RACH Resource Mapping for Synchronization Signal Blocks
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Solution Overview
Problem
In Next Generation Radio (NR) systems, the number of RACH resources required to transmit a preamble does not necessarily match the number of resources determined based on the RACH Configuration, making it challenging to appropriately select RACH resources according to an SS block in an SS burst set.
Innovation Solution
User equipment is equipped with a reception unit to detect synchronization signals or physical broadcast channels and a control unit to select RACH resources based on a mapping rule, considering the duration of the synchronization signal burst set and the available transmission period, allowing for appropriate determination of RACH resources for preamble transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If RACH resources are determined based on RACH Configuration provided by base station, then preamble transmission resources are available, but the number of RACH resources does not necessarily match the number of SS blocks in SS burst set
Solution Approach 1:
The patent introduces dynamic mapping between SS blocks and RACH resources where the mapping relationship can be flexibly configured based on the number of SS blocks in the SS burst set. The base station can dynamically adjust the RACH resource allocation to match the actual number of detectable SS blocks, rather than using a fixed configuration. This dynamic adaptation resolves the contradiction between allocation flexibility and matching accuracy.
Solution Approach 2:
The patent changes the parameter of RACH resource configuration by introducing a mapping rule that relates the index of detectable SS blocks to the index of RACH resources. By parameterizing the mapping relationship (e.g., using formulas like n_RACH = (n_SS mod N_RACH) + offset), the system can adapt the number of RACH resources to match the number of SS blocks while maintaining configurable flexibility through parameters like offset and modulation index.
2Ease of operation
If user equipment selects RACH resources based on detected SS block, then preamble transmission can be performed, but appropriate determination of mapping period is challenging due to mismatch between SS burst set duration and RACH resource period
Solution Approach 1:
The patent establishes preliminary mapping rules between SS blocks and RACH resources that are determined in advance by the base station and provided to user equipment through system information. The mapping relationship, including the mapping period determination, is pre-configured using formulas and parameters that simplify the UE's selection process. The UE only needs to apply the predetermined mapping rule based on its detected SS block index, rather than performing complex period determination calculations.
3Productivity
If the period of RACH resources is aligned with SS burst set period, then resource allocation is simplified, but the duration during which mapping can be completed may not be sufficient
Solution Approach 1:
The patent introduces an additional dimension to the resource allocation by allowing the RACH resource period to be a multiple of the SS burst set period rather than strictly aligned with it. This dimensional extension (using multiples like 2x, 3x, etc.) provides enough time duration for complete mapping while maintaining the simplified periodic structure. The mapping can be completed within the extended period, and the periodicity is maintained for efficient resource allocation.
Data Source
AI summary
A terminal includes a receiver configured to receive from a base station a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a physical broadcast channel (PBCH) in a synchronization signal block; and a transmitter configured to transmit a random access preamble based on the synchronization signal block in which the PSS, the SSS, and the PBCH are received. A mapping period for mapping synchronization signal blocks included in a synchronization signal block set to resources for transmitting the random access preamble is determined based on a period determined based on configuration information regarding a random access channel, a value of a period of the synchronization signal block set, and a value of a duration in which a process of mapping synchronization signal blocks used for transmission by the base station in the synchronization signal block set to the resources for transmitting the random access preamble is completed.