Wireless Sensor Networks Service discovery and Mobility Ricardo Silva, Jorge Sá Silva, Cláudio Geyer, Luciano da Silva and Fernando Boavida...

Wireless Sensor NetworksService discovery and Mobility

Ricardo Silva, Jorge Sá Silva, Cláudio Geyer, Luciano da Silva and Fernando Boavida{rnsilva,sasilva,boavida}@dei.uc.pt. {geyer,lucc}@inf.ufrgs.br.

Pólo II - Pinhal de Marrocos, 3030-290 Coimbra, PORTUGAL

Outline

Saturday, April 22, 2023 © Ricardo Silva - I2TS 2008 2

Objectives StagesWSN – Architectures and ProtocolsDevice and Service Discovery (DSD)

- YouCatchMe and ICatchYou- Impact on battery life time

A new handover approach for Multi-Sink environments- ICatchYou without the Update method.- ICatchYou with RSSI check support.

Multicast communication over 6lowPAN-Multicast vs. Unicast over 6lowPAN.

Real scenario – Medicalcare.comFuture Work

Objectives• Study the WSN paradigms.• Explore and evaluate the main architectures of WSNs. • Improve the capabilities of WSNs by the IPv6 use.

– Design and implementation of new features, allowing mobility, self-configuration, self-handling, improving also the autonomy.

• Evaluate the impact of IP and the new features in WSNs.• Contribute to the international research community.• Implement the developed work in real scenarios.


Wireless Sensor Networks• Properties

– Networks constituted by autonomous devices, with:• Low complexity.• Low memory and processor capacity.• Short communication range.• Low data rates.• Low cost.• Energy limited.• …


Wireless Sensor Networks• Properties

– Based in IEEE802.15.4[1] standard, supporting two types of devices:• FFDs – Full Function Devices.• RFDs – Reduced Function Devices.• Duty Cycles.• CSMA/CA.


Wireless Sensor Networks• Mobility

– Capability of nodes to move between different WSNs, without loosing the connectivity.

– Benefit to:• Highly dynamic scenarios.• Increase the possible application scenarios.• Support efficient monitoring processes.

– Problem• Technical solutions to allow mobility without losing the connectivity• Duty cycles mechanism very complexes.

– Protocols like MS-MAC[2], MAMAC[3] or MMH-MAC[4] have been trying to provide a reliable MAC layer mobility support.


Wireless Sensor Networks• 6lowPAN [2]

– A middle layer to allow the interoperability between IEEE802.15.4 and IPv6.– Problems:

• IEEE802.15.4 the maximum data field length is 102bytes.• IPv6 Header is 40 bytes.

– Solution:• 6lowPAN compressed the IPv6 header to a maximum of 2 bytes.

– Implementation:• Developed by Matus Harvan [10] (Integrated with TinyOS-2.x).

– Support of ICMPv6 and UDP.– IPv6 Address with stateless configuration.– Doesn’t support the major features of IPv6, like:

» Neighbour discovery.» MobileIP.

– Neither the capability of Mesh topologies• Developed by Berkeley[11] (new contribution):

– Support of ICMPv6 and UDP.– Supports Mesh topologies.– Too heavy for some motes (for instance: micaz).

• μIPv6 for Contiki developed by Cisco, Atmel and SICS[12]- Released last week.


Wireless Sensor Networks• Hardware:

– Micaz+ mda100cb + mib520 [5]

• Software:– nesC [6]

• C based programming language.• A suite of components connected through their Interfaces. • Event-command architecture.

– TinyOS [7]• Operating System developed in nesC.• Designed specifically for sensor nodes.• Currently in version 2.0


Node and Service Discovery– Designed over 6lowPAN.– A system that automatically allows the discover of new sensor

nodes and their respective services. – Two different approaches:

• YouCatchMe• ICatchYou


Node and Service Discovery• YouCatchMe

– Based on periodic announcements.• Like an Access Point Broadcasting the essid.

– Without a registered database:• The nodes are detected and requested at specific time

slots


Node and Service Discovery

• ICatchYOU– Each sensor after deployed/arrived at a new WSN starts sending

beacons.– The local Sink Node listens the beacons and performs the registration

of the new node in that WSN.– The registered node gets a Time-to-Live (TTL) from that WSN, and

stops sending beacons.


Node and Service Discovery• ICatchYOU - protocol


Registration process Update process

Node and Service Discovery• YouCatchMe

– Advantages:• Simple architecture.• Intuitive.• The most common solution, working as an Access Point.

– Disadvantages:• The B and L periods must be manually configured.• For WSNs the number of broadcast messages must be reduced, in

order to save energy.• Nodes on edge received broadcast from both Sink Nodes.


Node and Service Discovery• ICatchYOU

– Advantages:• Efficient and reliable.• The Sink node knows all nodes in the network.• There is an update database.• No remove method is necessary.• Use of the TTL.

– Disadvantages:• It is difficult to achieve the right TTL value for the right application.


Saturday, April 22, 2023 15

Properties of micaz batteries consumption

• Vbat = (Vref x ADC_FS)/ADC_Count [21]– Vbat means Battery Voltage, Vref means Internal Voltage reference

and is equal to 1233mV, ADC_FS is equal to 1024, and ADC_count is equal to measured value.

Fig.8 . Micaz battery consumption properties[13]

15©Ricardo Silva - ISWCS 2008© Ricardo Silva - I2TS 2008

DSD practical performance.– ICatchYou TTL impact in energy consumption


N&SD practical performance• Comparing with other solutions.


Protocol Version Initial (mV) Final (mV) Difference (mV)

6lowPAN w/o discov. 2545,38 2535,07 10,31

TTL=30 2435,07 2404,65 30,42

TTL=60 2404,65 2384,77 19,88

TTL=90 2384,77 2370,07 14,07

XMesh 2678,45 2659,43 19,02

802.15.4 2582,11 2571,51 10,06

Multi-Sink Node• Why?

– The main multi-hop protocols were designed for ad-hoc networks with conventional and more powerful devices.

– The synchronization between neighbors and all information maintenance, necessary to implement multi-hop, is extremely complex, heavy and energetically expensive.

– The future trend is the total coverage, accomplishing with the 4G concept.

– It is lighter a handover system than a multi-hop solution. Possible solution:

• ICatchYou without Update Method,• Use the RSSI value to select the best sink node.


Multi-Sink Node• ICatchYou without Update method

– Each time the TTL value expires, the node starts to require a new registration.– As defined by ICatchYou, each node broadcasts a REG message until receive a

WAIT command.


Multi-Sink Node• ICatchYou integrated with a RSSI value checker.

– The node checks the RSSI value for each received message.– There is a Critical point and a Rupture point for the RSSI value.

• Between both, the node should search for a new Sink Node.

Lab Environment Open Space


c = Vx Ei

Multicast Support over 6lowPAN• Wireless communication:

– Shared environment. All nodes of the same network, check the destination address of any packet, in one of the follow layers:

• Physical Layer;• MAC Layer (IEEE802.15.4);• IP Layer (6lowPAN implementation);


Why Multicast, if everyone says that broadcast should be avoided in WSNs?

Multicast Vs Unicast


Medicalcare.com– Controls in real time the patients vital signs. – Provides an user-interface for remote access.– Based on ICatchYou, supporting the Multi-Sink Node architecture and

multicast communication.– Introduces a new concept of

Multicast over WSNs.


Medicalcare.com• Central Server


Real Implementations• MedicalCare.com – Website


Future Work• Optimize the ICatchYou architecture:

– Improve mobility:• Re-enforce the threshold given by RSSI.• Develop a micro MIPv6 for WSNs.

– Identify the main security constrains• Protect the ICatchYou integrity.

– Apply our architecture in benefit of the society.• Medical, educational, environmental,…


References[1] IEEE Std. 802.15.4 – 2006 “IEEE Standard forInformation technology-Telecommunications and information exchange between

systems- Local and metropolitan area networks- Specific requirements - Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Low Rate Wireless Personal Area Networks (WPAN)”.

[2] H.Pham, S. Jha, “Addressing Mobility in Wireless Sensor Media Access Protocol,” IEEE International Conference on Mobile Ad-hoc and Sensor Systems, 2004

[3] L. Bing, Y. Ke, Z. Lin and Z. Huimin, “Mac Performance and Improvement in Mobile Wireless Sensor Networks,” Eighth ACIS International Conference on Software Engineering, Artificial Intelligence, Networking, and Parallel/Distributed Computing, 2007

[4] H. Água et all, “A MAC protocol for Mobile Wireless Sensor Networks with Bursty Traffic Monitoring Application,”RTCM, Jun., 2008

[5] http://www.xbow.com/Home/HomePage.aspx [6] http://nescc.sourceforge.net/ [7] http://www.tinyos.net/ [8] http://www.ietf.org/html.charters/6lowpan-charter.html[9] R. Hinden, Nokia, S. Deering and Cisco Systems, “IP Version 6 Addressing Architecture,” IETF, RFC4291, Feb. 2006 [10] M. Harvan, “Connecting Wireless Sensor Networks to the Internet – a 6lowPAN implementation for TinyOS-2.0,” May 2007 [11] (2008) b6lowPAN website. [Online]. Available: http://smote.cs.berkeley.edu:8000/tracenv/wiki/b6loWPAN . [12] (2008) Contiki website [Online] Available: http://www.sics.se/contiki/current-events/uipv6-contiki-is-ipv6-ready.html [13] M. Kramer and A. Gerldy, “Energy measurements for micaz node,” presented at the ” Fachgespr¨ach, Dahtlose Sensornetze,

GI/ITG KuVS, 2006.



“Wireless Sensor Networks”Service Discovery and Mobility

Ricardo Nuno Mendão da Silva

University of CoimbraDepartment of Informatics Engineering

[email protected]

Wireless Sensor Networks Service discovery and Mobility Ricardo Silva, Jorge Sá Silva, Cláudio Geyer, Luciano da Silva and Fernando Boavida...

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