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 :
- Cat 0 is the category that meets the criteria of MTC (Refer to MTC for the details)
- Cat 0 is the category that supports PSM (Refer to PSM for the details)
- Therefore, Cat 0 is the category that is best fit for M2M or IoT.
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.
- ue log
- Network RRC layer log
- Network NAS layer log (MME log)