PRACH Resource Selection via SSB Association
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Solution Overview
Problem
The increasing demand for network resources due to advanced devices and data-intensive applications poses challenges in the random access procedures of user equipment (UE) in next-generation communication systems, particularly in uplink data transmission to the gNB, leading to compatibility issues with previous systems and complex communication systems.
Innovation Solution
The implementation of a combined communication system that integrates 3GPP LTE/4G and 5G New Radio (NR) networks, utilizing physical random access channel (PRACH) resources with frequency division multiplexing (FDM) and time division multiplexing (TDM) to optimize random access procedures, allowing UE to select appropriate RACH occasions and preamble formats for efficient initial access and data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PRACH resources are increased to handle more UEs and data traffic, then network capacity and productivity improve, but device complexity and system complexity increase
Solution Approach 1:
The PRACH resources are segmented into multiple RACH occasions within a RACH occasion set, allowing UEs to select from divided time-frequency resources. This segmentation increases network capacity by accommodating more simultaneous access attempts while keeping individual UE complexity low through standardized selection algorithms.
Solution Approach 2:
The patent introduces frequency division multiplexing as an additional dimension for PRACH resource organization, creating RACH occasions across both time and frequency domains. This dimensional expansion increases network capacity without proportionally increasing device complexity, as UEs follow standardized procedures for selecting resources across multiple dimensions.
2Reliability
If multiple RACH occasions are configured for PRACH transmission, then random access reliability improves, but collision rates may increase due to more UEs selecting the same resources
Solution Approach 1:
The patent associates different RACH occasions with specific SSBs (synchronization signal blocks), creating local quality differentiation. UEs select RACH occasions based on which SSB they detected, distributing access attempts across different time-frequency resources. This reduces collisions by ensuring UEs experiencing similar channel conditions select different resources, while maintaining high reliability through multiple available occasions.
3Productivity
If PRACH resources are multiplexed using FDM and TDM, then resource utilization efficiency improves, but compatibility issues arise with previous systems
Solution Approach 1:
The patent designs the RACH occasion structure to serve multiple functions: it supports both legacy TDM-based access and new FDM-based access patterns within the same framework. The RACH occasion set can be configured with multiple occasions that UEs select based on SSB associations, enabling efficient resource utilization through FDM/TDM multiplexing while maintaining compatibility with existing systems through standardized selection procedures.
Data Source
AI summary
Systems and methods of selecting a PRACH resource opportunity are described. One of multiple Synchronization Signal Blocks (SSBs) is received. Each SSB has PSSs, SSSs and a PBCH that contain system information. A RACH occasion (RO) is selected from among multiple ROs associated with the SSB. A PRACH is transmitted on resources of the RO. The ROs are configured in a TDM and/or FDM manner. The RO is selected randomly or, if TDM is used, an earliest of the ROs from a UE-initiated RACH transmission in a previous period. A preamble of the RO is selected randomly with equal probability.