Muhammad Nazmul Islam, Senior Engineer Qualcomm Technologies, Inc. December 2015

Transcription

1 Muhammad Nazmul Islam, Senior Engineer Qualcomm Technologies, Inc. December Qualcomm Technologies, Inc. All rights reserved. 1

2 This presentation addresses potential use cases and views on characteristics of millimeter wave technology and is not intended to reflect a commitment to the characteristics or commercialization of any product or service of Qualcomm Technologies, Inc. or its affiliates. 2

3 Millimeter Wave Networks Large bandwidths and spatial reuse counter-balanced by robustness and device aspects Example: Outdoor Deployment Characteristics Integrated Backhaul MWB ~ m cell size LOS Availability of large bandwidths Dense spatial reuse Mobile mmwb or UE Beamforming advantage Coverage through reflections and LOS NLOS Key System Challenges Indoor distribution UErelay Robust beam search & tracking Device and RF challenges at MMW Effective fallback to low frequency System design with directional transmissions 3

4 Focus of this Talk Propagation Measurements Coverage & Capacity Results PHY Design Considerations Upper Layer Design Considerations 4

5 Propagation Measurements 5

6 Normalized path loss (db) Normalized path loss (db) Normalized path loss (db) Similar path loss characteristics across sub-6ghz & mmwave Non-line of sight path loss normalized to the path loss at 1 m for individual bands Path loss Normalized to 1m [db] Indoor office Path Loss (Referenced to 1m): NLOS Freespace 2.9 GHz (PLE = 2.9, = 6.09 db) 29 GHz (PLE = 3.3, = 7.9 db) Distance [m] Distance (m) Shopping mall Distance (m) Path loss Normalized to 1m [db] Outdoor Path Loss (Referenced to 1m): NLOS Freespace 2.9 GHz (PLE = 2.9, = 3.37 db) 29 GHz (PLE = 3.2, = 5.48 db) 10 2 Distance [m] Distance (m) Similar NLOS path loss exponents across frequencies 2.9 GHz 29 GHz 61 GHz Indoor Office Shopping Mall Outdoor Actual path loss = [reference loss at 1m for a given frequency] + [normalized PL as shown] 6

7 Indoor Propagation: Measurements Bridgewater Commons Shopping Mall 2.9GHz 29GHz Multi-floor propagation very similar to same floor NLOS Propagation within stores through diffraction is problematic Measurements support viability of mmwave system within a mall 7

8 Stadium Use-Case Modeling 400mm 161 positions 6.7' TX 5.7ft 8 deg 1.6ft RX Absorber panels 8.5ft Absorber panels 2.7ft 21.25ft Signal strength in stadium use-cases benefit from human bodies as reflectors 3D scan reveals reflections from various angles resulting in azimuth and elevation diversity Scattering from people at side and behind leads to signal strength 10.7dB below perfect LOS Low variance of 2.3dB, 10 th percentile around 15 db Blocking does not vary over scan of 40 wavelengths Blocking with 7 people seated Reflection from the person First row, left side Boresight direction Norm. to LOS 0dB Single blocking human, 10 db poorer than crowd scenario Peak value -15.5dB 8

9 Coverage & Capacity Results 9

10 F(x) Coverage: An Example 28GHz: Outdoor to Outdoor Path Loss & Coverage, Manhattan 3D Map Signal to Noise Ratio (SNR) CDF vs. Distance Approx. Outage Regime SNR (db) *Assumptions: 1GHz b/w, 50 dbm EIRP, -84 dbm/ghz noise floor, 18 base-stations * Results from ray-tracing Directional beamforming for coverage and minimizing interference Both very high and low SINRs observed Interference matters at m inter-site distance, but not at 300m 10

11 Effect of Multiple Spatial Streams BS can separate UEs both through azimuth and elevation angles in stadiums. BS can select multiple UEs simultaneously using multiple spatial streams. 50 percentile sum rate increases three-fold when number of digital chains increases four-fold. *Assumptions: 28 GHz band, 1GHz b/w, 55 dbm EIRP, 10 base-stations; 4000 devices, 11

12 PHY Design Considerations 12

13 Overview of mm wave System Design Aspects Challenge Higher path loss/shadowing Small number of digital beamforming chains Robustness to hand/body blocking Poorer RF Specs Fast system acquisition and call continuity Inherently small cell footprints System Design Aspect Beam formed transmissions exploiting array gain even for initial acquisition and control Simultaneous users in FDM limited, TDM of short TTIs to improve scheduling flexibility Enhanced path diversity and smart, closed-loop beam switching/steering/tracking Improve PA efficiency, architectures and baseband mitigation techniques Tight interworking with lower frequency anchor carrier for bootstrapping/control and fallback as needed Improve deployment flexibility by allowing integrated access and backhaul 13

14 Upper Layer Design Considerations 14

15 Integrated Access Backhaul vs Fixed Access Backhaul Fixed Access Backhaul: Access and backhaul links use semi-static resource partitioning Some BW is set aside for backhaul; All MWBs use a common partitioning Integrated Access Backhaul: Access and backhaul links use dynamic resource partitioning Fully flexible resource allocation between access and backhaul Area of MMW Coverage MWBs with Fiber-like connectivity MWBs without external connectivity Integrated Access Backhaul can be very advantageous in mmwave networks. 15

16 Uplink Flow between BS in Integrated Access Backhaul with Two Hop Constraint 18 BS Location BS with Fiber Point 1 2 Links go directly to fiber point Links require one more hop to reach fiber point *Assumptions: 28 GHz band, 1GHz b/w, 18 base-stations; 200m ISD; 600 devices, uniform distribution, UE demand in DL & UL = 25 Mbps 16

17 Integrated Access and Backhaul Performance Need well-managed wireless backhaul solution to enable dense small cells with low latency Number of Fiber Drops Needed Integrated access and backhaul techniques are more adaptive and reduce network cost Fewer fiber drop points needed compared to fixed backhaul for a given traffic demand Higher trunking efficiency results in better user experience Dynamically adjusts to changes in fiber drop locations & number 10 Mbps 20 Mbps 25 Mbps 30 Mbps 40 Mbps 50 Mbps UE data rate demand Integrated Access Backhaul Fixed Access Backhaul *Assumptions: 28 GHz band, 1GHz b/w, 18 base-stations; 200m ISD; 600 devices, uniform distribution Results obtained without a number of hop constraint 17

18 Concluding Remarks 18

19 Summary Millimeter wave bands offer a potential path for keeping up with wireless capacity demand due to higher bandwidths and spatial multiplexing Higher path loss and sensitivity to shadowing/blocking - Dynamic/agile beamforming necessary to set up and sustain links Many efforts within academia and industry to characterize the propagation properties towards usable models Many challenges remain in developing practical devices and algorithms 19

20 Backup 20

21 MMW Advantages High directivity: Received power, Pr [dbm] = Pt [dbm] + Gt [db] + Gr [db] - PL [db] Path loss increases with frequency In free space, PL f 2 Wavelength decreases at high frequency and one can pack higher number of antennas in a fixed aperture Antenna gain, G ( 4π λ 2 ) In LOS, MMW may lead to comparable received power as sub-6 GHz Challenges remain in NLOS Abundant bandwidth: 6 GHz MHz 1.3 GHz 3.5 GHz 7 GHz 7 GHz 10 GHz 3 GHz 21

22 mmw deployment scenarios Stand alone mmw access Collocated mmw + 5Gsub6 access Non-collocated mmw + 5Gsub6 access mmw integrated access & backhaul relay 5Gsub6 mmw 22

23 Penetration Loss: An Example Out-to-in penetration loss for a tinted external window Reference measurement Measured Loss 45⁰ angle of incidence Normal angle of incidence Penetration Loss = Reference-Measured Loss Out-to-in penetration loss can be challenging Suburban areas impacted heavily by foliage Windows with metallic tint tend to reflect rather than allow signal to pass through Insulation wrapped in metal foil can also cause reflections and reduce penetrability 23

24 Material Response: An Example Sample: Two layered dry wall, separated by air gap Structure construction can create deep notches, so just as important to consider as pure reflectivity Wide bandwidth frequency notches can occur and require path diversity to overcome 24

25 MMW Components Story Main challenge: Propagation in mm-wave bands Beamforming is essential to bridge the gap Optimal angle may change quickly over time due to movement (environment, receiver, transmitter) Need: High gain beamforming RF circuits to meet link budget while operating under cost, power, complexity, form-factor and regulation constraints Feasibility of various components of MMW RF frontend to provide high enough directional gains, Tx power and ability to switch/track multiple directions within the above constraints while providing good signal quality 25

26 Two RF architectures for MMW RF beamforming requires only 1 ADC/DAC per digital chain; independent of number of antennas Can support simultaneous beam at any given time; multiple beams require parallel RF components Focus Digital beamforming requires an ADC/DAC chain for each antenna Can support many parallel beams; more sophisticated interference management possible APs may or may not have DB; Handsets most likely RFB; Hybrid architectures also possible 14

27 Thank you Follow us on: For more information on Qualcomm, visit us at: & Qualcomm Technologies, Inc. and/or its affiliated companies. All Rights Reserved. Qualcomm is a trademark of Qualcomm Incorporated, registered in the United States and other countries, used with permission. Other product and brand names may be trademarks or registered trademarks of their respective owners. References in this presentation to Qualcomm may mean Qualcomm Incorporated, Qualcomm Technologies, Inc., and/or other subsidiaries or business units within the Qualcomm corporate structure, as applicable. Qualcomm Incorporated includes Qualcomm s licensing business, QTL, and the vast majority of its patent portfolio. Qualcomm Technologies, Inc., a wholly-owned subsidiary of Qualcomm Incorporated, operates, along with its subsidiaries, substantially all of Qualcomm s engineering, research and development functions, and substantially all of its product and services businesses, including its semiconductor business, QCT. 27