LTE FDD-TDD Carrier Aggregation Scheduling Mechanism
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Solution Overview
Problem
In LTE FDD-TDD CA systems, the increased number of DCI sizes due to different duplex modes leads to a higher number of blind decoding trials, and there are challenges in handling HARQ timing and flexible-TDD configurations, particularly in accommodating fluctuations in DL/UL traffic ratios and fast TDD configuration indications.
Innovation Solution
The method involves configuring UE for FDD-TDD CA by establishing RRC connections for data transmission on both FDD and TDD carriers, using either self-scheduling or cross-carrier scheduling, and employing specific DCI formats and timing rules to manage HARQ-ACK feedback and uplink grants across duplex modes, ensuring efficient data transmission and scheduling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cross-carrier scheduling is configured in LTE FDD-TDD CA system, then resource scheduling flexibility is improved, but the number of blind decoding trials increases due to different DCI format sizes
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the DCI format based on the duplex mode. When FDD carrier is configured, a first DCI format is used; when TDD carrier is configured, a second DCI format is used. This parameter adaptation allows the system to maintain appropriate scheduling flexibility for each mode while controlling the number of blind decoding trials by limiting the UE to expect only one DCI format size per configured carrier type.
2Adaptability or versatility
If TDD carrier is configured with flexible-TDD, then traffic adaptation capability is improved, but HARQ timing management complexity increases
Solution Approach 1:
The patent implements dynamics by enabling flexible-TDD configuration where the TDD carrier can dynamically adapt its uplink-downlink configuration according to traffic requirements. The system allows reconfiguration of the TDD carrier to switch between different uplink-downlink configurations, providing traffic adaptation capability while managing HARQ timing through standardized procedures that accommodate the dynamic changes.
3Productivity
If both FDD and TDD carriers are aggregated, then spectrum utilization is improved, but system configuration complexity increases
Solution Approach 1:
The patent applies segmentation by separating the handling of FDD and TDD carriers into distinct configuration procedures. The system configures the FDD carrier and TDD carrier independently with their respective DCI formats and scheduling parameters, then aggregates them at the physical layer. This segmentation approach allows efficient spectrum utilization across both duplex modes while managing configuration complexity through modular, independent setup procedures for each carrier type.
Data Source
AI summary
A signalling method is disclosed for use in an advanced wireless communication network that supports FDD-TDD carrier aggregation (CA). The signalling method comprises configuring the UE (by establishing radio resource control (RRC) connection with the network through the first access node) for data transmission between the UE and the network through the first access node on the first duplex mode carrier as a primary component carrier (PCell), configuring the UE (via dedicated RRC signalling on the PCell) for data transmission between the UE and the network through the second access node on the second duplex mode carrier as a secondary component carrier (SCell), and performing scheduling for data transmission on the aggregated SCell using either self-scheduling or cross-carrier scheduling.