4G/LTE - LTE NB |
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MIB/SIB and Scheduling
It seems there is pretty big difference in terms of design concept between LTE and LTE-NB MIB/SIBs. To me, LTE-NB design concept seems closer to WCDMA MIB/SIB logic.
Overall operation of MIB/SIB for LTE-NB is described in 36.300 7.4 as summarized below.
Followings are the topics with the details.
When we think of MIB/SIB decoding, we usually think of following factors
The answer to all of these questions may be answered (hopefully) by a single illustration shown below. First, just take a look at this figure and see if you can make your own story to explain the process to others. (This kind of practice would be very helpful for you to learn anything new)
As you see, in terms of sequence of decoding SIB LTE-NB has no special differences from the legacy LTE or LTE-BL/CE(M1). It goes as MIB decoding --> SIB1 --> SIB2 and others.
In terms of SIB1 decoding, LTE-NB(M2) take a similar approach to LTE-M1 which is a little different from the legacy LTE. In LTE-NB, a parameter in MIB (as shown in (2)) determines the exact transmission timing and periodicity and PHY/MAC configuration. This is similar concept to LTE BL/CE(M1). It is a little bit different from legacy LTE in which SIB1 decoding information is predefined by 3GPP specification and DCI.
In terms of SIB2 and other SIB decoding, all the information that is required to decode these SIBs are informed to UE via SIB 1 parameters as shown in (3). DCI is not used here.
The most outstanding difference between LTE-NB(M2) and the legacy LTE SIB decoding is that DCI is not used in LTE-NB SIB decoding. All the information (even PHY/MAC) that is required to decode SIBs are notified to UE over MIB or SIB1 as illustrated above.
In normal LTE, MIB carries very simple set of information. However, in LTE-NB MIB carries relatively large set of information. It carries following high level information.
Followings are from 36.331 5.2.1.2a Scheduling for NB-IoT MIB scheduling.
MasterInformationBlock-NB ::= SEQUENCE { systemFrameNumber-MSB-r13 BIT STRING (SIZE (4)), hyperSFN-LSB-r13 BIT STRING (SIZE (2)), schedulingInfoSIB1-r13 INTEGER (0..15), systemInfoValueTag-r13 INTEGER (0..31), ab-Enabled-r13 BOOLEAN, operationModeInfo-r13 CHOICE { inband-SamePCI-r13 Inband-SamePCI-NB-r13, inband-DifferentPCI-r13 Inband-DifferentPCI-NB-r13, guardband-r13 Guardband-NB-r13, standalone-r13 Standalone-NB-r13 }, spare BIT STRING (SIZE (11)) }
ChannelRasterOffset-NB-r13 ::= ENUMERATED {khz-7dot5, khz-2dot5, khz2dot5, khz7dot5}
Guardband-NB-r13 ::= SEQUENCE { rasterOffset-r13 ChannelRasterOffset-NB-r13, spare BIT STRING (SIZE (3)) }
Inband-SamePCI-NB-r13 ::= SEQUENCE { eutra-CRS-SequenceInfo-r13 INTEGER (0..31) }
Inband-DifferentPCI-NB-r13 ::= SEQUENCE { eutra-NumCRS-Ports-r13 ENUMERATED {same, four}, rasterOffset-r13 ChannelRasterOffset-NB-r13, spare BIT STRING (SIZE (2)) }
Standalone-NB-r13 ::= SEQUENCE { spare BIT STRING (SIZE (5)) }
ab-Enabled : It stands for "access barring Enabled". If this IE is enabled, UE shall wait for SystemInformationBlockType14-NB before initiating RRC connection establishment or resume
operationModeInfo : This IE indicates the operation mode of the LTE-NB. There are four different types of Operation Mode as listed below.
schedulingInfoSIB1 : This IE indicates the index of the following table. The IE value itself is indicates I_TBS for SIB1-NB transmission and for each I_TBS different number of repetition occurs as mapped in the second column (Number of NPDSCH repetitions).
< 36.213 Table 16.4.1.3-3: Number of repetitions for NPDSCH carrying SystemInformationBlockType1-NB >
< 36.213 Table 16.4.1.5.2-1:Transport block size (TBS) table for NPDSCH carrying SystemInformationBlockType1-NB >
systemFrameNumber-MSB : We need 10 bits to represents SFN(0~1023). This IE represents 4 MSB of SFN and 6 remaining bits are derived implicitely from PBCH decoding process.
Example 1 >
BCCH-BCH-Message-NB message systemFrameNumber-MSB-r13: 00 [bit length 4, 4 LSB pad bits, 0000 .... decimal value 0] hyperSFN-LSB-r13: 00 [bit length 2, 6 LSB pad bits, 00.. .... decimal value 0] schedulingInfoSIB1-r13: 4 NPDSCH repetitions - TBS 208 bits (0) systemInfoValueTag-r13: 0 .... ...0 ab-Enabled-r13: False operationModeInfo-r13: standalone-r13 (3) standalone-r13 spare: 00 [bit length 5, 3 LSB pad bits, 0000 0... decimal value 0] spare: 0000 [bit length 11, 5 LSB pad bits, 0000 0000 000. .... decimal value 0]
Like in normal (Legacy) LTE, SIB1-NB also carries the information as follows :
In terms of transmission schedule, SIB1-NB is transmitted as follows (based on 36.331 5.2.1.2a Scheduling for NB-IoT MIB scheduling)
As mentioned above, SIB1 periodicity is predefined to be same in all eNB, but the offset (Starting subframe = the subframe where the first SIB1 is transmitted) gets different depending on schedulingInfoSIB1 in MIB based on following tables.
Following is ASN structure of SIB1 defined in 3GPP 36.331.
SystemInformationBlockType1-NB ::= SEQUENCE { hyperSFN-MSB-r13 BIT STRING (SIZE (8)), cellAccessRelatedInfo-r13 SEQUENCE { plmn-IdentityList-r13 PLMN-IdentityList-NB-r13, trackingAreaCode-r13 TrackingAreaCode, cellIdentity-r13 CellIdentity, cellBarred-r13 ENUMERATED {barred, notBarred}, intraFreqReselection-r13 ENUMERATED {allowed, notAllowed} }, cellSelectionInfo-r13 SEQUENCE { q-RxLevMin-r13 Q-RxLevMin, q-QualMin-r13 Q-QualMin-r9 }, p-Max-r13 P-Max OPTIONAL, -- Need OP freqBandIndicator-r13 FreqBandIndicator-NB-r13, freqBandInfo-r13 NS-PmaxList-NB-r13 OPTIONAL, -- Need OR multiBandInfoList-r13 MultiBandInfoList-NB-r13 OPTIONAL, -- Need OR downlinkBitmap-r13 DL-Bitmap-NB-r13 OPTIONAL, -- Need OP, eutraControlRegionSize-r13 ENUMERATED {n1, n2, n3} OPTIONAL, -- Cond inband nrs-CRS-PowerOffset-r13 ENUMERATED {dB-6, dB-4dot77, dB-3, dB-1dot77, dB0, dB1, dB1dot23, dB2, dB3, dB4, dB4dot23, dB5, dB6, dB7, dB8, dB9} OPTIONAL, -- Cond inband-SamePCI schedulingInfoList-r13 SchedulingInfoList-NB-r13, si-WindowLength-r13 ENUMERATED {ms160, ms320, ms480, ms640, ms960, ms1280, ms1600, spare1}, si-RadioFrameOffset-r13 INTEGER (1..15) OPTIONAL, -- Need OP systemInfoValueTagList-r13 SystemInfoValueTagList-NB-r13 OPTIONAL, -- Need OR lateNonCriticalExtension OCTET STRING OPTIONAL, nonCriticalExtension SEQUENCE {} OPTIONAL }
PLMN-IdentityList-NB-r13 ::= SEQUENCE (SIZE (1..maxPLMN-r11)) OF PLMN-IdentityInfo-NB-r13
PLMN-IdentityInfo-NB-r13 ::= SEQUENCE { plmn-Identity-r13 PLMN-Identity, cellReservedForOperatorUse-r13 ENUMERATED {reserved, notReserved}, attachWithoutPDN-Connectivity-r13 ENUMERATED {true} OPTIONAL -- Need OP }
SchedulingInfoList-NB-r13 ::= SEQUENCE (SIZE (1..maxSI-Message-NB-r13)) OF SchedulingInfo-NB-r13
SchedulingInfo-NB-r13::= SEQUENCE { si-Periodicity-r13 ENUMERATED {rf64, rf128, rf256, rf512, rf1024, rf2048, rf4096, spare}, si-RepetitionPattern-r13 ENUMERATED {every2ndRF, every4thRF, every8thRF, every16thRF}, sib-MappingInfo-r13 SIB-MappingInfo-NB-r13, si-TB-r13 ENUMERATED {b56, b120, b208, b256, b328, b440, b552, b680} }
SystemInfoValueTagList-NB-r13 ::= SEQUENCE (SIZE (1.. maxSI-Message-NB-r13)) OF SystemInfoValueTagSI-r13
SIB-MappingInfo-NB-r13 ::= SEQUENCE (SIZE (0..maxSIB-1)) OF SIB-Type-NB-r13
SIB-Type-NB-r13 ::= ENUMERATED { sibType3-NB-r13, sibType4-NB-r13, sibType5-NB-r13, sibType14-NB-r13, sibType16-NB-r13, spare3, spare2, spare1}
downlinkBitmap : This indicate which subframe can be used for downlink transmission. If this IE is missing, it is assumed that any subframe except NPSS/NSSS/NPBCH/SIB1-NB subframe can be used for downlink transmission.
eutraControlRegionSize : This applies only to in-band Operation mode. It indicates how many OFDM symbols are used for control region.
si-RadioFrameOffset : This indicates the Offset to calculate the start of the SI window in the unit of radio frames. If the field is absent, no offset is applied.
si-Periodicity : This sepcifies periodicity of SI message (SIB message other than SIB1) in the unit of radio frames.
si-WindowLength : This specifies the SI window size for all SI messages (SIB message other than SIB1) in the unit of ms.
si-RepetitionPattern : This Indicates the starting radio frames within the SI window used for SI message transmission.
si-TB : This specifies the transport block size for all SI messages (SIB message other than SIB1) in the unit of bits.
Example 1 >
systemInformationBlockType1-r13 hyperSFN-MSB-r13: 00 [bit length 8, 0000 0000 decimal value 0] cellAccessRelatedInfo-r13 plmn-IdentityList-r13: 1 item Item 0 PLMN-IdentityInfo-NB-r13 plmn-Identity-r13 mcc: 3 items Item 0 MCC-MNC-Digit: 0 Item 1 MCC-MNC-Digit: 0 Item 2 MCC-MNC-Digit: 1 mnc: 2 items Item 0 MCC-MNC-Digit: 0 Item 1 MCC-MNC-Digit: 1 cellReservedForOperatorUse-r13: notReserved (1) attachWithoutPDN-Connectivity-r13: true (0) trackingAreaCode-r13: 0001 [bit length 16, 0000 0000 0000 0001 decimal value 1] cellIdentity-r13: 00000010 cellBarred-r13: notBarred (1) intraFreqReselection-r13: allowed (0) cellSelectionInfo-r13 q-RxLevMin-r13: -140dBm (-70) q-QualMin-r13: -34dB p-Max-r13: -30dBm freqBandIndicator-r13: 2 eutraControlRegionSize-r13: n2 (1) nrs-CRS-PowerOffset-r13: dB6 (12) schedulingInfoList-r13: 1 item Item 0 SchedulingInfo-NB-r13 si-Periodicity-r13: rf64 (0) si-RepetitionPattern-r13: every4thRF (1) sib-MappingInfo-r13: 1 item Item 0 SIB-Type-NB-r13: sibType3-NB-r13 (0) si-TB-r13: b256 (3) si-WindowLength-r13: ms160 (0)
SystemInformationBlockType2-NB-r13 ::= SEQUENCE { radioResourceConfigCommon-r13 RadioResourceConfigCommonSIB-NB-r13, ue-TimersAndConstants-r13 UE-TimersAndConstants-NB-r13, freqInfo-r13 SEQUENCE { ul-CarrierFreq-r13 CarrierFreq-NB-r13 additionalSpectrumEmission-r13 AdditionalSpectrumEmission }, timeAlignmentTimerCommon-r13 TimeAlignmentTimer, multiBandInfoList-r13 SEQUENCE (SIZE (1..maxMultiBands)) OF AdditionalSpectrumEmission lateNonCriticalExtension OCTET STRING ... }
RadioResourceConfigCommonSIB-NB-r13 ::= SEQUENCE { rach-ConfigCommon-r13 RACH-ConfigCommon-NB-r13, bcch-Config-r13 BCCH-Config-NB-r13, pcch-Config-r13 PCCH-Config-NB-r13, nprach-Config-r13 NPRACH-ConfigSIB-NB-r13, npdsch-ConfigCommon-r13 NPDSCH-ConfigCommon-NB-r13, npusch-ConfigCommon-r13 NPUSCH-ConfigCommon-NB-r13, dl-Gap-r13 DL-GapConfig-NB-r13 uplinkPowerControlCommon-r13 UplinkPowerControlCommon-NB-r13, ... }
RACH-ConfigCommon-NB-r13 ::= SEQUENCE { preambleTransMax-CE-r13 PreambleTransMax, powerRampingParameters-r13 PowerRampingParameters, rach-InfoList-r13 RACH-InfoList-NB-r13, connEstFailOffset-r13 INTEGER (0..15) OPTIONAL, -- Need OP ... }
RACH-InfoList-NB-r13 ::= SEQUENCE (SIZE (1.. maxNPRACH-Resources-NB-r13)) OF RACH-Info-NB-r13
RACH-Info-NB-r13 ::= SEQUENCE { ra-ResponseWindowSize-r13 ENUMERATED { pp2, pp3, pp4, pp5, pp6, pp7, pp8, pp10}, mac-ContentionResolutionTimer-r13 ENUMERATED { pp1, pp2, pp3, pp4, pp8, pp16, pp32, pp64} }
NPRACH-ConfigSIB-NB-r13 ::= SEQUENCE { nprach-CP-Length-r13 ENUMERATED {us66dot7, us266dot7}, rsrp-ThresholdsPrachInfoList-r13 RSRP-ThresholdsNPRACH-InfoList-NB-r13 nprach-ParametersList-r13 NPRACH-ParametersList-NB-r13 }
NPRACH-ParametersList-NB-r13 ::= SEQUENCE (SIZE (1.. maxNPRACH-Resources-NB-r13))
NPRACH-Parameters-NB-r13::= SEQUENCE { nprach-Periodicity-r13 ENUMERATED {ms40, ms80, ms160, ms240, ms320, ms640, ms1280, ms2560}, nprach-StartTime-r13 ENUMERATED {ms8, ms16, ms32, ms64, ms128, ms256, ms512, ms1024}, nprach-SubcarrierOffset-r13 ENUMERATED {n0, n12, n24, n36, n2, n18, n34, spare1}, nprach-NumSubcarriers-r13 ENUMERATED {n12, n24, n36, n48}, nprach-SubcarrierMSG3-RangeStart-r13 ENUMERATED {zero, oneThird, twoThird, one}, maxNumPreambleAttemptCE-r13 ENUMERATED {n3, n4, n5, n6, n7, n8, n10, spare1}, numRepetitionsPerPreambleAttempt-r13 ENUMERATED {n1, n2, n4, n8, n16, n32, n64, n128}, npdcch-NumRepetitions-RA-r13 ENUMERATED {r1, r2, r4, r8, r16, r32, r64, r128, r256, r512, r1024, r2048, spare4, spare3, spare2, spare1}, npdcch-StartSF-CSS-RA-r13 ENUMERATED {v1dot5, v2, v4, v8, v16, v32, v48, v64}, npdcch-Offset-RA-r13 ENUMERATED {zero, oneEighth, oneFourth, threeEighth} }
RSRP-ThresholdsNPRACH-InfoList-NB-r13 ::= SEQUENCE (SIZE(1..2)) OF RSRP-Range
Example >
sib2-r13 radioResourceConfigCommon-r13 rach-ConfigCommon-r13 preambleTransMax-CE-r13: n20 (7) powerRampingParameters-r13 powerRampingStep: dB4 (2) preambleInitialReceivedTargetPower: dBm-92 (14) rach-InfoList-r13: 1 item Item 0 RACH-Info-NB-r13 ra-ResponseWindowSize-r13: pp10 (7) mac-ContentionResolutionTimer-r13: pp8 (4) bcch-Config-r13 modificationPeriodCoeff-r13: n16 (0) pcch-Config-r13 defaultPagingCycle-r13: rf128 (0) nB-r13: fourT (0) npdcch-NumRepetitionPaging-r13: r1 (0) nprach-Config-r13 nprach-CP-Length-r13: us66dot7 (0) nprach-ParametersList-r13: 1 item Item 0 NPRACH-Parameters-NB-r13 nprach-Periodicity-r13: ms640 (5) nprach-StartTime-r13: ms8 (0) nprach-SubcarrierOffset-r13: n12 (1) nprach-NumSubcarriers-r13: n12 (0) nprach-SubcarrierMSG3-RangeStart-r13: one (3) maxNumPreambleAttemptCE-r13: n10 (6) numRepetitionsPerPreambleAttempt-r13: n1 (0) npdcch-NumRepetitions-RA-r13: r16 (4) npdcch-StartSF-CSS-RA-r13: v4 (2) npdcch-Offset-RA-r13: zero (0) npdsch-ConfigCommon-r13 nrs-Power-r13: 1dBm npusch-ConfigCommon-r13 ack-NACK-NumRepetitions-Msg4-r13: 1 item Item 0 ACK-NACK-NumRepetitions-NB-r13: r1 (0) dmrs-Config-r13 threeTone-BaseSequence-r13: 0 threeTone-CyclicShift-r13: 0 sixTone-CyclicShift-r13: 0 ul-ReferenceSignalsNPUSCH-r13 .... 0... groupHoppingEnabled-r13: False groupAssignmentNPUSCH-r13: 0 uplinkPowerControlCommon-r13 p0-NominalNPUSCH-r13: -92dBm alpha-r13: al1 (7) deltaPreambleMsg3-r13: -2dB (-1) ue-TimersAndConstants-r13 t300-r13: ms2500 (0) t301-r13: ms2500 (0) t310-r13: ms0 (0) n310-r13: n1 (0) t311-r13: ms1000 (0) n311-r13: n1 (0) freqInfo-r13 additionalSpectrumEmission-r13: 1 timeAlignmentTimerCommon-r13: infinity (7) sib-TypeAndInfo-r13 item: sib3-r13 (1)
Reference :
[1] 3GPP TS 36.331 [2] NB-IoT : A SUSTAINABLE TECHNOLOGY FOR CONNECTING BILLIONS OF DEVICES (Ericsson) [3] LTE evolution for IoT connectivity
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