Grant-Free Uplink RV Mapping by Transmission Time
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Solution Overview
Problem
Current wireless communication technologies face challenges in efficiently managing grant-free uplink transmissions for ultra-reliable low latency communications (URLLC), particularly in determining redundancy versions (RVs) for incremental redundancy (IR) schemes, which affects decoding reliability and performance.
Innovation Solution
The proposed solution involves a UE determining and signaling RVs based on transmission time, using a time-indexed approach to align RVs with HARQ transmissions, allowing the base station to decode data even if single RVs are not correctly received, and employing polar codes for efficient encoding and decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If explicit RV signaling is used in grant-free uplink transmissions, then decoding reliability is improved, but signaling overhead and complexity increase
Solution Approach 1:
The base station determines the RV value autonomously based on the reception time of the grant-free uplink transmission, without requiring explicit RV signaling from the UE. The BS uses a pre-configured mapping between time resources and RV values to select the appropriate RV for decoding, making the system self-sufficient and eliminating the need for additional signaling messages.
Solution Approach 2:
The patent changes the parameter determination approach from explicit signaling to implicit time-based determination. The RV value is derived from the time resource index where the transmission was received, transforming a signaling parameter into a function of temporal position, thereby reducing overhead while maintaining reliability.
2Reliability
If multiple RVs are transmitted for incremental redundancy, then decoding performance is improved, but transmission overhead increases
Solution Approach 1:
The base station pre-configures the mapping between time resources and RV values before grant-free transmissions occur. This preliminary setup allows the BS to determine the correct RV for each transmission opportunity in advance, enabling efficient incremental redundancy combining without requiring real-time RV negotiation or additional signaling overhead.
Data Source
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AI summary
Certain aspects of the present disclosure generally relate to wireless communications and, more particularly, to methods and apparatus for rate-matching a stream of bits encoded using polar codes. An exemplary method generally includes determining, based on a time of a transmission, a redundancy version (RV) of data to be transmitted in the transmission and transmitting the determined RV of the data via a wireless medium at the time.