PRACH Resource Allocation for 5G NR Random Access
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Solution Overview
Problem
In 5G NR technology, the random access process for unauthorized cells is affected by Listen Before Talk (LBT) mechanisms, leading to increased power consumption and reduced success rates for user equipment (UE) due to limited PRACH resource allocation, which results in inefficient resource utilization.
Innovation Solution
A method and device that include supplementary resource indication information in PRACH configuration, allowing the base station to enable a second physical resource only when the first resource is occupied, enabling the UE to transmit the random access preamble sequence on the second resource, thereby improving success rates and reducing power consumption without significantly increasing system resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the base station allocates limited PRACH resources for unauthorized cells, then system resource utilization is improved, but the random access success rate of UE deteriorates due to channel occupation by LBT mechanism
Solution Approach 1:
The patent implements dynamic PRACH resource allocation by introducing a second physical resource that is conditionally activated based on LBT outcomes. The base station dynamically switches between first and second physical resources according to channel availability, transforming the static resource allocation into a dynamic system that adapts to real-time channel conditions, thereby resolving the contradiction between resource utilization and access success rate
Solution Approach 2:
The patent applies preliminary action by pre-configuring both first and second physical resources along with supplementary resource indication information before the random access process. The UE is prepared in advance with alternative resources and the criteria for switching, so when LBT fails on the first resource, the UE can immediately transition to the second resource without delay, improving access success rate while maintaining efficient resource utilization
2Adaptability or versatility
If the UE performs LBT mechanism before transmitting random access preamble, then coexistence with WiFi is improved, but power consumption of UE increases
Solution Approach 1:
The patent implements partial action by having the base station perform LBT monitoring and channel status determination, then only instructing the UE to perform LBT when necessary through the supplementary resource indication information. This partial approach maintains WiFi coexistence capability where needed while avoiding unnecessary LBT operations by the UE, thereby reducing overall power consumption while preserving adaptability
Solution Approach 2:
The base station acts as an intermediary that performs LBT monitoring and channel assessment on behalf of the UE. The base station uses its own LBT results to determine which physical resource to allocate to the UE, eliminating the need for the UE to independently perform power-consuming LBT operations while maintaining coexistence with WiFi through the base station's monitoring
3Device complexity
If the base station configures only first physical resource for PRACH, then system resource allocation is simplified, but resource utilization efficiency deteriorates when first resource is occupied
Solution Approach 1:
The patent segments the PRACH resources into distinct first and second physical resources with different characteristics and usage conditions. The first resource is configured for normal operation while the second resource is specifically designated as a fallback option when the first resource is occupied. This segmentation allows the system to maintain simple configuration for each individual resource while achieving high overall utilization efficiency through conditional switching between segments
Solution Approach 2:
The supplementary resource indication information serves multiple functions: it conveys the configuration of the second physical resource, indicates the conditions for switching to the second resource, and provides the UE with alternative access options. This multi-functionality allows the system to maintain relatively simple configuration procedures while achieving improved resource utilization through a single versatile signaling mechanism
Data Source
AI summary
A method and device of random access are provided. The method may be applied to a base station. The base station may transmit a broadcast message to a user equipment (UE). The broadcast message may include physical random access channel (PRACH) configuration information and supplementary resource indication information. The PRACH configuration information may include first indication information for characterizing first physical resource and second indication information for characterizing a random access preamble sequence. The base station may obtain a location of a first reference synchronization broadcast block (SSB) synchronization signal according to the first physical resource corresponding to the PRACH configuration information. The base station may monitor, when the sending of the first reference SSB synchronization signal fails, the random access preamble sequence on the second physical resource corresponding to the supplementary resource indication information.