A Token-Based MAC Protocol for Achieving High Reliability ...A Token-Based MAC Protocol for...
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A Token-Based MAC Protocol for Achieving High Reliability in VANET Ali Balador (Ph.D.) Postdoctoral Research Fellow SICS Swedish ICT Västerås AB [email protected] -- +46 730532133 Goals Background Protocol Description Simulation Settings Highway Scenario Urban Scenario Conclusions Future Works Acknowledgements § CAM (Cooperative Awareness Messages) or beacon [1] o Short, periodic status messages (2-10 times per second) o Broadcasted by every car o No multi-hop intended (so far) o Include: position, speed, direction, other status information (e.g. blinker status) § DENM (Decentralized Environmental Notification Message) [2] o Event-based warning message o Broadcasted only during specific event o Broadcast stops when event is over 0 25 50 75 100 5 10 20 40 60 80 Vehicle density Beacon Delivery Ratio (%) DTB−MAC IEEE802.11P DTB−MAC IEEE802.11P 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 5 10 20 40 60 80 5 10 20 40 60 80 Vehicle density Channel Utilization (%) Successfully Used Idle Wasted § Beacon Send Rate: 10 packet/s § Beacon size: 500 Bytes § Data Rate: 6 Mbps § Transmission Range: 500 m § Simulation time: 300 s § Simulation package: Veins Simulation Scenarios § Highway Scenario o 2.2 km highway with 2 lanes § Urban Scenario o Downtown of Milan o 2.6*2.6 km 2 References § In low densities o difficulties for token circulation o low BDR 0 10 20 30 40 50 60 70 80 90 100 16 23 30 36 43 Vehicle density (vehicles/km/lane) Beacon Delivery Ratio (%) DTB−MAC IEEE802.11P DTB−MAC IEEE802.11P 0 10 20 30 40 50 60 70 80 90 100 16 23 30 36 43 16 23 30 36 43 Vehicle density (vehicles/km/lane) Channel Utilization (%) Successfully Used Idle Wasted § Metrics o Channel utilization o Beacon Delivery Ratio (BDR) Propose an alternative solution specially for high densities when IEEE 802.11p is not able to handle a high number of beacons. The way DTB-MAC uses the token passing not only does not produce more delay, but also improve it for some network densities. § To extend DTB-MAC protocol by adding support for event-driven messages for safety applications in highway and urban scenarios § To extend our token-based protocols to handle Platooning Application challenges o Selecting a token manager when two tokens are detected o Merging two platoons of cars driving in close proximity This work was partially supported by SICS Swedish ICT Västerås AB through the EU-project, SAFECOP. Moreover, Balador is funded by ERCIM Alain Bensoussan postdoctoral Fellowship. § Address the short-comings of IEEE 802.11p § Support the strict requirements on timing and reliability § Using standardized 802.11-based hardwares Ring establishment and maintenance Data age list generation o Each vehicle maintains a data age list logging the age of the latest successfully received beacon from individual nodes. o Next token holder is the node with the highest data age on the current token holder’s list. Token Passing o Token is circulated with beacon packets o Whoever holds the token has unique right to access the channel o Each token holder is responsible for the choice of the next token holder Transmission order 1 2 3 4 Data age list [1] “Its; vehicular communications; basic set of applications; part 2: Specification of cooperative awareness basic service,” ETSI Std. EN 637-2, Tech. Rep., November 2014. [2] “Its; vehicular communications; basic set of applications; part 2: Specification of decentralized environmental notification basic service,” ETSI Std. EN 637-3, Tech. Rep., November 2014. § Support for delay-sensitive data traffic through deterministic channel access is needed o In the current standard this support is compromised due to the properties of IEEE 802.11p MAC § A distributed, token-based MAC method supports reliable beacon broadcast before a given deadline o Prioritizing vehicle that is in most need to communicate to keep its deadline. o Built-in retransmission opportunities (if bandwidth available) BMW Summer School 2016 Bavaria, Germany, July 18-23
Transcript of A Token-Based MAC Protocol for Achieving High Reliability ...A Token-Based MAC Protocol for...
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A Token-Based MAC Protocol for Achieving High Reliability in VANET Ali Balador (Ph.D.) Postdoctoral Research Fellow SICS Swedish ICT Västerås AB [email protected] -- +46 730532133
Goals
Background
Protocol Description
Simulation Settings
Highway Scenario Urban Scenario
Conclusions
Future Works
Acknowledgements
§ CAM (Cooperative Awareness Messages) or beacon [1] o Short, periodic status messages (2-10 times per
second) o Broadcasted by every car o No multi-hop intended (so far) o Include: position, speed, direction, other status
information (e.g. blinker status)
§ DENM (Decentralized Environmental Notification Message) [2] o Event-based warning message o Broadcasted only during specific event o Broadcast stops when event is over
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25
50
75
100
5 10 20 40 60 80Vehicle density
Beac
on D
elive
ry R
atio
(%)
DTB−MAC IEEE802.11P
DTB−MAC IEEE802.11P
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101520253035404550556065707580859095
100
5 10 20 40 60 80 5 10 20 40 60 80Vehicle density
Cha
nnel
Util
izat
ion
(%)
Successfully Used Idle Wasted
§ Beacon Send Rate: 10 packet/s § Beacon size: 500 Bytes § Data Rate: 6 Mbps § Transmission Range: 500 m § Simulation time: 300 s § Simulation package: Veins
Simulation Scenarios § Highway Scenario o 2.2 km highway with 2 lanes
§ Urban Scenario o Downtown of Milan o 2.6*2.6 km2
References
§ In low densities o difficulties for token circulation o low BDR
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10
20
30
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50
60
70
80
90
100
16 23 30 36 43Vehicle density (vehicles/km/lane)
Beac
on D
elive
ry R
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(%)
DTB−MAC IEEE802.11P
DTB−MAC IEEE802.11P
0
10
20
30
40
50
60
70
80
90
100
16 23 30 36 43 16 23 30 36 43Vehicle density (vehicles/km/lane)
Cha
nnel
Util
izat
ion
(%)
Successfully Used Idle Wasted
§ Metrics o Channel utilization o Beacon Delivery Ratio (BDR)
Propose an alternative solution specially for high densities when IEEE 802.11p is not able to handle a high number of beacons.
The way DTB-MAC uses the token passing not only does not produce more delay, but also improve it for some network densities.
§ To extend DTB-MAC protocol by adding support for event-driven messages for safety applications in highway and urban scenarios
§ To extend our token-based protocols to handle Platooning Application challenges o Selecting a token manager when two tokens
are detected o Merging two platoons of cars driving in close
proximity
This work was partially supported by SICS Swedish ICT Västerås AB through the EU-project, SAFECOP. Moreover, Balador is funded by ERCIM Alain Bensoussan postdoctoral Fellowship.
§ Address the short-comings of IEEE 802.11p § Support the strict requirements on timing and
reliability § Using standardized 802.11-based hardwares
Ring establishment and maintenance
Data age list generation o Each vehicle maintains a data age list
logging the age of the latest successfully received beacon from individual nodes.
o Next token holder is the node with the highest data age on the current token holder’s list.
Token Passing o Token is circulated with beacon packets o Whoever holds the token has unique right
to access the channel o Each token holder is responsible for the
choice of the next token holder Transmission order
1
2
3
4
Data age list
[1] “Its; vehicular communications; basic set of applications; part 2: Specification of cooperative awareness basic service,” ETSI Std. EN 637-2, Tech. Rep., November 2014. [2] “Its; vehicular communications; basic set of applications; part 2: Specification of decentralized environmental notification basic service,” ETSI Std. EN 637-3, Tech. Rep., November 2014.
§ Support for delay-sensitive data traffic through deterministic channel access is needed o In the current standard this support is
compromised due to the properties of IEEE 802.11p MAC
§ A distributed, token-based MAC method supports reliable beacon broadcast before a given deadline o Prioritizing vehicle that is in most need to
communicate to keep its deadline. o Built-in retransmission opportunities (if
bandwidth available)
BMW Summer School 2016 Bavaria, Germany, July 18-23
