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ACAR: Adaptive Connectivity Aware Routing for Vehicular Ad Hoc Networks (VANET). Qing Yang , Alvin Lim, Shuang Li, Jian Fang and Prathima Agrawal Auburn University. 17th International Conference on Computer Communication and Networks (ICCCN), 2008, St. Thomas, Virgin Island, US. Outline.
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ACAR: Adaptive Connectivity Aware Routing for Vehicular Ad Hoc Networks (VANET) Qing Yang, Alvin Lim, Shuang Li, Jian Fang and Prathima Agrawal Auburn University 17th International Conference on Computer Communication and Networks (ICCCN), 2008, St. Thomas, Virgin Island, US 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Outline • Assumption • System model • Model of connectivity • Model of road quality • Routing algorithm • Simulation and result analysis • Related work • Conclusion 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Applications of VANET • Vehicular safety • Collision warning • Accident notification • Vehicular commercial • Toll collection • Drive through auto pay • Traffic congestion control • Office-on-wheels • On-road advertisement 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Assumption • GPS on each vehicle • Standard component • Digital maps [1,2] • Vehicle density • Average speed • Traffic light period 1. http://www.mapmechanics/ 2. http://www.yahoo.com/ 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Outline • Assumption • System model • Model of connectivity • Model of road quality • Routing algorithm • Simulation and result analysis • Related work • Conclusion 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
…. n cars m cells Divide road into cells • One lane • road (length is L) is equally divided into m cells • each cell can contain only one node • communication range is size of n0 cells 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
…. …. Number of empty cells • One lane • Number of empty cells is m-n • Multiple lanes • Number of lanes is n’ • Number of empty cells ranges [m-n, m-n/n’] 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
…. Number of empty cells • One lane • Number of empty cells is m-n • Multiple lanes • Number of lanes is n’ • Number of empty cells ranges [m-n, m-n/n’] 1 0 0 1 1 0 1 2 0 1 1 1 1 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Probability of connectivity • P1 (existing exactly k empty cells) • P2 (existing more than n0continuous empty cells) • P (Probability of connectivity) 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Effect of traffic light • Node blocked on road A • Probability of moving from road A to D • Expected number of nodes moving from A to D 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Outline • Assumption • System model • Model of connectivity • Model of road quality • Routing algorithm • Simulation and result analysis • Related work • Conclusion 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Packet error rate of single link • Path loss model • SINR (Signal plus interference to noise ratio) • BER (Bit error rate) 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
PER of single link (cont’) • FER (Frame error rate) • PER (Packet error rate) • PER of certain road segment Where N is the number of retransmission times, FER = 1 – (1 – BER)^L, L is the number of bits per frame Where t is the number of frames per packet 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Quliaty of road segments • PER of road segments • Quality of road segments Where P(u(n,m) = k} is the probability that there are exact k empty cells on the road with m cells Where Prs is the probability of connectivity of road segment 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Outline • Assumption • System model • Model of connectivity • Model of road quality • Routing algorithm • Simulation and result analysis • Related work • Conclusion 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Routing strategy in brief • Adaptively select the path Pr • On-the-fly collect the real-time density • Select next hop by minimizing the PER of whole path • Buffered packet if no available next hop • Send buffered packet until new next hop is in range 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Map transformation Q3 Q8 • Qn: Quality of of road segment n • Each road segment n become a vertex n Q1 Q11 Q6 Q4 Q9 Q1*Q4*Q7*Q12=Max? Q2 Q7 Q12 Q5 Q10 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Path Pr with best communication quality • Modified Dijkstra Algorithm • Final goal: maximize the quality of the whole path • Each step: add one more edge, the quality of new path decrease • Can be computed • Centralized • Distributed 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Adaptive path selection • Reason: inaccurate density • Possible solutions • Flood to collect density • Too much overhead • Our solution • Adaptive path selection • collects density data while forwarding packets • Update density information 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
On the fly density collection • Each forwarder add the local density into packet header 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Next hop selection • PER of link between A and B • Estimated PER of the path • Minimize the above value Where Dis is the residual distance to the sink, d is the distance between node A and B 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Wisitpongphan, N.; Bai, F.; Mudalige, P.; Tonguz, O. K., "On the Routing Problem in Disconnected Vehicular Ad-hoc Networks," INFOCOM 2007. 26th IEEE International Conference on Computer Communications. IEEE , vol., no., pp.2291-2295, May 2007 Carry and forward strategy • Buffer packets which can not be forwarded • Send out buffered packet if new next hop is available • Good for VANET • Lots of “holes” in VANET due to the traffic light • On path Pr, more chance to meet a new next hop • Big buffer is feasible in cars 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Outline • Assumption • System model • Model of connectivity • Model of road quality • Routing algorithm • Simulation and result analysis • Related work • Conclusion 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Simulation • Node movement • VanetMobiSim (mobility trace) • Validation of model • Map • TIGER/LINE (real map) • Real map from Tennessee • Network simulation • Ns2 setup • Result analysis 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
VanetMobiSim 3. http://vanet.eurecom.fr • Feature • multi-lane roads • separate directional flows • traffic signs at intersections • Intersection management • Lane changing • VanetMobiSim[3] mobility patterns have been validated against TSIS-CORSIM • a well known and validated traffic generator 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Validation of model • Length of road • 1000m, 1800m • Traffic light period • 30sec., 60sec. • Average velocity • 7.5m/s, 10m/s • Map 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Connectivity model validation • Dataset1:1000m, 7.5m/s, 120sec of traffic light • Dataset2:1800m, 10m/s, 60sec of traffic light 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
4. http://www.census.gov/geo/www/tiger/ 5. http://www.triusinc.com/latest.htm Map information • TIGER[4] • Topologically Integrated Geographic Encoding and Referencing • A format used by the United States Census Bureau to describe land attributes • Roads, buildings, rivers, and lakes • Can be read by Tivec[5] 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Map in simulation • Centered at • Long: -72530684 • Lat: 42095405 • Width: 2000m • Length: 2000m 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Ns2 setup • Simulation Area: 2000m*2000m • Nubmer of nodes: 200 • Communication range: 250m • Packet size: 512 Byte • CBR rate: 0.1 ~ 1packet/sec. • Random selected source and destination • Buffer size: 512kBytes • Beacon interval: 1.0 sec. • Velocity: 15 ~ 35 MPH 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Data delivery ratio 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Networking delay 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Throughput 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Impact of density error 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Impact of density error (cont’) 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Impact of buffer size 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Related Work • CAR (’08WCNC) • Connectivity aware routing • VADD (’06INFOCOM) • Vehicle-Assisted Data Delivery • MURU (’06MobiQuitous) • Multi-Hop Routing for Urban Vanet • GSR (’05MC2R) • Geographic source routing • GPSR (’00MobiCom) 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
Questions & comments Thanks! 17th International Conference on Computer Communication and Networks, 2008, Virgin Island, US
