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4G/LTE - CAT 0 |
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Category 0
Category 0 is a category that is added to LTE in Rel 12 with the maximum data rate of 1 Mbps. Why the lowest throughput category become so special in such a high throughput oriented technology like LTE ? It is because it has several important features as follows :
RRC Aspect for Category 0
As any other categories, UE need to inform to network that it supports Category 0 on UE Capability Information message. One thing you would notice is that Category 0 is specified in Rel 12 category and in Release 12 DL category and UL category is specified separately.
< UE Capability Information >
Following is an example of UE capability Information from a Cat 0 device captured by Amarisoft LTE Network Simulator. (I simplified the contents so that you can easily identify Cat 0 related IEs. For full UE capability message, click here) message c1: ueCapabilityInformation: { rrc-TransactionIdentifier 0, criticalExtensions c1: ueCapabilityInformation-r8: { ue-CapabilityRAT-ContainerList { { rat-Type eutra, ueCapabilityRAT-Container { accessStratumRelease rel12, ue-Category 1, pdcp-Parameters { supportedROHC-Profiles { .... } }, phyLayerParameters { ue-TxAntennaSelectionSupported FALSE, ue-SpecificRefSigsSupported TRUE }, rf-Parameters { supportedBandListEUTRA { { bandEUTRA 7, halfDuplex TRUE // halfDuplex is not mandatory for Category 0. // but network can apply Halfduplex if UE support // and network decided to do } } }, measParameters { bandListEUTRA { { interFreqBandList { { interFreqNeedForGaps FALSE } } } } }, featureGroupIndicators '5a000002'H interRAT-Parameters { }, nonCriticalExtension { phyLayerParameters-v920 { enhancedDualLayerFDD-r9 supported, enhancedDualLayerTDD-r9 supported }, ... nonCriticalExtension { lateNonCriticalExtension { nonCriticalExtension { nonCriticalExtension { ... } } } }, nonCriticalExtension { ... }, nonCriticalExtension { nonCriticalExtension { nonCriticalExtension { pdcp-Parameters-v1130 { }, phyLayerParameters-v1130 { .. }, rf-Parameters-v1130 { }, measParameters-v1130 { }, interRAT-ParametersCDMA2000-v1130 { }, otherParameters-r11 { }, nonCriticalExtension { nonCriticalExtension { nonCriticalExtension { nonCriticalExtension { rf-Parameters-v1250 { supportedBandListEUTRA-v1250 { { ... } } }, ue-CategoryDL-r12 0, // this indcate UE support Cat 0 for DL ue-CategoryUL-r12 0 // this indcate UE support Cat 0 for UL } } } } } } } } } } } } }, nonCriticalExtension { nonCriticalExtension { ue-RadioPagingInfo-r12 { ue-Category-v1250 0 } } } } }
NAS Asepect of Category 0
Usually NAS layer does not play much role to defining the service for UE category, but in case of Category 0 (in Category M in Rel 13 as well) there is special mode of operation called PSM (Power Saving Mode) and this PSM operation is defined by two specific NAS timer as shown below.
< Attach Request >
Following is an example of UE capability Information from a Cat 0 device captured by Amarisoft LTE Network Simulator. (I simplified the contents so that you can easily identify Cat 0 related IEs. For full UE capability message, click here)
EMM: Attach request Protocol discriminator = 0x7 (EPS Mobility Management) Security header = 0x0 (Plain NAS message, not security protected) Message type = 0x41 (Attach request) EPS attach type = 1 (EPS attach) NAS key set identifier: TSC = 0 NAS key set identifier = 1 Old GUTI or IMSI: ... UE network capability: ... ESM message container: Protocol discriminator = 0x2 (EPS Session Management) EPS bearer identity = 0 Procedure transaction identity = 1 Message type = 0xd0 (PDN connectivity request) Request type = 1 PDN type = 3 (IPv4v6) Protocol configuration options: ... Last visited registered TAI: MCC = 001 MNC = 01 TAC = 0x0001 T3324 value: value = 10 unit = 2 (decihours) T3412 extended value: value = 24 unit = 0 (10 minutes)
< Attach Accept >
Following is an example of UE capability Information from a Cat 0 device captured by Amarisoft LTE Network Simulator. (I simplified the contents so that you can easily identify Cat 0 related IEs. For full UE capability message, click here)
EMM: Attach accept Protocol discriminator = 0x7 (EPS Mobility Management) Security header = 0x2 (Integrity protected and ciphered) Auth code = 0xdbbf1ea2 Sequence number = 0x01 Protocol discriminator = 0x7 (EPS Mobility Management) Security header = 0x0 (Plain NAS message, not security protected) Message type = 0x42 (Attach accept) EPS attach result = 1 (EPS only) T3412 value: value = 0 unit = 7 (deactivated) TAI list: Length = 6 Data = 00 00 f1 10 00 01 ESM message container: Protocol discriminator = 0x2 (EPS Session Management) EPS bearer identity = 5 Procedure transaction identity = 1 Message type = 0xc1 (Activate default EPS bearer context request) EPS Qos: Length = 1 Data = 09 Access point name = "www.test.org" PDN address: PDN type = 1 (IPv4) IPv4 = 10.0.0.2 ESM cause = 0x32 (PDN type IPv4 only allowed) Protocol configuration options: ... GUTI: ... T3412 extended value: value = 24 unit = 0 (10 minutes) T3324 value: value = 10 unit = 2 (decihours)
For your study purpose, I put the link for full signaling logs below with the permission from Amarisoft. It looks a little intimidating but this is how real life log looks like.
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