10.2.6 Narrowband reference signal (NRS)

36.2113GPPEvolved Universal Terrestrial Radio Access (E-UTRA)Physical channels and modulationRelease 17TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

Before a UE obtains operationModeInfo:

– If frame structure type 1 is used, the UE may assume narrowband reference signals (NRSs) are transmitted in subframes #0 and #4 and in subframes #9 not containing NSSS.

– If frame structure type 2 is used, the UE may assume narrowband reference signals (NRSs) are transmitted in subframes #9 and in subframes #0 not containing NSSS.

On an NB-IoT carrier for which a UE receives higher-layer parameter operationModeInfo indicating guardband or standalone.

– If frame structure type 1 is used, before the UE obtains SystemInformationBlockType1-NB, the UE may assume narrowband reference signals are transmitted in subframes #0, #1, #3, #4 and in subframes #9 not containing NSSS.

– If frame structure type 2 is used, before the UE obtains SystemInformationBlockType1-NB, the UE may assume narrowband reference signals are transmitted in subframes #9, and in subframes #0 not containing NSSS, and in subframes #4 if subframes #4 is configured for SystemInformationBlockType1-NB transmissions.

– If frame structure type 1 is used, after the UE obtains SystemInformationBlockType1-NB, the UE may assume narrowband reference signals are transmitted in subframes #0, #1, #3, #4, subframes #9 not containing NSSS, and in NB-IoT downlink subframes.

– If frame structure type 2 is used, after the UE obtains SystemInformationBlockType1-NB, the UE may assume narrowband reference signals are transmitted in subframes #9, subframes #0 not containing NSSS, in subframes #4 if subframes #4 is configured for SystemInformationBlockType1-NB transmissions, and in NB-IoT downlink subframes.

On an NB-IoT carrier for SystemInformationBlockType1-NB for which sib1-carrierInfo-NB indicates non-anchor for frame structure type 2, before the UE obtains SystemInformationBlockType1-NB, the UE may assume narrowband reference signals are transmitted in subframes #0 and #5. After the UE obtains SystemInformationBlockType1-NB, the UE may assume narrowband reference signals are transmitted in subframes #0, #5, and in NB-IoT downlink subframes indicated by tdd-SI-SubframesBitmap.

On an NB-IoT carrier for which DL-CarrierConfigCommon-NB is present and no inbandCarrierInfo is present.

– If frame structure type 1 is used and when an NB-IoT UE is configured by higher layers to decode NPDCCH with CRC scrambled by the P-RNTI and higher-layer indicates nrs-NonAnchorConfig is enabled, the UE first determines the starting subframe of NPDCCH search space associated with NRS transmission according to [10].

– If higher-layer nB is configured as fourT, the UE may assume NRSs are transmitted in the 10^th NB-IoT DL subframe before the determined starting subframe of NPDCCH search space.

– If higher-layer nB is configured as twoT, the UE may assume NRSs are transmitted in the 9^th and 10^th NB-IoT DL subframes before the determined starting subframe of NPDCCH search space.

– If higher-layer nB is configured as oneT, the UE may assume NRSs are transmitted in the 6^th, 7^th, 8^th, 9^th and 10^th NB-IoT DL subframes before the determined starting subframe of NPDCCH search space.

– For other nB values, the UE may assume NRSs are transmitted in 10 NB-IoT DL subframes before the determined starting subframe of NPDCCH search space.

– When an NB-IoT UE is configured by higher layers to decode NPDCCH with CRC scrambled by the P-RNTI, the UE may assume NRSs are transmitted in the NPDCCH candidate where the UE finds a DCI with CRC scrambled by the P-RNTI. The UE may also assume NRSs are transmitted in 10 NB-IoT DL subframes before and in 4 NB-IoT DL subframes after the NPDCCH candidate where the UE finds a DCI with CRC scrambled by the P-RNTI, where NB-IoT DL subframes without NRS are not counted. If the DCI with CRC scrambled by the P-RNTI schedules a NPDSCH, the UE may assume NRSs are transmitted in the NB-IoT DL subframes carrying the NPDSCH as well as in 4 NB-IoT DL subframes before and after the scheduled NPDSCH, where NB-IoT DL subframes without NRS are not counted.

– During the window controlled by higher layers where the UE shall attempt to decode the NPDCCH with DCI scrambled by RA-RNTI (see [8], clause 5.1.4), the UE may assume NRSs are transmitted in the Type-2 CSS configured by higher layers, as well as in 10 NB-IoT DL subframes before and in 4 NB-IoT DL subframes after each Type-2 CSS, where NB-IoT DL subframes without NRS are not counted. If a DCI scrambled by the RA-RNTI is detected, the UE may assume NRSs are transmitted in the NPDSCH scheduled by the DCI scrambled by the RA-RNTI, as well as in 4 NB-IoT DL subframes before and after the scheduled NPDSCH, where NB-IoT DL subframes without NRS are not counted. In addition, when the UE attempts to decode a DCI with CRC scrambled by the RA-RNTI as well as receiving the NPDSCH scheduled by the DCI scrambled by the RA-RNTI, the UE may assume NRSs are transmitted in subframes #0, #1, #3, #4 and #9.

– During random access procedure, when an NB-IoT UE is configured by higher layers to decode NPDCCH with CRC scrambled by the temporary C-RNTI and/or the C-RNTI, before the DCI scrambled by temporary C-RNTI and/or C-RNTI is detected, the UE may assume NRSs are transmitted in the Type-2 CSS configured by higher layers, as well as in 10 NB-IoT DL subframes before the start of each Type-2 CSS and in 4 NB-IoT DL subframes after the end of each Type-2 CSS until the mac-ContentionResolutionTimer expires, where NB-IoT DL subframes without NRS are not counted. If a DCI scrambled by the temporary C-RNTI or C-RNTI is detected, the UE may assume NRSs are transmitted in the NPDSCH scheduled by the DCI scrambled by the temporary C-RNTI or C-RNTI as well as in 4 NB-IoT DL subframes before and after the scheduled NPDSCH, where NB-IoT DL subframes without NRS are not counted.

– An NB-IoT UE may assume NRSs are transmitted in NB-IoT DL subframes that are used for Type1A-NPDCCH common search space, and Type2A-NPDCCH common search space, as well as in 10 NB-IoT DL subframes prior and in 4 NB-IoT DL subframes after each Type1A-NPDCCH common search space and Type2A-NPDCCH common search space. A UE may assume NRSs are transmitted in NB-IoT DL subframes carrying NPDSCH scheduled by DCI CRC scrambled by G-RNTI or SC-RNTI as well as 4 NB-IoT DL subframes prior and after the scheduled NPDSCH, where NB-IoT DL subframes without NRS are not counted.

– In other cases, if frame structure typ1 is used, the UE may assume NRSs are transmitted in subframes #0, #1, #3, #4, #9, and in NB-IoT downlink subframes and shall not expect NRSs in other downlink subframes.

On an NB-IoT carrier for which a UE receives higher-layer parameter operationModeInfo indicating inband-SamePCI or inband-DifferentPCI.

– If frame structure type 1 is used, before the UE obtains SystemInformationBlockType1-NB, the UE may assume narrowband reference signals are transmitted in subframes #0, #4 and in subframes #9 not containing NSSS, and in subframes #3 which contain SystemInformationBlockType1-NB when additionalTransmissionSIB1 is configured as TRUE.

– If frame structure type 1 is used, after the UE obtains SystemInformationBlockType1-NB, the UE may assume narrowband reference signals are transmitted in subframes #0, #4, subframes #9 not containing NSSS, subframes #3 which contain SystemInformationBlockType1-NB when additionalTransmissionSIB1 is configured as TRUE, and in NB-IoT downlink subframes.

On an NB-IoT carrier for which DL-CarrierConfigCommon-NB is present and inbandCarrierInfo is present:

– If frame structure type 1 is used, when an NB-IoT UE is configured by higher layers to decode NPDCCH with CRC scrambled by the P-RNTI and higher-layer indicates nrs-NonAnchorConfig is enabled, the UE first determines the starting subframe of NPDCCH search space associated with NRS transmission according to [10].

– If higher-layer nB is configured as fourT, the UE may assume NRSs are transmitted in the 10^th NB-IoT DL subframe before the determined starting subframe of NPDCCH search space.

– If higher-layer nB is configured as twoT, the UE may assume NRSs are transmitted in 9^th and 10^th NB-IoT DL subframes before the determined starting subframe of NPDCCH search space.

– If higher-layer nB is configured as oneT, the UE may assume NRSs are transmitted in 6^th, 7^th, 8^th, 9^th and 10^th NB-IoT DL subframes before the determined starting subframe of NPDCCH search space.

– For other nB values, the UE may assume NRSs are transmitted in 10 NB-IoT DL subframes before the determined starting subframe of NPDCCH search space.

– When an NB-IoT UE is configured by higher layers to decode NPDCCH with CRC scrambled by the P-RNTI, the UE may assume NRSs are transmitted in the NPDCCH candidate where the UE finds a DCI with CRC scrambled by the P-RNTI. The UE may also assume NRSs are transmitted in10 NB-IoT DL subframes before and in 4 NB-IoT DL subframes after the NPDCCH candidate, where NB-IoT DL subframes without NRS are not counted. If the DCI with CRC scrambled by the P-RNTI schedules a NPDSCH, the UE may assume NRSs are transmitted in the NB-IoT DL subframes carrying the NPDSCH as well as 4 NB-IoT DL subframes before and after the scheduled NPDSCH, where NB-IoT DL subframes without NRS are not counted.

– During random access procedure, when an NB-IoT UE is configured by higher layers to decode NPDCCH with CRC scrambled by the temporary C-RNTI and/or the C-RNTI, before the DCI scrambled by temporary C-RNTI and/or C-RNTI, is detected, the UE may assume NRSs are transmitted in the Type-2 CSS configured by higher layers, as well as in 10 NB-IoT DL subframes before the start of each Type-2 CSS and in 4 NB-IoT DL subframes after the end of each Type-2 CSS until the mac-ContentionResolutionTimer expires, where NB-IoT DL subframes without NRS are not counted. If a DCI scrambled by the temporary C-RNTI or C-RNTI is detected, the UE may assume NRSs are transmitted in the NPDSCH scheduled by the DCI scrambled by the temporary C-RNTI or C-RNTI as well as in 4 NB-IoT DL subframes before and after the scheduled NPDSCH, where NB-IoT DL subframes without NRS are not counted.

– An NB-IoT UE may assume NRSs are transmitted in NB-IoT DL subframes that are used for Type1A-NPDCCH common search space, and Type2A-NPDCCH common search space, as well as in 10 NB-IoT DL subframes prior and in 4 NB-IoT DL subframes after each Type1A-NPDCCH common search space and Type2A-NPDCCH common search space, where NB-IoT DL subframes without NRS are not counted. A UE may assume NRSs are transmitted in NB-IoT DL subframes carrying NPDSCH scheduled by DCI CRC scrambled by G-RNTI or SC-RNTI as well as in 4 NB-IoT DL subframes prior and after the scheduled NPDSCH, where NB-IoT DL subframes without NRS are not counted.

– In other cases, if frame structure type 1 is used, the UE may assume NRSs are transmitted in subframes #0, #4, #9, and in NB-IoT downlink subframes and shall not expect NRSs in other downlink subframes.

On an NB-IoT carrier for which DL-CarrierConfigDedicated-NB is present and no inbandCarrierInfo is present:

– If frame structure type 1 is used, the UE may assume NRSs are transmitted in subframes #0, #1, #3, #4, #9, and in NB-IoT downlink subframes and shall not expect NRSs in other downlink subframes.

On an NB-IoT carrier for which DL-CarrierConfigDedicated-NB is present and inbandCarrierInfo is present:

– If frame structure type 1 is used, the UE may assume NRSs are transmitted in subframes #0, #4, #9, and in NB-IoT downlink subframes and shall not expect NRSs in other downlink subframes.

An NB-IoT UE may assume NRSs are not transmitted in subframes that are configured by higher layer parameter nprsBitmap for narrowband positioning reference signal transmission.

10.2.6.1 Sequence generation

The narrowband reference sequence shall be initialised according to clause 6.10.1.1 where is replaced with .

10.2.6.2 Mapping to resource elements

Narrowband reference signals are transmitted on one or two antenna ports .

If the higher layer indicates UE may assume that is equal to , UE may assume

– the number of antenna ports for the cell-specific reference signals as defined in clause 6.10.1 is the same as for the narrowband reference signals,

– the antenna ports for cell-specific reference signals {0, 1} are equivalent to antenna ports for narrowband reference signals {2000, 2001}, respectively, and

– the cell-specific reference signals are available in all subframes where the narrowband reference signals are available.

If the higher layer does not indicate UE may assume that is equal to , UE may assume

– the number of antenna port for the cell-specific reference signals as defined in clause 6.10.1 is obtained from the higher layer parameter eutra-NumCRS-Ports,

– the cell-specific reference signals are available in all subframes where the narrowband reference signals are available, and

the cell-specific frequency shift for cell-specific reference signals as defined in clause 6.10.1.2 is given by .

The reference signal sequence shall be mapped to complex-valued modulation symbols used as reference symbols for antenna port in slot according to

where

When frame structure type 2 is used, the following values of apply for the generation of NRSs in special subframes

– in each slot for special subframe configurations {3, 4, 8}

– in the first slot for special subframe configurations {9, 10}

– in the first slot for special subframe configurations {1, 2, 6, 7}.

The variables and define the position in the frequency domain for the different reference signals where is given by

The cell-specific frequency shift is given by .

Resource elements used for transmission of narrowband reference signals on any of the antenna ports in a slot shall not be used for any transmission on any other antenna port in the same slot and set to zero.

Narrowband reference signals shall not be transmitted in subframes containing NPSS or NSSS.

For frame structure type 2, narrowband reference signals shall not be transmitted in special subframe for configurations 0 and 5.

Figure 10.2.6.2-1 illustrates the resource elements used for reference signal transmission according to the above definition. The notation is used to denote a resource element used for reference signal transmission on antenna port.

Figure 10.2.6.2-1. Mapping of downlink narrowband reference signals (normal cyclic prefix)