Transcript Tree networks

Tree network based on Bluetooth 4.0
for wireless sensor network
applications
SPEAKER： CHUN-TING LIN
ADVISOR： DR. HO-TING WU
DATE: 2015/12/31
Outline
• Introduction
• Bluetooth Low Energy (BLE)
• Network Size and Data Routing
• Hardware Design and Implementation
• Software Design
• Measurements and Results
• Conclusion
• Reference
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Introduction
• WSNs are deployed to collect information about
physical parameters of interest using the respective
sensors (eg. temperature, acceleration, light, etc.) in its
nodes.
• The important parameters of the wireless technologies
used in WSNs are power consumption, throughput,
latency, range, and network topology.
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Introduction(Cont.)
Comparison of wireless technologies in WSNs
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Introduction(Cont.)
• Star topology is the default BLE topology.
• This topology is its lack of ability to extend the network’s
range.
• Tree networks are implemented to address this limitation.
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Bluetooth Low Energy (BLE)
• Bluetooth 4.0 (including BLE) is the latest specification
update in this trend which was introduced in the year 2010.
• Advantage：
• ultra-low power consumption
• wireless products working on standard coin-cell batteries for
years
• low cost of the components
• multi-vendor operability
• enhanced range
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Bluetooth Low Energy (BLE) (Cont.)
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Implementation of Tree Network
• BLE, which only supports star topology, is used.
• Mesh networking is the preferred topology for WSNs but it is
complex to implement.
• In comparison, tree topology is simpler and can still be used to
extend the range of the network
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Implementation of Tree Network(Cont.)
• Root node:
• This is the main node in the tree network.
This node can be viewed as a gateway
sensor or a data collecting center in analogy
to WSNs.
• Intermediary node:
• A node which connects two or more nodes
located at higher and lower positions in the
hierarchy of a tree network.
• Leaf node:
• A node which connects to just one node
higher up in the hierarchy of the tree network
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Network Size and Data Routing
• Network size is an important parameter which determines if a
network can cover the area where the WSN is to be deployed.
• Using the hardware and software developed, the maximum
possible size of a network is limited by the fact that each node is
given a unique identity number.
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Network Size and Data Routing(Cont.)
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Network Size and Data Routing(Cont.)
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Hardware Design and Implementation
• Three possible devices which can act as root nodes in
this project are:
• USB dongle from TI CC2540 mini DK in conjunction with Btool
(included in BLE-stack 1.4.0 provided by Texas Instrument).
• SMARTRF05 evaluation board (EB) mounted on the CC2540DK
central evaluation module (EM).
• a smartphone with BLE technology supported by third party
applications.
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Hardware Design and Implementation(Cont.)
• For the other two types of nodes, a single piece of hardware is
designed and adjusted as necessary to enable specific sensors
on the different boards (peripheral BLE).
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Hardware Design and Implementation(Cont.)
Hardware implementation
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Software Design
• The software used in this project is organized under five
different sections:
•
•
•
•
•
Operating System Abstraction Layer (OSAL)
Hardware Abstraction Layer (HAL)
Protocol stack
Profiles
Applications
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Software Design(Cont.)
• Peripheral BLE devices need the GATT (GENERIC ATTRIBUTE
PROFILE) profile so that central devices can discover the services
available and request to read and write data.
• The GATT profile allows for the data exchange between central
and peripheral devices.
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Software Design(Cont.)
• This custom profile defines five characteristics
(SIMPLEPROFILE_CHAR1 to SIMPLEPROFILE_CHAR5).
SIMPLEPROFILE_CHAR1
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Software Design(Cont.)
• Characteristic number 4 includes configuration settings defined
in the profile so that notification can be enabled .
SIMPLEPROFILE_CHAR4
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Measurements and Results
• There are some parameters which are important from the WSN
perspective.
• The parameters include :
• the power consumption of the network
• latency
• data transmission
• Speed
• node recognition
• Routing
• failure detection
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Measurements and Results(Cont.)
Node life based on power consumption
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Measurements and Results(Cont.)
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Conclusion
• With appropriate software modification, the size of the network
can be enlarged as demanded by a WSN application.
• The tree topology can be used with Bluetooth low energy for the
purposes of range extension, extending the number of network
nodes or data processing by the central node.
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Reference
1. B.K. Maharjan, U. Witkowski and R. Zandian,“Tree network
based on Bluetooth 4.0 for wireless sensor network
applications,”in: Proc. 6th European Embedded Design
Education Research Conf., 2014, pp. 172- 176.
2. E. Mackensen, M. Lai, T.M. Wendt,“Bluetooth low energy (BLE)
based wireless sensors,”Proceedings of IEEE Sensors , 2012, pp.
1–4
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Thanks for listening !
Happy New Year !
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