delay tolerant mobility aware routing/mobility dissemination protocol for the airborne network

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Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network Kevin Lee & Adam Piechowicz 10/10/2009

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Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network. Kevin Lee & Adam Piechowicz 10/10/2009. Problem Statement. An end-to-end path is not always guaranteed Packets have to be delivered in a delay-tolerant fashion - PowerPoint PPT Presentation

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Page 1: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Delay Tolerant Mobility Aware Routing/Mobility

Dissemination Protocol for the Airborne Network

Kevin Lee & Adam Piechowicz10/10/2009

Page 2: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Problem Statement

• An end-to-end path is not always guaranteed– Packets have to be delivered in a delay-tolerant

fashion

• How to use planned AN backbones’ trajectories to deliver packets to minimize:– Packet failure rate– Delay– Local buffer

Page 3: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Contributions

• Provide best next forwarding hop in the delay tolerant network based on current network condition

• Provide congestion avoidance and load balancing by local queuing awareness mechanism

Page 4: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

MARP/MDP+DTN Design

• Think of the topology as a time-varying graph• We can select the best next hop given a specified

metric (minimum delay)• Use modified Dijkstra’s algorithm with time-varying

edge costs • w(e(u,v), t) indicates the cost of using edge (u, v)

after time time t• The cost is predominantly the time after t that (u, v) is up• Propagation delay negligible• Transmission rate not considered

Page 5: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Example 1

• Source node at 1 and each edge cost is 1N Node 1, Pre Node 2, Pre Node 3, Pre Node 4, Pre

{1,2,3,4} 0,1 ∞ ∞ ∞

{2,3,4} 0,1 1,1 5,1 1,1

{3,4} 0,1 1,1 5 < 1 + w(e(2,3), 1) = 1 + (4+1) = 6

1 < 1 + w(e(2,4),1) = 1 +

(2 + 1) = 4

{3} 0,1 1,1 5,1 1,1

{} 0,1 1,1 5,1 1,1

Page 6: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Example 2

N Node 1, Pre Node 2, Pre Node 3, Pre Node 4, Pre Node 5, Pre

{1,2,3,4,5} 0,1 1,1 ∞ 7,1 4,1

{2,3,4,5} 0,1 1,1 2,2 7,1 4,1

{3,4,5} 0,1 1,1 2,2 7 > 2 + w(e(3,4),2) = 2 + (0 + 1) = 3,3

4,1

{5} 0,1 1,1 2,2 3,3 4 < 3 + w(e(4,5), 3) =

3 + ∞

{0} 0,1 1,1 2,2 3,3 4,1

Page 7: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Predecessor Computation

• Take Node 3 from Example 2• 2, 2 means:

– It will take Node 1 to reach Node 3 with cost of 2 (the first 2)

– The predecessor of Node 3 is Node 2 (the second 2)

• One can then trace back to get the complete route traversal and the time at which the packet should be sent

Page 8: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Local Queuing Aware Scheduling

• Network disconnectivity increases queuing delay• Queuing delay increases congestion• Route around congestion by considering

neighbors’ queue size• w(e, L[u] + T) will incorporate:

– The cost of sending packets already in the queue plus,– The cost of sending the last packet scheduled to use u

to deliver to v

Page 9: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Importance of Encountering for Queuing Awareness

• The more frequently a node encounters with another node, the more packets the node can offload to that node

• Intuitively, the link between these two nodes provide lower delay to the destination

• Two types of encountering:– Single– Multiple

Page 10: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Single Encountering• A node A single encounters another node B if node A meets node B only once in a period

• Where time(1,e,L[u]+T) indicates the time Node u meets Node v at which time one packet in Node u’s queue is delivered since L[u] + T• P is the period of the time-varying graph• Qsize is the queue size at Node u

( , [ ] ) (1, , [ ] ) ( 1)w e L u T time e L u T P Qsize

Page 11: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Single Queuing Example

• Assume there are 2 messages in Node 2’s queueN Node 1, Pre Node 2, Pre Node 3, Pre Node 4, Pre

{1,2,3,4} 0,1 ∞ ∞ ∞

{2,3,4} 0,1 1,1 5,1 1,1

{3,4} 0,1 1,1 5 < 1 + w(e(2,3), 1) = 1 + 5 + 6 + 6

= 18

1 < 1 + w(e(2,4),1) = 1 +

3 + 6 + 6 = 16

{3} 0,1 1,1 5,1 1,1

{} 0,1 1,1 5,1 1,1

Page 12: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Single Queuing Example (cont.)

• w(e(2,3), 1) = 5 + 6 + 6 because it takes – 5 more seconds to dequeue the first packet,– 6 seconds to dequeue the second packet, – another 6 seconds to dequeue the last packet

• By the eqn, w(e(2,3), 1) = 5 + 6 * 2 = 17• Packets in Node 2’s queue will use the same edge

in consideration, e.g.,– w(e(2,3),1) considers first two packets going to Node 3– w(e(2,4),1) considers first two packets go to Node 4

Page 13: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Multiple Encountering

• A node A multiple encounters another node B if node A meets node B more than once in a period

• Tx(e,t) is the # of times e is up during the remaining time t of one period

( , )

( , ( [ ] ))( , [ ] ) ( , ( [ ] ))

( , )

( , ( [ ] ))( ( , ( ( ) )) , ,0)

( , )

if ( , ( [ ] )) (2)

Tx e P

Qsize Tx e P L u Tw e L u T Tx e P L u T P

Tx e P

Qsize Tx e P L u Ttime Qsize Tx e P L u T e

Tx e P

Qsize Tx e P L u T

( , [ ] ) ( , , [ ] ) if ( , ( [ ] )) (1)w e L u T time Qsize e L u T Qsize Tx e P L u T

Page 14: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Multiple-Encounter Queuing Example

• Assume there are 2 messages in Node 2’s queueN Node 1, Pre Node 2, Pre Node 3, Pre Node 4, Pre

{1,2,3,4} 0,1 ∞ ∞ ∞

{2,3,4} 0,1 1,1 5,1 1,1

{3,4} 0,1 1,1 5 < 1 + w(e(2,3), 1) = 1 + 3 + 2 + 4

= 10

1 < 1 + w(e(2,4),1) = 1 +

3 + 6 + 6 = 16

{3} 0,1 1,1 5,1 1,1

{} 0,1 1,1 5,1 1,1

4 3

21

3 sec

4 3

21

1 sec

4 3

21

1 sec

4 3

21

1 sec

Page 15: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Multiple-Encounter Queuing Example (cont.)

• w(e(2,3), 1) = 3 + 2 + 4 because it takes– 3 more seconds to dequeue the first packet,– 2 more seconds to dequeue the second packet, – 4 seconds to dequeue the last packet

• Since Qsize (=3) > Tx (=2), eqn (2) is used:– w(e(2,3), 1) = (6 – 1) + 0 + 4 = 10

Page 16: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Handling Multiple-Traffic Flows• Contacts (the time-varying at any given point in time)

is known• Local queuing is known; approximate global queuing

by keeping track of messages along each routing path• Traffic demand is known,

– It is a set of messages– Each message is a tuple (u,v,t,m), where u is the source of

the msg, v is the destination, t is the time the msg is sent, m is size

– Buffer constraints are given• THE ORACLE HAS COMPLETE KNOWLEDGE! – A linear

programming exercise

Page 17: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Approximate Optimality

• LP is computationally expensive! – Computation become too large for practical example

• Use contacts and queuing oracle (EDAQ) instead– “EDAQ compares favorably, in terms of average delay,

with the optimal solution.”• However,

– Global knowledge may not be required for good performance in many cases

– Implementing the queuing oracle, in particular, may not be worthwhile

Page 18: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Approximate Optimality (contd.)

• Contact oracles (ED) might just be enough for our scenarios!

• Lesson: TOO MUCH KNOWLEDGE MAY NOT ALWAYS BE GOOD!

Page 19: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Evaluation

Page 20: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

MARP/MDP vs. MARP/MDP+DTN

• Network Flow from GlobalHawk to AWACs 2• Solid arrow shows the desired network flow• Dotted lines shows current available

connections• 3 experimental variables

– Radio range– Delay tolerance– Flow volume

Page 21: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Results

• Delay tolerance represents largest improvement in packet delivery, 52% (col1 &2)

• Fixed range: Low flow has higher delivery and lower latency (col 1 & 3)

• Fixed flow: High radio range has higher delivery ratio and lower latency than low radio range

Page 22: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

• Two separate rate flows from 1 and 2 to 5• Transmission rates range from 2.048 Mbps to

1024 kbps

MARP/MDP+DTN vs. MARP/MDP+DTN+QC

Page 23: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Results

• When transmission rate is high, PDR for MARP/MDP+DTN is 0%

Page 24: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Packet Difference between Node 3 and 4

• Both flow forward to Node 3 heavily in MARP/MDP+DTN

• MARP/MDP+DTN+QC is able to divert traffic and achieve load balancing

Page 25: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Latency

• Delay extremely long in MARP/MDP+DTN• Result indicates the need for local queuing

awareness

Page 26: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network
Page 27: Delay Tolerant Mobility Aware Routing/Mobility Dissemination Protocol for the Airborne Network

Conclusion & Future Work

• MARP/MDP+DTN shows the benefit of delay tolerance

• MARP/MDP+DTN+QC shows the benefit of local queuing awareness

• Congestion scenario configuration to verify local queuing aware scheduling

• Tune parameters/routing metrics of MARP/MDP+DTN+QC protocol in accordance with flight and link data obtained from real flight tests like Capstone II