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u SAVES: Center for Situation-Aware Vehicular Engineering Systemsu Focuses on wireless, networking, and sensing challenges in vehicular systems u Brings together stakeholders in different aspects of the automotive market
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SAVES is built around TOYOTA as a founding member, lookging for partners
u Automated cars needs sensing capabilitiesª Increased number of sensors in a vehicleª Vehicular communications to share sensing data and improve sensing capability
6*5G-PPP White Paper on Automotive Vertical Sector, October 2015, https://5g-ppp.eu/white-papers/
New challenges for the underlying communication system
DSRC: current technology for vehicular communications
u Forward collision warning, do not pass warning, blind intersection warning, etc.u Non-safety apps also possible – improve congestion, weather, toll collection u Based on IEEE 802.11p, IEEE 1609.x, SAE standardsu Supports very low data rates (27 Mbps max, much lower in practice)
7*NHTSA, “Vehicle-to-Vehicle Communications: Readiness of V2V Technology for Application,” Aug. 2014**John B. Kenney, “DSRC: Deployment and Beyond,” WINLAB presentation, May 2015.
DSRC is expected to be mandated for all vehicles in US by NHTSA by 2017
u Connected vehicle is expected to drive 1.5GB monthly mobile data in 2017ª May be handled with a combination of conventional cellular and DSRC
u Autonomous vehicle can generate up to 1 TB of data in a single tripª 4G and DSRC can not support these data rates
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*http://low-powerdesign.com/sleibson/2011/05/01/future-cars-the-word-from-gm-at-idc’s-smart-technology-world-conference/**Cisco, “The Internet of Cars: A Catalyst to Unlock Societal Benefits of Transportation,” Mar. 2013***http://www.sas.com/en_us/insights/articles/big-data/the-internet-of-things-and-connected-cars.html
Each sensor generates data
Lots of sensors in a vehicle
Massive amount of data per vehicle
MmWave is the only viable approach for high bandwidth connected vehicles
* T. Rappaport et al., “Millimeter wave mobile communications for 5G cellular: It will work!” IEEE Access, 2013.** W. Roh et al., "Millimeter-wave beamforming as an enabling technology for 5G cellular communications: theoretical feasibility and prototype results,“, IEEE Commun. Mag.,, 2014*** A. Osseiran et al.,"Scenarios for 5G mobile and wireless communications: the vision of the METIS project," iIEEE Commun. Mag., May 2014
60 GHz7 GHz
Unlicensed6 GHz 100 GHz
E-band10 GHz total
28 GHz1.3 GHz
39 GHz1.4 GHz
37/42 GHz2.1 GHz
20 GHz x100 GHz<1 GHz
MmWave
2.4 GHz100 MHz
900 MHz2.6 MHz
5.2 GHz555 MHz
CmWave
More spectrum, in bands not previously used for cellular
u Mathematical expression relating coherence time and beamwidthª Accounts for beam pointing angular difference as oppose to classical models
u Optimum beamwidth is a tradeoff between pointing error and Doppler
14*Vutha Va, and Robert W. Heath, Jr, "Basic Relationship between Channel Coherence Time and Beamwidth in Vehicular Channels,'' IEEE Vehicular Technology Conference (VTC 2015-Fall), 2015.
Using position information to reduce beam alignment overhead in mmWave V2X
u Each vehicle decides candidate beams from other vehicles’ position and size info
16Junil Choi, Nuria Gonzáalez-Prelcic, Robert Daniels, Chandra R. Bhat, and Robert W. Heath Jr, “Millimeter Wave Vehicular Communication to Support Massive Sensing”, to be submitted December 2015
DSRC modules or automotive sensors can be used to reduce overhead
u Channel classifications considered at 5.9GHz is unlikely to scaleª More sensitive to antenna orientationª More sensitive to traffic density (higher blockage probability)ª Effect of directive transmission is unknown
u Few measurements available
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Typical antenna height: 1.5 m
* T. S. Rappapport, R. W. Heath Jr., R. C. Daniels, and J. N. Murdock, “Millimeter Wave Wireless Communications,” Pearson Prentice-Hall, 2014** S. Takahashi, et al., “Distance dependence of path loss for millimeter wave inter-vehicle communications,” in VTC 2003-Fall, Oct. 2003, ** W. Schafer, “Channel modelling of short-range radio links at 60 GHz for mobile intervehicle communication,” in IEEE 41st VTC, May 1991.
u New models must account for mmWave propagation characteristicsu Channels are sparse in the angular domain, a few paths existu Blockage has to be introduced in the channel model
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Modified Sen-Matolak model*
Persistence process for each cluster modellating blockage
Delay of cluster c and ray p
Doppler shift for each multipath component
Steering vectors
θ
* V. Va, N. Gonzalez-Prelcic and R. W. Heath Jr., “A cluster-based approach for vehicular channel models at millimeter wave”, in preparation.
u A classic problem even at low frequencies*ª Shadowing becomes blockage for mmWaveª Directional transmission adds another challenge
u V2V require 360 degree coverage but antennas can not penetrate carª Front bumper location causes blockage at the back sideª Rooftop location causes blockage at the front side due to roof curvatureª Sensitive to antenna orientation
21* C. Mecklenbrauker, et al., “Vehicular channel characterization and its implications for wireless system design and performance,” Proc. of the IEEE, July 2011.
MmWave propagation add new challenges to antenna placement
u A BS with a radar is assumed at the infrastructure sideª Antennas are assumed to be placed at the virtual scattering points in the carª Radar info is used to design a multi-beam pattern to track several antennas
u High mobility is considered and the positions of the antennas are predicted
22* N. González-Prelcic, R. Méndez-Rial and R. W. Heath Jr., “Radar-aided multibeam directional beamforming for mmWave vehicle to infrastructure communications”, in preparation.
Sensing at the infrastructure can help to manage blockage
u A BS equipped with a radar is assumedu Radar and communication operate at different mmWave bandsu Radar can detect potential obstacles and their associated mobilityu Machine learning can classify particular radar responses as blockages
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Sensing & learning are symbiotic technologiesJunil Choi, Nuria Gonzáalez-Prelcic, Robert Daniels, Chandra R. Bhat, and Robert W. Heath Jr, “Millimeter Wave Vehicular Communication to Support Massive Sensing”, to be submitted December 2015
u MmWave radars widely used in automotive safety applicationsª Expensive: automotive radar modules cost around $1,500ª Easy to get spoofed compared to communication
u Why not share common equipment with communication?ª Combines the objectives of radar and communication
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Direction of Cruise
Communication Signal
Emergency Van
Radar Multi-beam
Emergency Event
Shared hardware reduces cost/size and makes efficient spectrum usage
LFM# : Linear frequency modulated waveform, which is a radar waveformDSSS# : Direct spread spectrum, which is a communication waveform*L. Han and K.Wu,``Joint wireless communication and radar sensing systems-state of the art and future aspects,'' IET Microwaves, Antennas & Propagation, vol. 7, no. 11, pp. 876-885, 2013.
Communication-radar (RadCom) Application Scenario
u Optimization of sensing and data communication ª LFM # waveform provides low data rate ª DSSS# exhibits poor radar performance ª No single waveform yet available ª Interference issue
u Assumption of full-duplexª Separate transmit and receive antennaª Use directional antennas
Many open problems to design joint communication and radar systems
Joint automotive radar and communications based on 802.11ad
u IEEE 802.11ad mmWave waveform works well for radarª Special structure of preamble enables good ranging performanceª Leverages existing WLAN receiver algorithms for radar parameter estimation
u Target vehicle information from 11ad radar can be directly used for communication
27*P. Kumari, N. González Prelcic and R. W. Heath, Jr, ̀ `Investigating the IEEE 802.11ad Standard for Millimeter Wave Automotive Radar,'' IEEE VTC-Fall, 2015.
Joint system provides safety capabilities at lower cost
Opportunities• Millimeter wave is ripe for V2X applications• Natural synergies with automotive radar, circuit design, etc.• Only feasible way to enable connected + autonomous
Challenges• Unlicensed band, co-exist with radar, new spectrum?• Complete redesign of physical layer required, mobility• Support of full duplex for more complicated waveforms• Antenna mounting, packaging, cabling