PRACH Occasion Allocation for Multi-Operator RACH Latency
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Solution Overview
Problem
Current wireless communication systems, particularly in New Radio (NR) networks, face latency issues during User Equipment (UE) access to Random Access Channel (RACH) procedures due to the need for UEs to compete for channel access, especially with multiple guest operators at a cell site.
Innovation Solution
The proposed solution involves configuring Bandwidth Parts (BWPs) to map Physical Random Access Channel (PRACH) occasions to public land mobile network identifications (PLMN-IDs) of different operators, allowing the host operator to broadcast System Information (SI) messages containing PLMN-IDs and associated PRACH occasions. This enables UEs to access the appropriate PRACH occasion allocated to their operator, reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple guest operators share the same cell site resources, then resource utilization is improved, but RACH access latency increases due to competition for channel access
Solution Approach 1:
The patent segments the shared cell site resources by creating separate PRACH occasion subsets for different operators. Each operator is assigned specific time-frequency resources within the uplink transmission, allowing UEs to access their designated PRACH occasions without competing with other operators. This segmentation resolves the contradiction by maintaining resource sharing at the cell site level while eliminating access competition through operator-specific resource partitioning.
Solution Approach 2:
The patent applies preliminary action by pre-configuring and pre-allocating specific PRACH occasions to each operator before the actual RACH procedure begins. The host operator broadcasts system information messages that contain pre-defined mappings between operators and their assigned PRACH occasions. This preliminary allocation eliminates the need for dynamic competition during access, thereby reducing latency while maintaining efficient resource utilization.
2Loss of time
If separate RACH procedures are implemented for each operator, then access latency is reduced, but system complexity increases
Solution Approach 1:
The patent implements universality by creating a unified RACH framework that serves multiple operators simultaneously through a single host operator's infrastructure. The host operator's gNB handles PRACH reception for all operators, and the resource allocation mechanism is universally applied across all operator-UE pairs. This multi-functional approach reduces access latency through dedicated resources while avoiding the complexity of completely separate RACH procedures for each operator.
Solution Approach 2:
The host operator acts as an intermediary that manages resource allocation between multiple guest operators and their UEs. The host operator broadcasts system information containing PLMN-ID to PRACH occasion mappings, mediating the access process for all operators through a centralized control mechanism. This intermediary approach simplifies the system architecture compared to fully distributed multi-operator RACH procedures while still providing operator-specific resource allocation benefits.
3Adaptability or versatility
If PRACH occasions are dynamically allocated during RACH procedure, then flexibility is improved, but access time increases due to additional signaling
Solution Approach 1:
The patent applies preliminary action by pre-configuring PRACH occasion allocations in system information messages before UEs need to access the network. The mappings between operators (identified by PLMN-ID) and their designated PRACH occasions are established in advance and broadcast to all UEs. This eliminates the need for dynamic allocation signaling during the RACH procedure itself, thereby reducing access time while maintaining the flexibility of operator-specific resource management.
Solution Approach 2:
The patent implements self-service by enabling UEs to autonomously determine their designated PRACH occasion based on their operator affiliation (PLMN-ID) and the pre-published mappings in system information. UEs do not require additional signaling or dynamic allocation procedures to identify their access resources; they simply select the PRACH occasion corresponding to their operator from the pre-configured options. This self-service mechanism maintains flexibility while eliminating signaling delays.
Data Source
AI summary
A system and method for performing a Random Access Channel (RACH) procedure is provided. The method includes configuring a plurality of Bandwidths Parts (BWPs) to one or more Physical Random Access Channel (PRACH) occasions mapped to a public land mobile network identification (PLMN-ID) of a set of different PLMN-IDs, each different PLMN-ID is assigned with at least one operator of a set of operators; assigning each PRACH occasion within an uplink (UL) transmission wherein each PRACH occasion is allocated by the host operator to at least one operator; separating each PRACH occasion of a set of PRACH occasions based on each PLMN-ID of the set of PLMN-IDs; and enabling a User Equipment (UE) operating at a cell site of the RACH procedure via at least one PRACH occasion allocated by the host operator based on the PLMN-ID that has been mapped to subscribers for at least one operator.