Operation Mode

LTE BL/CE can operate in two different mode and these two mode are specified for RRC Connected state.  The operation mode are configured by the eNB. In general, which mode to use is dependent on CE Level. (Ref [4])

• CE Mode A
• CE Mode B
• Mode vs Level vs Preamble Group
• How to Configure CE Mode ?
• PDSCH / PUSCH / PUCCH Max Repetition Differences between CE Mode A and B
• RACH Random Access Response Grant Content field size difference between CE Mode A and B

CE Mode A

• No repetition or small number of repetition (Ref [4])
• Operation in CE Mode A would have an equivalent coverage as that of UE Category 1.  The difference in coverage between LTE-M1 and UE Category 1 lies in the fact that LTE-M1 uses only 1 Rx, 6 PRB narrowband and reduced uplink transmit power. The redeuced Uplink power in LTE-M1 is compensated by utilising a small number of repetitions.(Ref [4])
• Power control mechanism is same as in legacy LTE(non-MTC) power control mechanism. Basically Uplink power is controlled by DCI format 6-0A(UL Grant=PUSCH Scheduling),6-1A(PDSCH Scheduling),3,3A. If the transmission is in repetition mode, the power remain same within the same repetition period (36.213-5.1.1.1,5.1.2.1)

CE Mode B

• Large number of repetitions(Ref [4])
• CE Mode B has coverage up to 15 dB coverage enhancement with reference to that of UE Category 1.(Ref [4])
• Transmission power for both PUCCH and PUSCH is set to be MAX. Since the power does not changes (i.e, no power control is performed) DCI format 6-0B and 6-1B does not carry TPC(Trnasmission Power Control) field. As you may guess, this mode is designed to be used in very poor propagation condition.(36.213-5.1.1.1,5.1.2.1)

Mode vs Level vs Preamble Group

When you read the specifications of LTE M1(BL/CE) or any other technical documents, you often see the cases where CEmode is used with CE Level and sometimes with RACH Preamble Group, and got confused a lot.  My suggestion is

• Understand the concept of CE Mode and CE Level first
• Understand how CE Mode and CE Levels are related (The table in CE Level page would give you the answer)
• Understand how UE notifies the network about the CE Mode / Level it is taking (See Preamble Group page)

How to Configure CE Mode ?

Network can configure CE Mode via the following IE in a RRC Message like RRC Connection Setup, RRCConnectionReconfiguration or RRCConnectionReestablishment

ce-Mode-r13 CHOICE {

    release     NULL,

    setup       ENUMERATED {ce-ModeA,ce-ModeB}

}   

Example 1 > ====================================================================

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

  +-radioResourceConfigDedicated ::= SEQUENCE [100101]

  | +-srb-ToAddModList ::= SEQUENCE OF SIZE(1..2) [1] OPTIONAL:Exist

  | +-drb-ToAddModList ::= SEQUENCE OF OPTIONAL:Omit

  | +-drb-ToReleaseList ::= SEQUENCE OF OPTIONAL:Omit

  | +-mac-MainConfig ::= CHOICE [explicitValue] OPTIONAL:Exist

  | +-sps-Config ::= SEQUENCE OPTIONAL:Omit

  | +-physicalConfigDedicated ::= SEQUENCE [1101000011] OPTIONAL:Exist

  | | +-pdsch-ConfigDedicated ::= SEQUENCE OPTIONAL:Exist

  | | +-pucch-ConfigDedicated ::= SEQUENCE [0] OPTIONAL:Exist

  | | +-pusch-ConfigDedicated ::= SEQUENCE OPTIONAL:Omit

  | | +-uplinkPowerControlDedicated ::= SEQUENCE [1] OPTIONAL:Exist

  | | +-tpc-PDCCH-ConfigPUCCH ::= CHOICE OPTIONAL:Omit

  | | +-tpc-PDCCH-ConfigPUSCH ::= CHOICE OPTIONAL:Omit

  | | +-cqi-ReportConfig ::= SEQUENCE OPTIONAL:Omit

  | | +-soundingRS-UL-ConfigDedicated ::= CHOICE OPTIONAL:Omit

  | | +-antennaInfo ::= CHOICE [defaultValue] OPTIONAL:Exist

  | | +-schedulingRequestConfig ::= CHOICE [setup] OPTIONAL:Exist

  | | +-EXTENSION ::= SEQUENCE [00010010]

  | |   +-VERSION-BRACKETS1 ::= SEQUENCE OPTIONAL:Omit

  | |   +-VERSION-BRACKETS2 ::= SEQUENCE OPTIONAL:Omit

  | |   +-VERSION-BRACKETS3 ::= SEQUENCE OPTIONAL:Omit

  | |   +-VERSION-BRACKETS4 ::= SEQUENCE [0000100000] OPTIONAL:Exist

  | |   +-VERSION-BRACKETS5 ::= SEQUENCE OPTIONAL:Omit

  | |   +-VERSION-BRACKETS6 ::= SEQUENCE OPTIONAL:Omit

  | |   +-VERSION-BRACKETS7 ::= SEQUENCE [0000000000100] OPTIONAL:Exist

  | |   | +-pdsch-ConfigDedicated-v1310 ::= SEQUENCE OPTIONAL:Omit

  | |   | +-pucch-ConfigDedicated-r13 ::= SEQUENCE OPTIONAL:Omit

  | |   | +-pusch-ConfigDedicated-r13 ::= SEQUENCE OPTIONAL:Omit

  | |   | +-pdcch-CandidateReductions-r13 ::= CHOICE OPTIONAL:Omit

  | |   | +-cqi-ReportConfig-v1310 ::= SEQUENCE OPTIONAL:Omit

  | |   | +-soundingRS-UL-ConfigDedicated-v1310 ::= CHOICE OPTIONAL:Omit

  | |   | +-soundingRS-UL-ConfigDedicatedUpPTsExt-r13 ::= CHOICE OPTIONAL:Omit

  | |   | +-soundingRS-UL-ConfigDedicatedAperiodic-v1310 ::= CHOICE OPTIONAL:Omit

  | |   | +-soundingRS-UL-ConfigDedicatedAperiodicUpPTsExt-r13 ::= CHOICE OPTIONAL:Omit

  | |   | +-csi-RS-Config-v1310 ::= SEQUENCE OPTIONAL:Omit

  | |   | +-ce-Mode-r13 ::= CHOICE [setup] OPTIONAL:Exist

  | |   | | +-setup ::= ENUMERATED [ce-ModeA]

  | |   | +-csi-RS-ConfigNZPToAddModListExt-r13 ::= SEQUENCE OF OPTIONAL:Omit

  | |   | +-csi-RS-ConfigNZPToReleaseListExt-r13 ::= SEQUENCE OF OPTIONAL:Omit

  | |   +-VERSION-BRACKETS8 ::= SEQUENCE OPTIONAL:Omit

HEX : 60 12 9B 07 E8 68 C3 06 4C 00 08 C0 E2 41 A1 04 52 0C 07 00 00 00 14 0F C4 00 00 00 40 04 80

PDSCH / PUSCH / PUCCH Max Repetition Differences between CE Mode A and B

PDSCH-ConfigCommon-v1310 ::=    SEQUENCE {

    pdsch-maxNumRepetitionCEmodeA-r13   ENUMERATED { r16, r32 }     

    pdsch-maxNumRepetitionCEmodeB-r13   ENUMERATED { r192,r256,r384,r512,r768,r1024,r1536,r2048}   

}

PUSCH-ConfigCommon-v1310 ::=    SEQUENCE {

    pusch-maxNumRepetitionCEmodeA-r13   ENUMERATED { r8, r16, r32 }                  

    pusch-maxNumRepetitionCEmodeB-r13   ENUMERATED { r192,r256,r384,r512,r768,r1024,r1536,r2048}  

    pusch-HoppingOffset-v1310  INTEGER (1..maxAvailNarrowBands-r13) 

}

pucch-NumRepetitionCE-r13 CHOICE {

        release                     NULL,

        setup                       CHOICE {

            modeA   SEQUENCE {

                pucch-NumRepetitionCE-format1-r13   ENUMERATED {r1, r2, r4, r8},

                pucch-NumRepetitionCE-format2-r13   ENUMERATED {r1, r2, r4, r8}

            },

            modeB   SEQUENCE {

                pucch-NumRepetitionCE-format1-r13   ENUMERATED {r4, r8, r16, r32},

                pucch-NumRepetitionCE-format2-r13   ENUMERATED {r4, r8, r16, r32}

            }

        }

    }   

Example 1 > ====================================================================

+-sib2 ::= SEQUENCE [00]

  +-ac-BarringInfo ::= SEQUENCE OPTIONAL:Omit

  +-radioResourceConfigCommon ::= SEQUENCE

  | +-bcch-Config ::= SEQUENCE

  | +-pcch-Config ::= SEQUENCE

  | +-prach-Config ::= SEQUENCE

  | +-pdsch-ConfigCommon ::= SEQUENCE

  | +-pusch-ConfigCommon ::= SEQUENCE

  | +-pucch-ConfigCommon ::= SEQUENCE

  | +-soundingRS-UL-ConfigCommon ::= CHOICE [release]

  | +-uplinkPowerControlCommon ::= SEQUENCE

  | +-ul-CyclicPrefixLength ::= ENUMERATED [len1]

  | +-EXTENSION ::= SEQUENCE [0001]

  |   +-VERSION-BRACKETS1 ::= SEQUENCE OPTIONAL:Omit

  |   +-VERSION-BRACKETS2 ::= SEQUENCE OPTIONAL:Omit

  |   +-VERSION-BRACKETS3 ::= SEQUENCE OPTIONAL:Omit

  |   +-VERSION-BRACKETS4 ::= SEQUENCE [1111111] OPTIONAL:Exist

  |     +-bcch-Config-v1310 ::= SEQUENCE OPTIONAL:Exist

  |     +-pcch-Config-v1310 ::= SEQUENCE [1] OPTIONAL:Exist

  |     +-freqHoppingParameters-r13 ::= SEQUENCE [000000] OPTIONAL:Exist

  |     +-pdsch-ConfigCommon-v1310 ::= SEQUENCE [11] OPTIONAL:Exist

  |     | +-pdsch-maxNumRepetitionCEmodeA-r13 ::= ENUMERATED [r16] OPTIONAL:Exist

  |     | +-pdsch-maxNumRepetitionCEmodeB-r13 ::= ENUMERATED [r192] OPTIONAL:Exist

  |     +-pusch-ConfigCommon-v1310 ::= SEQUENCE [110] OPTIONAL:Exist

  |     | +-pusch-maxNumRepetitionCEmodeA-r13 ::= ENUMERATED [r8] OPTIONAL:Exist

  |     | +-pusch-maxNumRepetitionCEmodeB-r13 ::= ENUMERATED [r192] OPTIONAL:Exist

  |     | +-pusch-HoppingOffset-v1310 ::= INTEGER OPTIONAL:Omit

  |     +-prach-ConfigCommon-v1310 ::= SEQUENCE [11] OPTIONAL:Exist

  |     +-pucch-ConfigCommon-v1310 ::= SEQUENCE [11100] OPTIONAL:Exist

  |       +-n1PUCCH-AN-InfoList-r13 ::= SEQUENCE OF SIZE(1..maxCE-Level-r13[4]) [1] OPTIONAL:Exist

  |       +-pucch-NumRepetitionCE-Msg4-Level0-r13 ::= ENUMERATED [n1] OPTIONAL:Exist

  |       +-pucch-NumRepetitionCE-Msg4-Level1-r13 ::= ENUMERATED [n1] OPTIONAL:Exist

  |       +-pucch-NumRepetitionCE-Msg4-Level2-r13 ::= ENUMERATED OPTIONAL:Omit

  |       +-pucch-NumRepetitionCE-Msg4-Level3-r13 ::= ENUMERATED OPTIONAL:Omit

  +-ue-TimersAndConstants ::= SEQUENCE

  +-freqInfo ::= SEQUENCE [00]

  +-mbsfn-SubframeConfigList ::= SEQUENCE OF OPTIONAL:Omit

  +-timeAlignmentTimerCommon ::= ENUMERATED [infinity]

HEX : 00 00 6C 59 3F 60 20 9B 00 0A 02 02 C7 B3 00 01 E4 00 00 04 26 00 01 BD F0 00 01 88 87 F8 00 06 18 19 24 00 19 80 00 11 00 F0 07 20 05 B4 10 03 00 E0 00 E0

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

  +-radioResourceConfigDedicated ::= SEQUENCE [100101]

  | +-srb-ToAddModList ::= SEQUENCE OF SIZE(1..2) [1] OPTIONAL:Exist

  | +-drb-ToAddModList ::= SEQUENCE OF OPTIONAL:Omit

  | +-drb-ToReleaseList ::= SEQUENCE OF OPTIONAL:Omit

  | +-mac-MainConfig ::= CHOICE [explicitValue] OPTIONAL:Exist

  | +-sps-Config ::= SEQUENCE OPTIONAL:Omit

  | +-physicalConfigDedicated ::= SEQUENCE [1101000011] OPTIONAL:Exist

  | | +-pdsch-ConfigDedicated ::= SEQUENCE OPTIONAL:Exist

  | | +-pucch-ConfigDedicated ::= SEQUENCE [0] OPTIONAL:Exist

  | | +-pusch-ConfigDedicated ::= SEQUENCE OPTIONAL:Omit

  | | +-uplinkPowerControlDedicated ::= SEQUENCE [1] OPTIONAL:Exist

  | | +-tpc-PDCCH-ConfigPUCCH ::= CHOICE OPTIONAL:Omit

  | | +-tpc-PDCCH-ConfigPUSCH ::= CHOICE OPTIONAL:Omit

  | | +-cqi-ReportConfig ::= SEQUENCE OPTIONAL:Omit

  | | +-soundingRS-UL-ConfigDedicated ::= CHOICE OPTIONAL:Omit

  | | +-antennaInfo ::= CHOICE [defaultValue] OPTIONAL:Exist

  | | +-schedulingRequestConfig ::= CHOICE [setup] OPTIONAL:Exist

  | | +-EXTENSION ::= SEQUENCE [00010010]

  | |   +-VERSION-BRACKETS1 ::= SEQUENCE OPTIONAL:Omit

  | |   +-VERSION-BRACKETS2 ::= SEQUENCE OPTIONAL:Omit

  | |   +-VERSION-BRACKETS3 ::= SEQUENCE OPTIONAL:Omit

  | |   +-VERSION-BRACKETS4 ::= SEQUENCE [0000100000] OPTIONAL:Exist

  | |   +-VERSION-BRACKETS5 ::= SEQUENCE OPTIONAL:Omit

  | |   +-VERSION-BRACKETS6 ::= SEQUENCE OPTIONAL:Omit

  | |   +-VERSION-BRACKETS7 ::= SEQUENCE [0100000000100] OPTIONAL:Exist

  | |   | +-pdsch-ConfigDedicated-v1310 ::= SEQUENCE OPTIONAL:Omit

  | |   | +-pucch-ConfigDedicated-r13 ::= SEQUENCE [0000000001] OPTIONAL:Exist

  | |   | | +-ackNackRepetition-r13 ::= CHOICE [release]

  | |   | | +-tdd-AckNackFeedbackMode-r13 ::= ENUMERATED OPTIONAL:Omit

  | |   | | +-pucch-Format-r13 ::= CHOICE OPTIONAL:Omit

  | |   | | +-twoAntennaPortActivatedPUCCH-Format1a1b-r13 ::= ENUMERATED OPTIONAL:Omit

  | |   | | +-simultaneousPUCCH-PUSCH-r13 ::= ENUMERATED OPTIONAL:Omit

  | |   | | +-n1PUCCH-AN-RepP1-r13 ::= INTEGER OPTIONAL:Omit

  | |   | | +-nPUCCH-Param-r13 ::= CHOICE OPTIONAL:Omit

  | |   | | +-nkaPUCCH-Param-r13 ::= CHOICE OPTIONAL:Omit

  | |   | | +-spatialBundlingPUCCH-r13 ::= BOOLEAN [FALSE]

  | |   | | +-spatialBundlingPUSCH-r13 ::= BOOLEAN [FALSE]

  | |   | | +-harq-TimingTDD-r13 ::= BOOLEAN [FALSE]

  | |   | | +-codebooksizeDetermination-r13 ::= ENUMERATED OPTIONAL:Omit

  | |   | | +-maximumPayloadCoderate-r13 ::= INTEGER OPTIONAL:Omit

  | |   | | +-pucch-NumRepetitionCE-r13 ::= CHOICE [setup] OPTIONAL:Exist

  | |   | |   +-setup ::= CHOICE [modeA]

  | |   | |     +-modeA ::= SEQUENCE

  | |   | |       +-pucch-NumRepetitionCE-format1-r13 ::= ENUMERATED [r1]

  | |   | |       +-pucch-NumRepetitionCE-format2-r13 ::= ENUMERATED [r1]

  | |   | +-pusch-ConfigDedicated-r13 ::= SEQUENCE OPTIONAL:Omit

  | |   | +-pdcch-CandidateReductions-r13 ::= CHOICE OPTIONAL:Omit

  | |   | +-cqi-ReportConfig-v1310 ::= SEQUENCE OPTIONAL:Omit

  | |   | +-soundingRS-UL-ConfigDedicated-v1310 ::= CHOICE OPTIONAL:Omit

  | |   | +-soundingRS-UL-ConfigDedicatedUpPTsExt-r13 ::= CHOICE OPTIONAL:Omit

  | |   | +-soundingRS-UL-ConfigDedicatedAperiodic-v1310 ::= CHOICE OPTIONAL:Omit

  | |   | +-soundingRS-UL-ConfigDedicatedAperiodicUpPTsExt-r13 ::= CHOICE OPTIONAL:Omit

  | |   | +-csi-RS-Config-v1310 ::= SEQUENCE OPTIONAL:Omit

  | |   | +-ce-Mode-r13 ::= CHOICE [setup] OPTIONAL:Exist

  | |   | | +-setup ::= ENUMERATED [ce-ModeA]

  | |   | +-csi-RS-ConfigNZPToAddModListExt-r13 ::= SEQUENCE OF OPTIONAL:Omit

  | |   | +-csi-RS-ConfigNZPToReleaseListExt-r13 ::= SEQUENCE OF OPTIONAL:Omit

  | |   +-VERSION-BRACKETS8 ::= SEQUENCE OPTIONAL:Omit

HEX : 60 12 80 03 A1 A3 0C 19 30 00 23 03 89 06 84 11 48 30 1C 00 00 00 50 3F 10 00 00 02 A0 10 01 08 20 00

RACH Random Access Response Grant Content field size difference between CE Mode A and B

Depending on the CE mode, the contents of UL Grant in RAR message gets different according to the following table. Interpretation of this table is pretty complicated and it is out of scope of this page. If you want to understand the full details of interpreting this table, refer to Step (D) : RACH Response (RAR) of RACH page.

< 36.213-Table 6-2: Random Access Response Grant Content field size >

Reference

[1] 3GPP TS 36.211 V13.2.0 (2016-06)

[2] 3GPP TS 36.213 V13.2.0 (2016-06)

[3] 4G, LTE-Advanced Pro and The Road to 5G by By Erik Dahlman, Stefan Parkvall, Johan Skold

[4] 3GPP R1-156979 : TSG RAN WG1 Meeting #83 - On CE Mode Capability of eMTC