Cross-Carrier Scheduling DCI Alignment for LBT Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In LTE systems, the integration of unlicensed bands using Licensed-Assisted Access (LAA) faces challenges with control signaling efficiency due to the need for listen-before-talk (LBT) procedures, which can lead to PDCCH failure and increased blind decoding complexity, especially when cross-scheduling is employed across licensed and unlicensed carriers.
Innovation Solution
The approach involves cross-scheduling on a non-LBT carrier to enhance DCI transmission robustness and efficiency by aligning DCI sizes and using a carrier indication field to differentiate between carriers, allowing for opportunistic transmission and reducing blind decoding efforts, while maintaining error resilience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cross-scheduling is employed across licensed and unlicensed carriers, then resource allocation flexibility is improved, but blind decoding complexity increases
Solution Approach 1:
The patent segments the control signaling by introducing a carrier indication field (CIF) that divides the scheduling information into distinct carrier-specific segments. This allows the UE to identify and process DCI for specific carriers (licensed or unlicensed) separately, reducing the overall blind decoding complexity while maintaining cross-scheduling flexibility.
Solution Approach 2:
The carrier indication field acts as an intermediary element within the DCI structure. It mediates between the cross-scheduling mechanism and the UE's blind decoding process by providing explicit carrier identification, thereby reducing the search space and decoding complexity without sacrificing resource allocation flexibility.
2Adaptability or versatility
If LBT procedures are implemented on unlicensed carriers, then spectrum sharing compliance is improved, but PDCCH transmission reliability deteriorates
Solution Approach 1:
The patent applies preliminary action by performing LBT procedures before transmitting PDCCH on unlicensed carriers. The system checks channel availability in advance and only transmits control signaling when the channel is clear, thereby ensuring spectrum sharing compliance while maximizing transmission reliability through opportunistic transmission.
Solution Approach 2:
The patent introduces dynamic behavior by making PDCCH transmission on unlicensed carriers conditional based on LBT outcomes. The transmission strategy adapts dynamically to channel conditions, switching between transmission and silence based on real-time spectrum availability, thus balancing compliance and reliability.
3Productivity
If DCI sizes are aligned across carriers, then control signaling efficiency is improved, but scheduling flexibility is reduced
Solution Approach 1:
The patent changes the DCI structure by introducing a carrier indication field and aligning DCI sizes across different carriers. This parameter change enables efficient blind decoding while the CIF provides the necessary flexibility to schedule different carrier types (licensed/unlicensed, LBT/non-LBT) with uniform DCI formats.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to transmission and reception of data in a wireless communication system, the wireless communication system supporting aggregation of a plurality of component carriers and an additional carrier accessible by a listen before talk approach. In particular, monitoring is performed of a search space on a cross-scheduling component carrier for detecting downlink control information having a carrier identification field indicating the cross-scheduling component carrier as well as for detecting downlink control information with the carrier identification field indicating the additional carrier, wherein the search space is specified by a subset of resources, associated with carrier identification of the cross-scheduling component carrier but is not associated with carrier identification of the additional carrier. Then data are transmitted or received on the carriers in accordance with the received downlink control information.