ACK/NACK Transmission for Multi-Carrier Wireless Systems
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Solution Overview
Problem
In multi-carrier wireless communication systems, the increased number of uplink control signals requires a method to efficiently transmit HARQ ACK/NACK responses, which is different from the existing single carrier system due to the limitation of transmitting uplink control signals through one uplink component carrier.
Innovation Solution
User equipment (UE) configured with two serving cells sends an HARQ ACK/NACK response by receiving a transport block through a first serving cell set in a transmission mode supporting up to two transport blocks, determining the ACK/NACK response, and sending it, where the response is identical to that used when two transport blocks are received through the first serving cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a terminal receives transport blocks through multiple downlink component carriers in a multi-carrier system, then the data transmission capacity is improved, but the number of uplink control signals increases and must be transmitted through one uplink component carrier, causing signal congestion and transmission complexity
Solution Approach 1:
The patent segments the HARQ-ACK feedback for multiple transport blocks into separate acknowledgment signals (ACK1, ACK2, NACK1, NACK2, etc.), each corresponding to a specific transport block. This segmentation allows the terminal to independently acknowledge each received transport block, reducing the complexity of managing multiple simultaneous acknowledgments through a single uplink component carrier.
Solution Approach 2:
The patent introduces a new dimension for control signal transmission by using Physical Uplink Control Channel (PUCCH) resources with different cyclic shifts and orthogonal cover codes. Instead of simply increasing the number of uplink component carriers, the solution exploits the code domain dimension to multiplex multiple HARQ-ACK signals, thereby reducing uplink control signal congestion while maintaining the benefit of multi-carrier data transmission.
2Productivity
If a serving cell is configured in transmission mode supporting up to two transport blocks, then the downlink data throughput is improved, but the terminal must send separate HARQ acknowledgments for each transport block, increasing uplink control overhead
Solution Approach 1:
The patent merges multiple HARQ-ACK signals into a single uplink transmission by combining ACK/NACK information for multiple transport blocks into one PUCCH message. Specifically, the terminal generates a combined HARQ-ACK codebook that includes acknowledgments for all received transport blocks, which are then transmitted together through a single uplink component carrier using code division multiplexing.
Solution Approach 2:
The patent creates a universal HARQ-ACK feedback mechanism that can handle any combination of transport block receptions (1 or 2 blocks) through a single standardized procedure. The same PUCCH resource and coding scheme are used regardless of whether one or two transport blocks are received, making the uplink control mechanism universal and reducing the need for multiple specialized control channels.
3Adaptability or versatility
If the transmission mode of a serving cell changes between supporting one or two transport blocks, then the system flexibility is improved, but the terminal may send incorrect HARQ responses, reducing transmission reliability
Solution Approach 1:
The patent implements a feedback mechanism where the terminal determines the actual number of transport blocks received and generates HARQ-ACK responses accordingly. The base station receives these feedback signals and uses them to adjust subsequent transmissions, ensuring that the transmission mode is dynamically adapted to the actual channel conditions and terminal capabilities, thereby maintaining reliability despite mode changes.
Solution Approach 2:
The patent changes the HARQ-ACK response parameters (such as the number of acknowledgment bits and the PUCCH resource allocation) based on the transmission mode and the actual number of transport blocks received. When a serving cell switches between transmission modes supporting one or two transport blocks, the terminal adjusts its HARQ feedback parameters to match the current configuration, ensuring accurate responses are sent regardless of mode transitions.
Data Source
AI summary
A method for transmitting acknowledgement/negative-acknowledgement (ACK/NACK) information of a user equipment (UE) configured with two serving cells including a first serving cell and a second serving cell, the method including receiving two transport blocks (TBs) through a downlink subframe of the first serving cell, receiving one TB through a downlink subframe of the second serving cell and transmitting ACK/NACK information informing ACK/NACKs for the two TBs and the one TB through an uplink subframe of the first serving cell, wherein the ACK/NACK information informs the ACK/NACKs for the two TBs and the one TB by a combination of one resource selected from a plurality of candidate resources and two bits transmitted through the one resource.