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UE Capability Information

 

UE Capability Information is an RRC message that UE sents to Network (in most case during initial registration process). It informs on all the details of its capabilities. As LTE release goes higher and more features are added, UE Capability Information has become the longest and most complicated Radio Message.

 

Very high level view of UE Capability Information message structure is shown below. The more you know of the contents the more you can understand about the UE and the better position you are at for troubleshooting. But I would suggest you to understand at least on how to interprete the contents of the highlighted items.

 

 

Since the message is too long and too complicated, it would be tricky to describe all of the contents in the single page. So I would split the message into a couple of categories as shown below and post separate pages for each of the categories. Try to get the high level understandings of UE capability information message and refer to following pages for the details.

 

In some case, we spend pretty much time and effort to troubleshoot something which is not supported by UE. So I recommend you to check before troubleshoot (especially for radio stack issue). Followings are some of the RRC message and IEs you can get UE capability information.

 

Note 1 : Take this as a guideline but don't trust too much. Sometimes UE information says 'Supported' but in reality does not working correct. Sometimes UE information does not mention something 'supported' but seems to work.

 

 

< LTE >

 

Release 8 FDD LTE, I see most of features are pretty mature and most of functions would work as expected, but Rel 8 TDD LTE and Rel 9 or higher both FDD and TDD I strongly recommend you to check on all these information before you test. Also it would be a good idea to check these information first before you test anything on Measurement, InterRAT.

 

RRC : UE Capability Information

    UE-EUTRA-Capability.accessStratumRelease

    UE-EUTRA-Capability.ue-Category

    UE-EUTRA-Capability.pdcp-Parameters.supportedROHC-Profiles

    UE-EUTRA-Capability.rf-Parameters.supportedBandListEUTRA

    UE-EUTRA-Capability.measParameters

    UE-EUTRA-Capability.interRAT-Parameters

    UE-EUTRA-Capability.featureGroupIndicators

      • Intra-subframe freq hopping for PUSCH scheduled by UL grant; DCI format 3a; Aperiodic CQI/PMI/RI report on PUSCH: Mode 2-0 & 2-2
      • Simultaneous CQI & ACK/NACK on PUCCH (format 2a/2b); Absolute TPC command for PUSCH; Resource alloc type 1 for PDSCH; Periodic CQI/PMI/RI report on PUCCH: Mode 2-0 & 2-1
      • 5bit RLC UM SN; 7bit PDCP SN
      • Short DRX cycle
      • Long DRX cycle; DRX command MAC control element
      • Prioritised bit rate
      • RLC UM
      • EUTRA RRC_CONNECTED to UTRA CELL_DCH PS handover
      • EUTRA RRC_CONNECTED to GERAN GSM_Dedicated handover
      • EUTRA RRC_CONNECTED to GERAN (Packet_) Idle by Cell Change Order; EUTRA RRC_CONNECTED to GERAN (Packet_) Idle by Cell Change Order with NACC
      • EUTRA RRC_CONNECTED to CDMA2000 1xRTT CS Active handover
      • EUTRA RRC_CONNECTED to CDMA2000 HRPD Active handover
      • Inter-frequency handover (within FDD or TDD)
      • Measurement reporting event: Event A4 - Neighbour > threshold; Measurement reporting event: Event A5 - Serving < threshold1 & Neighbour > threshold2
      • Measurement reporting event: Event B1 - Neighbour > threshold
      • non-ANR related periodical measurement reporting
      • ANR related intra-frequency measurement reporting events
      • ANR related inter-frequency measurement reporting events
      • ANR related inter-RAT measurement reporting events
      • SRB1 and SRB2 for DCCH + 8x AM DRB; SRB1 and SRB2 for DCCH + 5x AM DRB + 3x UM DRB (if indicator 7 is supported)
      • Predefined intra- and inter-subframe frequency hopping for PUSCH with N_sb > 1; Predefined inter-subframe frequency hopping for PUSCH with N_sb > 1
      • UTRAN measurements, reporting and measurement reporting event B2 in E-UTRA connected mode
      • GERAN measurements, reporting and measurement reporting event B2 in E-UTRA connected mode
      • 1xRTT measurements, reporting and measurement reporting event B2 in E-UTRA connected mode
      • Inter-frequency measurements and reporting in E-UTRA connected mode
      • HRPD measurements, reporting and measurement reporting event B2 in E-UTRA connected mode
      • EUTRA RRC_CONNECTED to UTRA CELL_DCH CS handover
      • TTI bundling
      • Semi-Persistent Scheduling
      • Handover between FDD and TDD
      • Mechanisms defined for cells broadcasting multi band information

    UE-EUTRA-Capability...nonCriticalExtension...featureGroupIndRel9Add-r9

      • Inter-RAT ANR features for UTRAN FDD
      • Inter-RAT ANR features for GERAN
      • Inter-RAT ANR features for 1xRTT
      • Inter-RAT ANR features for HRPD
      • Inter-RAT ANR features for UTRAN TDD
      • EUTRA RRC_CONNECTED to UTRA TDD CELL_DCH PS handover
      • UTRAN TDD measurements, reporting and measurement reporting event B2 in E-UTRA connected mode
      • EUTRA RRC_CONNECTED to UTRA TDD CELL_DCH CS handover
      • Measurement reporting event: Event B1 - Neighbour > threshold for UTRAN FDD

Followings are some of the complete message example for UE Capability Information message.

 

Example 1 : UE Capability Information

 

 

< WCDMA/TDSCDMA >

 

Regarding WCDMA,

since WCDMA is pretty mature now, most of basic features are supported and works OK, but if you try to some recent feature (e.g, DRX, CPC, e-dch, F_DPCHenhanced Cell FACH) and interRAT (e.g, with LTE or TDSCDMA or GSM) it is highly recommended to check on this.

 

Regarding TDSCDMA,

Even thought TDSCDMA has been in the market for several years, but it doesn't seem to be as mature and stable as WCDMA. As a result, I see much more issues related to 'lack of capability' or 'mismatch between UE capability report and real implementation'.

 

You may get some high level WCDMA/TDSCDMA capability from LTE UE Capability Information message, but if you want to have full details of UE capability I would suggest you to look into WCDMA/TDSCDMA RRC Message as shown below.

 

 

RRC : RRC Connection Request

 

Followings are the UE capability information you can get from RRC Connection Request. This list would get longer as the technology evolves

  • rrcConnectionRequest-v4b0ext.accessStratumReleaseIndicator
  • rrcConnectionRequest-v690ext.ueCapabilityIndication
  • rrcConnectionRequest-v6e0ext.supportForFDPCH
  • rrcConnectionRequest-v770ext.hspdschReception-CellFach
  • rrcConnectionRequest-v770ext.mac-ehsSupport
  • rrcConnectionRequest-v770ext.discontinuousDpcchTransmission
  • rrcConnectionRequest-v7b0ext.supportForE-FDPCH
  • rrcConnectionRequest-v860ext.supportOfCommonEDCH
  • rrcConnectionRequest-v860ext.multiCellSupport
  • rrcConnectionRequest-v860ext.pre-redirectionInfo.supportEUTRA-FDD
  • rrcConnectionRequest-v860ext.pre-redirectionInfo.supportEUTRA-TDD
  • rrcConnectionRequest-v860ext.supportOfMACiis
  • rrcConnectionRequest-v860ext.supportOfSPSOperation

 

Example 1 : RRC Connection Request

 

 

RRC : RRC Connection Setup Complete

 

Followings are some of common items you'd better check. Some of them are TDSCDMA sepcific.

  • ue-MultiModeRAT-Capability.multiRAT-CapabilityList.supportOfGSM
  • ue-MultiModeRAT-Capability.multiRAT-CapabilityList.supportOfMulticarrier
  • ue-MultiModeRAT-Capability.multiModeCapability
  • rrcConnectionSetupComplete-v7e0ext.ue-RadioAccessCapability.supportForTwoDRXSchemesInPCH
  • rrcConnectionSetupComplete-v7e0ext.ue-RadioAccessCapability.supportEDPDCHPowerInterpolation
  • ue-RadioAccessCapability-v4b0ext.accessStratumReleaseIndicator
  • ue-RadioAccessCapability-v590ext.physicalChannelCapability.fdd-hspdsch.hsdsch-physical-layer-category
  • ue-RadioAccessCapability-v590ext.physicalChannelCapability.tdd128-hspdsch
  • ue-RadioAccessCapability-v690ext.physicalchannelcapability-edch.fdd-edch.edch-PhysicalLayerCategory
  • v6b0NonCriticalExtensions.v6e0NonCriticalExtensions.ue-RadioAccessCapability-v6e0ext.supportForFDPCH
  • ue-RadioAccessCapability-v770ext.physicalChannelCapability.fddPhysChCapability.downlinkPhysChCapability.hsdsch-physical-layer-category-ext
  • ue-RadioAccessCapability-v860ext.physicalChannelCapability.fddPhysChCapability.downlinkPhysChCapability.hsdsch-physical-layer-category-ext2
  • ue-RadioAccessCapability-v860ext.physicalChannelCapability.fddPhysChCapability.downlinkPhysChCapability.supportOfHsdschDrxOperation
  • ue-RadioAccessCapability-v770ext.physicalChannelCapability.fddPhysChCapability.downlinkPhysChCapability.enhancedFdpch
  • ue-RadioAccessCapability-v770ext.physicalChannelCapability.fddPhysChCapability.uplinkPhysChCapability.discontinuousDpcchTransmission
  • ue-RadioAccessCapability-v770ext.physicalChannelCapability.fddPhysChCapability.uplinkPhysChCapability.slotFormat4
  • ue-RadioAccessCapability-v860ext.multiModeRAT-Capability.supportOfEUTRAFDD
  • ue-RadioAccessCapability-v860ext.multiModeRAT-Capability.supportOfInterRATHOToEUTRAFDD
  • ue-RadioAccessCapability-v860ext.multiModeRAT-Capability.supportOfEUTRATDD
  • ue-RadioAccessCapability-v860ext.multiModeRAT-Capability.supportOfInterRATHOToEUTRATDD
  • ue-RadioAccessCapability-v770ext.mac-ehsSupport
  • ue-RadioAccessCapability-v860ext.multiModeRAT-Capability.supportOfEUTRAFDD
  • ue-RadioAccessCapability-v860ext.multiModeRAT-Capability.eutraFeatureGroupIndicators
  • ue-RadioAccessCapability-v880ext.supportForPriorityReselectionInUTRAN
  • ue-RadioAccessCapability.rf-Capability.tddRF-Capability.chipRateCapability
  • ue-RadioAccessCapability.rf-Capability.multiRAT-CapabilityList.supportOfGSM
  • ue-RadioAccessCapability.rf-Capability.multiRAT-CapabilityList.supportOfMulticarrier
  • ue-RadioAccessCapability.rf-Capability.multiModeCapability
  • ue-RadioAccessCapability-v4b0ext.tdd-CapabilityExt.physicalChannelCapability-LCR.tdd128-PhysChCapability.downlinkPhysChCapability.supportOfPDSCH
  • ue-RadioAccessCapability-v4b0ext.tdd-CapabilityExt.physicalChannelCapability-LCR.tdd128-PhysChCapability.uplinkPhysChCapability.supportOfPUSCH
  • ue-RadioAccessCapability-v590ext.physicalChannelCapability.tdd128-hspdsch
  • ue-RadioAccessCapability-v590ext.physicalChannelCapability.multiModeRAT-Capability-v590ext.supportOfUTRAN-ToGERAN-NACC
  • ue-RadioAccessCapability-v770ext.physicalChannelCapability.tddPhysChCapability-128.uplinkPhysChCapability.tdd128-edch

 

Example 1 : RRC Connection Setup Complete

 

 

< GSM >

 

UE Capability for GSM is specified in gsm-Classmark(gsm-Classmark2, gsm-Classmark3). This IE is usually carried by WCDMA RRC Connection Setup Complete message and by GSM Attach Request message.

 

gsm-Classmark

  • PS capability (pseudo-synchronization capability)
  • SM capability (MT SMS pt to pt capability)
  • FC Frequency Capability
  • UCS2 treatment
  • Multiband supported field.GSM 1800 Supported
  • Multiband supported field.E-GSM or R-GSM Supported
  • Multiband supported field.P-GSM Supported
  • Extended Measurement Capability
  • MS measurement capability
  • GSM 400 Band Information present
  • GSM 850 Associated Radio Capability present
  • GSM 1900 Associated Radio Capability present
  • UMTS FDD Radio Access Technology Capability
  • CDMA 2000 Radio Access Technology Capability
  • DTM E/GPRS Multi Slot Information present
  • Single Band Support
  • GSM 750 Associated Radio Capability present
  • UMTS 1.28 Mcps TDD Radio Access Technology Capability
  • T-GSM 400 Band Information present
  • T-GSM 900 Associated Radio Capability present
  • DTM Enhancements Capability

 

Example 1 : RRC Connection Setup Complete

Example 2 : GSM Attach Request

 

 

< Other Factors >

 

Followings are not directly related to UE Capability, but sometimes we see various issues caused by these message correlation.

 

Message Correlation : WCDMA/TDSCDMA

Message Correlation : LTE

 

 

How long the message can be ?

 

I am not aware if there is any explicit size limit for any RRC message. Why we need to worry about the size limitation of RRC message ?  We haven't even thought of this for most of the case, but we start worrying about size limitation of RRC message as UE Capability Information message gets almost exploded in terms of message length (size).

When LTE first got deployed with Release 8 specification, the UE Capability Information message was just like any other RRC messages in terms of the length. However, As LTE Release goes higher, the size gets larger as each release add its own FGI (Feature Group Indicator). But the size increase by FGI was minor. The real explosion of the size came out with the support of Carrier Aggregation. At the early phase of Carrier Aggregation (Early Release 10), only 2 CC CA(Component Carrier Carrier Aggregation) was supported and the supported band combination was not so complicated. However, as higher carrier aggregation (i.e, 2CC CA, 3CC CA, 4CC CA) is supported and more band combinations are supported, the size of UE Capability Information message got exploded. As of Release 13, we have almost several hundreds possible band combinations. As you MAY noticed, UE Category 17 in Release 13 support 32 CC CA (I hope this would not be really deployed :) and I am pretty sure that it will not be deployed in real network). The current several hundred different combination is not with 3CC CA.

In my personal experience, I think I had experience with Software Crash on a Network Simulator for almost every new 3GPP Release. The root cause was a kind of message buffer overflow, meaning that the size of the incoming signaling message hit the size of memory allocated to store the message.

What would be the solution for handling this kind of too over-sized message ?  One brutal solution would be to reserve super-large message buffer size and ensure that your ASN decoder works properly for such a super large tree structure.

Another possible solution (seemingly better solution) would be to limit the scope of the information that UE report in UE Capability Information message.

Until the early phase of Carrier Aggregation, we normally used to use UE Capability Enquiry message as in [Case 1]. The Enquiry item is configured very simple. It just says 'Tell me everything about your capability on 'EUTRA'. If the UE support full capability of Rel 13 and a lot of band combination.. be careful of system crash :)

In recent release, 3GPP support additional Information Elements as in Case 2 by which Network can specify (limit) the scope of UE capability report. With this, Network can force UE to send the only capability information that are necessary to the current Network.

 

 

< Case 1 >

 

DL-DCCH-Message ::= SEQUENCE

  +-message ::= CHOICE [c1]

    +-c1 ::= CHOICE [ueCapabilityEnquiry]

      +-ueCapabilityEnquiry ::= SEQUENCE

        +-rrc-TransactionIdentifier ::= INTEGER (0..3) [0]

        +-criticalExtensions ::= CHOICE [c1]

          +-c1 ::= CHOICE [ueCapabilityEnquiry-r8]

            +-ueCapabilityEnquiry-r8 ::= SEQUENCE [0]

              +-ue-CapabilityRequest ::= SEQUENCE OF SIZE(1..maxRAT-Capabilities[8]) [1]

              | +-RAT-Type ::= ENUMERATED [eutra]

              +-nonCriticalExtension ::= SEQUENCE OPTIONAL:Omit

 

 

< Case 2 >

 

DL-DCCH-Message ::= SEQUENCE

  +-message ::= CHOICE [c1]

    +-c1 ::= CHOICE [ueCapabilityEnquiry]

      +-ueCapabilityEnquiry ::= SEQUENCE

        +-rrc-TransactionIdentifier ::= INTEGER (0..3) [0]

        +-criticalExtensions ::= CHOICE [c1]

          +-c1 ::= CHOICE [ueCapabilityEnquiry-r8]

            +-ueCapabilityEnquiry-r8 ::= SEQUENCE [1]

              +-ue-CapabilityRequest ::= SEQUENCE OF SIZE(1..maxRAT-Capabilities[8]) [1]

              | +-RAT-Type ::= ENUMERATED [eutra]

              +-nonCriticalExtension ::= SEQUENCE [11] OPTIONAL:Exist

                +-lateNonCriticalExtension ::= OCTET STRING SIZE(ALIGNED) OPTIONAL:Exist

                +-nonCriticalExtension ::= SEQUENCE [11] OPTIONAL:Exist

                  +-requestedFrequencyBands-r11 ::= SEQUENCE OF SIZE(1..16) [4] OPTIONAL:Exist

                  | +-FreqBandIndicator-r11 ::= INTEGER (1..maxFBI2[256]) [1]

                  | +-FreqBandIndicator-r11 ::= INTEGER (1..maxFBI2[256]) [3]

                  | +-FreqBandIndicator-r11 ::= INTEGER (1..maxFBI2[256]) [17]

                  | +-FreqBandIndicator-r11 ::= INTEGER (1..maxFBI2[256]) [28]

                  +-nonCriticalExtension ::= SEQUENCE [11111] OPTIONAL:Exist

                    +-requestReducedFormat-r13 ::= ENUMERATED [true] OPTIONAL:Exist

                    +-skipFallbackCombinations-r13 ::= ENUMERATED [true] OPTIONAL:Exist

                    +-requestedMaxCCsDL-r13 ::= INTEGER (2..32) [2] OPTIONAL:Exist

                    +-requestedMaxCCsUL-r13 ::= INTEGER (2..32) [2] OPTIONAL:Exist

                    +-nonCriticalExtension ::= SEQUENCE OPTIONAL:Exist