1 A Distributed Architecture for Multimedia in Dynamic Wireless Networks By UCLA C.R. Lin and M....
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Transcript of 1 A Distributed Architecture for Multimedia in Dynamic Wireless Networks By UCLA C.R. Lin and M....
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A Distributed Architecture for Multimedia in Dynamic Wireless
Networks
By UCLA C.R. Lin and M. GerlaIEEE GLOBECOM'95.
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Outline
IntroductionDefinitionsThe Multicluster Architecture and its PropertiesAdaptive Routing for Real-Time TrafficConclusionDiscussion
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Introduction
To support multimedia services (voice, data, video, and image) Real-time traffic (voice, video) delay-sensitiveBursty traffic (data, image) error-sensitive
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Definition Definition 1:
(System Topology) Is a graph G=(V,E)
V is the set of nodes E is the set of edges
One transceiver (half-duplex) in each node
Definition 2: (Distance of Two Nodes) Distance d (x ,y )
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Definition(cont.)
Definition 3: (Cluster) Ci V is a set of nodes Ci: A cluster
V = and Ci ∩ Cj = , if i ≠ j
x , y Ci , d (x ,y )≤ 2
Definition 4: (Center and Radius of a Cluster) How to choose center(xo) in Ci
d (x,y), x,y Ci d (x0,y) is called the radius of a cluster
i
iC
maxy
maxminyx
3
2
1
113
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Definition(cont.)
Definition 5: (Degree of Topology)
Is the number of clusters in a topology ( )
Definition 6: Repeater Bridge u=(x,y) The Order of a Repeater
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Definition(cont.)
Definition 7: (Bridge Partially in a Cluster) 1 1 1
)()()( CCC www
:)(Cw
:)(Cw
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The Multicluster Architecture and its Properties (cont.)
Centralized Clustering Algorithm:0. i = 01. x = min(V )2. Ci = {x } ∪ Γ1(x )
V = V – Ci
E = E – ω(Ci )
3. If V ≠ then i = i + 1 and goto 1; else stopΓ1(x ) be the set of one-hop neighbors of x
C0
x
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The Multicluster Architecture and its Properties (cont.)
Robust Cluster structure Because can Re-cluster approach
d (1,4)=d (0,4)= 3>2 Find a highest degree node and its
neighbors to stay in the original cluster to as a center, and remove the other nodes
The other nodes should either join another cluster or form a new cluster
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Adaptive Routing for Real-Time Traffic
Objective Real-time traffic can to transmit over the
dynamic network, and the routing protocol is keep communication
The routing optimality is of secondary importance
Choose a hierarchical routing protocol
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The Two-level Hierarchical Routing Protocol
Route construction and Route maintenance The construction phase establishes an initial
set of routes The maintenance phase maintains loop-free
routing in the face of arbitrary topological changes
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The Two-level Hierarchical Routing Protocol(cont.)
Construction Phase Assume every node has no global
connectivity information, but keeps some information of its locality Locality information
destination
Cluster 0 Cluster 1
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Construction Phase
IFDB (internal forward database) Every node has to maintain for each
repeater in its cluster a list of nodes to which the repeater has one or more routes
EFDB (external forward database) every repeater has to maintain for each
adjacent cluster a list of nodes to which the cluster has routes
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Construction Phase(cont.)
IFDB of node 1 may be ((4, {8, 15}) (3, {8, 16})), destination is node 15EFDB of node 6 may be ((C2, {1, 18}) (C3, {1, 4}) (C5, {17})) destination is node 4
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Input repeater Output repeater
repeater
destinationoutput repeater
destination
input repeater
IFDBEFDB
Case 1
Case 2
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Construction Phase(cont.)
If IFDB and EFDB do not include the destination
Discovery packet
Update IFDB
Update IFDB
Update IFDB
Reply packet
destination
source
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Construction Phase(cont.)
The cluster-level topology be described to a graph A vertex represents a cluster and a link
between two vertices Routes are built depending on the order of
the reply packet transmission the cluster-level topology would be an
acyclic directed graph (ADG)
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Maintenance Phase
Destination nodeThe ID is DID
x deletes DID fromEFDB (Cj , {DID, . . . })
x y
z
z deletes DID fromIFDB(x , {DID, . . . })
Ci Cj
Update packet
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Maintenance Phase(cont.)
Ex:
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Re-clustering and how to establish a new route
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Simulationrange : N nodes randomly in 100x100 area Fig.3 Transmission range
connectivity
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Fig.4 transmission rangecluster number
(the degree of a topology)
(the average number of nodes in a cluster)
Simulation
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Simulation
Fig.6 The order of most repeaters is either 2 or 3
Fig.7 That more than 50% of nodes are repeatersover the interval(30, 80)
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Simulation
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Simulation
Direction: U(0, 2π), distance: U(0, 3)
Fig.10 The average number of nodes which switch clusters per 100ms is relatively small
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Conclusion
Provide a distributed multicluster architecture for transporting real-time traffic in a multihop dynamic radio networksA hierarchical routing protocol over the architecture is stable and loop-free in the face of topological change
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Discussion
Re-cluster problem
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The Multicluster Architecture and its Properties
ClusterheadMay become bottleneck
Fully distributed algorithm
The system topology G(V , E ) is divided into small partitions (clusters ) with independent control
Advantage:Permits us to
avoid vulnerable
centers and hot spots of packet traffic flow.
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A hierarchical routing protocol’s main reasons
Attempts to reduce traffic by hiding information about the content of a clusterHierarchical structure can scale to large populationsThe multicluster infrastructure is quite stable in the mobile environment(Fig.10) and multiple links connect two adjacent clusters(Fig.8)
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