LAA PUCCH Transmission Control via Clear Channel Assessment
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Solution Overview
Problem
The introduction of Licensed-Assisted Access (LAA) to LTE communication networks poses challenges, particularly in dual connectivity scenarios, where the 'listen-before-talk' (LBT) mechanism can block uplink control signals, leading to potential interference and inefficient scheduling request handling.
Innovation Solution
A communication device and method that perform clear channel assessment (CCA) before transmitting control signals on a Physical Uplink Control Channel (PUCCH) and block transmissions if the channel is not clear, allowing for efficient scheduling request handling and hybrid automatic repeat request (HARQ) acknowledgments by prioritizing transmissions on specific PUCCHs to avoid LBT-related blockages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If LBT mechanism is implemented in LAA cell, then interference with other systems is reduced, but uplink control signal transmission is blocked
Solution Approach 1:
The patent segments the PUCCH transmission function by introducing separate PUCCH resources in both PCell and PSCell. This allows control signals to be transmitted through multiple paths, so if LBT blocks one path, the other can still function, thereby resolving the contradiction between interference reduction and transmission reliability.
Solution Approach 2:
The patent changes the transmission parameters by configuring different PUCCH resources with different LBT requirements. Specifically, PCell PUCCH uses one set of parameters while PSCell PUCCH uses another set, allowing flexible adaptation to LBT conditions and maintaining reliability while managing interference.
2Object-affected harmful factors
If CCA is performed before PUCCH transmission, then channel interference is avoided, but transmission delay increases
Solution Approach 1:
The patent performs CCA in advance before PUCCH transmission is needed. By conducting the clear channel assessment beforehand and preparing transmission opportunities, the system avoids last-minute delays while still ensuring interference-free transmission when the actual control signal needs to be sent.
3Device complexity
If PUCCH is configured only in PCell, then device complexity is reduced, but scheduling request handling efficiency deteriorates in dual connectivity
Solution Approach 1:
The patent segments the PUCCH functionality by creating separate PUCCH resources in both PCell and PSCell for dual connectivity scenarios. This segmentation allows scheduling requests to be handled more efficiently by distributing the load across multiple PUCCH resources, while the segmentation is only applied when needed, keeping complexity manageable.
Solution Approach 2:
The patent applies different PUCCH configurations locally depending on the cell type and connectivity scenario. PCell gets one configuration while PSCell gets another, optimized for their specific roles. This local quality approach improves scheduling request handling efficiency without unnecessarily complicating the entire system.
Data Source
AI summary
A communication system is disclosed in which a communication device communicates with communication apparatus that operates a cell within which the communication device is located. The cell is operated as a licensed assisted access (LAA) cell and has an associated physical uplink control channel (PUCCH). The communication device has a controller that is adapted to: generate a control signal for transmitting to said communication apparatus; perform a clear channel assessment (CCA) on said PUCCH before the control signal is transmitted; and block transmission of the control signal on said PUCCH when said CCA indicates that said channel is not clear. The communication device is further adapted, when said controller has not blocked said transmission of the control signal, to transmit the control signal to said communication apparatus in said PUCCH.