FDD TDD Carrier Aggregation HARQ Timing Coordination
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Solution Overview
Problem
Wireless communication systems face inefficiencies in transmitting and receiving signals in systems that simultaneously support Frequency Division Duplex (FDD) and Time Division Duplex (TDD), particularly in carrier aggregation scenarios where signal timing coordination across different duplex modes is challenging.
Innovation Solution
A method and device for efficiently transmitting uplink signals in a wireless communication system by configuring a first cell set to FDD and a second cell set to TDD, allowing for the reception of PHICH or PDCCH signals in specific subframes and subsequent transmission of PUSCH signals, aligning with the same HARQ process, thereby optimizing signal transmission timing across different duplex modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carrier aggregation is used to aggregate FDD and TDD cells, then system bandwidth and capacity are improved, but signal timing coordination and HARQ process management become complex
Solution Approach 1:
The patent segments the HARQ process management by separating FDD and TDD HARQ processes into distinct sets. Each cell set (FDD and TDD) has its own HARQ process identification and timing management, preventing interference between different duplex modes while maintaining carrier aggregation benefits.
Solution Approach 2:
The patent introduces a cell set indicator as an intermediary element in the Downlink Control Information (DCI) to identify which HARQ process set should be used. This mediator enables the system to switch between FDD and TDD HARQ processes seamlessly when aggregating carriers from different duplex modes.
2Productivity
If FDD and TDD cells are aggregated, then frequency diversity and bandwidth are improved, but HARQ timing alignment becomes difficult
Solution Approach 1:
The patent dynamically adjusts the HARQ timing based on the cell set indicator in the DCI. When a TDD cell is scheduled, the system dynamically switches to TDD HARQ timing parameters; when an FDD cell is scheduled, it uses FDD timing parameters. This dynamic adaptation eliminates fixed timing alignment issues.
Solution Approach 2:
The patent changes the HARQ timing parameters according to the duplex mode indicated by the cell set indicator. The system modifies timing offsets, feedback intervals, and retransmission schedules based on whether FDD or TDD parameters should be applied, optimizing timing for each duplex mode's characteristics.
Data Source
AI summary
The present invention relates to a wireless communication system. More particularly, the present invention relates to a method and a device for a terminal to transmit an uplink signal according to a normal HARQ operation in a wireless communication system supporting a carrier merge, the method comprising the steps of: forming a first cell set with a FDD and a second serving cell set with a TDD; receiving a PHICH signal from a subframe #(n−m−p) of the first serving cell, or receiving a PDCCH signal from a subframe #(n−m) of the first serving cell; and transmitting a PUSCH signal from a subframe #n of the second serving cell, in correspondence to the PHICH signal or the PDCCH signal, wherein n is an integer greater than or equal to 0, m is an integer greater than or equal to 1, and p is an integer greater than or equal to 1.