3GPP RAN1 Status: LTE Licensed-Assisted Access (LAA) to Unlicensed Spectrum Richard Li Mar. 4, 2016 1
Agenda Status Overview of RAN1 Working/Study Items Narrowband Internet of Things (NB-IoT) (Rel-13) Study on latency reduction techniques Study on LTE-based V2X services Support for V2V services based on LTE sidelink Study on channel model for frequency spectrum above 6 GHz LTE Licensed-Assisted Access (LAA) to Unlicensed Spectrum 2
Narrowband Internet of Things (NB-IoT) A non-backward-compatible variant of E-UTRA Improved indoor coverage, massive number of low throughput devices, low delay sensitivity, ultra low device cost, low device power consumption and (optimised) network architecture Three modes of operation Stand-alone operation: a replacement of one or more GSM carriers Guard band operation: the unused RBs within a LTE carrier s guard-band In-band operation: resource blocks (RBs) within a normal LTE carrier Basic Transmissions 180 khz UE RF bandwidth for both DL/UL DL: 15 khz sub-carrier spacing for all the modes of operation UL single tone transmissions: 3.75 khz and 15 khz, CP, freq. domain sinc UL multi-tone transmissions: SC-FDMA with 15 khz subcarrier spacing NB-IoT UE: Only needs to support half duplex operations 3
Narrowband Internet of Things (NB-IoT) A resource unit, schedulable in NPUSCH transmission For single-tone transmission A single 3.75 khz sub-carrier for 32 ms; A single 15 khz sub-carrier for 8 ms; For multi-tone transmission 3 subcarriers for 4 ms / 6 subcarriers for 2 ms / 12 subcarriers for 1ms. A UL-SCH transport block can be scheduled over more than one resource unit in time Synchronization signals... NB-PSS: per 10 ms, at subframe 5, length-11 Zadoff-Chu Sequence NB-SSS: per 10 ms, at subframe 9, length-11, NB-IoT vs. LTE Cat.1, Cat.0, LTE-M 4
Latency Reduction: Shortened TTI Latency reductions Protocol enhancements is created and packetized UE enodeb MME S-GW PDN-GW SR Application Server Shortened TTIs Grant BSR (+) Delay per packet exchange Grant Grant between UE & enodeb Request, Grant, or 1 ms UE enodeb MME S-GW PDN-GW packet Shortened TTI candidates 1, 2, 3, 4, 7 symbols packet to higher layers 5
Shortened TTI(s) Design assumptions No shortened TTI spans over subframe boundary At least for SIBs and paging, PDCCH and legacy PDSCH are used for scheduling From enb perspective, existing non-stti and stti can be FDMed in the same subframe in the same carrier PSS/SSS, PBCH, PCFICH and PRACH, Random access, SIB and Paging procedures are not modified 6
LTE-based V2X Services Vehicle wireless communications V2V: Between vehicles. V2P: Between a vehicle and a device carried by an individual E.g. handheld terminal carried by a pedestrian, cyclist, driver or passenger V2I/N (vehicle-to-infrastructure/network): between a vehicle and a roadside unit (RSU: enb / stationary UE.) / network Pedestrian Vehicle Network V2P V2V V2I Vehicle 7
LTE-based V2X Services RSU Traffic-Safety Server Car accident Ahead Pedestrian Vehicle Pedestrian 8
V2X Operation only based on PC5 SL SL UE (RSU) UE (RSU) SL SL SL 9
V2X Operation only based on Uu (RSU) UL DL (RSU) UL DL UL DL UL DL 10
V2V Services based on LTE Sidelink LTE sidelink enhancements for V2V services With and without LTE network coverage DM-RS enhancements Adopt DMRS location option 1 PSCCH/PSSCH for V2V Option 1: #2, #5, #8, #11 (i.e. the regular spacing) Working Assumption: 15 khz subcarrier spacing with 1 msec TTI length Intel & ITRI proposed to support increased subcarrier spacing, e.g. 30 khz. Sensing with semi-persistent transmission is supported Sets of resources among which a UE selects can be restricted based on the geo information of the UE Mechanisms to report UE geographical information to the enb are supported 11 SL
Channel Model for Frequency Spectrum above 6 GHz A channel model from 6 GHz to 100 GHz Further evolution beyond LTE-Advanced / towards 5G Bandwidth: up to 1GHz (vs. LTE-A s 100MHz by CA) Channel Modeling Scenarios 1 st priority: UMi street canyon, Indoor office, and Uma 2 nd priority: UMi open square, Indoor shopping mall Channel Modeling Requirements Blocking, atmosphere attenuation, etc. Large channel bandwidths (up to 10% of carrier frequency) Mobile speed up to [500] km/h Support large antenna arrays Channel Modeling Methodology Stochastic modeling methodology (3D spatial CM of TR 36.873) 12
1 st Priority UMi - Street Canyon O2O and O2I Cell radii: less than 100 m BS: below rooftops (e.g., 3-20 m) UMa O2O and O2I Cell radii: above 200 m BS: Rooftops (e.g. 25-35 m) 13
1 st Priority (cont d) Indoor office Sub scenario 1 Open office: open office with cubicles, chairs, etc. Sub scenario 2 Mixed office: open cubicle areas, meeting rooms, walled offices, corridors, etc. APs: Ceilings or walls (e.g.2-3 m) AP density: depending on the frequency band and output power Range from one per floor to one per room 14
2 nd Priority UMi Open Square O2O and O2I Cell radii: less than 100 m BS: below rooftops (e.g., 3-20 m) Indoor - Shopping Malls BS: Ceilings Details FFS 15
LTE Licensed-Assisted Access to Unlicensed Spectrum Access to unlicensed spectrum LAA deployment scenarios (vs. LWA, LTE-U, and MulteFire) 16
LAA in Rel-13 DL-only LAA Cat. 4 LBT Random back-off Contention window of variable sizes Four LBT priority classes Transmissions PDSCH Discovery signal Multiple channel access Type A (A1 & A2) Type B (B1 & B2) 17
LAA in Rel-14 UL support for LAA SCell operation in unlicensed spectrum UL carrier aggregation for LAA SCell(s) using Frame Structure type 3 Channel access mechanism Use the decisions made in RAN1 during Rel-13 as a starting point PUSCH and SRS Self-scheduling and cross-carrier scheduling from licensed spectrum. If needed, specify support for PUCCH If needed, specify support for PRACH Complete support for 10 MHz system BW as an LAA SCell 18
Channel Access and PUSCH in LAA Channel access Support UL LBT based on a Cat-4 channel access procedure. Support UL LBT based on a CCA of at least 25 µs before the UL transmission burst. PUSCH At least RB-level multi-cluster transmission (>2) is supported For elaa, flexible timing between UL grant and UL transmission is supported For UL transmission in elaa Scells, flexible timing between the subframe carrying the UL grant and subframe(s) of the corresponding PUSCH(s) is supported Working assumption: The minimum latency is 4ms In Rel-14 LAA, UL grant(s) for a UE in a subframe can enable PUSCH transmission for the UE in multiple subframes in LAA SCell for both cross-cc scheduling case and self-scheduling case. 19
SRS, PUCCH, and PRACH in LAA SRS Aperiodic SRS transmission with PUSCH is supported in elaa PUCCH Transmission of HARQ ACK for serving cells at licensed carriers on an LAA SCell is NOT supported Transmission of HARQ ACK and CSI for serving cells at unlicensed carriers on an LAA SCell is supported PRACH Contention based PRACH on LAA Scell is NOT supported in Rel-14 Non-contention based PRACH on LAA Scell is supported in Rel-14 subject to LBT 10 MHz BW as an LAA Scell Shall not be used if the absence of Wi-Fi cannot be guaranteed Unless additional work on channel access is agreed 20