Link capacity estimation in QOLSR Ignacy Gawędzki <i@lri.fr> Hakim Badis <badis@lri.fr> Khaldoun Al Agha <alagha@lri.fr> LRI laboratory July 29th, 2005
Introduction Link capacity in radio networks Clique constraints Clique constraints with OLSR Conclusion Introduction 1 What is QOLSR? Link capacity in radio networks 2 Correlated capacities Simple example Clique constraints 3 Conflict graphs Cliques of conflict graphs Clique constraints with OLSR 4 Additional topology information Routing with capacity Conclusion 5 Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Clique constraints What is QOLSR? Clique constraints with OLSR Conclusion QOLSR = OLSR with QoS routing Routing metrics: Hop count Delay Capacity (available bandwidth) Packet loss probability Security Constraint: independence with respect to NIC driver More info: http://qolsr.lri.fr Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Correlated capacities Clique constraints Simple example Clique constraints with OLSR Conclusion Radio link vs. wired link capacity One antenna per interface = ⇒ sending XOR receiving Omnidirectional antennas = ⇒ implicit broadcasting Capacities of links are correlated and not independent. Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Correlated capacities Clique constraints Simple example Clique constraints with OLSR Conclusion Transmission example without flow control a b c d e f c wants to transmit to d Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Correlated capacities Clique constraints Simple example Clique constraints with OLSR Conclusion Transmission example without flow control a b DATA c DATA d e f c transmits the data frame to d Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Correlated capacities Clique constraints Simple example Clique constraints with OLSR Conclusion Transmission example without flow control a b DATA c DATA d e f b and d cannot emit anymore Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Correlated capacities Clique constraints Simple example Clique constraints with OLSR Conclusion Transmission example without flow control a b c d e f ACK ACK d acknowledges the frame Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Correlated capacities Clique constraints Simple example Clique constraints with OLSR Conclusion Transmission example with flow control a b c d e f c wants to transmit to d Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Correlated capacities Clique constraints Simple example Clique constraints with OLSR Conclusion Transmission example with flow control a b c d e f RTS RTS c sends the RTS frame Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Correlated capacities Clique constraints Simple example Clique constraints with OLSR Conclusion Transmission example with flow control a b c d e f RTS RTS b and d cannot emit anymore Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Correlated capacities Clique constraints Simple example Clique constraints with OLSR Conclusion Transmission example with flow control a b c d e f CTS CTS d sends the CTS frame Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Correlated capacities Clique constraints Simple example Clique constraints with OLSR Conclusion Transmission example with flow control a b c d e f CTS CTS now b, d and e cannot emit anymore Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Correlated capacities Clique constraints Simple example Clique constraints with OLSR Conclusion Transmission example with flow control a b DATA c DATA d e f c transmits the data frame to d Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Correlated capacities Clique constraints Simple example Clique constraints with OLSR Conclusion Transmission example with flow control a b c d e f ACK ACK d acknowledges the frame Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Conflict graphs Clique constraints Cliques of conflict graphs Clique constraints with OLSR Conclusion Some links do share a common resource Conflict graph: vertices are links edges are conflict relations ab de a b c d e bc cd Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Conflict graphs Clique constraints Cliques of conflict graphs Clique constraints with OLSR Conclusion Necessary condition Links in the same clique of conflict graph share a common capacity resource. ab de a b c d e bc cd Necessary condition: sum of loads on links of one clique must be lower than the common capacity. Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Conflict graphs Clique constraints Cliques of conflict graphs Clique constraints with OLSR Conclusion Necessary but not sufficient Perfect graph: chromatic number = size of greatest clique Conflict graph perfect = ⇒ Clique constraints sufficient Unit Disc Graph (UDG): edge { a , b } exists iff d ( a , b ) ≤ 1 Topology graph is UDG = ⇒ β × Clique constraints sufficient Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Additional topology information Clique constraints Routing with capacity Clique constraints with OLSR Conclusion How to do that? General idea: Nodes advertise transmitted load in HELLOs Each node performs capacity estimation on incident links Nodes calculate routes using capacities But: Nodes need total (all nodes and all links) vs. partial topology Two-hops neighborhood is not enough Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Additional topology information Clique constraints Routing with capacity Clique constraints with OLSR Conclusion (N+1)-hops neighborhood (N+1)-hops neighborhood is necessary to compute the conflict graph with N-hop correlations. d e d e b c b c a a We need to retransmit HELLO messages. Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Additional topology information Clique constraints Routing with capacity Clique constraints with OLSR Conclusion How to calculate routes? A flow is possible if it satisfies the clique constraints on its path. Simple heuristics: 1-hop-long paths are trivial 2-hops-long paths No more than one link used simultaneously. 3-hops-long or more N=2: no more than 1 / 3 of the links used simultaneously. Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Additional topology information Clique constraints Routing with capacity Clique constraints with OLSR Conclusion How to calculate routes? A flow is possible if it satisfies the clique constraints on its path. Simple heuristics: 1-hop-long paths are trivial 2-hops-long paths No more than one link used simultaneously. 3-hops-long or more N=2: no more than 1 / 3 of the links used simultaneously. Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Additional topology information Clique constraints Routing with capacity Clique constraints with OLSR Conclusion How to calculate routes? A flow is possible if it satisfies the clique constraints on its path. Simple heuristics: 1-hop-long paths are trivial 2-hops-long paths No more than one link used simultaneously. 3-hops-long or more N=2: no more than 1 / 3 of the links used simultaneously. Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
Introduction Link capacity in radio networks Additional topology information Clique constraints Routing with capacity Clique constraints with OLSR Conclusion How to calculate routes? A flow is possible if it satisfies the clique constraints on its path. Simple heuristics: 1-hop-long paths are trivial 2-hops-long paths No more than one link used simultaneously. 3-hops-long or more N=2: no more than 1 / 3 of the links used simultaneously. Ignacy Gawędzki, Hakim Badis, Khaldoun Al Agha Link capacity estimation in QOLSR
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