Data Preference Matters: A New Perspective of Safety Data Dissemination in Vehicular Ad Hoc Networks

Transcription

1 Data Preference Matters: A New Perspective of Safety Data Dissemination in Vehicular Ad Hoc Networks Qiao Xiang 1, Xi Chen 1, Linghe Kong 1, Lei Rao 2 and Xue Liu 1 1 School of Computer Science, McGill University 2 General Motors Research Lab April 29th, 2015 Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/2015 1/ 31

2 Outline Introduction 1 Introduction 2 Quantifying Data Preferences 3 PVCast: a Packet-Value-Based Dissemination Protocol 4 Performance Evaluation 5 Conclusion and Future Work Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/2015 2/ 31

3 Introduction Introduction Background Vehicular Ad Hoc Networks Communication infrastructure for Intelligent Transportation Systems (ITS) Operate in a dynamic environment Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/2015 3/ 31

4 Introduction Introduction Background Safety Data Dissemination Crucial for vehicle safety Contain periodic routine data and event-driven emergency data More emphasis on QoS, e.g., small delay and high coverage (a) Collision Avoidance (b) Lane Change Sources: and Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/2015 4/ 31

5 Introduction Data Preferences Background When collecting safety data, vehicles have preferences on Closer, Newer and More important data Related works do not consider these preferences Counter-Based Dissemination Farthest-First Dissemination Probabilistic Forwarding Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/2015 5/ 31

6 Our Focus Introduction Our Focus Quantifying data preferences Designing lightweight distributed dissemination protocol Satisfying data preferences of all the vehicles Understanding system benefits Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/2015 6/ 31

7 Outline Introduction Our Focus 1 Introduction 2 Quantifying Data Preferences 3 PVCast: a Packet-Value-Based Dissemination Protocol 4 Performance Evaluation 5 Conclusion and Future Work Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/2015 7/ 31

8 Quantifying Data Preferences Outline 1 Introduction 2 Quantifying Data Preferences 3 PVCast: a Packet-Value-Based Dissemination Protocol 4 Performance Evaluation 5 Conclusion and Future Work Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/2015 8/ 31

9 Quantifying Data Preferences Data Preferences Vehicles show the following preferences when collecting safety data: Spatial preference: the closer, the better; Temporal preference: the newer, the better; Type preference: the more important, the better. Quantify these preferences on a per-packet level Packet Value = Spatial Value Temporal Value Type Value. Given a packet p, its packet-value for vehicle v: PV v (p) = S v (p) T v (p) W p. Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/2015 9/ 31

10 Quantifying Data Preferences Spatial-Value Function Given a data packet p, its spatial-value decreases as p is disseminated away from its origin; becomes zeros after p exceeds the Range of Interest. Figure: Region of Interest Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

11 Quantifying Data Preferences Spatial-Value Function Sv(p) Range of Interest 0 Distance S v (p) = Figure: Spatial-Value vs. Dissemination Distance. { max(α βdpv, 0), if vehicle v moves towards (x p, y p ) 0 otherwise. Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

12 Quantifying Data Preferences Temporal-Value Function Collecting real-time data is crucial for safety applications; New packets have much higher temporal-value than old ones; Figure: New data should be disseminated first. Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

13 Quantifying Data Preferences Temporal-Value Function Temporal-value decreases as time elapses; The decreasing speed becomes slower with time; Old packets still have value, e.g., for statistic analysis. Tv(p) T v (p) = e µ typep t e(p). Emergency Message Routine Message 0 Elapsed Time Figure: Temporal-Value vs. Elapsed Time. Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

14 Quantifying Data Preferences Type-Value Function Emergency messages are more important than routine messages. Wp Emergency Message Routine Message 0 Figure: Type-Value vs. Message Types. Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

15 Quantifying Data Preferences Quantifying Data Preferences Putting pieces together, PV v (p) = S v (p) T v (p) W p. Packet-value data preference: Given any two packets p 1 and p 2, vehicle v always has a higher data preference to p 1 over p 2 if PV v (p 1 ) > PV v (p 2 ). Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

16 PVCast: a Packet-Value-Based Dissemination Protocol Outline 1 Introduction 2 Quantifying Data Preferences 3 PVCast: a Packet-Value-Based Dissemination Protocol 4 Performance Evaluation 5 Conclusion and Future Work Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

17 PVCast: a Packet-Value-Based Dissemination Protocol PVCast in A Nutshell PVCast in A Nutshell A new packet p Packet Value No Update PV A (p)=0 1-Hop Dissemination Utility Computation Probabilistic Broadcast Test Fail Discard packet Contention Window Size Assignment Broadcast Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

18 PVCast: a Packet-Value-Based Dissemination Protocol 1-Hop Dissemination Utility 1-Hop Dissemination Utility Utility = Packet Value Effective Dissemination Coverage. Effective Dissemination Coverage U A edc A (p) = 5 2 = 3 Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

19 PVCast: a Packet-Value-Based Dissemination Protocol Probabilistic Broadcast Test Probabilistic Broadcast Test Piecewise function of dissemination utility Higher dissemination utility Higher chance for broadcasting Broadcast Probability 0 Dissemintation Utility Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

20 PVCast: a Packet-Value-Based Dissemination Protocol Contention Window Size Assignment Contention Window Size Assignment Piecewise function of dissemination utility Higher dissemination utility Smaller minimum CW size Higher priority to get channel access Minimum CW Size 0 Dissemintation Utility Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

21 Performance Evaluation Outline 1 Introduction 2 Quantifying Data Preferences 3 PVCast: a Packet-Value-Based Dissemination Protocol 4 Performance Evaluation 5 Conclusion and Future Work Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

22 Performance Evaluation Simulation Settings Simulation Settings 2000m 30m two-way road Speed limit: 100kph SUMO-generated vehicle trace, N {20, 40, 60, 80, 100} Transmission range: 300m Range of interest: 1200m Routine message: 10/sec Emergency message: 1/sec with 0.5 probability in certain segment Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

23 Performance Evaluation Simulation Settings Simulation Settings Comparison CBD, FARTHEST, slottedp and PVCast Metrics Per-Vehicle Throughput Broadcast Rate Broadcast Efficiency Per-Packet Delivery Delay Per-Packet Vehicle Coverage Per-Vehicle Emergency Throughput Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

24 Performance Evaluation Evaluation Results Evaluation Results Per-Vehicle Throughput (pkt/sec) Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

25 Performance Evaluation Evaluation Results Evaluation Results Broadcast Rate Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

26 Performance Evaluation Evaluation Results Evaluation Results Broadcast Efficiency Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

27 Performance Evaluation Evaluation Results Evaluation Results Per-Packet Delivery Delay (ms) Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

28 Performance Evaluation Evaluation Results Evaluation Results Per-Packet Vehicle Coverage Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

29 Performance Evaluation Evaluation Results Evaluation Results Per-Vehicle Emergency Throughput (pkt/sec) Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

30 Conclusion and Future Work Outline 1 Introduction 2 Quantifying Data Preferences 3 PVCast: a Packet-Value-Based Dissemination Protocol 4 Performance Evaluation 5 Conclusion and Future Work Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31

31 Conclusion and Future Work Conclusion and Future Work Conclusion Quantification of data preferences in VANET Integration of data preferences in the design of dissemination protocol System benefits in terms of low latency and high coverage Future Work A more comprehensive model of data preference Joint adaption of power, data rate and contention window based on packet-value Qiao Xiang et al. (McGill) IEEE INFOCOM 15 04/29/ / 31