Download Routing protocols for wireless networks

無線網路路由及模擬實驗簡介
演講人：王朱福
(屏東教育大學資訊科學系)
Outline…
Wireless networks architectures
Routing protocols for wireless networks
Mobile ad-hoc Networks (MANETs)
Wireless Sensor Networks (WSNs)
Vehicle ad-hoc networks (VANETs)
Network Simulator for performance evaluation
Concluding remarks
2
Wireless network architectures
Infrastructure-based wireless networks
 Fixed base stations / access points are
used.
Infrastructure-less wireless networks
(Ad-hoc networks)
 No fixed infrastructure support are
available.
Hybrid wireless networking
architecture
3
Two types of wireless networks – with infrastructure
Single-hop communication
4
Two types of wireless networks
– without infrastructure
(also known as ad-hoc network)
No centralized server
Multi-hop communications
5
Outline…
Wireless networks architectures
Routing protocols for wireless networks
Mobile ad-hoc Networks (MANETs)
Wireless Sensor Networks (WSNs)
Vehicle ad-hoc networks (VANETs)
Network Simulator for performance evaluation
Concluding remarks
6
Routing protocols for wireless networks – MANETs
Some challenges to MANETs routing.
 MANETs are more unstable than wired-networks
because of the lack of a centralized entity.
 Mobility will cause network topology to change, which
results in a great change in connection between two hosts.
 The connectivity between network nodes is not
guaranteed, so intermittent connectivity is common.
7
The main routing
problems for MANETs
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10
9
7
4
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Node mobility 
Routing path broken
frequently
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3
5
1
Traditional routing protocols will be no longer fit.
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Ad-hoc routing protocols
9
Routing protocols for MANETs
Flooding-type routing protocol (flooding)
Table-driven routing protocol (proactive)
On-demand routing protocol (reactive)
Hybrid routing protocol
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Flooding
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10
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2
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3
11
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1
Broadcast storm problem
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Routing protocols for MANETs (cont.)
Table-driven routing protocol (proactive):
They maintain the global topology information in the
form of tables at every node.
These tables are updated frequently in order to
maintain consistent and accurate network state
information.
For example, DSDV, WRP, and STAR.
enhanced version of the distributed Bellman-Ford algorithm
12
DSDV (Destination Sequenced Distance-Vector Routing Protocol)
Example:
Routing table for Node 1
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6
4
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5
3
1
2
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Dest
2
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15
NextNode
2
2
5
5
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2
5
2
6
6
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6
5
Dist
1
2
2
1
1
3
3
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2
2
3
4
3
4
seqNo
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26
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134
144
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256
DSDV (cont.)
Routing table for Node 1
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Dest NextNode
2
2
3
2
4
5
5
5
6
6
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2
8
5
9
2
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Dist
1
2
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1
1
3
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2
4
3
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3
4
seqNo
22
26
32
134
144
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170
186
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256
Routing protocols for MANETs (cont.)
On-demand routing protocol (reactive):
They execute the path-finding process and
exchange routing information only when a
path is required by a node to communicate
with a destination.
For example, AODV and DSR.
15
The AODV routing procedure (cont.)
The Route discovery process:
 It begins with the creation of a RouteRequest (RREQ)
packet. Broadcasting is done via flooding.
 Broadcast ID gets incremented each time a source node uses
RREQ.
 Broadcast ID and source IP address form a unique identifier
for the RREQ.
Type
Reserved Hop Count
Broadcast ID
RREQ packet format
Destination IP Address
Destination Sequence Number
Source IP Address
Source Sequence Number
Time Stamp
16
The AODV routing procedure (cont.)
2. Sender S broadcasts a RREQ to all its neighbors, each node
receiving RREQ forwards RREQ to its neighbors.
*Sequence numbers help to avoid the possibility of forwarding
the same packet more than once.
3. An intermediate node (not the destination) may also send a
RouteReply (RREP) packet provided that it knows a more
recent path than the one previously known to sender S.
Type
Reserved
Hop Count
Destination IP Address
RREP packet format
Destination Sequence Number
Source IP Address
Life Time
17
The AODV routing procedure (cont.)
4. As an intermediate node receives the RREP packet,
it sets up a forward path entry to the destination in
its routing table.
5. The source node can begin data transmission upon
receiving the first RREP.
18
Outline…
Wireless networks architectures
Routing protocols for wireless networks
Mobile ad-hoc Networks (MANETs)
Wireless Sensor Networks (WSNs)
Vehicle ad-hoc networks (VANETs)
Network Simulator for performance evaluation
Concluding remarks
19
WSNs & VANETs
 Two special types of ad-hoc network
• WSNs (Wireless Sensor Networks)
• VANETs (Vehicular Ad-hoc Networks)
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Introduction to WSNs -- Applications
Military applications
Home
applications
Environmental
applications
Applications
Health applications
21
Other commercial
applications
Introduction to WSNs – Sensor node
Introduction to WSNs – Sensor node (cont.)
Aqua node
Introduction to WSNs – Sensor node (cont.)
Aqua node
The applications of WSNs
Precision Agriculture, Water
quality management
25
The differences between WSNs and ad-hoc networks
 The number of sensor nodes in a sensor network
can be several orders of magnitude higher.
 Sensor nodes are densely deployed.
 Sensor nodes are prone to failures.
 Sensor nodes are limited in power,
computational capacities, and memory.
Routing protocols for WSNs
 Flat-based
 All nodes are typically assigned equal roles
or functionality.
 Hierarchical-based
 Nodes will play different roles in the
network.
 Location-based
 Sensor node’s positions are exploited to
route data in the network.
Flat-based routing example
SPIN (Sensor Protocols for Information via Negotiation)
ADV
DATA
REQ
A
ADV
REQ
DATA
1. Data is described by meta-message (ADV).
2. Send ADV to neighbors.
3. If neighbor do not have the data, sends REQ; otherwise,
do nothing.
4. As the REQ received by sender, then it sends the data
to the neighbor.
Hierarchical-based routing
 Hierarchical routing is two-layer routing.
 Higher-energy nodes can be used to process and send
the information, while low-energy nodes can be used
to perform the sensing in the proximity of the target.
 The creation of clusters and assigning special tasks
to cluster heads can greatly contribute to overall
system scalability, lifetime, and energy efficiency.
Hierarchical-based routing example
TEEN (Threshold-Sensitive Energy Efficient Sensor Network
SProtocol)
Sink
Cluster
Node
1st cluster head
2nd cluster head
D
Hierarchical-based routing example
TEEN (Threshold-Sensitive Energy Efficient Sensor Network
Protocol)
 Cluster-based routing.
 Node transmits sensed data only if both of the
following conditions hold:
1. The sensed value is greater than a Hard
Threshold.
2. The sensed value differs from last transmitted
value by more than a Soft Threshold.
Routing compare
Hierarchical-based routing
Flat-based routing
Reservation-based scheduling
Contention-based scheduling
Collisions avoided
Collision overhead present
Reduced duty cycle due to periodic
sleeping
Variable duty cycle by controlling
sleep time of nodes
Data aggregation by cluster head
Node on multi-hop path aggregates
incoming data from neighbors
Simple but non-optimal routing
Routing can be made optimal but
with an added complexity
Requires global and local
synchronization
Links formed on the fly without
synchronization
Overhead of cluster formation
throughout the network
Routes formed only in regions that
have data for transmission
Lower latency as multiple hops
network formed by cluster heads
always available
Latency in waking up intermediate
nodes and setting up the multipath
Research view of WSNs’ routing
Forest fire detection
sin k
From: www.nps.gov/slbe/planyourvisit/psbeechmaple.htm
33
Research view of WSNs’ routing (cont.)
Forest fire detection (cont.)
Sink
Sensor
Sensor
Sensor
Event
Sensor
Sensor
User
Sensor
Sensor
Sensor
From: www.nps.gov/slbe/planyourvisit/psbeechmaple.htm
34
Sensor
The most important design issue is . . .
Energy saving!
Energy saving!
The objective:
To maximize the network lifetime
(網路壽命最大化)
How to estimate the network lifetime of a WSN?
35
How to estimate the network lifetime of a WSN?
Example:
 Routing (energy-aware routing)
Sink
Sensor
Sensor
Sensor
Energy consumption for
Event
Sensor
Sensor
Data transmitting: Etx=6
User
Sensor
Sensor
Data receiving: Erx=3
Sensor
45 -9
50 -9
70 -6
40
∞
35
60
55
36
Sensor
-9
90
65
Objective: To maximize network lifetime
Example:
 Routing (energy-aware routing)
Sink
Sensor
Sensor
Sensor
Energy consumption for
Event
Sensor
Sensor
Data transmitting: Etx=6
User
Sensor
Sensor
Data receiving: Erx=3
Sensor
36
41
Sensor
64 -6
31
∞
35 -9
60 -9
37
55 -9
90 -9
65 -9
How to estimate the network lifetime of a WSN
– an expected approach
Define: E_consumptionv(u)
Etx (k , d (u, successor (u ))

E _ consumptionv (u )  Erx (k )  Etx (k , d (u, successor (u )))
0

if u  v


if u  v and u  Pvs 

if u  Pvs

Define:The expected energy consumption for
node u during one transmission round (ELE(u))
ELE(u )   P(v)  E _ consumpionv (u )
vV
p(v): the probability of an
event occurring in node v
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How to estimate the network lifetime of a WSN
– an expected approach (cont.)
Let Etx=6
E_consumptionE(B)=6+3=9
Erx=3
E_consumptionF(B)=6+3=9
E
and let p(v)=1/n
F
E_consumptionA(B)=0
A
B
B
E_consumptionB(B)=6
D
C
E_consumptionD(B)=6+3=9
E_consumptionc(B)=0
ELE(B)  P( A)  E _ consumpionA ( B)  P(B)  E _ consumpionB (B))  ... 
P(F )  E _ consumpionF ( B) =1/6(0+6+0+9+9+9)=5.5
S
39
How to estimate the network lifetime of a WSN
– an expected approach (cont.)
The expected network lifetime (ENL(G))
ENL(G)  min vV r (v) / ELE(v)
10
30
E
F18
ELE(E)=3
ELE(F)=2
50
A
12.5
40
B
ELE(A)=4
7.27
ELE(B)=5.5
ELE(C)=10
S
40
D
ELE(D)=4
70
C
20
7
5
9
Sensors deployment issues
1
Pre-deployment
Sensor
Sensor
Sensor
Sensor
2
Post-deployment
Sensor
Sensor
Sensor
Sensor
Sensor
3
Topology adjustment
41
The major concerns of sensor deployment
 No coverage holes
 No communication holes
 Maximize network lifetime
Uniformly distributed v.s. Non-uniformly distributed
sin k
sin k
42
Introduction to some deployment problems
Post-deployment problem
Topology adjustment
 The Optimization of Sensor Relocation in Wireless Mobile Sensor
Networks
Pre-deployment problem
 Joint Optimization of Energy Allocation and Routing Problems in
Wireless Sensor Networks
43
Topology adjustment
The Optimization of Sensor Relocation in Wireless
Mobile Sensor Networks
Mobile node
sin k
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Problem formulation
Network model
B
F
cluster
cluster
D
A
cluster
cluster
E
cluster
C
cluster
Sink
sensor
sensor
sensor
sensor
sensor
sensor
sensor
sensor
sensor
sensor
cluster
cluster
45
sensor
Problem formulation (cont.)
B
F
sensor
sensor
sensor
sensor
sensor
sensor
sensor
sensor
sensor
cluster
sensor
D
A
cluster
sensor
sensor
sensor
sensor
sensor sensor
sensor
sensor
sensor
sensor
sensor
cluster
sensor
cluster
sensor
E
sensor
sensor
sensor
C
sensor
sensor
sensor
cluster
sensor
sensor
sensor
sensor
sensor
KEY
Sensor moving
cluster
Routing
Sink
46
Problem formulation (cont.)
To determine a relocation scheme to optimize
the resulting network lifetime.
B
F
sensor
sensor
sensor
sensor
sensor
sensor
sensor
sensor
cluster
sensor
cluster
A
D
sensor
sensor
sensor
sensor
sensor
sensor
sensor
sensor
sensor sensor
sensor
sensor
cluster
cluster
E
C
sensor
sensor
sensor
sensor
sensor
sensor
sensor
sensor
sensor
sensor
cluster
cluster
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Introduction to some deployment problems
Post-deployment problem
Topology adjustment
 The Optimization of Sensor Relocation in Wireless Mobile Sensor
Networks
Pre-deployment problem
 Joint Optimization of Energy Allocation and Routing Problems in
Wireless Sensor Networks
48
Pre-deployment problem
 Joint Optimization of Energy Allocation and Routing Problems
in Wireless Sensor Networks
Energy-aware routing problem
45 -9
50 -9
70 -6
40 -9
∞
35
60
55
49
90
65
Pre-deployment problem
 Joint Optimization of Energy Allocation and Routing Problems
in Wireless Sensor Networks
Energy allocation problem
r(B)=150
p(B)=1/6
r(D)=90
p(D)=1/6
r(A)=100
p(A)=1/6
50
r(C)=200
p(C)=1/6
r(F)=300
p(F)=1/6
r(E)=250
p(E)=1/6
Pre-deployment problem
 Joint Optimization of Energy Allocation and Routing Problems
in Wireless Sensor Networks
Joint energy allocation and routing problem
r(B)=150
p(B)=1/6
r(D)=90
p(D)=1/6
r(A)=100
p(A)=1/6
51
r(C)=200
p(C)=1/6
r(F)=300
p(F)=1/6
r(E)=250
p(E)=1/6
Pre-deployment problem
 Joint Optimization of Energy Allocation and Routing Problems
in Wireless Sensor Networks
52
Introduction to VANETs
Applications in a VANET fall into two
categories
comfort applications
safety applications
Introduction to VANETs (cont.)
Vehicle mobility creates a highly dynamic
topology.
VANETs are potentially large-scale networks.
Vehicles can provide more resources than
other types of mobile networks such as：
large batteries
antennas
processing power
Routing for VANETs
Disconnected due to sparse
Two Paths： (1) Ia => Ic => Id => Ib
(2) Ia => Ib
Delayacdb < Delayab
The Intermittent connected routing problem
In case of the nodes density of a VANET is
sparse, it will cause the intermittent connected
routing problem, and consequently the
traditional routing protocols will be no longer
fit.
56
Intermittent connected routing problem
57
Epidemic routing protocol
Epidemic is a simple routing protocol to resolve the
intermittent connected routing problem.
The nodes adopt store-carry-forward communication
scheme.
 A node can carry the messages in its cache if no any direct
routing path to the destination is available.
 If a node moves into the node’s transmission range, they
will exchange the carried messages between them.
58
3
5
2
4
1
(Epidemic routing)
S
59
Outline…
Wireless networks architectures
Routing protocols for wireless networks
Mobile ad-hoc Networks (MANETs)
Wireless Sensor Networks (WSNs)
Vehicle ad-hoc networks (VANETs)
Network Simulator for performance evaluation
Concluding remarks
60
Introduction to network simulator -- NS-2
Network Simulator (Version 2) is an event driven
simulation tool for studying communication networks.
NS2 is a free simulation tool.
NS2 can be used to evaluate the performance of a
routing protocol.
NS2 installation
62
NS-2 architecture
Network simulation
兩部機器n0及n1透過2Mbps的有線網路來進
行資料傳遞(參數設定如下圖所示)。
Scenario --- tcl file description
創造節點n0,n1
開啟*.tr記錄檔並寫入。*為檔名可更改。
開啟*.nam記錄檔並寫入。*為檔名可更改。
Scenario --- tcl file description (cont.)
設定節點的Agent
設定封包產生器
開始發送的時間
、封包大小及發
送區間、
Scenario --- tcl file description (cont.)
執行完ns指令，自動
執行 nam animation
Simulation results
Simulation results (cont.)
Wireless network routing simulation (Flooding)
 移動範圍: 1,000m*1,000m大小
 模擬時間100秒
 利用Flooding路由協定
情境設定:
固定節點n0(100,100)為來源節點並發送封包，在第5秒時，n1節點(目的端節點)開始以每
秒5公尺的速率往(500,100)地方前進，而第60秒時，n1節點開始以每秒10公尺速率往
(200,100)方向移動回去，最後停留在(200,100)位置。
Wireless network routing simulation (AODV)
移動範圍:1,000m*1,000m
模擬時間200秒
各節點座標及移動情境如下圖所示。
利用AODV路由協定
TCL codes for Flooding (partial)
MFlood
TCL codes for AODV (partial)
Simulation results