Keysight p WAVE (wireless access in vehicular environments)

Transcription

1 Keysight p WAVE (wireless access in vehicular environments)

2 Agenda Page p Overview & Structure p Test Solution How to test p with SA/SG

3 V2X Market Forecast Registered vehicles with IoT application by type Word market. Forecast: ABI research Global V2V Penetration in new Cars is expected to increase from 10.9% in 2018 to 69% in 2027 Source: ABI research, Nov Page 3

4 802.11p Overview p is an approved amendment to the to add wireless access in vehicular environments (WAVE, aka ITS, DSRC, V2X) Application: communications between vehicles and infrastructure (V2I) or vehicle to vehicle (V2V) etc. V2X Vehicle safety services Commerce transactions via cars Toll collection Traffic management Page 4

5 V2V Safety Motivation Warning dangerous area to avoid threatening accident Page 5

6 V2V Safety Applications Scenario and warning type Scenario example Forward collision warning Rear end collision scenarios Approaching a vehicle that is decelerating or stopped. Emergency electronic brake light warning Approaching a vehicle stopped in roadway but not visible due to obstructions. Blind spot warning Lane change scenarios Beginning lane departure that could encroach on the travel lane of another vehicle traveling in the same direction; can detect vehicles not yet in blind spot. Do not pass warning Encroaching onto the travel lane of another vehicle traveling in opposite direction; can detect moving vehicles not yet in blind spot Blind intersection warning Intersection scenarios Encroaching onto the travel lane of another vehicle whom driver is crossing paths at a blind intersection or an intersection without a traffic signal GAO Analysis Page 6

7 V2V Configuration Security system Provides and verifies V2V security certificates to ensure trust between vehicles GPS,DSRC Antenna In-vehicle components Dedicated Short Range Communications (DSRC) radio Receives and transmits data through antenna GPS receiver - Provides vehicle position and time to DSRC radio - Provides timekeeping signal for applications Driver-vehicle interface Generate warning Issued to driver Memory Stores security certificates, Application data, and Other information Safety application Electronic control unit Stores Runs safety applications Vehicle s internal Communications network Existing network that Interconnects components This in-vehicle equipment can consist of either a single integrated unit or a discrete set of components GAO Analysis Page 7

8 802.11p Structure Tree ITS Technologies and applications Page 8

9 Communication Method Communication method Conventional WLAN IEEE g Conventional WLAN IEEE n V2V (vehicle-to vehicle) V2I (vehicle-to infrastructure) Theoretical data rate Mobility support Architecture Connection delays Theoretical range 54 Mbps Low Local cells Low 140 m 600 Mbps Very low2 Local cells Low 250 m 3 27 Mbps Good Local cells Very low 1 km 3 27 Mbps Good Local cells Very low 1 km GPRS cellular data kbit/s Good Cellular Moderate Unlimited 3G cellular data 0.2 Mbps Moderate Cellular Moderate High LTE cellular data 300 Mbps Moderate Cellular Moderate Low Page 9

10 802.11p Standards Protocol Stack IEEE 1609.x Higher layers IEEE p MAC PHY The higher layers of ITS are depending on regional regulatory issues Page 10

11 802.11p Standards Protocol Stack An amendment to the WiFi standard IEEE Ratified in July, 2010 No access point functionality No authentication or association procedures Medium access control (MAC) Carrier sense multiple access with collision avoidance (CSMA/CA) Support for Quality of (802.11e) Page 11

12 802.11p PHY Physical layer of p Derived from the a Defines 3 different channel widths: 5,10, and 20 MHz Orthogonal Frequency Division Multiplexing (OFDM) 48 data carriers and 4 pilots Subcarrier spacing of khz Symbol interval 8 μs (GI of 1.6 μs) 8 different transfer rates 3, 4.5, 6, 9, 12, 18, 24, 27 Mbps BPSK, QPSK, 16 QAM, 64 QAM Page 12

13 IEEE WAVE WSMP WAVE short message protocol (WSMP) Developed to avoid excessive overhead WAVE Short Messages (WSM) WAVE Advertisements (WSA) SAE J2735 DSRC message set dictionary 15 message types Basic Safety Message (BSM) ~300B, 10Hz Conveys state information about the sending vehicle Periodic Here I am messages Security Page 13

14 IEEE WAVE Multichannel operation One Control channel (CCH) Six channels (SCH) Page 14

15 802.11p Packet Structure & Channel Allocation Packet Structure Channel Allocation Page 15

16 802.11p PPDU Frame Structure Packet Structure signal detection, automatic gain control (AGC) and diversity selection coarse frequency offset and timing synchronization To avoid interference between STS and LTS channel estimation and fine frequency acquisition in the receiver specify rate and length information Page 16

17 802.11p PHY Feature Parameters Transmission method OFDM Frequency 5.8 GHz and 5.9 GHz Channel bandwidth 5 MHz 20 MHz FFT size Data subcarriers / pilots 52 / 4 52 / 4 52 / 4 Subcarrier spacing kHz kHz khz OFDM symbol duration 16us 8 us 4us Guard interval 3.2us 1.6 μs 0.8 μs Modulation types BPSK, QPSK, 16QAM, 64QAM Forward error correction Binary convolutional coding (BCC) Coding rates 1/2, 2/3, 3/4 Page 17

18 The PHY difference between a and p Feature a p 10MHz half clocked mode Bit rate (Mbit/s) 6, 9, 12, 18, 24, 36, 48, 54 3, 4.5, 6, 9, 12, 18, 24, 27 Channel bandwidth 20 MHz FFT size Data subcarriers / pilots 52 / 4 52 / 4 Subcarrier spacing KHz kHz OFDM symbol duration 4us 8 us Guard interval 0.8us 1.6 μs Preamble duration 16us 32us Modulation types BPSK, QPSK, 16QAM, 64QAM Coding rates 1/2, 2/3, 3/4 Page 18

19 802.11p Channel Allocation Seven channels from 5.85 to 5.925GHz 5850 MHz 5925 MHz CH MHz CH MHz CH 172 CH 174 CH 176 CH 178 CH 180 CH 182 CH 184 Reserve Control 5 MHz Reference document: Page 19

20 Spectrum (Channel 172) 5850 MHz 5925 MHz CH MHz CH MHz CH 172 CH 174 CH 176 CH 178 CH 180 CH 182 CH 184 Reserve Control 5 MHz FCC designated exclusively for vehicle-to-vehicle safety communications for accident avoidance and mitigation, and safety of life and property applications Extensive industry research, testing, and field trials of safety applications using Ch. 172 Will host 3 message types: Basic Safety Message (V2V) MAP Message (V2I) Signal Phase and Timing Message (V2I) Nominal transmit power +20 dbm with 0 dbi antenna Page 20

21 Spectrum (Channel 184) 5850 MHz 5925 MHz CH MHz CH MHz CH 172 CH 174 CH 176 CH 178 CH 180 CH 182 CH 184 Reserve Control 5 MHz FCC designated exclusively for high-power, longer-distance communications to be used for public safety applications involving safety of life and property, including road intersection collision mitigation Road authorities and public agencies primarily responsible for usage Max. power 40 dbm Page 21

22 Spectrum (Channel 178 & Others) 5850 MHz 5925 MHz CH MHz CH MHz CH 172 CH 174 CH 176 CH 178 CH 180 CH 182 CH 184 Reserve Control 5 MHz Ch. 172: Collision Avoidance Safety Ch. 184: Public Safety Ch. 178: Control Channel WAVE Advertisements are broadcast here, indicating how to access services on other Channels Page 22

23 802.11p Protocol Protocol V2V / I2V Pros Cons Real-time I2V (Böhm) Multi-channel VANET V2I V2I / V2V -Provides bounded delay -Location based priority zones -Adaptable ratio between contention free phase and contention based phase. -No real-time analysis. -Basis for multi-channel WAVE proposal. RT-WiFi N/A -Centralized mechanism. -Allows coexistence of RT stations and non-rt stations. -RSU uses polling mechanism. -Unspecified: vehicles change their warning message rate. -RSU coordination is not defined. -RSU uses polling mechanism. -RSU Beacon must contend with other messages. -It is not destined to vehicular environments. -The RT cycle grows with the number of RT stations. -No study yet on maximum number of RT stations it can allow. Page 23

24 802.11p Protocol Protocol V2V / I2V Pros Cons V2Vicle Deterministic Access (VDA) V2I -Provides bounded delay. -High-density scenarios. -Two-hop range. Self-organizing TDMA V2V -Adaptable ratio between contention free phase and contention based phase. -Provides bounded delay. -Lower probability of packet drop than regular CSMA/CA. V2Vloha N/A -Scalable with upper bounded delay -Requires GPS for synchronization -Requires GPS for tight node synchronization -Overhead introduced by Frame Information Field Page 24

25 Vehicular Flexible Time-triggered Protocol(V-FFT) RSUk RSU2 RSU1 B Motorway Safety Zone (Sz) A B Vehicle leaves safety zone A Vehicle enters safety zone RSU OBU ITS Technologies and applications Page 25

26 RSU Infrastructure ITS Technologies and applications Page 26

27 RSU Infrastructure ITS Technologies and applications Page 27

28 Vehicular FFT(V-FTT) protocol Elementary Cycle(EC[i]) Infrastructure Window (IW) (I2V) Synchronous OBU Window (SOW) (V2I) Free Period (FP) (V2I/V2V) TM1 WM1 TM2 WM2 TMIW WMIW S M 1 S M 2 S M n 1 2 SIW SOWSLOTS ITS Technologies and applications Page 28

29 IEEE p/WAVE synchronization interval Sync Interval SCH Interval CCH Interval SCH Interval G.I. G.I. G.I. G.I. SCH Interval Page 29

30 V-FTT protocol adaptation to IEEE802.11p/WAVE CCH Interval SCH Interval G.I. G.I. SCH Interval Page 30

31 Security and Privacy Requirements Authenticated senders Protect privacy of drivers Prevent message manipulation Prevent replay attacks Use of certificates But this is a unique Identifier! Privacy? Pseudonym Certificates(PC) Long Term Certificates(LTC) C2C-CC Page 31

32 Security and Privacy Long Term Certificates are valid for several years. Depend on the vehicle manufacturers. Elliptic Curves for all certificates ECDSA 256 NIST Curve Prevent replay attacks Pseudonym change Valid for one week >=20 pseudonyms valid at the same time At engine start Every 10 to 30 minutes It is not allowed to use the same pseudonym twice successively C2C-CC Page 32

33 Autotalks PANGAEA4 Autotalks V2X Page 33

34 PANGAEA4 WLAN Rx Test (N7617B Signal Studio) waveform setup MacHeader settings are different from default setting Page 34

35 System Configuration MXG/MXA RF Cable Connection LAN BNC Cable Connection GPIB/LAN Page 35

36 802.11p Automation Tool Automated test for p Test Coverage Tx Power Spectral Flatness Constellation Error Symbol Clock Freq Tolerance Tx Center Freq Leakage Tx SEM Rx Min Input Sensitivity Page 36

37 802.11p Automation Tool Report (CSV) p Page 37

38 Single Channel Fading What Problem Does It Solve? p Designers of mobile devices need to: Test the performance (FER/BER/BLER) of their receivers under realistic channel conditions Have accurate and repeatable results Do it at a reasonable price MXG/EXG + N7605B Signal Studio for Real-time Fading Page 38

39 Simple Fading UI N7605B Real Time Fading Page 39

40 Fading Channel Test Page 40

41 Real Time Fading Test Fading mode ON (Profile 5) Page 41

42 802.11p Power classes Power class Max. output power (dbm) Class A 0 Class B 10 Class C 20 Class D 28.8 Page 42

43 802.11p ACP Requirement Modulation Coding rate Adjacent channel rejection (db) Nonadjacent channel rejection (db) BPSK 1/ BPSK 3/ QPSK 1/ QPSK 3/ QAM 1/ QAM 3/ QAM 2/ QAM 3/ Much stricter ACP are defined in p standard Page 43