Sub-band Control Information for NR-U Wideband Operation
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Solution Overview
Problem
In wireless communication systems operating in unlicensed bands, the uncertain availability of sub-bands within a wideband carrier poses challenges for efficient data transmission, as existing Listen-before-talk (LBT) methods lead to high computational complexity and poor spectral utilization when not all sub-bands are available.
Innovation Solution
The method involves a base station determining and communicating the set of available sub-bands to mobile devices through control information, allowing for efficient data transmission even when not all sub-bands are available, using techniques such as configuring a common control resource set and transmitting preambles to indicate active sub-bands, thereby improving spectral efficiency and reducing resource overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional LBT methods are applied to wideband carriers in unlicensed bands, then channel access control is achieved, but computational complexity increases and spectral utilization deteriorates
Solution Approach 1:
The wideband carrier is divided into multiple sub-bands, and LBT procedures are performed independently on each sub-band rather than on the entire wideband carrier. This segmentation reduces the computational complexity of channel assessment while maintaining reliable channel access control, as each sub-band can be evaluated separately and transmitted independently if available.
Solution Approach 2:
The base station performs LBT only on the necessary sub-bands rather than requiring all sub-bands to be clear before transmission. This partial action approach allows the system to transmit data on available sub-bands even when other sub-bands are occupied, thereby reducing computational overhead while maintaining channel access reliability.
2Reliability
If traditional LBT methods require all sub-bands to be clear before transmission, then channel access control is maintained, but spectral utilization deteriorates
Solution Approach 1:
By segmenting the wideband carrier into multiple sub-bands and allowing independent transmission on each clear sub-band, the system can utilize available spectrum resources more effectively. This enables partial bandwidth transmission when only some sub-bands are clear, significantly improving spectral utilization compared to requiring all sub-bands to be clear.
Solution Approach 2:
The system dynamically adjusts transmission parameters based on sub-band availability. When only certain sub-bands are clear, the base station modifies transmission to occur only on those sub-bands, changing the operational parameters from all-or-nothing transmission to selective sub-band transmission, thereby improving spectral utilization.
3Measurement precision
If control information is transmitted for each sub-band, then accurate sub-band availability indication is achieved, but resource overhead increases
Solution Approach 1:
The base station merges control information for multiple sub-bands into a single downlink control information (DCI) message. Instead of transmitting separate control information for each sub-band, the DCI contains aggregated sub-band availability indications that inform UEs about which sub-bands are available for uplink transmission, thereby reducing resource overhead while maintaining accurate sub-band availability indication.
Solution Approach 2:
The downlink control information serves multiple functions simultaneously: it provides sub-band availability indications, uplink grants, and other control parameters in a single transmission. This multi-functionality reduces the need for separate control messages for each sub-band, thereby reducing resource overhead while maintaining precise sub-band availability information.
Data Source
AI summary
Methods of data communication in a cellular communications network based on an unlicensed wideband carrier, the method performed by a base station of the cellular communications network, the base station being in communication with one or more mobile devices. The methods comprise the steps of determining a set of used sub-bands of the plurality of sub-bands available for data transmission, generating used sub-band control information pertaining to a plurality of sub-bands in the wideband carrier based on the set of used sub-bands, and providing the used sub-band control information to the one or more mobile devices.