Clear Channel Assessment Timing for Shared Spectrum Downlink
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Solution Overview
Problem
Conventional clear channel assessment (CCA) procedures in wireless communication systems operating in shared or unlicensed radio frequency spectrum bands are inefficient and do not provide suitable flexibility for medium capture and reservation, particularly in millimeter wave networks, leading to ineffective transmission attempts.
Innovation Solution
Implementing enhanced clear channel assessment (eCCA) techniques, including transmitter-based energy detection procedures, such as extended and one-shot CCA, to allow base stations and user equipment to perform CCA during gaps between control signals and transmissions, enabling efficient medium reservation and transmission opportunities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CCA procedures are used in shared spectrum bands, then medium capture and reservation are performed, but transmission efficiency is reduced due to unnecessary delays and ineffective transmission attempts
Solution Approach 1:
The base station performs CCA procedures in advance during the gap between control signal transmission and data transmission. The base station determines whether the channel is clear before the actual transmission, allowing it to prepare transmission resources and avoid last-minute channel access failures, thereby reducing transmission delays and improving overall transmission efficiency
2Productivity
If LBT procedure is performed by both devices before transmitting, then channel access is achieved, but communication efficiency deteriorates due to redundant procedures
Solution Approach 1:
The base station combines control signal transmission with channel assessment functions. By performing CCA procedures during the gap between control signals and data transmission, the base station consolidates channel access responsibilities, eliminating the need for UEs to perform separate LBT procedures and reducing overall procedure complexity while maintaining communication efficiency
3Duration of action of stationary object
If conventional medium capture techniques are used, then channel access is attempted, but medium reservation capability is insufficient for suitable time periods
Solution Approach 1:
The base station performs CCA procedures in advance during the gap period before data transmission, determining channel availability ahead of time. This preliminary channel assessment allows the base station to reliably reserve the medium for the entire transmission duration, ensuring both adequate reservation time and capture reliability
Data Source
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AI summary
Methods, systems, and devices for wireless communications are described. A base station may transmit to a user equip-ment (UE) a control signal comprising a grant for a downlink transmission. The base station may perform, during a gap between the control signal and the downlink transmission, a clear channel assessment (CCA) procedure on a shared radio frequency spectrum band associated with the downlink transmission. The base station may perform, based at least in part on a success of the CCA procedure, the downlink transmission to the UE over the shared radio frequency spectrum band.