Introduction Unfairness Example (unicast) Goal & Contribution ProbeCast: key insights ProbeCast: Example

Introduction Unfairness Example (unicast) Goal & Contribution ProbeCast: key insights ProbeCast: Example www.phwiki.com

Introduction Unfairness Example (unicast) Goal & Contribution ProbeCast: key insights ProbeCast: Example

McCown, Sean, Contributing Editor has reference to this Academic Journal, PHwiki organized this Journal ProbeCast: MANET Admission Control via Probing Soon Y. Oh, Gustavo Marfia, in addition to Mario Gerla Dept. of Computer Science, UCLA Los Angeles, CA 90095, USA {soonoh, gmarfia, gerla}@cs.ucla.edu Introduction Multicast “inelastic” streams Inelastic flow – the rate cannot be elastically controlled (unlike TCP) Real time flows: situation awareness dissemination; surveillance data/video, etc Important in tactical/emergency MANETs Traditional resource reservation ineffective in MANETs Bookkeeping is very cumbersome in multicast (as number of destinations increases); Also, mobility requires continuous re-adjustments Without reservations: Flow allocation can be “unfair” possible capture Network may get congested Unfairness Example (unicast) 3 parallel inelastic flows; 500Kbps each Interference between Flow 1 in addition to 2 in addition to Flow 2 in addition to 3

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Goal & Contribution Achieving reliable QoS support of inelastic flows (e.g., video in addition to audio stream) ProbeCast: Enable Call Admission Control in addition to fair allocation of inelastic flows in MANETs without requiring prior resource reservation ProbeCast: key insights Insight 1: Resource Probing No a priori resource allocation Rather “probe” as long as resources to see if available Insight 2: Pruning via Back-pressure Back-pressure (“prune”) toward the source when resource is unavailable Re-route or reject the inelastic flow Insight 3: Neighborhood Proportional Drop (NPROD) Local rate balancing using proportional dropping En as long as ces fair channel sharing “fair back-pressure” ProbeCast: Example Proportional Drop Backpressure (Pruning)

ProbeCast: Probing Assumptions: End-to-End FEC – e.g. erasure coding – always ON Each flow has packet drop threshold (say, 20%), beyond which the flow must be back-pressured Probing Each node measures own packet drop rate It broadcasts to one hop neighbors own drop rate via piggybacking on data packets The node estimates packet drop probability DPF as long as each flow F It broadcasts to one hop neighbors the DPF value ProbeCast: N-PROD Neighborhood Proportional Drop (N-PROD) Distributed fairness scheme First introduced in addition to evaluated in FairCast (MSWIM 2008) Overhearing neighbors’ drop probabilities En as long as cing proportional drop among flows competing in the same contention domain Forced drop from the queue After transient, nodes in the same contention domain converge to fair share of the channel

ProbeCast: Pruning Pruning Flow Drop based on Threshold Threshold is traffic class in addition to flow age dependent; Drop Threshold stamped in packet header Typically, incoming flow has lower threshold than incumbent When drop rate is > threshold, a flow is backpressured BckPr signal piggybacked on data packets whenever possible Upstream node in turn will backpressure when all “children” have sent BckPr signal Source action (upon receiving backpressure signal): Re-route if there is alternate route; Otherwise reject the flow ProbeCast Example Three flows in the same contention domain. Bar graphs shows packet delivery ratios Flow 3 starts transmitting in addition to other flows’ rate decreases (N-PROD). Since Flow 3 drop rate exceeds the threshold, it is backpressured. Simulation Simulation setup Qualnet simulations Radio range 376m; 2Mbps capacity; 802.11b 512B packets; 50KB queue in each node Topologies Three parallel flows 30 nodes uni as long as mly distributed in a 1000x1000m field Experiments N-PROD: to show proportional fairness ProbeCast: to show proper rejection

Three Parallel Flow Topology F1, F2, in addition to F3 are within the same contention domain No interference between sources in addition to as long as warders No interference between as long as warders in addition to receivers Staggered Transmission starts: 1s, 10s, 20s Three Even Parallel Flows Uni as long as m nominal rate = 500Kpbs Flows 2 has higher packet drop rate without N-PROD N-PROD restores fairness Three Even Parallel Flows (cont) Uni as long as m nominal rate = 500Kpbs Aggregated throughput of the three flows Fairness comes at the cost of degraded total throughput

Three Uneven Parallel Flows Flow1 = 800Kbps, Flow2 = 400Kbps, in addition to Flow3=200Kbps Without N-PROD, Flow 1 in addition to 3 capture the channel With N-PROD proportional drop yields 8:4:2 ratio Three Uneven Parallel Flows (cont) Aggregated throughput of 3 flows Flow1 = 800Kbps, Flow2 = 400Kbps, in addition to Flow3=200Kbps Proportional fairness again comes at the cost of degraded total throughput Two Flows in R in addition to om Topology 30 nodes in 1000 by 1000 meter Flow 1: 200Kbps video stream, 9 members Flow 2: 40Kbps audio stream, 3 members Session 2

Two Flows in R in addition to om Topology Session 1 captures channel in ODMRP so session 2 starves N-PROD achieves fairness All members in session 1 in addition to 2 receive more than 50% packets Drop Threshold = 50% Three Flows in R in addition to om Topology Three multicast sessions, each session has 1 source in addition to 3 members 30 nodes in 1000 by 1000 meter Data transmission starts Session1 T=1s, Session2 T=10s, in addition to Session3 T=20s 500Kbps traffic; drop threshold = 50% Three Flows in R in addition to om Topology (cont) Three multicast sessions compete within the same collision domain Session 2 is rejected (it came after Session 1 – initially lower threshold)

Conclusion N-PROD achieves proportional b in addition to width share in the same contention domain ProbeCast uses probing in addition to backpressure to accept feasible flows in addition to reject unfeasible ones. Probecast can also h in addition to le inelastic unicast (a special case of multicast)

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