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QoS Provisionings in Intelligent Vehicular Networks

QoS Provisionings in Intelligent Vehicular Networks. Xi Zhang Networking and Information Systems Laboratory Department of Electrical & Computer Engineering Texas A&M University College Station, Texas, USA.

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QoS Provisionings in Intelligent Vehicular Networks

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  1. QoSProvisioningsin Intelligent Vehicular Networks Xi Zhang Networking and Information Systems Laboratory Department of Electrical & Computer Engineering Texas A&M University College Station, Texas, USA This research is supported in part by the U.S. NSF CAREER Award under Grant ECS-0348694 • August 3, 2012 • Seminar at Institute of Network Coding, The Chinese University of Hong Kong

  2. Outline • Background and motivation of ITS • Intelligent vehicular networks • DSRC/802.11 p/ WAVE (protocols) • Challenges and QoS requirements • QoSprovisionings in vehicle-to-vehicle (V2V) communications • Clustering-based multi-channel communications architecture • Conclusions and future work Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  3. > 3M 1M - 3M 0.5 - 1M < 0.5 Million Source: 2005 Annual Urban Mobility Report (http://mobility.tamu.edu) Texas Natural Resource Conservation Commission (http://www.tnrcc.state.tx.us/air) ITS Background and Motivations: Costs and Problems of Moving Vehicles Safety: 6 Million crashes, 41,000 fatalities in U.S. per year ($150 Billion) Congestions: 3.5 B hours delay, 5.7 Billion gal. wasted fuel per year in U.S. ($65 Billion) Pollutions: produce > 50% hazardous air pollutants in U.S.; contributes up to 90% of the carbon monoxide (CO) in space air of urban area Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  4. What is ITS – Solutions ? Quoted from Research and Innovative Technology Administration (RITA)of U.S. DOT Intelligent transportation systems (ITS) encompass a broad range of wireless and wire line communications-based information and electronics technologies. ITS improves transportation safety and mobility and enhances American productivity through the integration of advanced communications technologies into the transportation infrastructure and in vehicles. Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  5. Examples of the Traditional ITS Technologies • Many infrastructure based ITS technologies are already in use traditionally: • Variable vehicles speed limits • Adaptive signal timing systems • Speed activated curve-warning systems (e.g., GPS, or road-side signal signs) Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  6. Vehicle to Vehicle Communications Vehicle to Infrastructure Communications Modern Intelligent Vehicular Networks – Our Focus (fleet manager) (Highway admin/driver) Empowered/driven by Information Technology, especially High-speed broadband Wireless and Wired Communications Tech. GOAL: increase the safety, efficiency, and convenience of the transportation system. Communications link between vehicles on the road, and between vehicles and the roadside infrastructure ITS Architectures  Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  7. International Efforts/Standards Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  8. Def.: Common Techniques/Terms/Devices V2I: Vehicle to Infrastructure V2V: Vehicle to Vehicle V2R: Vehicle to Roadside unit DSRC: Dedicated Short Range Communications Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  9. V2I Communications/Applications • Vehicle to Infrastructure • Probe Data • Trip Path Data • Transaction Data (e.g., E-Payment) • Infrastructure to Vehicle • Advisory Message Data • Localized Map Data (safety) • Signal Phase & Timing Data • Position Corrections • Transaction Data (e.g., E-Payment) Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  10. V2V Communications • Vehicle to Vehicle • Heartbeat Data (periodic vehicle info renew) • Intersection-crossing assistance • blind spot warning • lane switch assistance • do-not-pass warning • control loss warning Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  11. Introduction of DSRC for V2V (our focus) and V2I • History • On December 17, 2003 the FCC adopted a Report and Order establishing licensing and service rules for the Dedicated Short Range Communications (DSRC) Service in the Intelligent Transportation Systems (ITS) Radio Service in the 5.850-5.925 GHz band (10 MHz centered at 5.9 GHz band point). • What is it? • The DSRC Service involves V2V and V2I communications, • Help protect the safety of the traveling public. It can save lives by warning drivers of an impending dangerous condition or event in time to take corrective or evasive actions. • The band is also eligible for use by non-public safety entities for commercial or private DSRC operations. Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  12. 5.9 GHz DSRC “7- BAND PLAN” with 10 MHz for each CHANNEL Shared Public Safety/Private Dedicated Public Safety Med Rng Service Veh-Veh Intersections Short Rng Service Control US DSRC Allocation US Spread Spectrum Allocation Uplink / / Downlink / / CH172 CH 180 CH 182 CH 184 CH 178 CH 174 CH 176 5.875 5.880 5.905 5.910 5.850 5.855 5.860 5.865 5.870 5.885 5.890 5.895 5.900 5.920 5.925 5.825 5.845 5.835 5.830 5.915 5.840 Frequency (GHz) Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  13. DSRC/802.11p/WAVE Protocols • DSRC (Dedicated Short Range Communications) • ASTM Standard E2213-03, based on IEEE 802.11a • Name of the 5.9 GHz Band allocated for the ITS communications • IEEE 802.11p • Based on ASTM Standard E2213-03 • Currently draft standard • WAVE (Wireless Access in Vehicular Environments) • Mode of operation used by IEEE 802.11 devices to operate in the DSRC band • Specified by IEEE 1609 standards Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  14. Challenges in Vehicular Networks Vehicular environment Network layer Security and privacy MAC layer Physical layer Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  15. PHY Layer • Multi-path channels • May destroy the orthogonality of channels • High relative speed between vehicles or between vehicles and RSU • Doppler Spread • Coherence BW vs. carrier BW • if >, then frequency selective fading • Coherence time vs. packet length • Should be longer than a packet for fading corrections • Wireless channel modeling for vehicular environment Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  16. Network Layer • Vehicle’s high mobility • Time-varying topology • Neighboring discovery • Neighbors change in a short time • Network connectivity • Depends on highway traffic Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  17. Security and Privacy Concerns • OBU addresses are randomized • prevents vehicles from being tracked • Authenticated RSU application announcements • Prevents WLAN from receiving the fake message • Link level encryption • prevents overhearings • Authentication • Public key infrastructure (PKI) Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  18. QoS Requirements • Safety Messages: • Bounded Delay • Hop by hop (e.g., collision warning between neighboring vehicles in V2V) • End to end (e.g., accident-ahead-warning) • Jitter (e.g., voice communications) • Successful delivery Rate • Non-Safety Messages • Non-real-time traffic • Throughput • Connection Opportunity • Packet error rate Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  19. MAC Layer • High relative-speed • Fast establish time • Short connection time (esp. for V2I) • Handoff issues • Power control • Hidden terminal problem • Reliable and timely delivery of safety messages Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  20. (II) V2V: Our Proposed Scheme: Clustering-Based Multi-Channel V2V Scheme (1) Aims at supportingQoS for timely delivery of real-time data and increasing the throughput for non-real-time traffics over V2V-based VANET. Integrates the clustering algorithm with both the contention-free and contention-based MAC protocols under the DSRC architecture. Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  21. (II) V2V: Our Proposed Scheme: Clustering-Based Multi-Channel V2V Scheme (2) • Handles three tasks: • Cluster-membership management • Real-time traffic delivery • Non-real-time data communications • Complies with the DSRC7-channel band plan • Incorporates with IEEE 802.11p • Each vehicle is equipped with two sets of transceivers, that is, it can work on two separated channels simultaneously. Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  22. Overview of our proposed scheme Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  23. Scheme structure diagram Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  24. The vehicle’s states • Due to the highly mobility of the vehicle networks, even the well designed clustering algorithm cannot guarantee the stability of the cluster topology. • Cluster-head vehicles may malfunction due to the unreliable wireless channel or crash failure. • We divide the vehicle’s states into two types in terms of functionality • Cluster-head • Cluster-member Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  25. The Intra-Cluster Coordination and Communication Protocol In the Cluster Range Control (CRC) channel, time is partitioned into regular time intervals (TDMA frame) with the equal-length of T, called “repetition period”. The repetition period consists of TDMA upstream period and downstream period Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  26. Notations/Variables Defs. : the average gap between the leading vehicle and the following vehicle : the average length of the vehicle : the cluster radius : the number of lanes The length of time slot assigned to (taken by) each member (vehicle) within a cluster is Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  27. Timely safety message delivery The TDMA scheme can guarantee that each vehicle within a cluster has a chance to transmit data in every T time unit. Denote the updating interval of safety messages by , the channel rate by R, and the packet length of safety message by The condition (delay bound) for the timely delivery of the safety messages is: (delay-bound) and min BW is: Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  28. The Inter-Cluster Communication Protocol • Two types of traffics on two separate channels between clusters • The real-time safety messages over Inter-Cluster-Control Channel • The non-real-time traffic over Inter-Cluster-Data Channel Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  29. Delay for the cluster-member vehicle in the neighboring cluster to receive the safety message from its cluster-head Delay for a safety message to be sent from a cluster-member to its cluster-head Delay of transmitting the consolidated safety message from a cluster-head to its neighboring cluster-head Delay QoS Modeling (1) The transmission delay of the safety messages is the most important performance metric. The delay of a safety message from a cluster-member vehicle to another cluster-member vehicle in the neighboring cluster consists of 3 parts:

  30. Delay Modeling (2) • The TDMA nature of the Intra-Cluster Coordination and Communication Protocol ensures that (upstream) and (down) • The maximum total delay • The maximum allowable delay for CH-to-CH communications for vehicle i Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  31. Delay Modeling (3) Recall that the inter-cluster communication protocol is based on IEEE 802.11 over ICC channel. Three types of vehicles can send safety messages over ICC channel, i.e., consolidated safety messages by cluster-head, non-consolidated safety messages by quasi-cluster-head and quasi-cluster-member. Now we use the mature IEEE 802.11 models to investigate the delay for CH-to-CH communications. Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  32. Hidden terminal set Bi: the set of broadcast receivers for vehicle i Hi: the set of hidden terminals for vehicle i Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  33. Transmission probability (802.11) For the saturation network, the probability, , that a given cluster-head iattempts to send a safety message is For the non-saturation network, the probability  that cluster-head i attempts to send a safety message is Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  34. Delay • On average, each node successfully transmits one packet during the cycle time of this regenerative process, which includes: • the back-off time, E[bi] • the successful transmission time, E[mi] • the channel busy time, E[ei] • Thus, the average delay is Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  35. Successful delivery rate The probability pithat the cluster-head i successfully broadcast to all neighbors can be derived as follows using algebra: When the contention window goes to infinity, we can get its limit: Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  36. Parameters in analyses/simulations Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  37. Tradeoff between delay and delivery rate for safety messages Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  38. Summary Introduced the background of ITS Discussed the challenges and QoS requirements in intelligent vehicular networks Proposed the clustering-based multi-channel communications architecture Conducted delay QoS Modeling for safety messages transmissions Analyzed the trade-off between delay and delivery rate Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  39. Future Work • Future work • Applying cognitive radio technology to improve the spectrum utilization in V2V and V2I networks • Extending the effective capacity theory to vehicular networks • Applying more complicated network coding technique in vehicular networks • Furthering the investigation of the privacy issue and its impact on QoS in ITS Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

  40. Thanks for your participation!! http://www.ece.tamu.edu/~xizhang xizhang@ece.tamu.edu Seminar at INC/CUHK Xi Zhang Texas A&M University, ECE Dept.

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