Post on 09-Jan-2016
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Communication Between Peer Wireless Sensor Networks over 2.5G/3G Mobile Networks
Srdjan Krco
R&D
Ericsson Ireland
srdjan.krco@ericsson.com
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About Ericsson Ireland
• 3G research and development;• Training center;• Applied Research Lab
– Network management;– Wireless sensor networks;– Ad-hoc networks;– Distributed systems;
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Acknowledgments
• Skylark project team• David Cleary• Daryl Parker
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Presentation outline
• Introduction;• Wireless sensor networks gateway architecture; • P2P sensor networks;• Conclusion;
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Introduction – Ericsson Interests
• Ericsson fields of interest:– Mobile infrastructure;– Mobile services – design and development of new services that
will increase number of mobile network subscribers;
• Sensor networks in mobile networks context;• Potential source of new traffic and hence revenue;• Issues:
– How to connect sensor networks to mobile networks;– How to enable easy access to sensor networks and information
they provide;– Impact of numerous sensors connected to a mobile network;
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Introduction – Wireless Sensor Networks
• Number of small nodes with sensing, computing and wireless communication capability;
• Data gathered in one node; • Hop-by-hop communication; • Redundant number of nodes;• Data fusion;• Querying and tasking;
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Introduction – Wireless Sensor Networks
• Gateway node – injects queries and tasks;– gathers responses;
• User-gateway communication– using short-range wireless technology or – wide area networks (fixed and mobile);
• Sensor networks deployed, maintained, operated and used by one organization;
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Introduction – Wireless Sensor Networks
Mobile Network(GPRS/UMTS)
PDA
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Introduction – Resarch Focus
• Popular research topics:– Routing; – MAC layer issues;– Data aggregation;– Security;– Middleware;
• Less popular:– Interaction with external networks;– Interaction between wireless sensors networks;
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Introduction – Standard Assumptions
• Users have applications designed for a particular sensor network;
• Available services known in advance (temperature monitoring, military vehicles tracking);
• Means for establishing communication links with gateways (protocol, gateway address, etc.) known in advance;
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Focus of Our Research
• Design and development of software and protocol architecture of a wireless sensor network gateway– Generic, supports various sensor types and data format;– Independent of underlying transmission technologies;
• Creation of a peer-to-peer sensor network over a 2.5/3G mobile network, where each sensor network represents one peer node– Peers able to exchange data and provide more complex services;– Users also peers or have access to services provided by any peer
via communication with one peer node only;
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Our Testbed
GPRS
MemoryBT
Controller
MemoryBT
Controller
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Smart Sensor
• Micro controller– Controls Bluetooth link;– Implements communication protocol for interaction with gateway; – Controls attached sensors;
• Memory– Stores sensor data temporarily;
• Sensors– One or more attached;– Described by attributes;
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WSN Gateway Implementation
• Linux OS laptop;• Java;• Bluetooth PCMCIA card;• GPRS PCMCIA card or infrared connection to a GPRS
enabled mobile phone;
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WSN Gateway
• Entry point into a sensor network;• Short-range wireless communication
– With sensors;– With users in the vicinity;
• Wide area network access– Remote users;– Other gateways;
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WSN Gateway
• Hides internal organization of the sensor network; • Aware of all sensor types in the network and their
characteristics– Sensor attributes (sensor type, location, data format, accuracy
etc.) described and transferred as XML string;– Sensor querying based on sensor attributes (XML based);– Describes supported functions (max, min, average);
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WSN Gateway Functionality
• Discovers smart sensors;• Gathers description of available sensors;• Controls communication with and functionality of sensors;• Creates an object for each available sensor
– Has methods for communication with the sensor;– Keeps an up to date description of the sensor;
• Provides API for access and control of the sensor network;
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WSN Gateway – Architecture
SN Comm InterfaceBluetooth
Sensor Network API
Network InterfaceGPRS
Abstraction LayerJXTA middleware
JXTA API
Cor
e Ser
vice
s
Applications
Sensor Network
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Core Services
• Common procedures and services required by all layers– Logging;– Scheduling;– Event subscription;– Services required for automatic application start and restart;
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Sensor Network Communication Interface
• Transmission technology specific;• Provides methods for data transfer to/from sensors over
the chosen communication interface;• Provides additional, interface specific methods (Inquiry,
Service Discovery);
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Sensor Network Abstraction Layer
• Each sensor in the network represented as one object:– Methods for sending and receiving data to/from sensors;– Stores the complete description of sensor’s capabilities;
• Data transmission specifics hidden from users;• Uses XML based communication protocol
– Discover sensors’ characteristics;– Transfer data and commands;– Change sensor settings;
• Applications access objects using SN interface;• Collected replies are formatted into a structured XML
document and forwarded to users;
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Sensor Network Abstraction Layer – GetData
<?xml version="1.0" encoding="UTF-8"?><getData>
<sensor> <sensorID>
2 </sensorID> <transmitMode>
<attribute name=”periodical”> <attribute name=”period”>
5 </attribute> <attribute name=”unit”>
min </attribute></attribute>
</transmitMode></sensor>
</getData>
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<sensorProfile><attributeProfile>
<attribute name="location"><attribute name="town">
Dublin</attribute><attribute name="building">
<attribute name="name">Woodpark
</attribute></attribute><attribute name=“floor">
3</attribute><attribute name="room">
<attribute name="name">Conference room
</attribute><attribute name="number">
12394</attribute>
</attribute></attribute>
</attributeProfile>
Sensor Profile
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<dataProfile><dataAttribute>
<name>temperature
</name><unit>
Celsius</unit><sampleLength>
4</sampleLength>
</dataAttribute></dataProfile></sensorProfile>
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Sensor Network API
• Generic methods, provide consistent interface regardless of sensor type and characteristics;
• List of sensors in the network;• Description of available sensors (sensor attributes);• XML querying based on description of required data;• Listeners:
– Sensor has been added/removed from the network;– New data available;
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Sensor Network API – Query
• Users define data they are interested in (for example: temperature on the first floor in the HQ building) instead of defining the network address of a particular sensor;
• Query definition similar to the sensor attribute profile;• Constraints given in the query compared against
characteristics (attributes) of available sensors and returns a list of sensor IDs that correspond to the query;
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Sensor Network API – Query<?xml version="1.0" encoding="UTF-8"?><querySensors>
<constraint attrName="location"><constraint attrName="building">
<constraint attrName="name"><equals>
HQ House</equals>
</constraint></constraint><constraint attrName="level">
<moreThan>1
</moreThan><lessThan>
4</lessThan>
</constraint></constraint>
</querySensors>
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P2P Sensor Networks
• Sensor networks – Deployed on ad-hoc basis by various entities;– Appear and disappear based on the operator needs, requirements
and schedule;
• Short-range (Bluetooth) and wide-range (UMTS) wireless interface for communication with users;
• Users interact with networks in an ad-hoc manner based on theirs needs at a given moment and location;
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P2P Sensor Networks
Mobile Network(GPRS/UMTS)
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P2P Sensor Networks
• Users are external to the network– do not know about the existence of the network or services they
provide;– Sensor network’s characteristics, type or format of data unknown;
• Sensor network detection, service discovery and service provision mechanisms required;
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P2P Sensor Networks
• Numerous services– Traffic congestion info;– Water pollution of a river;– Weather info;– Personal health care network;– Free spaces in a car park;
• Not feasible to have a central service listing server;
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P2P Sensor Networks
• Individual sensor networks – Cooperate;– Form groups;– Provide more comprehensive service;– Available to more users;
• Users – Communicate with one sensor network gateway;– Able to get information about/from all other sensor networks in the
group;
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P2P Sensor Networks
• Possible scenarios:– Users access sensor network over a short-range wireless interface
(Bluetooth):• Bluetooth Inquiry;• Access to information from via the gateway;
– Users access sensor network over a mobile network:• Join peer group;• Access to information using P2P protocols;
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P2P Sensor Networks and Users
Mobile Network(GPRS/UMTS)
PDA
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P2P Sensor Networks
• Issues– Detection of other sensor networks;– Information exchange between sensor networks;– Description of sensor network services;– Forwarding users request and sensor network responses to/from
proper sensor network;
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JXTA
• Network programming and computing platform for creating interoperable P2P applications and services;
• Designed for ad-hoc, pervasive, multi-hop P2P networks;• Allows any connected heterogeneous device on the
network (mobile phone, PDA, PC et.) to communicate and collaborate with one another;
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JXTA - Architecture
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JXTA – Core Layer
• Peers: any networked device that implements JXTA;• Peer Groups: collection of peers that have a common set
of interests;• Pipes: the basic communication means – a virtual
unidirectional connection between peers;• Advertisements: Describe all entities (resources), such
as peers, peer groups, pipes, or services;– XML structured documents;
• Network Transport: provides a mechanism to handle the transmission of data over the network;
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JXTA – Protocols
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JXTA – Protocols
• Peer Resolver Protocol – mechanism by which a peer can send a generic query to other peers;
• Peer Discovery Protocol (PDP) – used to discover any published resources represented as advertisements. The PDP is based on the use of rendezvous peers;
• Peer Membership Protocol – mechanism by which peers can organize themselves to form groups. Peer groups are discovered using the PDP;
• Pipe Binding Protocol – used to establish pipe connections between peers;
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JXTA - Protocols
• Rendezvous Protocol – propagates messages within the specified group on behalf of peers from within the same group– primary purpose is to provide a service whereby peers can
connect to a rendezvous peer to avail of a service that will propagate messages on their behalf;
• Rendezvous Peers – Special type of peers with the ability to cache advertisements and forward requests to help peers discover resources;– Interact with different rendezvous peers;
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JXTA Services
• Discovery Service– Provides access to the PDP;– Limited to the context of the peer group;– Searches for JXTA resources;
• Pipe Service – Manages and creates virtual channels of communication between
peers in a peer group– Limited to the context of the peer group;
• Resolver Service– Implements the resolver service to distribute queries among peers;
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Platform Specific Services
• Position Service– Provides peer-positioning services by querying the MPS (Mobile
Positioning Service) for a given MSISDN embedded within a PeerID;• Scheduler service
– Allows tasks to be remotely scheduled on peers within our network (scheduled code updates, scheduled migration of services between peers);
• Sensor Service– JXTA wrapper service around the WSN Gateway functionality;
– Communication between peer sensor networks over GPRS network;
– Provides remote querying of sensor networks and individual sensors as well as providing sensor event subscription mechanisms;
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Example
• Gateway gathers sensor profiles, compiles a list of available services/sensors characteristics (type, location, accuracy, …) and structure it as its advertisement;
• Rendevouz peer has information about all available sensor services in the peer group;
• User interacts with a gateway over a short-range interface or becomes a mobile peer;
• Gets information about all services in the peer group from the local gateway or a rendevouz peer;
• Query network based on description of available services;
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Conclusion
• Gateway architecture:– Supports various types of sensors;– Easily adaptable to different communication technologies;– XML structured sensor profiles and communication protocol;– WSN API supports attribute based querying;
• JXTA platform can be used as a P2P middleware layer, but: – Poor performance;– Slow, consumes large amount of memory, quite unreliable;
• Prototype scaling-down required;