TDD Carrier Aggregation Timing Definition for HARQ ACK/NACK
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Solution Overview
Problem
In LTE-A systems supporting carrier aggregation, the timing relationship between Physical Downlink Control Channel (PDCCH), Physical Downlink Shared Channel (PDSCH), and uplink Hybrid Automatic Repeat Request (HARQ) ACK/NACK is not adequately defined, leading to inefficiencies in resource allocation and increased system operation complexity due to differing TDD uplink-downlink configurations between aggregated carriers.
Innovation Solution
The method defines the timing relationship among PDCCH, PDSCH, and uplink HARQ ACK/NACK transmission resources in a TDD wireless communication system, ensuring broadband resource allocation through carrier aggregation by establishing rules for HARQ ACK/NACK transmission timing, including fixing the HARQ ACK/NACK transmission timing in the primary cell, synchronizing transmission timings between primary and secondary cells, and distributing HARQ ACK/NACK transmissions across subframes to maintain efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carrier aggregation with different TDD uplink-downlink configurations is supported, then broadband service capability and data rate are improved, but timing relationship definition complexity and system operation complexity increase
Solution Approach 1:
The patent applies universality by establishing a common reference timing mechanism that works across multiple component carriers with different TDD configurations. The base station determines uplink HARQ timing relative to downlink subframe timing, creating a universal timing relationship that adapts to various carrier configurations without requiring separate timing definitions for each carrier pair.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting HARQ timing parameters (k values) based on the specific TDD configuration of each component carrier. The timing relationship is defined by parameters such as k1 and k2, which are selected according to the downlink-uplink configuration, allowing the system to adapt timing to different carrier characteristics while maintaining a unified framework.
2Measurement precision
If HARQ ACK/NACK transmission timing is determined separately for each component carrier, then timing accuracy for each carrier is improved, but system operation complexity and resource allocation complexity increase
Solution Approach 1:
The patent merges the timing determination process by establishing that uplink HARQ timing is derived from a common reference point (downlink subframe timing) rather than being independently determined for each carrier. This combining approach maintains timing accuracy through mathematical relationships while reducing operational complexity by providing a unified timing determination procedure.
Solution Approach 2:
The patent introduces downlink subframe timing as an intermediary reference that mediates between the timing requirements of multiple component carriers. By using the downlink timing as an intermediate reference point, the system achieves accurate timing relationships for uplink HARQ transmissions across different carriers without requiring direct carrier-to-carrier timing synchronization.
3Adaptability or versatility
If cross-carrier scheduling is implemented, then resource allocation flexibility is improved, but timing synchronization complexity and resource allocation complexity increase
Solution Approach 1:
The patent uses downlink subframe timing as an intermediary to resolve timing synchronization in cross-carrier scheduling scenarios. When scheduling is performed on one carrier but data transmission occurs on another, the timing relationship is established relative to the downlink subframe timing, serving as a common reference that simplifies the coordination between scheduling and data transmission across different carriers.
4Adaptability or versatility
If multiple uplink HARQ timing options are provided for different TDD configurations, then compatibility with various configurations is improved, but device complexity and processing complexity increase
Solution Approach 1:
The patent manages configuration compatibility through parameter changes by defining timing relationships using configurable parameters (k values) that are selected based on the specific TDD configuration. Rather than hardcoding separate timing rules for each configuration, the system uses parameter-based timing definitions that automatically adapt to different configurations, reducing processing complexity while maintaining compatibility.
Data Source
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AI summary
A method for transmitting a signal in a wireless communication system, wherein the method comprises transmitting, by a base station, information on a first uplink/downlink, UL/DL, configuration for a primary cell; transmitting, by the base station, information on a second UL/DL configuration for a secondary cell; transmitting, by the base station, first data on a first subframe of the secondary cell based on the second UL/DL configuration; and receiving, by the base station, a response corresponding to the first data on a second subframe of the primary cell, the second subframe being identified based on the first UL/DL configuration.