Transcript A Paper Presentation of ”Multihop Sensor Network Design

Ad-Hoc Networking Course
Instructor: Carlos Pomalaza-Ráez
A Paper Presentation of
”Multihop Sensor Network Design for
Wide-Band Communications”
Proceedings of the IEEE, VOL.91, NO.8, August 2003
Terho Hautala
13.1.2004
Outline
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Introduction
New Cluster-Based Network
AODV
Mobility and handoff
Ipv6-in-IPv4 Tunneling
IEEE 802.11
Measurements
Conclusions
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Introduction
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New cluster-based network architecture
Mixture of two different types of network:
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Infrastructure (master-and-slave)
Ad-hoc
Slave Nodes (SN) are communicating via their
respective Master Nodes (MNs)
Base stations (MNs) are mobile (AODV routing)
MNs act as a Home Agent (HA) and gateways for
the cluster
All nodes in a cluster typically move as a group
If node changes cluster MIPv6 is deployed
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Introduction
Ad-hoc Mobility
Relatively fixed
Increasing mobility
Headquarters
Airbase
Wireless only
Wired and wireless
Static addressing
Mobile IP
Mobile IP + Ad-hoc routing
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Introduction
• Traditional cluster-based networking has
difficulties when the number of nodes
increases
• routing complexity
• network management
• large overheads
• In the paper a simple cluster networking is
proposed. There WLAN is utilized. The goal is
to provide a wide-band access for multimedia
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communication (video).
New Cluster-Based Network
Slave Node
(SN)
AP
LAN GW
WLAN
Master Node 1 (MN1)
Master node 2 (MN2)
WLAN
LAN
AP
Ad-hoc channel
Infrastructure channel
AP
LAN
WLAN
Master node 3 (MN3)
Master node 4 (MN4)
WLAN
LAN
AP
AP
LAN
WLAN
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AODV
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AODV is used to manage routes between
Master Nodes.
Instead of AODV DSR could also have been
used, but it was not further investigated in
the paper.
AODV discovers routes by means of route
request (RREQ) and route reply (RREP).
Each node will reply to RREQ if it is either
destination node or an intermediate node.
In the case on link breakage error message
(RERR) will be sent back to the source.
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Mobility and handoff
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If SN moves to a new cluster mobile IPv6
(MIPv6) handoff is performed.
SN will automatically configure link-local
address and care-of-address (CoA) address
based on the router advertisements.
The home-agent is informed of the new
CoA, so it can tunnel packets arriving to the
home network (original cluster) to the new
location.
If SN receives a tunneled packet it should
inform the source SN of the new location
(route optimization).
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Mobility and handoff
(MN1)
AP
LAN
WLAN
(MN3)
AP
LAN
WLAN
BU
BACK
(MN2)
WLAN
LAN
AP
(MN4)
WLAN
LAN
AP
SN sends
Master
Node1
Binding
(HAUpdate
for SN1)
to replies
inform with
Master
Binding
Node 1
Router
• SN automatically
configures
care-of-address
about
Acknowledgement
the movement.
andBinding
tunnels
Cache
the packets
is updated.
to(CoA)
SN1
BUs
Advertisement
by
address
based
on the
advertisements
should
also
be sent
to router
Correspondent
Nodes (CNs)9of
IPv6
ROUTER
SN
IPv6-in-IPv4 Tunneling
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IPv6 is used for operation in the
infrastructure mode.
The communication in the ad-hoc mode
(between the master nodes) is based on
IPv4 and AODV.
If SN communicates with SN in another
cluster, IPv6-in-IPv4 tunneling is used.
Master node encapsulates the IPv6 packets
received from SN and sends them to the
master node of the destination cluster.
The source address in IPv4 header is the
address of the master node.
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IPv6-in-IPv4 tunneling
IPv6
SN1
AP
LAN
WLAN
(MN3)
AP
LAN
WLAN
(MN1)
Data packets
(MN2)
WLAN
LAN
AP
Packets are sent to the master node of the
destination cluster.
MN1 encapsulates the IPv6 packets received from
The source address in IPv4 header is the address of
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SN1
the master node.
IEEE 802.11
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IEEE 802.11 supports direct sequence
spread spectrum (DSSS) and frequency
hopping spread spectrum (FHSS) modes.
The DSSS mode is preferred if the number
of clusters if small.
If the number of clusters is large, FHSS can
be more suitable.
FHSS can select 79 possible hopping
sequences to avoid inteference.
IEEE 802.11 is allowed several
retransmission attempts (the number
retransmission affects the performance) 12
Experimental setup
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Stationary , throughput and delay
Retrans = 0 and retrans = 3
Bitrate = 128 / 384 / 768 kb/s
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Experimental setup
SN1
AP
LAN
WLAN
(MN3)
AP
LAN
WLAN
(MN1)
(MN2)
WLAN
LAN
AP
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Scenarios
SN-S
SN-S
SN-D
AP
LAN
WLAN
(MN1)
1-hop case:
Same radio
channel 
resources are
overwhelmed at
higher bit rates
SN-D
2 hops case:
3-hops case:
WLAN
LAN
AP
(MN2)
WLAN
LAN
AP
(MN3)
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Results(throughput)
Fig.1. Throughput performance for one node
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Results(throughput)
Fig.2. Throughput performance for two node
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Results(delay)
Fig.3. Propagation delay distributions for 1-hop communication
(time resolution 10ms)
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Results(delay)
Fig.4. Propagation delay distributions for 2-hop communication
(time resolution 10ms)
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Results(delay)
Fig.5. Propagation delay distributions for 3-hop communication
(time resolution 10ms)
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Results(delay)
Fig.6. Average delay
(time resolution 10ms)
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AODV Route Change Scenario
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Cluster is moving (routes change), delay +
tput
Route change: 2-hop => 3-hop
At low bitrate delay remains almost the
same
At high bitrate delay increases
Route change a->b, duration about 2 sek
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AODV route change scenario
SN-D
(MN3)
2-hops
(MN1)
(MN2)
SN-S
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AODV route change scenario
3-hops
SN-D
(MN3)
(MN2)
(MN1)
SN-S
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AODV route change results
Fig.7. Delays in AODV route change
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Mobile IP handoff scenario
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SN is moving (MIPv6 handover ja tunneling
+ BUs), delay + troughput
Route A (original)
Route B (BU has sent to HA and it is
receiving packets from CN)
Route C ( CN has received BU because SN
sent it after receiving a tunneled packet)
Handover delay remains same regardless
the bitrate and max retries
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Mobile IP handoff scenario
SN-D
SN-D
(MN3)
(MN1) HA
(MN2)
CN
SN-S
Route C: SN-S  MN-2  MN-3  SN-D
Route A: SN-S  MN-2  MN-1  SN-D
Route
RouteB:
B:SN-S
SN-S
MN-2
MN-2
 MN-1
MN-1

 MN-2
MN-2
 MN-3
MN-3
SN-D
SN-D
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Mobile IP handoff scenario
• In he pa
Fig.8. Average packet loss in Mobile IP
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Mobile IP handoff scenario
Fig.9. Delays in Mobile IP
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Future work
• Use forward error correction (FEC)
• In heatpa
codes
the application layer
• Use Dynamic Source Routing (DSR)
and Optimized Link State Routing (OLSR)
• Measure the network performance
when a larger number of clusters have
been utilized
• Develop robust error resilient coding
for video streaming
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Conclusions
• Assumption was that all the nodes within
• In he pa
each cluster move as a group
• To allow handoffs for some isolated nodes
Mobile IP has been considered
• AODV routing protocol has been used for
ad-hoc routing
• Experimental testbed was developed for
video based sensor network and was
successfully tested
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• In he pa
Thanks!
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