Uplink Transmission PRU Selection for 5G RRC Inactive State
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Solution Overview
Problem
In the 2-step random access procedure of 5G wireless communications, there is no specification for the User Equipment (UE) to select a Physical Uplink Shared Channel (PUSCH) resource unit (PRU) for payload transmission during Msg-A transmission.
Innovation Solution
A method for PUSCH resource unit (PRU) selection, where the UE receives a configuration from the base station (BS) including a preamble and multiple PRUs for payload transmission. The UE determines the number of PRUs to use based on an indication from the BS or a predefined number, and then selects at least one PRU using random, criterion-based, or self-information-based selection methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple UEs transmit payloads on the same PRU when selecting the same preamble, then the random access procedure can be initiated efficiently, but payload collision occurs and decoding fails
Solution Approach 1:
The PRU pool is segmented into multiple individual PRUs that can be independently selected by different UEs. Instead of all UEs using the same PRU, each UE selects a specific PRU from the segmented pool based on its preamble selection, thereby dividing the resource usage and avoiding collisions while maintaining efficient access.
2Reliability
If the BS configures a large number of PRUs for payload transmission, then payload collision is reduced, but resource overhead and system complexity increase
Solution Approach 1:
The system changes the parameter of PRU pool size dynamically or configures it appropriately based on network conditions and traffic load. By optimizing the number of PRUs in the pool, the system achieves sufficient reliability to avoid collisions without unnecessarily increasing resource overhead and configuration complexity.
3Ease of operation
If the UE selects PRUs randomly from the PRU pool, then selection simplicity is maintained, but PRU collision probability increases
Solution Approach 1:
The system incorporates feedback mechanisms where the BS monitors PRU selection and transmission outcomes, and adjusts the PRU pool configuration or provides guidance to UEs based on observed collision patterns. This feedback loop maintains the simplicity of random selection while improving collision avoidance through adaptive resource management.
Data Source
AI summary
A method of uplink transmission for a user equipment (UE) is disclosed. The method comprises receiving, from a base station (BS), a threshold; determining at least one uplink grant according to the threshold; performing a payload transmission on the at least one uplink grant while the UE is in an RRC inactive state; and not transmitting only padding bits for the payload transmission on the uplink grant.