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Author: Admin | 2025-04-28
L139 : 91, msg1-SubcarrierSpacing kHz120, restrictedSetConfig unrestrictedSet prach-ConfigurationIndex : This value Points to Table for prach-ConfigurationIndex In 38.211. The table defines which PRACH format to use and when to send PRACH in time domain and number of RACH occasions available. msg1-FDM: The number of PRACH transmission occasions FDMed in one time instance. Upto eight RACH occasions can be used in one time instance. Below Image illustrates the relation between msg-FDM and Rach occasions available per SSB. msg1-FrequencyStart: This value refers to the Offset of lowest PRACH transmission occasion in frequency domain with respective to PRB 0. The value is configured so that the corresponding RACH resource is entirely within the bandwidth of the UL BWP. preambleTransMax : Max number of RA preamble transmission performed before declaring a failure. How many times a UE can transmit MSG1 before declaring RACH failure. powerRampingStep : Power ramping steps for PRACH. This value indicates the amount of power UE needs to increase for RACH transmissions if previous RACH attempt failed. ra-ResponseWindow: Msg2 (RAR) window length in number of slots. UE scans for PDCCH looking for msg2 response from gNB within the ra-ResponseWindow, if UE did not receive msg2 within the window it will consider RACH failure and start msg1 transmission again. totalNumberOfRA-Preambles: totalNumberOfRA-Preambles indicates the total number of preambles available per PRACH occasion for both contention based and contention free RACH. This IE has a range of 0-63, If this IE is missing then All 64 preambles are available and If this IE is present then less than 64 preambles are available to UE’s. In this case 8 Preambles are available to UE. ra-ContentionResolutionTimer : The initial value for the contention resolution timer. value sf16 corresponds to 16 subframes, and so on. Recommended by LinkedIn msg1-SubcarrierSpacing: Defines Subcarrier spacing of PRACH. ssb-perRACH-OccasionAndCB-PreamblesPerSSB : The meaning of this field is twofold: ssb-perRACH-Occasion conveys the information about the number of SSBs mapped per RACH occasion and CB-PreamblesPerSSB indicates the number of Contention Based preambles available per SSB So in the above example there is one RACH Occasion per SSB and 8 Preambles are available for each RACH Occasion as illustrated below For the purpose of slot numbering in the prach-ConfigurationIndex tables, the following subcarrier spacing is be assumed: - 15 kHz for FR1 - 60 kHz for FR2. prach-ConfigurationIndex is 75, and From the below table we can find out more details what are the corresponding
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