Random Access Backoff for PRACH Repetition Load Control
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Solution Overview
Problem
The existing random access backoff mechanism based on backoff time is inadequate for addressing cell overload issues caused by PRACH repetition, which increases time-frequency resource occupancy and complicates load balancing in cellular networks.
Innovation Solution
A method that adjusts the calculation of backoff time and parameter values based on whether PRACH repetition is performed, using a product of backoff parameter values and factors specific to PRACH repetition scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PRACH repetition is performed to enhance uplink coverage, then coverage is improved, but cell overload increases and load balancing becomes more difficult
Solution Approach 1:
The patent changes the parameters of the backoff mechanism by introducing separate backoff parameter values and scaling factors for PRACH repetition scenarios. The base station configures different backoff parameters (e.g., longer backoff times or larger scaling factors) specifically for UEs performing PRACH repetition, thereby controlling their access probability and reducing cell overload while maintaining coverage enhancement benefits.
2Reliability
If PRACH repetition is performed, then uplink coverage is enhanced, but time-frequency resource occupancy increases
Solution Approach 1:
The patent introduces dynamic backoff parameter adjustment where the backoff time or scaling factor is configured differently based on whether PRACH repetition is performed. This dynamic parameter change allows the system to adapt resource allocation to the actual needs of coverage enhancement scenarios, managing time-frequency resource occupancy more effectively.
3Ease of manufacture
If existing random access backoff mechanism is used for PRACH repetition, then implementation is simple, but cell load balancing performance is insufficient
Solution Approach 1:
The patent segments the backoff mechanism into different configurations for different scenarios: standard random access and PRACH repetition. By dividing the backoff parameter configuration into scenario-specific parameters (with separate backoff parameter values and scaling factors for PRACH repetition), the system achieves better load balancing performance while maintaining manageable implementation complexity through structured parameter management.
Data Source
AI summary
Disclosed is a method and an apparatus used in a wireless communication node. The communication node sends at least one preamble according to whether PRACH repetition is performed; in response to the at least one preamble being sent, receives a first MAC subPDU in a first time window, wherein the first MAC subPDU indicates a first backoff parameter value; determines a first backoff time according to the product of at least the first backoff parameter value and a first backoff factor; at least either the first backoff parameter value or the first backoff factor depends on whether PRACH repetition is performed. The present application provides an enhanced method for calculating the backoff time for the random access backoff mechanism for enhanced uplink coverage of PRACH, and the solution is capable of adjusting the load state of the cell and increase the probability of random access success of the UE.