A V2X Message Evaluation Methodology and Cross- Domain Modeling of Safety Applications in V2Xenabled E/E- Architectures

Transcription

1 A V2X Message Evaluation Methodology and Cross- Domain Modeling of Safety Applications in V2Xenabled E/E- Architectures Harald Bucher, Marius-Florin Buciuman, Alexander Klimm, Oliver Sander, Jürgen Becker KIT University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz Association

2 Outline Motivation & Challenges Fundamentals Heterogeneous Co-Simulation Tool-Chain V2X Message Evaluation Methodology System Design Cluster-based Message Evaluation Strategy Cost Functions and Acceptance Policies Network Monitoring and Evaluation Case Studies: Cross-Domain CACC Evaluation Scenario I - Plattoon Turnaround: Message Savings Scenario II - CACC Verification Summary & Outlook H. Bucher A V2X Message Evaluation Methodology and Cross-Domain

3 Motivation Communication between vehicles as well as infrastructure and environment (V2X Communication) Enlargement of information exchange area beyond line of sight by cooperative applications Enhancement of Efficiency Traffic Flow Management Energy Usage Energy Preservation Increasing Vehicle Safety Collision Warning Adaptive Cruise Control Traffic Jam Warning all-electronics.de H. Bucher A V2X Message Evaluation Methodology and Cross-Domain

4 Challenges Smart Traffic Internet based Services V2X-Interface Smart City V2X-Interface Sensors ECUs Actuators Sensors ECUs Actuators Challenge I: How to holistically model and simulate V2X processing and communication chain? Challenge II: How to cope with heavy incoming data traffic (up to 2500 Msg/s*) in E/E Architecture and (real-time) safety applications? * B. Glas et al., Car-to-car communication security on recongurable hardware," in VTC Spring'09, 2009.

5 Fundamentals V2X Communication Vehicles regularly broadcasting their state as beacons or SAE Basic Safety Message (BSM) at 2-10Hz New Protocol and Message Type with minimized protocol overhead optimized for V2X and safety applications PHY & MAC based on ordinary Wi-Fi with some extensions One Control Channel (CCH) for Safety Messages and Beacons 4-6 Service Channels for non-safety traffic IEEE WAVE Short Message Protocol (WSMP) IEEE WAVE Short Message (WSM) contains Service Identifier (PSID) Priority Channel Number Receiver Address Payload (e.g. BSM) Security Management Plane WME (1609.3) Safety Application Sublayer Message Sublayer (SAE J2735) WSMP (1609.3) Security (1609.2) Data Plane LLC Sublayer (802.2) Application Layer Transport Layer TCP/UPD Network Layer IPv6 MLME Ext. (1609.4) MLME (802.11) MAC Extension Multichannel Coordination (1609.4) MAC Sublayer (802.11p) PLME (802.11) PHY (802.11p) H. Bucher A V2X Message Evaluation Methodology and Cross-Domain

6 Solution Challenge I: Heterogeneous Co- Simulation Tool-Chain* Framework based on Ptolemy II as central heterogeneous manager tool and High-Level Architecture (HLA) as simulation backbone Used for Case Studies Traffic Simulation Coop. Adaptive Cruise Control (CACC) App Residual E/E Architecture Simulation C2X Network Simulation * C. Roth, H. Bucher et al., A Simulation Tool Chain for Investigating Future V2X-based Automotive E/E Architectures," in Embedded Real Time Software and Systems (ERTS²), 7th European Congress on, Feb. 2014, pp

7 Solution Challenge II: Proposed V2X Message Evaluation Methodology for Safety Applications Goal: Reduce internal E/E processing efforts and network traffic by discarding irrelevant V2X messages Idea WAVE compliant methodology Needs only beacon s WSM header and payload data for evaluation Cluster-based evaluation reduces evaluation complexity Adaptive Acceptance Policies based on network and vehicle state monitoring H. Bucher A V2X Message Evaluation Methodology and Cross-Domain

8 V2X Message Evaluation System Design Intelligent Gateway inside V2X ECU for evaluation based on incoming beacons as well as local sensor data and network/vehicle state monitoring WAVE p V2X ECU... from WSM Ch. Monitor 7 Channel/Bus Evaluation from E/E Network Monitor DSRC/WAVE Interface WSM Message Evaluation App Data Sensor/GPS Data E/E Architecture Interface WSM Forwarding WSM WSM Scheduler App Msg H. Bucher A V2X Message Evaluation Methodology and Cross-Domain

9 Cluster-based V2X Message Evaluation Create virtual traffic view Classification into Farfield and Nearfield Networks (FFN / NFN) Vehicles within NF range are potentially safety-critical Vehicles outside NF range are clustered FF Master/Slave with own NF range (First-Come-First-Serve) inherent prefiltering of slaves Weighting of relations between nodes (vehicles) with costfunctions Generic FF function individual application-specific nearfield functions Farfield (FF)- Cluster C 1,0 APP FF Graph C 1,5 FF 1 NF Graph APP C 1,3 10 C 1,10 FF Nearfield (NF)-Cluster Legend Vehicle with Msg Eval Cluster-Master Cluster-Slave FF-Cluster C 1,2 APP H. Bucher A V2X Message Evaluation Methodology and Cross-Domain

10 Refined Cluster-based V2X Message Evaluation System NF and FF Stage composed of Static Filter Unit Dynamic Data Fusion Unit Filter Unit Compares current Acceptance Policies with incoming WSM data Data Fusion Unit Determines Acceptance Policies based on network monitoring and vehicle state Forwards incoming event-driven WSMs based on PSID Calculates cost functions C FF and C NF(CACC) Periodic forwarding of most relevant NF data frames to destination application (in this work CACC) WSM Sensor GPS WSM WSM Data Fusion Filter Message Evaluation WSM Forwarding Bus Eval Bus Eval Farfield Evaluation Stage WSM Bus Eval Sensor GPS WSM Sensor/GPS Data WSM Forwarding Data Fusion Filter App Data Sensor/GPS Data Bus Eval Bus Eval Nearfield Evaluation Stage Periodic Data Frame H. Bucher A V2X Message Evaluation Methodology and Cross-Domain

11 Hybrid Clustering and Hierarchical Evaluation Strategy Procedure Update FF/NF Node: Updates mobility information between local vehicle v i and remote vehicle v j and calculates cost functions C i, j FF j FFN and C i, j CACC j NFN, j i Update FF/NF Accpetance Policy: Update Acceptance Policies A FF and A NF based on cost function and vehicle state as well as network utilization Farfield Eval Stage Nearfield Eval Stage FF Acceptance Policy OK NF Acceptance Policy OK yes yes yes no yes Discard WSM WSM in NF Area no New Cluster Entry (ID) yes WSM covered by FF Clusters no New Cluster Master Entry no Update Cluster Master Update FF Acceptance Policy New Sensor/GPS Data Polling no Update NF Node Update NF Acceptance Policy New Cluster Entry (ID) yes New NF Node Entry no Discard WSM New WSM H. Bucher A V2X Message Evaluation Methodology and Cross-Domain

12 Cost Functions and Acceptance Policy Sets FF cost function detects hot-spots and serves as premature warning C FF i,j = a compdrivedir + b psideval + c normdistance + d comprelpos, a = c = 0.1, b = 0.5, d = 0.3 and a + b + c + d = 1.0 NF cost function for detection of the leading vehicle for CACC app. CACC Frame Rate λ CACC = 10Hz C CACC i,j = compdrivedir normdistance comprelpos, [0.0,1.0] Individual strong and weak Acceptance Policies for FF and NF A FF = {ID, psid, prio, age, range} A NF = {prio, age, range} H. Bucher A V2X Message Evaluation Methodology and Cross-Domain

13 Acceptance Policy Adjustments A FF are mainly determined by Driving State FSM highway [speed > (speed th + δ speed )] [speed (speed th - δ speed )] city [C max FF C th NU wsm == restricted] danger [C max FF C th NU wsm == restricted] [C max FF C th NU wsm == restricted] [C max FF < (C th - δ C ) NU wsm!= restricted] relaxation [speed > (speed th + δ speed )] [speed (speed th - δ speed )] A NF must not depend on FSM but mainly on internal network utilization (NU) because of the prefiltering in FF stage High network utilization results in strong policies in order to relax internal network traffic for safety critical applications H. Bucher A V2X Message Evaluation Methodology and Cross-Domain

14 Network Monitoring and Evaluation Protocol independent metric for monitoring Based on byte-rate B wsm, B ee measured over time interval T and nominal byte-rate N wsm, N ee Activity relaxed active1 active2 active3 active4 active5 restricted Smoothed linearly* NU x τ = 0.5 NU x τ B x N x, x = {wsm, ee} Discretized into 7 NU activity states* % NU min =15% 20% 25% 30% 35% 40%=NU max NU * Intelligent Transport Systems (ITS); De-centralized Congestion Control Mechanisms for Intelligent Transport Systems operating in the 5 GHz range; Access layer part," ETSI TS V1.1.1, Jul

15 Case Study: Cross-Domain CACC Evaluation Simulation Setup Plattoon following scenario Approaching intersections every 200m OMNeT++ Transmit Power: 20 dbm WSM Channel: CCH WSM Bitrate N wsm = 6 Mbps Beacon Rate: 10Hz SUMO Vehicles: 30 Max. Speed: ~50 km/h Mobility Update Rate: 10Hz Message Evaluation (Ptolemy) Sensor Update Rate: 10Hz N ee = 500kbps CACC Frame Rate λ CACC = 10Hz Acceptance Policies: cp. Table 1 Table 1: Acceptance Policy Specification A FF weak strong PSID all safety related prio all prio(bsm) range (x,y,z) 300m 150m age 1.0s 0.5s A NF weak strong prio all prio(bsm) range (x,y,z) 300m 100m age 0.5s 0.2s H. Bucher A V2X Message Evaluation Methodology and Cross-Domain Modelling of Safety Applications in V2X-enabled E/E-Architectures

16 speed [m/s] position (x) [m] Results Scenario I: Plattoon Turnaround 14 speed leader speed local posx leader posx local Time [s] Time [s] H. Bucher A V2X Message Evaluation Methodology and Cross-Domain

17 # Messages Results Scenario I: Plattoon Turnaround 600 # Total Received Messages # Messages after FF Eval # Messages after NF Eval Time [s] Message Saving after FF Eval: Max. 69,3% and 37,0% in average Overall Message Saving after NF Eval: Max. 96,6% and 92,7% in average H. Bucher A V2X Message Evaluation Methodology and Cross-Domain

18 speed [m/s] Results Scenario II: CACC Verification Broke down leading vehicle after 30s Event-Driven warning with PSID 0x8005 sent out strong A FF Modeled worst case reception latency per beacon inside E/E architecture model: 10ms* Comparison of CACC behavior w/ and w/o Message Evaluation 14 speed leader speed local w/o msg eval speed local with msg eval Time [s] * SAE Standard for Dedicated Short Range Communications (DSRC) Message Set Dictionary, SAE Std J2735, Nov

19 Example Simulation Snapshot H. Bucher A V2X Message Evaluation Methodology and Cross-Domain

20 Summary Presentation of a WAVE compliant V2X Message Evaluation Methodology Hierarchical vehicle clustering strategy Vehicle and network (internal/external) state monitoring (Cost Functions) Adaptive Acceptance Policies Modeled inside V2X ECU together with abstract E/E architecture components reducing internal network traffic and message processing efforts Model-based cross-domain evaluation of CACC application with co-simulation framework Taking into account internal processing and communication latencies Enables early and deterministic exploration and evaluation of (abstract) E/E architectures in V2X scenarios Significant reduction of V2X messages need to be processed during run-time 92.7% in average in reverse traffic scenario Accident-free CACC behavior in case of worst-case WSM latencies and broke down leading vehicle H. Bucher A V2X Message Evaluation Methodology and Cross-Domain

21 Outlook Investigation of more complex traffic scenarios Deeper analysis of acceptance policies Analysis of power/energy consumption reduction of signature verification modules by the approach Implementing the approach on real target platforms Validation of the approach and CACC scenario by means of robot prototypes H. Bucher A V2X Message Evaluation Methodology and Cross-Domain

22 Thank you very much for your attention! H. Bucher A V2X Message Evaluation Methodology and Cross-Domain