Efficient AOI-Cast for Peer-to-Peer Networked Virtual Environments

Adaptive Computing and Networking Laboratory Lab

Outline

Background Proposed schemes Evaluation Conclusion

Adaptive Computing and Networking Laboratory Lab

Outline

Background Proposed schemes Evaluation Conclusion

Adaptive Computing and Networking Laboratory Lab

Background

Networked Virtual Environment (NVE) Nodes or Avatars

Coordinates Area of Interest (AOI)

Massively Multiplayer Online Game (MMOG)

World of Warcraft Second life

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Scalability

We would like to have high scalability to support massive users in NVE.System scalability

NVE’s ability to handle a growing number of total users in the system

AOI scalability NVE’s ability to handle a growing number of users

within a particular AOI

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System scalability Server-based architecture

Client-Server / Server-Cluster Problems：

Limited resources All loads are centered on the server

Server-based architecture has low system scalability.

Peer-to-Peer (P2P) architecture Advantages：

Distributing loads to all users Users consume and provide resources

P2P architecture has high system scalabilitysince a user focuses on AOI neighbors.

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AOI scalability

How come if there are a large number of nodes in AOI?.

Server-based architecture P2P-based architecture

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Goal

Bandwidth-Efficient AOI-Cast withhigh system scalability andhigh AOI scalability

for P2P NVEs

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AOI-Cast A node has to send message to all nodes within its AOI. AOI-Cast is a scoped multicast

Directly sending Forwarding

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VON – directly sending scheme

Direct connectionHigh consistencyLow latency

Too many connections Peak bandwidth consumption exceeds the

limitation

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VON – Forwarding model

Only connect with enclosing neighbors

Pro:Few connectionsAggregationCompression

Con:Redundant messages

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APOLO – forwarding scheme Each node connects to

closest neighbors in four quadrants (4 out-direction links)

Message transmission along the in-direction link

No redundant message (spanning tree)

Inefficient long (more-hop) message transmission path

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Comparison

We focus on reducing the bandwidth consumption, so we design our schemes by forwarding AOI-cast.

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Outline

Background Proposed schemes Evaluation Conclusion

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VoroCast & FiboCast

We proposed two forwarding AOI-cast schemes to reduce the bandwidth consumption VoroCast

No redundant message Low latency

FiboCast An extension of VoroCast Adjusting the message forwarding frequency by hop-distance

dynamically

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VoroCast

VoroCast divides the AOI neighbors by Voronoi diagram.

Each node has a unique ID and exchanges neighbor list with all neighbors periodically to maintain two-hop-neighbor information.

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VoroCast

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root

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Characteristics

Less bandwidth consumptionAggregationCompressionNon-redundancy

Each node has unique parent

Low latencyWithout restricting the message forwarding

direction (less hops than APOLO)

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FiboCast

Users in NVEs may pay more attention to activities that are more obvious in the vicinity.

We can adaptively adjust the transmission frequency so that neighbors with more hop counts away receive messages less frequently.

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FiboCast Two variables in a message:

current hop count (cpc): increased each hopmaximal hop count (mcp): set by a Fibonacci

sequence with the last being infinite in a round-robin manner

The message is dropped when cpc==mcp E.G.: For a Fibonacci sequence <0, 1, 1, 2, 3, 5,

8,>, the maximal hop counts would be 2, 3, 3, 4, 5, 7, 10, , 2, 3, 3, 4, 5, 7, 10, , 1, 2, 3, 3, 4, 5, 7, etc.

Adaptive Computing and Networking Laboratory Lab

Outline

Background Proposed schemes Evaluation Conclusion

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Performance metrics Bandwidth consumption

The major metric to measure the AOI scalability

Neighborship consistency The degree of the knowledge about the AOI

neighbors

Drift distance The difference between the virtual position and real

position of a node

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Simulation environment 1 sec = 10 steps Map = 1000 x 1000 (unit2) Nodes = 100 ~ 1000 (in increments of 100 nodes ) AOI radius = 200 units Steps = 1000 steps Move speed = 5 units / step by random waypoint pattern Data is compressed by zlib The initial values of Fibonacci number are

F1 = 0 ； F2 = 1

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Bandwidth consumptionTransmission size

0

5000

10000

15000

20000

25000

30000

35000

40000

100 200 300 400 500 600 700 800 900 1000

Number of nodes

TransimissionSize(s)

VoroCastFaboCastVON

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Neighborship consistency

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Drift distance

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Outline

Background Proposed schemes Evaluation Conclusion

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Conclusion We proposed VoroCast and FiboCast to improve

AOI scalability by reducing the bandwidth consumption.

VoroCast Non-redundant message Apply aggregation and compression mechanisms Low latency

FiboCast An extension of VoroCast The neighbors less hops away get messages more

frequently than those more hops away AOI scalability is even better

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Q & A