Grant-Free Uplink Redundancy Version Timing for Reliable URLLC
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wireless communication systems, particularly in ultra-reliable low latency communications (URLLC), face challenges in efficiently determining redundancy versions for grant-free uplink transmissions, leading to performance degradation due to unreliable uplink control information (UCI) and conflicts with scheduled eMBB traffic.
Innovation Solution
The implementation of incremental redundancy (IR) with a time-index based technique for determining redundancy versions, where user equipment (UE) selects and transmits different redundancy versions based on transmission time, allowing base stations to decode using a combination of received versions, and agreeing on RV patterns through RRC signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If grant-free uplink transmissions are used for URLLC, then latency is reduced and access efficiency is improved, but reliability deteriorates due to inability to determine redundancy versions for decoding
Solution Approach 1:
The system enables self-service by allowing the base station to autonomously determine the redundancy version based on the time index of the received transmission. The base station uses the time index to identify which RV was transmitted without requiring additional signaling from the UE, thus maintaining low latency while enabling reliable decoding through automatic RV determination and combination of multiple transmissions.
2Reliability
If incremental redundancy with multiple transmissions is implemented, then decoding reliability is improved, but device complexity increases due to need to track and combine multiple redundancy versions
Solution Approach 1:
The time index serves as an intermediary that bridges the transmitter and receiver. The base station uses the time index as a key to look up the corresponding redundancy version in a pre-configured RV pattern table. This intermediary mechanism simplifies the complexity by replacing complex tracking and signaling with a straightforward time-index-based lookup and combination process.
3Productivity
If grant-free transmissions are used, then access efficiency is improved, but harmful factors increase due to conflicts with scheduled eMBB traffic
Solution Approach 1:
The system segments the redundancy version transmission into multiple time instances rather than requiring a single high-power transmission. By distributing the same data across multiple grant-free transmissions with different RVs, the system reduces peak power requirements and minimizes interference with scheduled eMBB traffic, while still achieving reliable decoding through combination of the segmented transmissions.
Data Source
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.