Staggered Group Notification for PRACH Overload in 5G MBS
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Solution Overview
Problem
The existing 5G mobile communication systems face challenges in efficiently managing multicast broadcast services due to PRACH overloading and access delays caused by simultaneous random access preambles from multiple UEs, particularly in scenarios with large numbers of UEs in idle or inactive states.
Innovation Solution
The proposed solution involves a communication control method where a base station transmits group notifications to subgroups at different timings, allowing UEs to determine and transmit random access preambles at dispersed times, thereby reducing PRACH overload and improving access efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If group notification is transmitted to all UEs simultaneously, then multicast service activation is efficient, but PRACH overload and access delays occur due to simultaneous random access preambles
Solution Approach 1:
The group notification is segmented and transmitted to different subgroups of UEs at different timings. The base station divides the large group of UEs into multiple subgroups, each receiving the notification at a staggered time, which disperses the subsequent random access preamble transmissions and prevents PRACH overload while maintaining efficient service activation
Solution Approach 2:
The base station employs periodic or interval-based transmission of group notifications to different subgroups. By scheduling notifications at different time intervals for different subgroups, the system achieves both efficient service activation and reduced simultaneous access attempts, resolving the contradiction between productivity and reliability
2Speed
If UEs transmit random access preambles simultaneously upon receiving group notification, then access speed is fast, but PRACH overload occurs reducing system capacity
Solution Approach 1:
UEs are divided into subgroups that receive group notifications at different timings. This segmentation causes UEs in different subgroups to transmit random access preambles at different times, maintaining fast access speed for each UE while preventing PRACH overload by distributing the total number of access attempts across multiple time slots
Solution Approach 2:
The system dynamically adjusts the notification timing for different subgroups based on system conditions. By making the notification transmission timing flexible and adaptive rather than uniform, the system maintains fast access speeds while dynamically managing PRACH capacity to avoid overload
Data Source
AI summary
In a first aspect, a communication control method is a communication control method used in a mobile communication system for providing a multicast broadcast service (MBS). The communication control method includes: transmitting, by a base station to a group including a plurality of user equipments, a group notification indicating activation of a multicast session corresponding to the group; and receiving, by the base station, a random access preamble transmitted from the user equipment in response to reception of the group notification. The transmitting of the group notification includes transmitting, by the base station, the group notification to each of a plurality of subgroups at different timings, the plurality of subgroups being obtained by dividing the group.