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4G/LTE - Band 66 |
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Band 66
As LTE evolves, many new bands has been added. In Release 13, several new bands including the Band 66 were added as shown below.
< [36.521-1 V13.2.0] - Table 5.2-1: E-UTRA operating bands >
< [36.521-1 V13.2.0] - Table 5.4.2.1-1: E-UTRA channel bandwidth >
So what ? Is there anything special with Band 66 that gets you to create a special note like this ? In terms of Hardware implementation, I don't think there is any special about this band. It is just addition of a new frequency spectrum. However, there is a special things about Band 66 in terms of the number. EARFCN (Channel Number) for Band 66 is from 66436 through 57335. In the original ASN design for LTE, they allocated 4 bits (1~64) for Band Indicator and 16 bits (0~66535) for EARFCN. It means, in order to specify Band 66 we need a little bit of redesign RRC message specification (ASN specification) about Band Indicator and EARFCN settings. In this page, I will summarize several issues of Band 66 (mainly with the perspective of RRC message)
Overlapping with existing bands
First, let's get a brief overview of frequency range of Band 66 and check if it is overlapping with any existing bands. As indicated in the table below, Band 66 overlaps completely or partially with several other bands. In some case, it overlapps only downlink part (red) and in some other case it overlaps only uplink part. Of course, there are some cases where it overlaps both uplink and downlink spectrum.
RRC Message Issues
As I mentioned at the beginning, 3GPP ASN was not designed to specify this kind of big number like Band 66, EARFCN 66866 etc. So they need to revise ASN structure of some RRC messages to specify these big numbers. In this section, I will list the RRC messages that uses this newly added IE (Information Element).
As you may know, you need to configure the band indicator in SIB1. To specify the Band greater than 64, a new IE in red is added. To make the red part take effect, you have to set the max value in the existing IE marked in blue.
systemInformationBlockType1 cellAccessRelatedInfo plmn-IdentityList: 1 item Item 0 PLMN-IdentityInfo trackingAreaCode: 0001 cellIdentity: 00000010 cellBarred: notBarred (1) intraFreqReselection: allowed (0) .... ..0. csg-Indication: False cellSelectionInfo q-RxLevMin: -110dBm (-55) p-Max: 23dBm freqBandIndicator: 64 schedulingInfoList: 3 items si-WindowLength: ms20 (5) systemInfoValueTag: 0 nonCriticalExtension lateNonCriticalExtension: 6008 SystemInformationBlockType1-v8h0-IEs nonCriticalExtension freqBandIndicator-v9e0: 66 nonCriticalExtension
SIB5 specifies interfrequency neighbour cell info . To specify the EARFCN greater than 65535, a new IE in red is added. To make the red part take effect, you have to set the max value in the existing IE marked in blue.
sib5 interFreqCarrierFreqList: 1 item Item 0 InterFreqCarrierFreqInfo dl-CarrierFreq: 65535 q-RxLevMin: -110dBm (-55) p-Max: 23dBm t-ReselectionEUTRA: 0s threshX-High: 4dB (2) threshX-Low: 2dB (1) allowedMeasBandwidth: mbw25 (2) .... .0.. presenceAntennaPort1: False cellReselectionPriority: 4 neighCellConfig: No MBSFN subframes are present in all neighbour cells (1) q-OffsetFreq: dB3 (18) lateNonCriticalExtension: 6100a8c0 SystemInformationBlockType5-v8h0-IEs nonCriticalExtension interFreqCarrierFreqList-v9e0: 1 item Item 0 InterFreqCarrierFreqInfo-v9e0 dl-CarrierFreq-v9e0: 66886
< LTE - RRC Connection Reconfiguration (Adding B66 SCC) >
When you set up Carrier Aggregation with B66 as a SCC, you need to specify B66 EARFCN (big number greater than 65535). To specify the EARFCN greater than 65535, a new IE in red is added. To make the red part take effect, you have to set the max value in the existing IE marked in blue.
rrcConnectionReconfiguration rrc-TransactionIdentifier: 0 criticalExtensions: c1 (0) c1: rrcConnectionReconfiguration-r8 (0) rrcConnectionReconfiguration-r8 radioResourceConfigDedicated mac-MainConfig: explicitValue (0) .... physicalConfigDedicated pusch-ConfigDedicated ... pucch-ConfigDedicated-v1020 pucch-Format-r10: channelSelection-r10 (1) channelSelection-r10 n1PUCCH-AN-CS-r10: setup (1) setup n1PUCCH-AN-CS-List-r10: 2 items ... nonCriticalExtension nonCriticalExtension nonCriticalExtension sCellToAddModList-r10: 1 item Item 0 SCellToAddMod-r10 sCellIndex-r10: 1 cellIdentification-r10 physCellId-r10: 0 dl-CarrierFreq-r10: 65535 radioResourceConfigCommonSCell-r10 ... radioResourceConfigDedicatedSCell-r10 physicalConfigDedicatedSCell-r10 nonUL-Configuration-r10 ... ul-Configuration-r10 cqi-ReportConfigSCell-r10 ... dl-CarrierFreq-v1090: 66886
The Band 66 forced the ASN changes not only for LTE but also for WCDMA. WCDMA SIB 19 carries the neighbour cell of different radio technolgies. To configure Band 66 frequencies in SIB 19, SIB 19 should be revised as follows. To specify the EARFCN greater than 65535, a new IE in red is added. To make the red part take effect, you have to set the max value in the existing IE marked in blue
SysInfoType19 utra-PriorityInfoList utra-ServingCell priority: 0 s-PrioritySearch1: 0 threshServingLow: 0 eutra-FrequencyAndPriorityInfoList: 1 item Item 0 EUTRA-FrequencyAndPriorityInfo earfcn: 65535 priority: 0 qRxLevMinEUTRA: -64 threshXhigh: 0 threshXlow: 0 ...0 .... eutraDetection: False v920NonCriticalExtensions sysInfoType19-v920ext utra-PriorityInfoList-v920ext eutra-FrequencyAndPriorityInfoList-v920ext: 1 item Item 0 EUTRA-FrequencyAndPriorityInfo-v920ext va80NonCriticalExtensions sysInfoType19-va80ext vb30NonCriticalExtensions sysInfoType19-vb30ext vb50NonCriticalExtensions sysInfoType19-vb50ext eutra-FrequencyAndPriorityInfoExtensionList: 1 item Item 0 EUTRA-FrequencyAndPriorityInfoExtension-vb50ext earfcn: 66866 measurementBandwidth: mbw75 (4) priority: 7 qRxLevMinEUTRA: -62 threshXhigh: 4 threshXlow: 2 0... .... eutraDetection: False
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