DSRC Spectrum Sharing: Can unlicensed devices share the 5.9 GHz band without causing interference to DSRC?

Transcription

1 DSRC Spectrum Sharing: Can unlicensed devices share the 5.9 GHz band without causing interference to DSRC? IEEE GLOBECOM Industry Forum: Opportunities and Challenges with Vehicular Networks John Kenney Toyota InfoTechnology Center, USA December 10, 2015

2 Outline What is the issue and why does it matter? Who are the stakeholders and what are they doing? What is likely to happen, and when? 2

3 What is the issue? FCC has given DSRC a Primary allocation in GHz Wi-Fi community has asked FCC to let them share the spectrum on the condition that they cause no harmful interference to DSRC Basic question: Is this feasible and if so how would it work? 3

4 More details DSRC Initial FCC allocation 1999 definition of channels and rules in 2003 & MHz 5925 MHz CH MHz CH MHz CH 172 CH 174 CH 176 CH 178 CH 180 CH 182 CH 184 Reserve Service Service Service Control Service Service Service 5 MHz 10 MHz 10 MHz 10 MHz 10 MHz 10 MHz 10 MHz 10 MHz Ch. 172: Collision Avoidance Safety Ch. 184: Public Safety Ch. 178: Control Channel, advertises services on service channels 4

5 DSRC Deployment Attention on V2V safety: Ch. 172 GM Cadillac model year 2017 NHTSA mandate likely ~2020 US DOT Pilot Deployments: Awarded 2015 New York, Tampa, Wyoming I-80 Likely to use channels throughout the band DSRC can address ~80% of crash scenarios 32,719 US traffic fatalities in

6 USDOT Application Research 6 Source: US Department of Transportation Most of these use V2I, on channels other than Ch. 172

7 Cooperative Automated Driving DSRC devices share sensor information to aid automated driving application High data rate communication with strict performance requirements, e.g. using DSRC service channels See: Adaptive Content Control for Communication Amongst Automated Vehicles, F. Fanei et al., IEEE WiVec

8 US Spectrum is Crowded GHz 8

9 The movement toward spectrum sharing Demand for Wi-Fi is high and growing Impacts economic growth Finding more spectrum for Wi-Fi is considered strategic by US Government FCC approach is to selectively allow Wi-Fi (more broadly unlicensed or U-NII) to share some spectrum with licensed primary users Strict requirement is U-NII does not harmfully interfere with primary Lost and delayed packets degrade DSRC s ability to carry out its safety-of-life mission: Harmful Interference 9

10 U-NII Sharing to Date in 5 GHz U-NII2 represents successful sharing with radar, e.g. 45 locations of Terminal Doppler Weather Radar Sharing is based on detect & vacate called Dynamic Frequency Selection Source: Cisco Systems 10

11 Comparison: Good & Bad News Sharing with radar and sharing with DSRC have similarities and differences: Primary Radar DSRC Signal Power High Low (10-20 dbm) Locations Signal Structure Few, static, and known (?) Pulse, specifics not always known Many and mobile (ubiquitous) Well defined preamble, similar to Wi-Fi Detect & Vacate? Yes Maybe Implications for technical sharing proposal discussed below 11

12 Major Stakeholders US Congress US President 12

13 Timeline Phase 1: February July 2013 Congress directs study of 5.9 GHz sharing FCC NPRM (asks for comments on many 5 GHz sharing issues, including 5.9 sharing) Phase 2: August 2013 March 2015 DSRC Coexistence Tiger Team (sponsored by ) DSRC and Wi-Fi stakeholders join in discussion Two sharing concepts brought forward Phase 3: April 2015 Main focus is testing Cisco developed prototypes of their proposal Joint testing with automotive stakeholders ongoing 13

14 Detect & Vacate Concept Wi-Fi devices listen for DSRC If no DSRC Wi-Fi ok to operate in 5.9 GHz Continues to listen while WLAN operates WiFi Network WiFi Network Wi-Fi with DSRC detector Building Wi-Fi with DSRC detector Building When car appears, Wi-Fi detects DSRC If DSRC detected Wi-Fi NOT ok to operate in 5.9 GHz (minimum TBD second delay after each DSRC packet) Detection leverages DSRC s heritage as p Note: in-car Wi-Fi will never use 5.9 GHz 14

15 Rechannelization Concept GHz GHz CH 175 CH MHz 20 MHz 5 CH 172 DSRC CH 174 CH 176 DSRC CH 178 CH 180 CH 182 CH 184 Service Ch. 173 Service Service Ch. 177 Control Service Service Service 20 MHz 10 MHz 10 MHz 20 MHz 10 MHz 10 MHz 10 MHz 10 MHz 10 MHz Reserved MHz 20 MHz 20 MHz 20 MHz 20 MHz 40 MHz 80 MHz 40 MHz Overlapping Wi-Fi 160 MHz Move V2V safety from Ch. 172 to upper band (non-overlap portion) Cancel highest 20 MHz Wi-Fi (Ch. 181) DSRC use 20 MHz channels in overlap portion instead of 10 MHz 15

16 Feedback from DSRC community Detect & Vacate has potential, should be tested Fundamentally opposed to Rechannelization Cannot protect DSRC from harmful interference Detailed critique in /r1: Core idea is to try to share in same time & place Note: Rechannelization is a high level concept with many details not provided 16

17 Tiger Team R.I.P. Wi-Fi interests divided on proposals Unable to agree to move ahead with Detect & Vacate IEEE Regulatory Chair ended TT in March Final action of Tiger Team was to poll members on what to do next TT voting members approximately equally split between Wi-Fi and DSRC interests 17

18 Tiger Team Poll #1: Do you believe it is technically feasible to protect DSRC systems from harmful interference if unlicensed (Part 15) devices share the 5.9 GHz band? 18

19 Tiger Team Poll #2: Do you believe [Detect & Vacate] proposed band sharing technique has merit and, after developing a more complete definition and field testing, should be considered a basis for a band sharing solution? 19

20 Tiger Team Poll #3: Do you believe [Rechannelization] proposed band sharing technique has merit and, after developing a more complete definition and field testing, should be considered a basis for a band sharing solution? 20

21 Compare preference directly: Team Polls #2 and #3: D&V proposal has merit Rechannelization proposal does not have merit 21

22 Tiger Team Poll #4: Which proposal do you support for further specification development and field testing? Detect & Vacate Rechannelization Some combination of both 22

23 Testing May 6, 2015 FCC Filing by Auto Alliance, Global Automakers and Cisco: successful efforts to begin testing in the coming weeks the enhanced Listen, Detect, and Avoid protocol that is under development by Cisco August 21, 2015 FCC Filing by Cisco: Cisco provided a status update on its proof of concept testing with respect to [DSRC] devices. Cisco noted that its technology has been reliably able to listen for DSRC signals at a -95dBm level, which is the first step in ensuring that unlicensed users of the bands can detect DSRC. Lab work is proceeding 23

24 Testing Principles Encouraged by legislators, stakeholder groups discussed testing principles: Auto Alliance, Global Automakers, Intelsat, NCTA, Qualcomm, SES (satellite) Letter of agreement sent to FCC, US DOT, US Dept. of Commerce Sept. 9, 2015 Principles include: FCC to take testing lead, coordinate testing methods Engineers, not lawyers, should decide testing Only fully defined proposals with prototypes tested All reasonable options to be considered Test results of DSRC research should be made public Complete testing by end of 2016 if possible 24

25 European Spectrum Sharing Spectrum Engineering committee SE24 Direct committee input ETSI BRAN is preparing TR : Mitigation Techniques to enable sharing. Broadband Radio Access Networks (BRAN) Coordinated ETSI input Radio Spectrum Matters (ERM) ETSI ITS Liaison to BRAN notes requirement for significant vacate time after detection. Intelligent Transport Systems (ITS) 25

26 What will happen, and when? Cannot predict with any confidence All parties want resolution Possible scenario (not a prediction): Details of Detect & Vacate fully defined (e.g. power, timing) D&V tested rigorously, shown not to harmfully interfere Rechannelization proponents not able to fully define a proposal that can be shown to avoid harmful interference DSRC/Wi-Fi consensus to allow sharing based on D&V. FCC rule reflects agreement. Individual Wi-Fi suppliers decide whether to offer products with 5.9 GHz support based on business decision 2016 will be critical for testing and resolution. 26

27 Summary DSRC safety-of-life mission. Primary allocation from FCC in licensed 5.9 GHz band. Wi-Fi stakeholders want to share 5.9 GHz Government stakeholders recognize value of increased Wi-Fi spectrum & need to protect DSRC Two sharing concepts. D&V: no sharing same time and space. Testing started. Rechannelization uses aggressive sharing, cannot protect DSRC Both technical and non-technical forces at play Biggest threat to successful DSRC deployment 27

28 Backup Slides Some harmful interference scenarios 28

29 DSRC Harmful Interference: Loss of safety message Packet collisions U-NII U-NII packet U-NII packet time OLLISION SRC Packet ot received DSRC pckt DSRC pckt COLLISION DSRC Packet not received Lead vehicle transmits DSRC safety message. Host vehicle attempts to receive safety message. U-NII packet prevents DSRC reception Note: Second case mitigated if U-NII has DSRC detector, but first case is not 29

30 DSRC Harmful Interference: Delay of safety message Indefinite Delay U-NII U-NII U-NII U-NII U-NII U-NII Frame Concatenation or alternating use among multiple U-NII devices Inter-frame space DSRC pckt time DSRC ready to send packet, backoff Lead vehicle s safety message is delayed indefinitely DSRC packet sent 30