing spatial direction as an additional dimension. Each beam performs LBT in its specific spatial direction, enabling the system to exploit spatial diversity and improve both channel occupation success and spatial reuse.
2Productivity
If multiple beams are used for transmission, then spatial diversity and spatial multiplexing are leveraged, but the complexity of channel access procedure increases
Solution Approach 1:
The patent segments the channel access procedure into independent directional LBT processes for each beam, allowing parallel execution. This segmentation enables the system to leverage spatial diversity across multiple beams while managing complexity through modular, independent processing units that can operate simultaneously.
Solution Approach 2:
The patent implements LBT procedures for all beams (excessive action) rather than selecting a single beam, thereby fully leveraging spatial diversity and multiplexing capabilities. This approach accepts increased procedural complexity as a necessary investment to maximize productivity through comprehensive spatial utilization.
3Reliability
If directional clear channel assessment is performed on each beam, then the probability of successful channel occupation improves, but the time required for channel access increases
Solution Approach 1:
The patent segments the channel access process into parallel directional LBT operations for each beam. By performing clear channel assessment simultaneously in multiple directions rather than sequentially, the system improves channel occupation success probability through comprehensive spatial sensing while minimizing additional access time through parallel execution.
Solution Approach 2:
The patent performs preliminary directional clear channel assessment on all beams before transmission begins. This preliminary action in multiple directions simultaneously prepares the system for efficient transmission by identifying available spatial channels in advance, thereby improving success probability without significant time penalty.
Data Source
AI summary
A system and a method are disclosed for accessing a wireless medium for a NR-U deployed at 60 GHz. A directional CCA sensing is performed on a set of multiple beams in the medium in which each beam is oriented in a different direction. It is determined whether at least one beam of is busy and, if so, a back-off timer is initialized. The back-off timer is decreased by a predetermined amount based on a determination that all beams of the set of multiple beams are idle. The back-off timer is repeatedly decreased the predetermined amount based on a determination that all beams of the set of multiple beams are idle until the back-off timer equals a predetermined amount. Data is transmitted at least one beam of the set of multiple beams based on the back-off timer equaling the predetermined amount.