Terminal RA-RNTI Calculation for Multi-Band Random Access
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Solution Overview
Problem
In next-generation communication systems like the New Radio (NR) system, terminals face challenges in determining the Random Access Radio Network Temporary Identifier (RA-RNTI) due to the complexity of sub-bands and sub-timeslots with different subcarrier spacings and transmission time intervals, making it difficult to detect and receive Physical Downlink Control Channel (PDCCH) signaling for random access.
Innovation Solution
A communication method where a terminal determines a first identifier based on a resource index number indicated by the network device, using this identifier to scramble signaling for random access response, and detects the signaling using a radio interface technology specified in a handover command, allowing for flexible resource allocation and identification across multiple PRACH resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the system supports multiple sub-bands and sub-timeslots with different subcarrier spacings and TTIs, then the system flexibility and adaptability are improved, but the terminal cannot deduce t_id and f_id of PRACH resources, making it impossible to determine RA-RNTI and receive PDCCH signaling
Solution Approach 1:
The patent introduces a mapping relationship as an intermediary between the downlink sub-band/sub-timeslot and uplink sub-bands/sub-timeslots. This mapping relationship, provided by the base station, enables the terminal to determine the corresponding uplink PRACH resources for a given downlink resource without needing to know all uplink resource details, thus resolving the information loss problem while maintaining system flexibility
Solution Approach 2:
The patent segments the PRACH resources into different uplink sub-bands and sub-timeslots associated with a single downlink sub-band/sub-timeslot. This segmentation allows the terminal to focus on determining resources within specific segments rather than searching across all possible resources, making resource identification feasible in multi-band systems
2Reliability
If the terminal needs to blindly detect PDCCH signaling in a random access response window, then the terminal can receive RAR, but the terminal cannot deduce t_id and f_id without knowing the exact PRACH resource location
Solution Approach 1:
The base station performs preliminary action by providing the mapping relationship between downlink and uplink sub-bands/sub-timeslots before the terminal attempts to detect PDCCH signaling. This advance provision of mapping information enables the terminal to calculate the correct RA-RNTI and t_id/f_id values, transforming the blind detection process into a targeted detection process that is both reliable and feasible
3Adaptability or versatility
If there is one downlink sub-band corresponding to two or more uplink sub-bands, then resource allocation flexibility is improved, but the terminal cannot determine which uplink PRACH resource was used for preamble transmission
Solution Approach 1:
The mapping relationship serves as an intermediary that connects the downlink sub-band to multiple possible uplink sub-bands. The terminal uses this mapping to determine the correspondence between downlink resources and uplink PRACH resources, enabling reliable resource identification even when one downlink sub-band maps to multiple uplink sub-bands
Data Source
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AI summary
A communication method, a terminal, and a network device are disclosed. The method includes: determining, by a terminal, a first identifier based on a resource index number of a first resource, where the resource index number of the first resource is preset, or is indicated by a network device, the first resource is a resource used by the terminal to send a random access preamble, the first identifier is used to scramble first signaling, and the first signaling is used to schedule a random access response in a random access process; and detecting, by the terminal, the first signaling based on the first identifier.