Joint Unlicensed Spectrum Access With Synchronized TRPs
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Solution Overview
Problem
Existing technologies face challenges in accessing unlicensed spectrum efficiently, leading to downlink transmission collisions and inadequate coexistence fairness among TRPs, especially in dense deployments and high channel occupancy scenarios.
Innovation Solution
A group of TRPs, including gNBs or antenna panels, are coordinated through a central spectrum management control unit to jointly access unlicensed spectrum, using Listen-Before-Talk mechanisms and synchronized channel access to avoid collisions and improve coexistence fairness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If individual TRPs access unlicensed spectrum independently using LAA, then each TRP can access the channel when available, but downlink transmission collisions occur between TRPs and coexistence fairness is inadequate
Solution Approach 1:
The patent merges multiple independent TRPs into a coordinated group that performs joint channel access. The TRPs share channel access information and synchronize their transmissions, transforming from individual independent access to collective coordinated access, thereby eliminating collisions while maintaining spectrum utilization efficiency
Solution Approach 2:
The patent implements feedback mechanisms where TRPs exchange channel access status and transmission information with each other and with the network controller. This feedback enables dynamic adjustment of transmission timing and resource allocation, allowing the system to adapt to changing channel conditions and prevent collisions
2Reliability
If deferring time period is used between CCA completion and downlink transmission, then channel access is attempted, but unlicensed spectrum is not used during this period and transmission collisions may occur
Solution Approach 1:
The patent performs preliminary channel assessment and coordination among TRPs before the actual downlink transmission. By exchanging channel access information and synchronizing transmission timing in advance, the system eliminates the need for conservative deferring periods, allowing immediate transmission upon successful CCA while maintaining coordination
Solution Approach 2:
The patent introduces dynamic adjustment of transmission timing based on real-time channel conditions and coordinated TRP status. Instead of fixed deferring periods, the system adaptively determines transmission start times, optimizing the balance between collision avoidance and spectrum utilization efficiency
3Productivity
If aggressive schemes are used to access unlicensed spectrum, then spectrum access probability increases, but coexistence fairness with other radio access technologies deteriorates
Solution Approach 1:
The patent introduces a network controller as an intermediary that coordinates channel access among multiple TRPs. This intermediary manages the channel access process centrally, enabling aggressive spectrum access by coordinated TRPs while maintaining fairness with other radio access technologies through controlled and synchronized transmissions
4Device complexity
If LAA is directed to individual TRPs, then implementation is simpler, but spatial reuse capability is not supported
Solution Approach 1:
The patent segments the channel access function into two parts: local CCA execution at each TRP (maintaining simplicity) and centralized coordination through information exchange with the network controller (enabling spatial reuse). This segmentation allows each TRP to independently perform simple channel sensing while the coordination mechanism enables advanced spatial reuse capabilities
Data Source
Figure 1
Figure 2~3A
Figure 3B
AI summary
Aspects of the present disclosure provided methods and devices for a transmit receive point (TRP) to access one or more unlicensed channels in an unlicensed spectrum jointly with at least one other TRP. An example method may include a step of aligning a starting time of a potential transmission on at least one of the one or more unlicensed channels with a starting time of a potential transmission of at least one other TRP on the at least one of the one or more unlicensed channels. A further step includes performing channel access on the at least one of the one or more unlicensed channels by performing at least one of a spatial domain channel access procedure or a combination of a spatial domain channel access procedure and a frequency domain multi-channel access procedure. Another step includes transmitting at the aligned starting time on the at least one of the one or more unlicensed channels in the joint access period when the at least one of the one or more unlicensed channels is available.