Common HARQ Process Space for Unlicensed Spectrum
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Solution Overview
Problem
In wireless communication systems, especially in LTE/LTE-Advanced networks using unlicensed spectrum, existing technologies face challenges with interference and congestion, leading to delays and inefficiencies in data transmission due to independent HARQ processes across component carriers, which are not compatible with the unreliable nature of unlicensed spectrum access.
Innovation Solution
Implementing a method where two or more unlicensed spectrum component carriers share a common hybrid automatic repeat request (HARQ) process space, allowing for clear channel access checks and coordinated data transmission and response, thereby reducing latency and improving reliability across multiple carriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If independent HARQ processes are used across component carriers, then each carrier can operate autonomously, but transmission reliability and efficiency deteriorate due to interference and congestion in unlicensed spectrum
Solution Approach 1:
The patent merges independent HARQ processes across multiple unlicensed spectrum component carriers into a single shared HARQ process space. This allows carriers to operate autonomously for scheduling and CCA purposes while sharing feedback and retransmission responsibilities, thereby improving transmission reliability through coordinated operation without sacrificing carrier independence.
Solution Approach 2:
The shared HARQ process space serves multiple component carriers simultaneously, enabling a single HARQ process to handle transmissions across different carriers. This universal approach allows the system to leverage successful transmissions on one carrier for retransmissions on another carrier, improving overall system reliability while maintaining operational flexibility.
2Ease of operation
If independent HARQ processes are used across component carriers, then carrier independence is maintained, but transmission delay increases due to lack of coordination
Solution Approach 1:
By combining multiple independent HARQ processes into a shared process space, the patent enables coordinated retransmission decisions across carriers. When a transmission fails on one carrier, the system can quickly initiate retransmission on another carrier without waiting for individual carrier HARQ cycles to complete, thereby reducing transmission delay while preserving carrier independence for scheduling.
Solution Approach 2:
The shared HARQ process space implements unified feedback mechanisms where ACK/NACK information from multiple carriers is consolidated and processed collectively. This feedback approach allows the system to make informed retransmission decisions across carriers, reducing delay by leveraging successful receptions on one carrier to avoid retransmissions on others.
3Device complexity
If separate HARQ processes are used for each carrier, then implementation complexity is reduced per carrier, but overall system efficiency decreases due to redundant processing
Solution Approach 1:
The patent combines multiple carrier HARQ processes into a single shared process, eliminating redundant processing across carriers. This unified approach reduces overall system complexity by processing HARQ feedback and retransmission decisions once rather than multiple times, while significantly improving system efficiency through coordinated resource utilization and reduced redundancy.
Solution Approach 2:
The shared HARQ process space provides universal functionality that serves all component carriers simultaneously. This multi-functional design allows a single process to handle transmissions, feedback, and retransmissions across multiple carriers, thereby reducing overall system complexity while improving efficiency through resource sharing and coordinated operation.
Data Source
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AI summary
A sharing of common hybrid automatic repeat request (HARQ) process space by multiple unlicensed spectrum component carriers is described. Because communication access is not guaranteed over the unlicensed spectrum, a set of component carriers in the unlicensed spectrum is assigned to share a common HARQ process space, such that uplink or downlink data will be transmitted over any one or more of the set of component carriers that clear a clear channel assessment (CCA) check. The receiver then provides a HARQ process response over the same HARQ process space using the grouped component carriers that share that common HARQ process space. Thus, any one or more of the set of component carriers sharing the common HARQ process space may both carry the transmitted data and carry the HARQ process response to the attempted data transmission.