Sidelink HARQ Process Number and NDI Segmentation for Unicast Groupcast
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Solution Overview
Problem
In NR-V2X communication systems, there is a need to define Hybrid Automatic Repeat Request (HARQ) process numbers and New Data Indicators (NDI) for sidelink communication to ensure appropriate HARQ processing effects, as existing methods are unclear about sharing these parameters between unicast and groupcast, and among transmitting communication apparatuses.
Innovation Solution
A communication apparatus is designed with a control unit that separately defines HARQ process numbers and NDI for unicast and groupcast, and a transmitting unit that transmits sidelink control information including these defined parameters, allowing for independent HARQ processing for each mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If HARQ process number and NDI are shared between unicast and groupcast, then resource utilization is improved, but HARQ processing reliability deteriorates due to parameter confusion
Solution Approach 1:
The patent divides the HARQ parameter space by introducing a communication mode indicator that segments the identification of HARQ process numbers and NDI into mode-specific ranges. Unicast uses HARQ process numbers 0-7 with NDI 0-1, while groupcast uses HARQ process numbers 8-15 with NDI 0-3, creating distinct segments that prevent confusion while maintaining efficient resource utilization.
2Reliability
If separate HARQ processing is implemented for unicast and groupcast, then HARQ processing reliability is improved, but implementation complexity increases
Solution Approach 1:
The patent applies local quality by making the HARQ parameter interpretation dependent on the communication mode. The receiving device uses the communication mode indicator to locally adapt its parameter interpretation: for unicast mode, it interprets HARQ process numbers as 0-7 with 1-bit NDI; for groupcast mode, it interprets HARQ process numbers as 8-15 with 2-bit NDI. This localized adaptation ensures reliable processing without requiring completely separate implementation paths.
3Device complexity
If common HARQ parameters are used among transmitting communication apparatuses, then system simplicity is improved, but HARQ processing accuracy deteriorates due to parameter conflicts
Solution Approach 1:
The patent introduces a communication mode indicator as an intermediary element that mediates between the need for common HARQ parameters and the need for accurate parameter interpretation. This intermediary allows multiple transmitting devices to use the same HARQ parameter spaces while the mode indicator ensures that receiving devices can accurately interpret the parameters by knowing which communication mode is being used, thus resolving parameter conflicts without reducing system simplicity.
Data Source
AI summary
A communication apparatus includes a control unit that separately defines, for unicast and for groupcast, a Hybrid Automatic Repeat Request (HARQ) process number and a New Data Indicator (NDI) used for sidelink HARQ processing; and a transmitting unit that transmits sidelink control information including the HARQ process number and the NDI defined for the unicast, or including the HARQ process number and the NDI defined for the groupcast.