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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 :

  • 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.