We are using the RG255C-GL in a 5G SA RedCap and would like to clarify whether the module supports RC_INACTIVE.
Setup:
Module: Quectel RG255C-GL
Firmware: RG255CGLABR01A05M4G_A0.300.A0.300
Observation:
We captured the NGAP UERadioCapabilityInfoIndication messages for two separate registrations and decoded them with Wireshark. In both messages, the UE-NR-Capability is fully decoded: ccessStratumRelease = rel17, supportOfRedCap-r17 = supported, and the nonCriticalExtension chain is present from v1530 to v1700. However, the inactiveState field in UE-NR-Capability-v1530 is absent. TS 38.306 lists inactiveState as a per-UE capability with M = Yes.
Does the RG255C-GL support RRC_INACTIVE in 5G SA RedCap operation?
Dear @Jameel_Ali Summary: Absence of inactiveState in UE-NR-Capability-v1530 is normal and spec-compliant
The inactiveState field in UE-NR-Capability-v1530 indicates whether the UE supports RRC_INACTIVE. In TS 38.306 (Table 4.2.x, General parameters), it is listed as a per-UE capability with M = Yes, which means RRC_INACTIVE is a mandatory feature since NR Release 15 — any UE declaring an access stratum release of Rel-15 or higher must implement it.
The key point is that “mandatory” applies to the feature, not to the presence of the capability field:
In the ASN.1 definition (TS 38.331), inactiveState is an OPTIONAL field (ENUMERATED {supported} OPTIONAL), so omitting it is a perfectly legal encoding.
Per TS 38.306, for mandatory features that still carry a capability parameter, the field does not signal “whether the feature is supported” — it signals “whether the feature has been successfully tested/validated”. Therefore, an absent field simply means the vendor did not declare the feature as validated; it does not mean the UE lacks RRC_INACTIVE support.
From a pure signaling-compliance standpoint, the network must still treat RRC_INACTIVE as supported and can configure suspend/resume and RNA procedures regardless of this field.
The only practical impact is in test/acceptance scenarios: some conformance tools or operator acceptance criteria use this field as a marker for “RRC_INACTIVE flow (suspend → paging → resume) has been validated.” If it is missing, such checks may be flagged as “not validated” — but the root cause to investigate would be actual implementation behavior, not the capability reporting itself.
Bottom line: An absent inactiveState is normal and spec-compliant. It means the feature is supported (mandatory) but not explicitly marked as tested/validated. Vendors only need to add the field when there is an explicit requirement to declare validation status.