LTE UE Capability

"UE Capability Information" is an RRC message sent by the UE in response to "UE Capability Enquiry" message from the network. These messages are part of LTE attach procedure. It contains all the information that the UE is capable of, which are explained below. With the addition of LTE carrier aggregation and 4x4 MIMO the length of UE Capability Information message has become bigger.

  • Supported IRAT technologies

  • Supported bands on LTE, UMTS & GSM technologies

The list of supported LTE bands are reported in "supportedBandListEUTRA". The list of supported WCDMA and GSM bands are reported in IE "interRAT-Parameters" under "utraFDD" and "geran" respectively.

  • UE Category

The category that UE support is indicated in “UE Capability Information” message. Notice that IE “ue-Category” can specify only up to Cat 4.  The category higher than 4 should be assigned to another IE.

UE Category 5 & 6 will be assigned to IE “ue-Category-v1020”.

UE Category 9 & 10 will be assigned to IE “ue-Category-v1170”.

UE Category 11 & 12 will be assigned to IE “ue-Category-v11a0”.

The UE could report all of the above IE's but we will have to consider only the IE which contains the highest category.

  • Carrier Aggregation Band Combination in Downlink and Uplink

The list of CA band combinations supported by the UE are mentioned under the IE “supportedBandCombination-r10”. The “bandEUTRA-r10” mentions the LTE bands, the element “ca-BandwidthClassDL-r10” mentions the Aggregated Transmission Bandwidth Combination a, b or c in downlink and the element “ca-BandwidthClassUL-r10” mentions the Aggregated Transmission Bandwidth Combination a, b or c in uplink.

 

In Carrier Aggregation there is only one PCell(Serving cell) but can contain any number of SCell's(Neighboring cell). In each CA combination there will only be one PCell and the other bands will be the SCell(s). Please refer to page "Carrier Aggregation" for more information.

In the below image, the supported CA band combinations are 1c in downlink and 1c in uplink.

  • 256QAM Downlink and 64QAM in Uplink

We can check the "UE Capability Information" for the list of LTE bands supporting 256QAM in downlink and 64QAM in uplink. By default when 256QAM DL and 64QAM UL is supported by any device then it’s basically on all bands. The supported LTE bands in IE “supportedBandListEUTRA” are mapped sequentially to the IE “supportedBandListEUTRA-v1250”.

  • Dynamic UE Capability

There is a new method to save the length of LTE CA band combinations which will in turn reduce the length of "UECapabilityInformation" message sent by the UE. If the IE "freqBandRetrieval-r11" is reported by the UE in the capability then it means dynamic UE capability is supported.

  • Feature Group Indicator(FGI)

Feature Group Indicator is a special IE (Information Element) within UE Capability Information message. Feature Group Indicator mostly carries the information about Radio protocol aspects.

 

The meaning of each FGI bit is defined in 3GPP specification 36.331.

  • featureGroupIndicators : 36.331-Annex B Table B.1-1

  • featureGroupIndRel9Add : 36.331-Annex B Table B.1-1a

  • featureGroupIndRel10 : 36.331-Annex C Table C.1-1

​Please see below the complete list of Feature Group Indicator from a sample device.