Transcript TSMP vs 802.15.4 - UOIT.CA: Faculty Web Server

Advantages of
TSMP
By Kiana Karimpour
Scope
Today there are plenty of protocols available which could be useful for
a wireless data transmission such as:
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WiFi
Bluetooth
ZigBee
Z-Wave
6LoWPAN
ANT
ONE-NET
wirelessHART
MiFi
…
The scope of this presentation is to review the advantages of TSMP and
connection methods which deploy such advantages.
What Is TSMP
TSMP (Time Synchronized Mesh Protocol) is a networking protocol that
forms the foundation of reliable, ultra low-power wireless sensor networking. TSMP
provides redundancy and fail-over in time, frequency and space to ensure very
high reliability even in the most challenging radio environments. TSMP also
provides the intelligence required for self-organizing, self-healing mesh routing.
TSMP Overview
TSMP is a media access and networking protocol that is designed
specifically for low power, low-bandwidth reliable networking. Current TSMP
implementations operate in the 2.4 GHz ISM band on IEEE 802.15.4 radios and in
the 900 MHz ISM band on proprietary radios. Figure 1 shows the elements of TSMP
in the standard wireless network stack and the OSI network stack.
Challenges in WSNs
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RF interference : The small portion of the electromagnetic spectrum
devoted to general-purpose wireless communication devices is crowded
with traffic from Wi-Fi networks, cordless telephones, bar-code scanners,
and innumerable other devices that can interfere with communications
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Blocked Paths: Unlike wired networks, wireless paths often change; paths
may later be blocked by new equipment. Assuring reliability for the life of
the network, not just the first few weeks after installation, requires
continually working around these blockages in a transparent, automatic
fashion.
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Node Loss: Nodes may be damaged, destroyed or removed during the
life of the network. Additionally, power surges, blackouts, or brownouts
can cause nodes to fail unless they have an independent power source.
WSN Solution
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A well-designed wireless network architecture will transparently adapt to
changing environments, allowing long-term operation with zero-touch
maintenance.
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Applying self-organizing and self-healing intelligence to continuously adapt to
unpredictable conditions without constant tuning by wireless experts.
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Time Synchronized Mesh Protocol (TSMP) provides a mechanism for WSN
intelligence. By defining how a wireless node utilizes radio spectra, joins a
network, establishes redundancy and communicates with neighbors, TSMP
forms a solid foundation for WSN applications.
TSMP Key Components
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There are five key components of TSMP that contribute to end-to-end network
reliability, simple installation and power efficiency.
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Time synchronized communication
Frequency hopping
Automatic node joining and network formation
Fully-redundant mesh routing
Secure message transfer
Time Synchronized
Communication
All node-to-node communication in a TSMP network is transacted in a
specific time window. Commonly referred to as Time Division Multiple Access
(TDMA), synchronized communication is a proven technique that provides
reliable and efficient transport of wireless data. In a wireless system all devices
within range of each other must share the same media. Several other Media
Access Control (MAC) mechanisms are available including CSMA, CDMA and
TDMA. TSMP is based on TDMA.
Frequency hopping
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addition to slicing the wireless media across time, TSMP also slices it across
frequency. This provides robust fault tolerance in the face of common RF
interferers as well as providing a tremendous increase in effective bandwidth.
Commonly referred to as Frequency Hopping Spread Spectrum (FHSS).
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Another technique to overcome RF challenges is Direct Sequence Spread
Spectrum (DSSS). DSSS provides a few dB of coding gain and some
improvement in multi-path fading(see figure 4 below).
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It should be noted that a combination of FHSS and DSSS provides both
interference rejection (FHSS) and the coding gain (DSSS).
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The other technique for overcoming interference is increasing the radio power
effectively “turning up the volume”. Although often effective, turning up the
volume on 802.15.4 radios kills battery life and is not an ideal solution for lowpower WSNs.
Frequency Hopping
Automatic Node Joining
and Network Formation
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Every TSMP node has the intelligence to discover neighbors, measure RF signal
strength, acquire synchronization and frequency hopping information, and
then establish paths and links with neighbors.
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All TSMP nodes are fully capable mesh networking nodes. Every TSMP node
has the ability to route traffic from neighbors as dictated by RF connectivity
and/or network performance requirements. During the life of an installation it
may be the case that a node joins as an end node, becomes a routing node
due to changing RF conditions and then reverts back to an end node.
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All TSMP messages are encrypted and include a network ID. The network ID is
used to bind nodes together into a network, allowing multiple TSMP networks
to operate in the same radio space without the risk of sharing data or
misrouting messages
Fully-Redundant Mesh
Routing
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A full mesh topology with automatic node joining and healing lets the network
maintain long-term reliability. Only self-organizing full mesh networks can find
and utilize the most stable routes through the available node topology.
Fully redundant routing requires both spatial diversity (try a different route) and
temporal diversity (try again later). TSMP covers spatial diversity by enabling
each node to discover multiple possible parent nodes and then establish links
with two or more. Temporal diversity is handled by retry and failover
mechanisms.
Additionally, should an installed network need to be expanded, only a full
mesh network can gracefully accommodate new nodes by relying on edge
nodes to automatically assume routing duties
Secure Message Transfer
There are three pillars of secure message transfer:
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Encryption: TSMP uses industry-standard 128-bit symmetric key encryption
for end-to-end confidentiality of packet payload
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Authentication : , TSMP uses packet source addresses protected by 32-bit
Message Integrity Codes (MIC). Every packet carries two MIC codes to
provide authentication: end-to-end source address authentication
guaranteed by the network layer MIC, and node-to-node source address
authentication, guaranteed by the MAC layer MIC. The MAC layer
authentication is particularly important in protecting ACKs
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Integrity: The same 32-bit Message Integrity Codes (MICs) that
authenticate the sending node’s address also serve to ensure content
integrity
TSMP WSN Applications
Wireless Sensor networks based on TSMP are widely used in various
applications including:
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Data Centers
Industrial Automation
Renewable Energy
Building Automation
Remote Monitoring
Transportation
Most Popular TSMP
Standards
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WirelessHART:
Developed by HART communication
DigiMesh:
Developed by Digi International.[1].
Energy hole problem
Energy-hole means that nodes in the region near the sink have to spend
more energy and will be exhausted sooner than nodes in outer regions. Solution
for this problem is
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When deploying the sensors, we simply need to increase the density of sensors
While the distance from a node to the sink decreases.
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We can deploy the nodes with extra more energy in the energy-hole region.
System lifetime is the duration from the very beginning of the network
until a certain proportion of nodes die. The energy consumption model that we
use to analyze and simulate in this paper is Eq.
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𝐸𝑡𝑟𝑎𝑛 = 𝐸𝜔 + 𝐸
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𝐸𝑟𝑒𝑐 = 𝐿 . 𝐸𝜔
𝛼
. 𝐷𝛼
𝐸𝑞. 1
𝐸𝑞. [2]
Assume that there are N hops along the route, then we can calculate
the total energy consumption of transmitting the packet, and Eq. [3.1] is the
formula, or it can be abbreviated as Eq. [3.2].
𝑁
𝛼
𝑖=1( 𝐸 𝛼 . 𝐷i ) . L +(N_2)
𝛼
𝐸𝜔 . 𝐿 + 𝑁
𝑖=1( 𝐸 𝛼 . 𝐷i ) . L
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𝐸𝑠𝑢𝑛 =N. 𝐸𝜔 .L +
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𝐸𝑠𝑢𝑛 =(2N_2)
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L.Bit data
𝐸𝜔 = hardware energy consumption
𝐷𝑖 = the distance between two adjacent hops
𝛼 = 𝐷𝑖 /𝐷0
𝐸𝑟𝑒𝑐
Solution
Could adjust the transmission ranges of nodes in the outer region to reduce energy
consumption of nodes in the areas around the sink. Our solution to this problem is combining
transmission range to the original routing graph of the TSMP network. Then algorithm operates
as follows:
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a) Generate vectors that could contain all possible temporary transmitting trees whose
vertexes‘ number equals their sub-region number;
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b) Let i denotes the concentric circles number, when i equals I, it means that the circle is
the closest one to the sink, when i equals M it illustrates the outmost circle. The circulating
will not stop until i is bigger than M. Set i=i+1 ;
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c) Compute the value of each tree according to Eq. [3.2], and take the minimal value as
the major contribution to lifetime of the network;
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d) Each node in the temporary routing tree calculates its own energy consumption and
renews its state. 𝐸𝑛𝑜𝑑𝑒 stands for the total energy of each node. And it's kept by each
node. Set 𝐸𝑛𝑜𝑑𝑒 = 𝐸𝑛𝑜𝑑𝑒 - 𝐸𝑡𝑟𝑎𝑛 - 𝐸𝑟𝑒𝑐 ;
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e) Find the minimal 𝐸𝑠𝑢𝑚 among all these temporary trees and assign it to 𝑇𝑚𝑎𝑥 Type
equation here. in this loop;
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f) If i equals to M then stop the loop and select this transmission tree as the optimal routing
graph; if not, then go back to step b) and keep on circulating.
Simulation and
Evaluation
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We set each node has the initial state that battery contains 100 J
energy, the maximal transmission range of the radio is 10 m, the distributive
density of node is 3 nodes/m. Below table shows details about the parameters
and its value.
Conclusion
This algorithm will be executed every time the TSMP synchronizes the
whole network. By this way the routing graph can be renewed in time so that it
could provide stable and reliable performance. Meanwhile nodes in different
position of the network can choose their own transmission range and next hop
relay. Thus the sensor nodes can maintain adjustable transmission range and
preplanned routing graph and they can adjust their energy consumption and
cooperate with other nodes. Finally the network can maintain and function for
longer time to provide reliable, timely, secure delivery of data packets.[2].
Bibliography
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[1]. DUST Networks, Inc., Technical Overview of Time Synchronized Mesh
Protocol (TSMP), Hayward, California.
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[2]. Yao Zhen; Duan Hui-chuan; Qi Lin, "Prolonging Time Synchronized Mesh
Protocol network's lifetime by adjusting transmission range and routing graph,"
Information Technology in Medicine and Education (ITME), 2012 International
Symposium on , vol.2, no., pp.910,913, 3-5 Aug. 2012
Discussion
• What is TSMP?
 It is a mesh protocol for transmitting wireless data.
• Why it is very reliable?
 Since it uses FHSS and DSSS together.
• Which nodes consume more energy?
 Nodes are near the sink.