RACH-ConfigGeneric

RRC IE · TS 38.331 v19.4.0 (2026-09) · clause 6.3.2

RACH-ConfigGeneric is an RRC information element of 3GPP TS 38.331 (38331), the 5G NR Radio Resource Control (RRC) protocol.

First seen v15.1.0 (2018-04) · Last changed v19.0.0 (2025-10)

Definition

The IE RACH-ConfigGeneric is used to specify the random-access parameters both for regular random access as well as for beam failure recovery.

RACH-ConfigGeneric ::=              SEQUENCE {
    prach-ConfigurationIndex            INTEGER (0..255),
    msg1-FDM                            ENUMERATED {one, two, four, eight},
    msg1-FrequencyStart                 INTEGER (0..maxNrofPhysicalResourceBlocks-1),
    zeroCorrelationZoneConfig           INTEGER(0..15),
    preambleReceivedTargetPower         INTEGER (-202..-60),
    preambleTransMax                    ENUMERATED {n3, n4, n5, n6, n7, n8, n10, n20, n50, n100, n200},
    powerRampingStep                    ENUMERATED {dB0, dB2, dB4, dB6},
    ra-ResponseWindow                   ENUMERATED {sl1, sl2, sl4, sl8, sl10, sl20, sl40, sl80},
    ...,
    [[
        prach-ConfigurationPeriodScaling-IAB-r16    ENUMERATED {scf1,scf2,scf4,scf8,scf16,scf32,scf64}              OPTIONAL,   -- Need R
        prach-ConfigurationFrameOffset-IAB-r16      INTEGER (0..63)                                                 OPTIONAL,   -- Need R
        prach-ConfigurationSOffset-IAB-r16          INTEGER (0..39)                                                 OPTIONAL,   -- Need R
        ra-ResponseWindow-v1610                     ENUMERATED { sl60, sl160}                                       OPTIONAL,   -- Need R
        prach-ConfigurationIndex-v1610              INTEGER (256..262)                                              OPTIONAL    -- Need R
    ]],
    [[
        ra-ResponseWindow-v1700                     ENUMERATED {sl240, sl320, sl640, sl960, sl1280, sl1920, sl2560} OPTIONAL    -- Need R
    ]],
    [[
        sbfd-RACH-SingleConfig-preambleReceivedTargetPower-r19     INTEGER (-202..-60)                              OPTIONAL    -- Need R
    ]]
}

Fields (15)

Field	Description
prach-ConfigurationIndex INTEGER (0..255)	PRACH configuration index. For prach-ConfigurationIndex configured under beamFailureRecoveryConfig , the prach-ConfigurationIndex can only correspond to the short preamble format, (see TS 38.211 [16], clause 6.3.3.2). If the field prach-ConfigurationIndex-v1610 is present, the UE shall ignore the value provided in prach-ConfigurationIndex (without suffix).
msg1-FDM ENUMERATED {one, two, four, eight}	The number of PRACH transmission occasions FDMed in one time instance. (see TS 38.211 [16], clause 6.3.3.2).
msg1-FrequencyStart INTEGER (0..maxNrofPhysicalResourceBlocks-1)	Offset of lowest PRACH transmission occasion in frequency domain with respective to PRB 0. This field is used to configure the offset of lowest PRACH transmission occasion in frequency domain with respective to PRB 0 for the first PRACH occasions if sbfd-RACH-SingleConfig is configured and for both the first PRACH occasions and second PRACH occasions if sbfd-RACH-DualConfig is configured (see TS 38.213 [13], clause 8), or, the lowest PRB in PRBs that are both in the active UL BWP and in the UL sub-band for the second PRACH occasions if sbfd-RACH-SingleConfig is configured (see TS 38.213 [13], clause 8). The value is configured so that the corresponding RACH resource is entirely within the bandwidth of the UL BWP. (see TS 38.211 [16], clause 6.3.3.2).
zeroCorrelationZoneConfig INTEGER(0..15)	N-CS configuration, see Table 6.3.3.1-5 in TS 38.211 [16].
preambleReceivedTargetPower INTEGER (-202..-60)	The target power level at the network receiver side (see TS 38.213 [13], clause 7.4, TS 38.321 [3], clauses 5.1.2, 5.1.3). Only multiples of 2 dBm may be chosen (e.g. -202, -200, -198, ...). This field is set to the same value for different repetition numbers associated with a specific FeatureCombination .
preambleTransMax ENUMERATED {n3, n4, n5, n6, n7, n8, n10, n20, n50, n100, n200}	Max number of RA preamble transmission performed before declaring a failure (see TS 38.321 [3], clauses 5.1.4, 5.1.5). The UE shall ignore this field in case rach-ConfigGeneric is included within an EarlyUL-SyncConfig IE.
powerRampingStep ENUMERATED {dB0, dB2, dB4, dB6}	Power ramping steps for PRACH (see TS 38.321 [3],5.1.3). This field is set to the same value for different repetition numbers associated with a specific FeatureCombination.
ra-ResponseWindow ENUMERATED {sl1, sl2, sl4, sl8, sl10, sl20, sl40, sl80}	Msg2 (RAR) window length in number of slots. The network configures a value lower than or equal to 10 ms when Msg2 is transmitted in licensed spectrum and a value lower than or equal to 40 ms when Msg2 is transmitted with shared spectrum channel access (see TS 38.321 [3], clause 5.1.4). UE ignores the field if included in SCellConfig . If ra-ResponseWindow-v1610 or ra-ResponseWindow-v1700 is signalled, UE shall ignore the ra-ResponseWindow (without suffix). The field ra-ResponseWindow-v1700 is applicable to SCS 480 kHz and SCS 960 kHz. The UE shall ignore this field in case rach-ConfigGeneric is included within an EarlyUL-SyncConfig IE.
prach-ConfigurationPeriodScaling-IAB-r16 ENUMERATED {scf1,scf2,scf4,scf8,scf16,scf32,scf64} · OPTIONAL Need R since v16.1.0	Scaling factor to extend the periodicity of the baseline configuration indicated by prach-ConfigurationIndex and is used only by the IAB-MT . Value scf1 corresponds to scaling factor of 1 and so on. (see TS 38.211 [16], clause 6.3.3.2).
prach-ConfigurationFrameOffset-IAB-r16 INTEGER (0..63) · OPTIONAL Need R since v16.1.0	Frame offset for ROs defined in the baseline configuration indicated by prach-ConfigurationIndex and is used only by the IAB-MT. (see TS 38.211 [16], clause 6.3.3.2).
prach-ConfigurationSOffset-IAB-r16 INTEGER (0..39) · OPTIONAL Need R since v16.1.0	Subframe/Slot offset for ROs defined in the baseline configuration indicated by prach-ConfigurationIndex and is used only by the IAB-MT . (see TS 38.211 [16], clause 6.3.3.2).
ra-ResponseWindow-v1610 ENUMERATED { sl60, sl160} · OPTIONAL Need R since v16.1.0	Msg2 (RAR) window length in number of slots. The network configures a value lower than or equal to 10 ms when Msg2 is transmitted in licensed spectrum and a value lower than or equal to 40 ms when Msg2 is transmitted with shared spectrum channel access (see TS 38.321 [3], clause 5.1.4). UE ignores the field if included in SCellConfig . If ra-ResponseWindow-v1610 or ra-ResponseWindow-v1700 is signalled, UE shall ignore the ra-ResponseWindow (without suffix). The field ra-ResponseWindow-v1700 is applicable to SCS 480 kHz and SCS 960 kHz. The UE shall ignore this field in case rach-ConfigGeneric is included within an EarlyUL-SyncConfig IE.
prach-ConfigurationIndex-v1610 INTEGER (256..262) · OPTIONAL Need R since v16.1.0	PRACH configuration index. For prach-ConfigurationIndex configured under beamFailureRecoveryConfig , the prach-ConfigurationIndex can only correspond to the short preamble format, (see TS 38.211 [16], clause 6.3.3.2). If the field prach-ConfigurationIndex-v1610 is present, the UE shall ignore the value provided in prach-ConfigurationIndex (without suffix).
ra-ResponseWindow-v1700 ENUMERATED {sl240, sl320, sl640, sl960, sl1280, sl1920, sl2560} · OPTIONAL Need R since v17.0.0	Msg2 (RAR) window length in number of slots. The network configures a value lower than or equal to 10 ms when Msg2 is transmitted in licensed spectrum and a value lower than or equal to 40 ms when Msg2 is transmitted with shared spectrum channel access (see TS 38.321 [3], clause 5.1.4). UE ignores the field if included in SCellConfig . If ra-ResponseWindow-v1610 or ra-ResponseWindow-v1700 is signalled, UE shall ignore the ra-ResponseWindow (without suffix). The field ra-ResponseWindow-v1700 is applicable to SCS 480 kHz and SCS 960 kHz. The UE shall ignore this field in case rach-ConfigGeneric is included within an EarlyUL-SyncConfig IE.
sbfd-RACH-SingleConfig-preambleReceivedTargetPower-r19 INTEGER (-202..-60) · OPTIONAL Need R since v19.0.0	Configures preambleReceivedTargetPower for PRACH transmission in the second PRACH occasions or for Msg3 PUSCH transmission in SBFD symbols if sbfd-RACH-SingleConfig is configured, see clause 5 in TS 38.211 [16] and clause 8 in TS 38.213 [13].

Used by (8)

Uses (1)

maxNrofPhysicalResourceBlocks-1

RACH-ConfigGeneric

Definition

Fields (15)

Used by (8)

Uses (1)

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