5G/NR  -  NR Light/RedCap

 

 

 

 

 

NR-Light/RedCap

 

NR-Light, now officially terms as Reduced Capability (RedCap) in 3GPP NR Rel 17, is designed to function as LTE M1 /LTE NB IoT.  However there are some minor differences between RedCap and LTE counter part, some difference by design and some difference due to the difference of technology between NR and LTE. Followings are some of the highlights of Redcap.

  • Designed for simplified / low cost device ==> Same goal as LTE counterpart
  • Narrower bandwidth comparing to regular NR use case (eMBB), but narrowband here means up to 20 Mhz ==> Even though it is called narrow band, it is already same as the max bandwidth of single carrier LTE.
  • Low power is not the scope of RedCap ==> This is different from LTE counter part. It may reduce some power due to narrow bandwidth, but there is no RedCap specific power saving technique.
  • Half Duplex ==> RedCap would support ordinary FDD (full duplex FDD) and TDD, but it can support Half Duplex FDD

This is a super simplified summary of the RedCap feature and I would not extend it too much because I found a document about overall feature and usecase of RedCap that is much better than what I might have written here : What is reduced capability (RedCap) NR and what will it achieve?

 

For the implementation of RedCap, 3GPP release 17 added several features as listed below

  • SIB elements decaring the support of RedCap on gNB (e.g, SIB1, SIB4)
  • RRC-UE Capability Information : UE is supposed to inform its capability of RedCap support
  • RRC Reconfiguration : gNB may configure RedCap (e.g, RLC, PDCP configuration)
  • MAC CE : A few additional MAC CE elements for RedCap operation

 

 

MAC CE

 

 

 

 

UE Capability

 

 

UE-NR-Capability-v1700 ::= SEQUENCE {

   ...

   redCapParameters-r17                             RedCapParameters-r17 OPTIONAL,

   ...

}

 

RedCapParameters-r17::= SEQUENCE {

   -- R1 28-1: RedCap UE

   supportOfRedCap-r17                              ENUMERATED {supported} OPTIONAL,

   supportOf16DRB-RedCap-r17                        ENUMERATED {supported} OPTIONAL

}

 

BandNR ::= SEQUENCE {

   ...

   bwp-WithoutCD-SSB-OrNCD-SSB-RedCap-r17           ENUMERATED {supported} OPTIONAL,

   halfDuplexFDD-TypeA-RedCap-r17                   ENUMERATED {supported} OPTIONAL,

   ,,,

 

}

 

UERadioPagingInformation-v1700-IEs ::= SEQUENCE {

   ue-RadioPagingInfo-r17               OCTET STRING (CONTAINING UE-RadioPagingInfo-r17) OPTIONAL,

   inactiveStatePO-Determination-r17    ENUMERATED {supported} OPTIONAL,

   numberOfRxRedCap-r17                 ENUMERATED {one, two} OPTIONAL,

   hd-FDDRedCap-r17                     ENUMERATED {supported} OPTIONAL,

   nonCriticalExtension                 SEQUENCE {} OPTIONAL

}

 

 

 

RRC Parameters

 

SIB1-v1700-IEs ::= SEQUENCE {

   hsdn-Cell-r17                           ENUMERATED {true} OPTIONAL, -- Need R

   uac-BarringInfo-v1700 SEQUENCE {

      uac-BarringInfoSetList-v1700         UAC-BarringInfoSetList-v1700

   } OPTIONAL, -- Cond MINT

   sdt-ConfigCommon-r17                    SDT-ConfigCommonSIB-r17 OPTIONAL, -- Need R

   redCap-ConfigCommon-r17                 RedCap-ConfigCommonSIB-r17 OPTIONAL, -- Need R

   featurePriorities-r17 SEQUENCE {

      redCapPriority-r17                   FeaturePriority-r17 OPTIONAL, -- Need R

      slicingPriority-r17                  FeaturePriority-r17 OPTIONAL, -- Need R

      msg3-Repetitions-Priority-r17        FeaturePriority-r17 OPTIONAL, -- Need R

      sdt-Priority-r17                     FeaturePriority-r17 OPTIONAL -- Need R

   } OPTIONAL, -- Need R

   si-SchedulingInfo-v1700                 SI-SchedulingInfo-v1700 OPTIONAL, -- Need R

   hyperSFN-r17                            BIT STRING (SIZE (10)) OPTIONAL, -- Need R

   eDRX-AllowedIdle-r17                    ENUMERATED {true} OPTIONAL, -- Need R

   eDRX-AllowedInactive-r17                ENUMERATED {true} OPTIONAL, -- Cond EDRX-RC

   intraFreqReselectionRedCap-r17          ENUMERATED {allowed, notAllowed} OPTIONAL, -- Need S

   cellBarredNTN-r17                       ENUMERATED {barred, notBarred} OPTIONAL, -- Need S

   nonCriticalExtension                    SEQUENCE {} OPTIONAL

}

 

RedCap-ConfigCommonSIB-r17 ::= SEQUENCE {

   halfDuplexRedCapAllowed-r17             ENUMERATED {true} OPTIONAL, -- Need R

   cellBarredRedCap-r17 SEQUENCE {

      cellBarredRedCap1Rx-r17              ENUMERATED {barred, notBarred},

      cellBarredRedCap2Rx-r17              ENUMERATED {barred, notBarred}

   } OPTIONAL, -- Need R

   ...

}

 

SIB4 ::= SEQUENCE {

   interFreqCarrierFreqList                InterFreqCarrierFreqList,

   lateNonCriticalExtension                OCTET STRING OPTIONAL,

   ...,

   [[

   interFreqCarrierFreqList-v1610          InterFreqCarrierFreqList-v1610 OPTIONAL -- Need R

   ]],

   [[

   interFreqCarrierFreqList-v1700          InterFreqCarrierFreqList-v1700 OPTIONAL -- Need R

   ]]

}

 

InterFreqCarrierFreqInfo-v1700 ::= SEQUENCE {

   interFreqNeighHSDN-CellList-r17       InterFreqNeighHSDN-CellList-r17 OPTIONAL, -- Need R

   highSpeedMeasInterFreq-r17            ENUMERATED {true} OPTIONAL, -- Need R

   redCapAccessAllowed-r17               ENUMERATED {true} OPTIONAL, -- Need R

   ssb-PositionQCL-Common-r17       SSB-PositionQCL-Relation-r17 OPTIONAL, -- Cond SharedSpectrum

   interFreqNeighCellList-v1710     InterFreqNeighCellList-v1710 OPTIONAL -- Cond SharedSpectrum2

}

 

PosSI-SchedulingInfo-r16 ::= SEQUENCE {

   posSchedulingInfoList-r16         SEQUENCE (SIZE (1..maxSI-Message)) OF PosSchedulingInfo-r16,

   posSI-RequestConfig-r16           SI-RequestConfig OPTIONAL, -- Cond MSG-1

   posSI-RequestConfigSUL-r16        SI-RequestConfig OPTIONAL, -- Cond SUL-MSG-1

   ...,

   [[

   posSI-RequestConfig-RedCap-r17    SI-RequestConfig OPTIONAL -- Cond REDCAP-MSG-1

   ]]

}

 

DownlinkConfigCommon ::= SEQUENCE {

   frequencyInfoDL                   FrequencyInfoDL OPTIONAL, -- Cond InterFreqHOAndServCellAdd

   initialDownlinkBWP                BWP-DownlinkCommon OPTIONAL, -- Cond ServCellAdd

   ...,

   [[

   initialDownlinkBWP-RedCap-r17     BWP-DownlinkCommon OPTIONAL -- Need R

   ]]

}

 

DownlinkConfigCommonSIB ::= SEQUENCE {

   frequencyInfoDL                   FrequencyInfoDL-SIB,

   initialDownlinkBWP                BWP-DownlinkCommon,

   bcch-Config                       BCCH-Config,

   pcch-Config                       PCCH-Config,

   ...,

   [[

   pei-Config-r17 PEI-Config-r17     OPTIONAL, -- Need R

   initialDownlinkBWP-RedCap-r17     BWP-DownlinkCommon OPTIONAL -- Need R

   ]]

}

 

FeatureCombination-r17 ::= SEQUENCE {

   redCap-r17                        ENUMERATED {true} OPTIONAL, -- Need R

   smallData-r17                     ENUMERATED {true} OPTIONAL, -- Need R

   nsag-r17                          NSAG-List-r17 OPTIONAL, -- Need R

   msg3-Repetitions-r17              ENUMERATED {true} OPTIONAL, -- Need R

   spare4                            ENUMERATED {true} OPTIONAL, -- Need R

   spare3                            ENUMERATED {true} OPTIONAL, -- Need R

   spare2                            ENUMERATED {true} OPTIONAL, -- Need R

   spare1                            ENUMERATED {true} OPTIONAL -- Need R

}

 

PUCCH-ConfigCommon ::= SEQUENCE {

   pucch-ResourceCommon              INTEGER (0..15) OPTIONAL, -- Cond InitialBWP-Only

   pucch-GroupHopping                ENUMERATED { neither, enable, disable },

   hoppingId                         INTEGER (0..1023) OPTIONAL, -- Need R

   p0-nominal                        INTEGER (-202..24) OPTIONAL, -- Need R

   ...,

   [[

   nrofPRBs                          INTEGER (1..16) OPTIONAL, -- Need R

   intra-SlotFH-r17                  ENUMERATED {fromLowerEdge, fromUpperEdge} OPTIONAL, -- Need R

   pucch-ResourceCommon-RedCap-r17   INTEGER (0..15) OPTIONAL, -- Need R

   additionalPRBOffset-r17           ENUMERATED {n2, n3, n4, n6, n8, n9, n10, n12}OPTIONAL--Need S

   ]]

}

 

SI-SchedulingInfo-v1700 ::= SEQUENCE {

   schedulingInfoList2-r17           SEQUENCE (SIZE (1..maxSI-Message)) OF SchedulingInfo2-r17,

   si-RequestConfig-RedCap-r17       SI-RequestConfig OPTIONAL -- Cond REDCAP-MSG-1

}

 

UplinkConfigCommon-v1700 ::= SEQUENCE {

   initialUplinkBWP-RedCap-r17       BWP-UplinkCommon OPTIONAL -- Need R

}

 

UplinkConfigCommonSIB-v1700 ::= SEQUENCE {

   initialUplinkBWP-RedCap-r17       BWP-UplinkCommon OPTIONAL -- Need R

}

 

PDCP-Parameters ::= SEQUENCE {

   ...

   longSN-RedCap-r17                 ENUMERATED {supported} OPTIONAL,

   ...

}

 

RLC-Parameters ::= SEQUENCE {

   am-WithShortSN                    ENUMERATED {supported} OPTIONAL,

   um-WithShortSN                    ENUMERATED {supported} OPTIONAL,

   um-WithLongSN                     ENUMERATED {supported} OPTIONAL,

   ...,

   [[

   extendedT-PollRetransmit-r16      ENUMERATED {supported} OPTIONAL,

   extendedT-StatusProhibit-r16      ENUMERATED {supported} OPTIONAL

   ]],

   [[

   am-WithLongSN-RedCap-r17          ENUMERATED {supported} OPTIONAL

   ]]

}

 

 

 

 

Reference

 

 

YouTube

 

[1] Beginners: Introduction to NR-Light a.k.a. NR-Lite

[2] 5G NR-Light will serve sensors, wearables, and IoT

 

 

 

3GPP Reference

 

[1] RP-190831 : Key directions for Release 17 (Nokia)

[2] RP-190844 : NR-Lite for Rel-17 Qualcomm views (Qualcomm)

[3] RP-191047 : NR-Lite for Industrial Sensors and Wearables (Ericsson)

[4] RP-191175 : Motivation for NR-lite: IoT over NR (SamSung)

[5]