PRACH Resource Mapping for Low-Overhead Contention-Free Access
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Solution Overview
Problem
In the New Radio (NR) system, the limited carrying capacity of the Physical Downlink Control Channel (PDCCH) prevents efficient indication of a large number of Physical Random Access Channel (PRACH) resources, leading to bit waste and reduced availability for other uplink signals during contention-free random access procedures.
Innovation Solution
A method for configuring contention-free random access resources by utilizing a pre-defined mapping relationship to group PRACH resources based on identifiers, time positions, frequency positions, associated objects, or association groups, allowing reduced bit overhead through target resource indication information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a base station randomly selects a resource block for random access, then resource allocation flexibility is improved, but resource waste increases due to potential conflicts with pre-configured resources
Solution Approach 1:
The resource pool is segmented into two distinct parts: pre-configured resources (Type 0) and dynamically granted resources (Type 1). This segmentation allows the base station to selectively allocate resources based on UE capability and network conditions, avoiding waste while maintaining flexibility. The MAC CE message further segments the resource indication by specifying either Type 0 or Type 1 resource allocation.
Solution Approach 2:
The patent implements dynamic resource allocation where the base station can switch between static pre-configured resources and dynamic granted resources based on real-time network conditions and UE capabilities. The MAC CE control element enables dynamic selection and indication of resource types, allowing the system to adapt resource allocation strategies dynamically rather than relying solely on static pre-configuration.
2Reliability
If pre-configured random access resources are allocated to all UEs, then access reliability is improved, but resource efficiency deteriorates due to unused resources
Solution Approach 1:
Different quality levels of resource allocation are applied to different UEs based on their capabilities and network conditions. Capability-aware UEs receive dynamic Type 1 resource allocation with higher efficiency, while other UEs receive traditional Type 0 pre-configured allocation ensuring reliability. This local differentiation optimizes overall system performance.
Solution Approach 2:
The patent changes the resource allocation parameter from a single static type to two selectable types (Type 0 and Type 1). The MAC CE message dynamically changes the resource indication parameter to specify which type to use, allowing the system to adjust resource allocation characteristics based on UE capability and network conditions, thereby improving both reliability and efficiency.
3Productivity
If dynamic resource allocation is implemented, then resource efficiency is improved, but signaling overhead increases due to additional control messages
Solution Approach 1:
A MAC CE control element is introduced as an intermediary mechanism to efficiently convey dynamic resource allocation information. This intermediary carries compact resource indication information that can specify Type 0 or Type 1 allocation, reducing the need for extensive signaling while enabling dynamic resource management. The MAC CE acts as a mediator between the base station's resource decisions and the UE's resource selection.
4Reliability
If capability-aware random access is implemented, then access performance is improved, but device complexity increases due to capability reporting requirements
Solution Approach 1:
The UE self-determines its capability status and autonomously selects the appropriate resource type (Type 0 or Type 1) based on its capabilities and the network's MAC CE indication. This self-service approach eliminates the need for complex capability reporting mechanisms, as the UE independently makes resource selection decisions based on built-in capability knowledge and received control information.
Data Source
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AI summary
A method and a device for configuring a contention free random access resource are provided. The method includes: transmitting target resource indication information to a user equipment based on a pre-defined mapping relationship; where the target resource indication information is used to determine a physical random access channel transmission occasion (RO) resource, the target resource indication information includes at least one of a physical random access channel (PRACH) mask index or an RO resource index, and the pre-defined mapping relationship includes a correspondence between a value range of the target resource indication information and the RO resource.