3gpp nb-iot發展現況...complexity/cost reductions for lte-m and nb-iot evolution 5 source:“lte...
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3GPP NB-IoT發展現況
資策會
汪海瀚 工程師
IoT Use Cases
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Source:“LTE evolution for IoT connectivity” whitepaper, Nokia, July 2016
Technologies Addressing Different IoT
Segments
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Source:“Cellular networks for massive IoT” whitepaper, Ericsson, January 2016
Comparison of LPWA IoT solutions
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Source:“LTE evolution for IoT connectivity” whitepaper, Nokia, July 2016
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Complexity/cost Reductions for LTE-M and NB-
IoT Evolution
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Source:“LTE evolution for IoT connectivity” whitepaper, Nokia, July 2016
• Target for a NB-IoT module that costs less than 5 USD
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3GPP Evolution Steps for Massive IoT
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Source:“Cellular networks for massive IoT” whitepaper, Ericsson, January 2016
Rel-12Rel-8
Rel-12Rel-13
Rel-13
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History of 3GPP MTC (1/2)
• TSG Radio Access Network (TSG RAN) Work Items:
– Release 10: RAN mechanisms to avoid CN overload due to Machine-Type
Communications (NIMTC-RAN_overload, WID: RP-101026)
– Release 11: RAN overload control for Machine-Type Communications (SIMTC-RAN_OC,
WID: RP-111373)
• Introduced Extended Access Barring (EAB)
– Release 12:
• Low cost & enhanced coverage MTC UE for LTE (LC_MTC_LTE, WID: RP-130848)
– DL/UL category 0, downlink and uplink maximum TBS size of 1000 bits, Type B half-duplex FDD
operation.
• RAN enhancements for Machine-Type and other mobile data applications
Communications (MTCe-RAN, WID: RP-140752)
– Power Saving Mode (PSM)
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History of 3GPP MTC (2/2)
– Release 13:
• Further LTE Physical Layer Enhancements for MTC (LTE_MTCe2_L1 (often referred
as eMTC), WID: RP-141660)
– DL/UL category M1, bandwidth reduced to 1.4MHz, repetitions of PHY signal, cross-subframe
scheduling, asynchronous UL HARQ, 23/20dBm maximum output power,downlink and uplink
maximum TBS size of 1000 bits, Type B half-duplex FDD operation.
• RAN enhancements for extended DRX in LTE (LTE_extDRX, WID: RP-150493)
– Introduced extended DRX (eDRX)
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New Categories Introduced for MTC
• DL/UL category 0, DL/UL category M1 (TS36.306)
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Origin of NB-IoT (1/4)
• GERAN Study Item “Cellular System Support for Ultra Low Complexity and Low Throughput Internet of Things” (FS_IoT_LC) completed in GERAN GERAN#67 meeting.– The aim was to study both the possibility of evolving current GERAN system and
the design of a new access system “clean slate” towards low complexity and low throughput radio access technology to address the requirements of cellular internet of things.
– Technical Report: TR45.820
– The following is the outcome of the study:• EC-GSM concluded and shown compliance to all objectives.
• NB-CIoT concluded and shown compliance to all objectives.
• NB-LTE, NB-M2M, NB-OFDMA, N-GSM, C-UNB are partially described.
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Reference:RP-151148
Origin of NB-IoT (2/4)
• EC-GSM
– Re-using existing design
– Backwards compatibility and co-existence with GSM
– Achieving extended coverage
– Release 13 Work Item “Extended Coverage GSM (EC-GSM) for support of Cellular
Internet of Things” (CIoT_EC_GSM (often referred as EC-GSM-IoT), WID: GP-151039)
started from GERAN #67 meeting
– Release 14 Work Item “Radio Interface Enhancements for Extended Coverage GSM for
support of Cellular Internet of Things” (CIoT_EC_GSM_radio_enh, WID: RP-161806)
started from RAN #73 meeting
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Origin of NB-IoT (3/4)
• NB-CIoT– Not backward compatible with LTE
– DL: OFDMA, 48 subcarriers with subcarrier spacing=3.75kHz, 10kHz guard band at each end.
– UL: FDMA with single carrier GMSK modulation, 36 subcarriers with subcarrier spacing=5kHz, 10kHz guard band at each end.
• NB-LTE– Backward compatible with LTE. NB-LTE aims to reuse the higher layer user
plane designs of LTE to a very large extent.
– DL: OFDMA, same numerology as LTE (subcarrier spacing=15kHz)
– UL: SC-FDMA, 72 subcarriers with subcarrier spacing=2.5kHz
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Origin of NB-IoT (4/4)
• Release 13 Work Item “Narrowband IOT (NB_IOT, WID:
RP-151621)” was approved in RAN #69 meeting to
address the so called "Clean Slate" part of the GERAN SI
and the low end of the IOT market.
– Also to address some operators’ interests to have CIoT solution
deployable in-band LTE.
– Only one Work Item: Followed strong request from some
operators for a unified solution.
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Release 13 NB-IoT (1/6)
• Work Item completed in RAN# 72, June 2016.
• NB-IoT supports 3 operation modes– Inband:
• Use one (or more) PRB(s) of a LTE carrier.
• Mapping of symbols avoids LTE PDCCH, CRS in DL.
• Physical layer operations, i.e., IFFT, CP insertion, I/Q modulation, RF up-conversion,…etc., can be done together with LTE signal, ensuring orthogonality between subcarriers.
– Guardband:• Utilize one (or more) 200kHz carrier(s) within LTE carrier guardband
– Can also be used together with inband carrier(s)
• Physical layer operations can be done together with LTE signal as described above.
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Release 13 NB-IoT (2/6)
– Standalone:
• Utilize one (or more) 200kHz carrier(s) outside LTE system bandwidth
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Source:“LTE evolution for IoT connectivity” whitepaper, Nokia, July 2016
Release 13 NB-IoT (3/6)
• DL– OFDMA, 12 subcarriers with subcarrier spacing=15kHz
– Use TBCC instead of turbo code for data channel
– Redesigned synchronization channel, broadcast channel, control channel to fit in a carrier.
• UL– SC-FDMA, support 2 numerologies
• 12 subcarriers with subcarrier spacing=15kHz
• 48 subcarriers with subcarrier spacing=3.75kHz– NPRACH always uses single tone with 3.75kHz subcarrier spacing
• Modulation: 𝜋
2BPSK,
𝜋
4QPSK
– Support single tone transmission
– Asynchronous HARQ
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Release 13 NB-IoT (4/6)
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1 symbol
1 slot, 2ms
3.75kHz 15kHz
1 slot 1 slot 1 slot 1 slot
UL Resource Grid
Release 13 NB-IoT (5/6)
• New UE category: Cat. NB1
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Release 13 NB-IoT (6/6)
• Main radio protocol features
– Single HARQ process
– Only RLC AM mode with simplified status reporting
– Two PDCP options:• Option1, used for control plane solution. SRB 0 and 1bis only. No AS security
(only NAS security). PDCP operating in transparent mode.
• Option2, used for user plane solution. SRB 0, 1 and at most two DRB. AS security, which is cached upon RRC connection release.
– For PDCP option 2, RRC connection suspend/resume procedures to maintain AS security context.
– Significantly reduced broadcast system information
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Source:“3GPP Standards for the Internet-of-Things”, Smart Summit Singapore November 2016
Summary for eMTC, NB-IOT and EC-GSM-IoT
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Source:“3GPP Standards for the Internet-of-Things”, Smart Summit Singapore November 2016
Special Feature Introduced for NB-IoT (1/2)
• User plane solution supports RRC suspend/resume
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Special Feature Introduced for NB-IoT (2/2)
• Support inter-eNB UE Context Resume:
– Retrieval of UE context for a UE which attempts to resume its RRC
connection in an eNB different from where the RRC connection was
suspended.
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NB-IoT Design Objectives
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164dB MCL
Source: “NB-IoT-Enabling New Business Opportunities”, Huawei 2015
Release 14 eMTC• WI: Further enhanced MTC for LTE (LTE_feMTC (often referred as FeMTC),
WID: RP-161321)
• Main feature enhancements
– Support for positioning (E-CID and OTDOA)
– Support for Multicast (SC-PTM)
– Mobility for inter-frequency measurements
– Higher data rates
• Specify HARQ-ACK bundling in CE mode A in HD-FDD
• Larger maximum TBS
• Larger max. PDSCH/PUSCH channel bandwidth (5MHz for BL UE) in connected mode at least
in CE mode A in order to enhance support e.g. voice and audio streaming or other applications
and scenarios
• Up to 10 DL HARQ processes in CE mode A in FD-FDD
– Support for VoLTE (reduce DL repetitions, new repetition factors, and adjusted
scheduling delays)
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Source:“3GPP Standards for the Internet-of-Things”, Smart Summit Singapore November 2016
Release 14 NB-IoT
• WI: Enhancements of NB-IoT (NB_IOTenh (often referred as eNB-IoT), WID: RP-161324) approved at RAN #72.
• Objectives:
– Positioning: for tracking applications, fault location/fast repair, smart parking, medical wearable,…etc.
– Multicast: for firmware or software updates, group message delivery.
– Non-anchor carrier enhancements: more number of supportable devices.
– Mobility and service continuity enhancements: connected mode mobility
– New power class: lower maximum transmission power (14dBm)
– Power consumption and latency reduction (added at RAN #73): for higher throughput
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Positioning for eNB-IoT
• Support OTDOA (Observed Time Difference of Arrival)
and E-CID (Enhanced Cell ID).
• Reuse LPP (LTE Positioning Protocal)
• Introduce Narrowband Positioning Reference Signal
(NPRS)
• Support measurement in IDLE mode
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Narrowband Positioning Reference Signal
• Resource Element pattern
– Reuse Rel-9 PRS RE pattern for inband case
– Add more REs on top of Rel-9 PRS RE pattern for guardband,
standalone case
Figure 2: Mapping of NPRS (normal cyclic prefix) for
guardband and standalone scenario
R1-1613294, WF on NPRS pattern for NB-IoT OTDOA
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NPRS subframe configuration
• NPRS is configured per NB-IoT carrier transmitting NPRS– Each NB-IoT carrier can have different configuration parameter
– Part A:A bitmap for NPRS subframe indication in one NPRS occasion• bitmap length is the same as valid subframe configuration, i.e. 10 bits or 40 bits
– For Part-B NB-IoT specific assistance information:• Number of subframes of NPRS in one occasion is NPRS {10, 20, 40, 80, 160, 320, 640, 1280}
• Periodicity of NPRS occasion TPRS: 160ms, 320ms, 640ms, 1280ms.
• Valid configurations are those satisfying NPRS <= TPRS
• For a given periodicity of NPRS occasion, the starting subframe offset of NPRS occasion
=𝛼𝑇𝑃𝑅𝑆, 𝛼𝜖 0,1
8,2
8,3
8,4
8,5
8,6
8,7
8
– If part A and part B are both configured then a subframe contains NPRS if both configurations indicate it contains NPRS
– If NPRS subframe configuration is part B only, NPRS is punctured in OFDM symbols 5 and 6 in each slot
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SC-PTM for eNB-IoT
• SC-MCCH and SC-MTCH are dynamically scheduled by DCI (same as in
LTE)
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Source:R1-166178
Maximum TBS for SC-PTM
• Allow to use the even larger TBS agreed in RAN1 #87
• Maximum TBS value for NPDSCH carrying SC-MCCH or SC-MTCH is 2536 bits
–Cat NB-1 UE does not need to receive the NPDSCH if the DCI indicates a TBS larger than 680 bits
• Using larger TBS can reduce the number of TBs needed for each UDP/IP packet
• Increase the probability of successfully receiving a UDP/IP packet
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Non-Anchor Carrier Enhancements• For paging:
– Up to 15 non-anchor carrier can be used as paging carrier.
– For a Rel-14 NB-IoT UE, both anchor and non-anchor carrier can be selected as the paging carrier• A Rel-14 UE chooses the carrier based on UE_ID and weights of each paging carrier
• Paging message on NPDSCH is scheduled by NPDCCH on the same carrier.
• For random access:– Up to 15 non-anchor carrier can be used for random access.
– UE selects NPRACH resource (including selection of carrier) based on random draw.
– Use different carrier selection probability for anchor and non-anchor carriers.
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Mobility Enhancements
• Mobility is triggered by RLF (Radio Link Failure)
• RLF triggers RRC Connection Re-establishment
• No additional mechanism is introduced to avoid NAS
recovery for the CIOT UP solution
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2 HARQ Processes(1/2)
There is a new NB-IoT UE category with max UL and max DL TBS of 2536 bits
Introduce the {1 HARQ + 2536 bits UL/DL TBS} TBS tables in R1-1613508
Introduce the {2 HARQ + [1352] bits DL TBS, [1800] bits UL TBS and no change to any Rel-13
specification for NPUSCH}
o After receiving one DL grant, Rel-14 UE is required to continue monitoring any NPDCCH search spaces
containing candidates ending at least 2 ms (i.e., x1 ≥ 2 ms) before the start of the first NPDSCH.
o The gap between NPUSCH to any DL reception is ≥ 1ms.
o Reuse Rel-13 timing relationship and scheduling delay values for each of the 2 HARQ processes
o HARQ process ID is indicated DL grant DCI with one bit
Monitored only in USS
o FFS TBS table details.
Soft buffer size is FFS until next RAN1#88
The support of 2 HARQ by UE is an optional capability, signalling is left to RAN2
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RAN1 Chairman’s Notes, RAN1 #87
2 HARQ Processes(2/2)
•
Source:R1-1611865
Source:R1-1611866
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5G mMTC
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164dB MCL
15 Yrs 1M devices/km2
• At RAN #74
– 3GPP’s IMT-2020 self-evaluations towards mMTC requirements will
assess NB-IoT and/or LTE eMTC
Rel-15 NB-IoT
• Companies (Ericsson, Huawei) proposed to support NB-
IoT in unlicensed spectrum
– Offload lower priority traffic to unlicensed carrier
– Standalone (Ericsson)
– Licensed-Downlink Assisted (Huawei)
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