DTX DCI Format for Carrier Aggregation Blind Decoding Reduction
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Solution Overview
Problem
The increase in the number of carriers in carrier aggregation for LTE networks leads to a significant increase in blind decoding attempts, resulting in decreased bitrate and increased complexity and power consumption for user equipment (UE), especially when using the unlicensed spectrum.
Innovation Solution
The introduction of a new Downlink Control Information (DCI) format, referred to as Discontinuous Transmission (DTX) DCI format, which dynamically indicates the transmission state of serving cells, allowing the UE to selectively monitor only active cells and reduce blind decoding attempts by indicating which serving cells are in a discontinuous transmission state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the number of carriers is increased in carrier aggregation, then the bandwidth and bitrate are improved, but the number of blind decoding attempts increases linearly, causing increased UE complexity and power consumption
Solution Approach 1:
The patent divides the control channel monitoring into separate PDCCH and EPDCCH search spaces, and further segments EPDCCH monitoring by transmission mode (TM). The UE only monitors EPDCCH in TMs 10 and 11, not in TMs 0-9, which significantly reduces the number of blind decoding attempts while maintaining support for multiple carriers
Solution Approach 2:
The patent introduces dynamic adjustment of EPDCCH monitoring based on transmission mode configuration. The UE adapts its monitoring behavior according to the active transmission mode, monitoring EPDCCH only when in TMs 10 or 11, and using PDCCH for other TMs. This dynamic approach reduces complexity while maintaining flexibility for carrier aggregation
2Area of stationary object
If the number of carriers is increased in carrier aggregation, then the bandwidth and bitrate are improved, but the number of blind decoding attempts increases linearly, causing increased power consumption
Solution Approach 1:
The patent segments the control channel monitoring tasks by separating PDCCH and EPDCCH search spaces, and further dividing EPDCCH monitoring by transmission mode. This segmentation allows the UE to selectively monitor only relevant channels based on active transmission modes, reducing overall processing power consumption while supporting multiple carriers
Solution Approach 2:
The patent implements partial monitoring by having the UE monitor EPDCCH only in specific transmission modes (10 and 11) rather than all transmission modes. This partial action approach reduces power consumption by avoiding unnecessary blind decoding attempts in modes where EPDCCH is not used, while still maintaining full carrier aggregation capability
3Area of stationary object
If carrier aggregation includes unlicensed spectrum carriers, then bandwidth is improved, but transmission and reception of control signals is limited due to opportunistic spectrum use, decreasing bitrate
Solution Approach 1:
The patent separates control channel monitoring into PDCCH on licensed spectrum and EPDCCH on unlicensed spectrum carriers. By segmenting the monitoring approach and applying transmission mode-based filtering for EPDCCH, the system can efficiently utilize unlicensed spectrum resources while maintaining reliable control signal transmission, thereby achieving both high bandwidth and sustained bitrate
Data Source
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AI summary
Devices and methods of reducing blind decoding attempts of user equipment (UE) suing carrier aggregation are generally described. The UE determines at least one subframe in a modification period to monitor for a physical downlink control channel (PDCCH) formed in accordance with a Discontinuous Transmission Control Information (DTX DCI) format. The DTX DCI format indicates whether the serving cell is in a DTX or a non-DTX state. The UE determines the DTX state of each serving cell from the DTX DCI format and monitor an enhanced PDCCH of each serving cell in the non-DTX state to provide a scheduling assignment for the UE, without monitoring each serving cell in the DTX state. The UE receives higher layer signaling that indicates a repetition period and subframe offset for DTX DCI format transmissions or a bitmap of the DTX DCI format transmissions for subframes within each modification period.