One document matched: draft-ietf-6lowpan-usecases-09.xml


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<front>
	<title abbrev="6LoWPAN Design and Applications">Design and Application Spaces for 6LoWPANs</title>

	<author initials="E." surname="Kim" fullname="Eunsook Kim">
		<organization>ETRI</organization>
		<address>
			<postal>
				<street>161 Gajeong-dong</street>
				<street>Yuseong-gu</street>
				<city>Daejeon</city>
				<code>305-700</code>
				<country>Korea</country>
			</postal>
			<phone>+82-42-860-6124</phone>
			<email>eunah.ietf@gmail.com</email>
		</address>
	</author>

	<author initials="D." surname="Kaspar" fullname="Dominik Kaspar">
		<organization>Simula Research Laboratory</organization>
		<address>
			<postal>
				<street>Martin Linges v 17</street>
				<city>Snaroya</city>
				<code>1367</code>
				<country>Norway</country>
			</postal>
			<phone>+47-4748-9307</phone>
			<email>dokaspar.ietf@gmail.com</email>
		</address>
	</author>

	<author initials="N.G." surname="Chevrollier" fullname="Nicolas G. Chevrollier">
		<organization>TNO</organization>
		<address>
			<postal>
				<street>Brassersplein 2</street>
				<street>P.O. Box 5050</street>
				<city>Delft</city>
				<code>2600</code>
				<country>The Netherlands</country>
			</postal>
			<phone>+31-15-285-7354</phone>
			<email>nicolas.chevrollier@tno.nl</email>
		</address>
	</author>
	
	 <author initials="JP" surname="Vasseur" fullname="JP Vasseur">
		<organization>Cisco Systems, Inc</organization>
		<address>
			<postal>
				<street> 1414 Massachusetts Avenue </street>
				<street></street>
				<city>Boxborough</city>
				<code>MA 01719</code>
				<country>USA</country>
			</postal>
			<phone></phone>
			<email>jpv@cisco.com</email>
		</address>
	</author>

	<date year="2011" />
	<area>Internet</area>
	<workgroup>6LoWPAN Working Group</workgroup>
	<keyword>Internet-Draft</keyword>

	<abstract>
		<t>
		   This document investigates potential application scenarios and use cases 
		   for low-power wireless personal area networks (LoWPANs).
		   This document provides dimensions of design space for LoWPAN applications.
		   A list of use cases and market domains that may benefit
		   and motivate the work currently done in the 6LoWPAN WG is provided with 
		   the characteristics of each dimension. 
		   A complete list of practical use cases is not the goal of this document.		   
		</t>
	</abstract>
</front>

<middle>

	<section anchor="intro" title="Introduction">
		<t>
		    Low-power and lossy networks (LLNs) is the term commonly used to refer to networks 
		    made of highly constrained nodes (limited CPU, memory, power) interconnected by 
		    a variety of “lossy” links (low-power radio links or powerline communication (PLC)).
		    They are characterized by low speed, low performance, low cost, and unstable connectivity.
		    A LoWPAN is a particular instance of an LLN, formed by devices complying with the
		    IEEE 802.15.4 standard <xref target="refs.ieee802.15.4"/>.
		    Their typical characteristics can be summarized as follows:
		</t>

		<list style="symbols">
		    <t>
				Limited processing capability: the smallest common LoWPAN nodes have 8-bit processors 
				with clock rates around 10 MHz. Other models exist with 16-bit and 32-bit cores
				(typically ARM7), running at frequencies in the order of tens of MHz.
			</t>
			<t>
				Small memory capacity: the smallest common LoWPAN nodes have a few kBytes 
				of RAM with a few dozens of kBytes of ROM/flash memory. While the memory sizes of nodes
                continue to grow (e.g., IMote has 64K SRAM, 512K Flash memory),
				the nature of small memory capacity for LoWPAN nodes remains a challenge.
				<!-- RAM sizes for LoWPAN devices consist of a few kilobytes,
				4K or 8K bytes. However, a wide variety of RAM sizes is available, reaching
				from 1K up to 256K bytes. --> 
			</t>
			<t>
				Low power: wireless radios for LoWPANs are normally battery-operated. Their
				RF transceivers often have a current draw of about 10 to 30 mA, depending on the
				used transmission power level. In order to reach common indoor ranges of up to
				30 meters and outdoor ranges of 100 meters, the used transmission power is set
				around 0 to 3 dBm.
				Depending on the processor type, there is an additional battery current consumption
				of the CPU itself, commonly in the order of tens of milliamperes. However, the CPU power
				consumption can often be reduced by a thousandfold when switching to sleep mode.
			</t>
			<t>
				Short range: the Personal Operating Space (POS) defined by IEEE 802.15.4 implies 
				a range of 10 meters. For real implementations, the range of LoWPAN radios is 
				typically measured in tens of meters, but can reach over 100 meters in
				line-of-sight situations.
			</t>
			<t>
				Low bit rate: the IEEE 802.15.4 standard defines a maximum over-the-air rate of
				250K bit/s, which is most commonly used in current deployments. Alternatively,
				three lower data rates of 20K, 40K and 100K bit/s are defined.
			</t>
		</list>

		<t>
			As any other LLN, a LoWPAN does not necessarily comprise of sensor nodes only, 
			but may also consist of actuators. For instance, in an agricultural	environment, 
			sensor nodes might be used to detect low soil humidity and then send commands to
			activate the sprinkler system.
		</t>
		
		<t>
			After defining common terminology in <xref target="terminology"/> and describing
			the characteristics of LoWPANs in <xref target="designspace"/>, this document
			provides a list of use cases and market domains that may benefit
			and motivate the work currently done in the 6LoWPAN WG.
		</t>


        <!-- TERMINOLOGY -->
    
        <section anchor="terminology" title="Terminology"> 
            <t>
                The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
                "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
                document are to be interpreted as described in <xref target="RFC2119"/>.
            </t>
            <t>
                Readers are expected to be familiar with all the terms and concepts 
                that are discussed in <xref target="RFC4919">"IPv6 over Low-Power 
                Wireless Personal Area Networks (6LoWPANs): Overview, Assumptions, 
                Problem Statement, and Goals"</xref>, and
                <xref target="RFC4944">" Transmission of IPv6 Packets over IEEE 802.15.4 Networks"</xref>.
            </t>
            <t> 
                Readers would benefit from reading 6LoWPAN ND <xref target="I-D.ietf-6lowpan-nd"/>,
                6LoWPAN header compression <xref target="I-D.ietf-6lowpan-hc"/>, and
                6LoWPAN Routing Requirements <xref target="I-D.ietf-6lowpan-routing-requirements"/> for the details
                of the 6LoWPAN work.
            </t>
            <!--t>
                This document makes extensive use of the same terminology
                defined in 6LoWPAN ND <xref target="I-D.ietf-6lowpan-nd"/> unless otherwise redefined below.
            </t-->
        
            <t>
                This document defines the following terms:
				<list style="hanging">
				<!--t hangText="LN (LoWPAN Node)"></t>
					<t>	
						Any host or router participating in a LoWPAN. 
						This term is used when referring to situations in which either 
						a host or router can play the role described.
					</t>
                <t hangText="LR(LoWPAN Router)"></t>
                    <t>
                        An intermediate router in the LoWPAN who can communicate with other LoWPAN routers 
						in the same LoWPAN. LoWPAN routers are present only in Route Over topologies.
                    </t>
				<t hangText="LH (LoWPAN Host)"></t>
					<t>
						A node that only sources or sinks of IPv6 datagrams. 
					</t>
				<t hangText="LM (LoWPAN Mesh Node)"></t>	
					<t>
						A LoWPAN node that forwards data between arbitrary source-destination pairs
						using link-layer addresses and thus only exists in Mesh Under topologies. 
					</t-->
				<t hangText="LC (Local Controller)"></t>
                    <t>
                        A logical functional entity that performs the special role of coordinating and
						controlling its child nodes for local data aggregation, status management of local nodes, etc.
                        There may be multiple instances of local controller nodes in a LoWPAN. 
                    </t>
				<t hangText="LBR (LoWPAN Border Router)"></t>	
					<t>
						A border router is located at the junction of separate LoWPAN 
						networks or between a LoWPAN network and another IP network.
						There may be one or more LBRs at the LoWPAN network boundary. 
						A LBR is the responsible authority for IPv6 Prefix propagation for 
						the LoWPAN network it is serving. An isolated LoWPAN also 
						contains a LBR in the network, which provides the prefix(es) for 
						the isolated network.
					</t>
                </list>
			</t>
		</section>
	    <!-- end of section Terminology -->
	
        <!-- Basic network  -->	
	
		<section anchor="net-conf" title="Premise of network configuration">
		
		<t>
		    The IEEE 802.15.4 standard distinguishes between two types of nodes, reduced-function
		    devices (RFDs) and full-function devices (FFDs). As this distinction is based on some
            MAC features that are not always in use, we are not using this distinction in this document. 
			<!--
			However, some nodes in the network will limit themselves to the role of
			hosts only, while some other nodes will take part in the routing.  
			This host/router distinction can correlate with the processing capabilities 
			of the device and power available in a similar way to the idea of RFDs and FFDs. -->
        </t>
		<t> <!-- Jan 17,2011, Ralph-->
			6LoWPAN networks can be deployed using either route-over or mesh-under architectures.  
			As the choice of route-over or mesh-under does not affect the applicability of 6LoWPAN 
			technologies to the use cases described in the document, we will use the term "6LoWPAN network" 
			to mean either a route-over or mesh-under network.
		</t>
		<!--
  			<list style="hanging">
			<t>
				Note: The two device types have different capabilities, so that the capability requirements 
				of a LN must be considered to choose the type of devices.
				Through their inability to transmit link-layer beacons, 
				RFDs can only communicate with FFDs in a resulting "master/slave" relation, 
				thus can exist only as hosts in LoWPANs. 
				FFDs are able to communicate with peer FFDs and 
				with RFDs in the aforementioned relation. Thus, FFDs can perform as LMs or LRs. 
            </t>	
			</list>        

		<t>
			Example LoWPAN topologies are depicted in <xref target="fig.mlowpan"/> and
			<xref target="fig.rlowpan"/>. A definition of how mesh topologies are obtained and
			maintained is out of scope of this document.
  		</t>

		<figure title="Examples of LoWPAN topologies" anchor="fig.lowpan"> 
			<preamble> </preamble> 
			<artwork>        
A simple star topology                           A mesh topology

     n  n  n                                        n---n   n  n
      \ | /                                         |   |   | /
 LBR--- n ---n     LBR: LoWPAN Border Router    LBR---n---n---n---n
      / | \          n: LoWPAN Node                 / |   |   |   |
     n  n  n                                       n  n   n   n---n
			</artwork>
			<postamble></postamble>
		</figure>
		--!>
		
		<t>
			Communication to corresponding nodes outside of the LoWPAN is becoming increasingly
			important for convenient data collection and remote control purposes. The intermediate
			LoWPAN nodes act as packet forwarders (LM) or LoWPAN routers (LR) and connect the entire LoWPAN
			in a multi-hop fashion. LoWPAN Border Routers (LBRs) are used to interconnect a LoWPAN to other
			networks, or to form an extended LoWPAN by connecting multiple LoWPANs. Before LoWPAN
			nodes obtain their IPv6 addresses and the network is configured, each LoWPAN executes
			a link-layer configuration either by the mechanisms specified in 6lowpan ND
			<xref target="I-D.ietf-6lowpan-nd"/> or by using a coordinator who is responsible for
			link-layer short address allocation. However, the link-layer coordinator functionality
			is out of the scope of this document. Details of address allocation of 6LoWPAN ND is 
			in <xref target="I-D.ietf-6lowpan-nd"/>.
		</t>
		
		<t>
		    A LoWPAN can be configured as Mesh Under or Route Over (see Terminology in
		    <xref target="I-D.ietf-6lowpan-nd"/>). 
			In a Route Over configuration, multihop transmission is carried out by LRs
		    using IP routing. In a Mesh Under configuration,
		    the link-local scope reaches to the boundaries of the LoWPAN, 
			and multihop transmission is 
			achieved by forwarding data at the link layer or in an 6LoWPAN adaptation layer.
			More information about Mesh Under and Route Over is in 6LoWPAN ND <xref target="I-D.ietf-6lowpan-nd"/> and 6LoWPAN Routing
		    Requirements <xref target="I-D.ietf-6lowpan-routing-requirements"/>.
        </t>    
       -->		
      </section>
 
	</section>
	
    <!-- DESIGN SPACE -->	
	
	<section anchor="designspace" title="Design Space">
		<t>
			Inspired by <xref target="refs.roemer"/>, this section lists the dimensions 
			used to describe the design space of wireless sensor networks 
			in the context of the 6LoWPAN Working Group. The design space is already limited
			by the unique characteristics of a LoWPAN (e.g., low-power, short range, low-bit rate) 
			as described in <xref target="RFC4919"/>. The possible dimensions for scenario
			categorization used in this document are described as follows:
		</t>

		<list style="symbols">
			<t>
				Deployment: LoWPAN nodes can be scattered randomly or they may be deployed in 
				an organized manner in a LoWPAN. The deployment can occur at once, or as an
				iterative process. The selected type of deployment has an impact on node density
				and location. This feature affects how to organize (manually or automatically) the
				LoWPAN and how to allocate addresses in the network.
			</t>
			<t>
				Network Size: The network size takes into account nodes that provide the intended
				network capability. The number of nodes involved in a LoWPAN could be small
				(10 nodes), moderate (several 100s), or large (over a 1000).
			</t>
			<t>
				Power Source: The power source of nodes, whether the nodes are battery-powered or
				mains-powered, influences the network design. The power may also be harvested from
				solar cells or other sources of energy. Hybrid solutions are possible where only
				part of the network is mains-powered.
			</t>
			<t>
				Connectivity: Nodes within a LoWPAN are considered "always connected" when there is
				a network connection between any two given nodes. However, due to external factors
				(e.g., extreme environment, mobility) or programmed disconnections
				(e.g., sleeping mode), the network connectivity can be from "intermittent" 
				(i.e., regular disconnections) to "sporadic" (i.e., almost always disconnected network).
				Differences in L2 duty-cycling settings may additionally impact the connectivity due
				to highly varying bit-rates.
			</t>
			<t>
				Multi-hop communication: The multi-hop communication factor highlights the number of
				hops that has to be traversed to reach the edge of the network or a destination node
				within it. A single hop may be sufficient for simple star-topologies, but a multi-hop
				communication scheme is required for more elaborate topologies, such as meshes or
				trees. In previous work by academia and industry on LoWPANs, various routing
				mechanisms were introduced, such as data-centric, event-driven, address-centric,
				localization-based, geographical routing, etc. This document does not make use of
				such a fine granularity but rather uses topologies and single/multi-hop communication.
			</t>
			<t>
				Traffic Pattern: several traffic patterns may be used in LoWPANs. To name a few,
				Point-to-Multi-Point (P2MP), Multi-Point-to-Point (MP2P) and Point-to-Point (P2P).
			</t>
			<t>
				Security Level: LoWPANs may carry sensitive information and require high-level
				security support where the availability, integrity, and confidentiality of the
				information are crucial. This high level of security may be needed in case of
				structural monitoring of key infrastructure or health monitoring of patients.
			</t>
			<t>
				Mobility: Inherent to the wireless characteristics of LoWPANs, nodes could move or
				be moved around. Mobility can be an induced factor (e.g., sensors in an automobile),
				hence not predictable, or a controlled characteristic (e.g., pre-planned movement in
				a supply chain).
			</t>
			<t>
				Quality of Service (QoS): for mission-critical applications, support of QoS is
				mandatory in resource-constrained LoWPANs.
			</t>
		</list>
	</section>


    <!-- APPLICATION SCENARIOS -->	
	
	<section anchor="scenarios" title="Application Scenarios">
		<t>
			This section lists a fundamental set of LoWPAN application scenarios in terms of system
			design. A complete list of practical use cases is not the objective of this document.
		</t>
		
		
	    <!-- INDUSTRIAL MONITORING-->	

		<section title="Industrial Monitoring">
			<t>
				LoWPAN applications for industrial monitoring can be associated with a broad range
				of methods to increase productivity, energy efficiency, and safety of industrial
				operations in engineering facilities and manufacturing plants. Many companies
				currently use time-consuming and expensive manual monitoring to predict failures and
				to schedule maintenance or replacements in order to avoid costly manufacturing
				downtime. LoWPANs can be inexpensively installed to provide more frequent and more
				reliable data. The deployment of LoWPANs can reduce equipment downtime and eliminate 
				manual equipment monitoring that is costly to be carried out. Additionally, data
				analysis functionality can be placed into the network, eliminating the need for
				manual data transfer and analysis.
			</t>
			<t>
				Industrial monitoring can be largely split into the following application fields:
				<list style="symbols">
				<t>
					Process Monitoring and Control: combining advanced energy metering and
					sub-metering technologies with wireless sensor networking in order to optimize
					factory operations, reduce peak demand, ultimately lower costs for energy, avoid
					machine downtimes, and increase operation safety. 
					<vspace blankLines='1' />	
					A plant's monitoring boundary often does not cover the entire facility but only
					those areas considered critical to the process. Easy to install wireless
					connectivity extends this line to include peripheral areas and process
					measurements that were previously infeasible or impractical to reach with wired
					connections.
				</t>
				<t>
					Machine Surveillance: ensuring product quality and efficient and safe equipment
					operation. Critical equipment parameters such as vibration, temperature, and
					electrical signature are analyzed for abnormalities that are suggestive of
					impending equipment failure (see <xref target="scenario1"/>).
				</t>
				<t>
					Supply Chain Management and Asset Tracking: with the retail industry being
					legally responsible for the quality of sold goods, early detection of inadequate
					storage conditions with respect to temperature will reduce risk and cost to
					remove products from the sales channel. Examples include container shipping,
					product identification, cargo monitoring, distribution and logistics.
				</t>
				<t>
					Storage Monitoring: sensor systems designed to prevent releases of regulated
					substances to ground water, surface water and soil. This application field may
					also include theft/tampering prevention systems for storage facilities or other
					infrastructure, such as pipelines.
				</t>
				</list>
			</t>

        	<!-- (industrial monitoring) -->
        	
			<section title="A Use Case and its Requirements">
				<t>
					Example: Hospital Storage Rooms
				</t>
				<t>
					In a hospital, maintenance of the right temperature in storage rooms is very
					critical. Red blood cells need to be stored at 2 to 6 degrees Celsius, blood
					platelets at 20 to 24 C, and blood plasma below -18 C. For anti-cancer medicine,
					maintaining a humidity of 45% to 55% is required. Storage rooms have temperature
					sensors and humidity sensors every 25m to 100m, based on the floor plan and the
					location of shelves, as indoor obstacles distort the radio signals. At each
					blood pack a sensor tag can be installed to track the temperature during
					delivery. A LoWPAN node is installed in each container of a set of blood packs. 
					In this case, highly dense networks must be managed.
				</t>
				<t>
					All nodes are statically deployed and manually configured with either a single-
					or multi-hop connection. Different types of LoWPAN nodes are configured based on
					the service and network requirements. Especially, LCs play a role in aggregation 
					of the sensed data from blood packs. 
					In the extended networks, more than one LoWPAN LCs can be installed in a storage room.
					In the case that the sensed data from an individual node 
					is urgent event-driven data such as outrange of temparature or humidity, 
					it will not be accumulated (and further delayed) by the LCs but immediately relayed.
				</t>
				<t>
					All LoWPAN nodes do not move unless the blood packs or a container of blood
					packs is moved. Moving nodes get connected by logical attachment to a new LoWPAN. 
					When containers of blood packs are transferred to another place of the hospital
					or by ambulance, the LoWPAN nodes on the containers associate to a new LoWPAN.
				</t>
				<t>
					This type of application works based on both periodic and event-driven
					notifications. Periodic data is used for monitoring the temperature and humidity
					in the storage rooms. The data over or under a pre-defined threshold is
					meaningful to report. Blood cannot be used if it is exposed to the wrong
					environment for about 30 minutes. Thus, event-driven data sensed on abnormal
					occurrences is time-critical and requires secure and reliable transmission. 
				</t>
				<t>
				    LoWPANs must be provided with low installation and management costs, and for the
				    transportation of blood containers, precise location tracking of containers is
				    important. The hospital network manager or staff can be provided with an early
				    warning of possible chain ruptures, for example by conveniently accessing
				    comprehensive online reports and data management systems. 
				</t>
				<t>
					Dominant parameters in industrial monitoring scenarios:
					<list style='symbols'>
						<t>Deployment: pre-planned, manually attached</t>
						<t>Mobility: no (except for asset tracking)</t>
						<t>Network Size: medium to large size, high node density</t>
						<t>Power Source: most of the time battery-operated</t>
						<t>Security Level: business-critical. Secure and reliable transmission must
						   be guaranteed.</t>
						<t>Multi-hop communication: multi-hop networking</t>
						<t>Connectivity: always on for crucial processes</t>
						<t>QoS: important for time-critical event-driven data</t>
						<t>Traffic Pattern: P2P (actuator control), MP2P (data collection)</t>
						<t>Other Issues: Sensor network management, location tracking, real-time early warning</t>
					</list>
				</t>
			</section>
		
		<!-- 6LOWPAN APPLICABILITY -->
		
			<section title="6LoWPAN Applicability">
				<t>
					The network configuration of the above use case can differ substantially by
					system design. As illustrated in <xref target="fig.storage"/>, the simplest way
					is to build a star topology inside of each storage room.  
					Based on the layout and size of the storage room, the LoWPAN can be configured 
					in a different way of mesh topology as shown in <xref target="fig.Ext-storage"/>. 
				</t>
				<t>
					Each LoWPAN node may reach the LBR by a predefined routing/forwarding mechanism. 
					Each LoWPAN node configures its link-local address and obtains a prefix from its
					LBR by an 6LoWPAN ND procedure <xref target="I-D.ietf-6lowpan-nd"/>. 
					LoWPAN nodes need to build a multi-hop connection to reach the LCs and LBR. <!-- by either mesh-under or route-over. [DK]-->
				</t>
				<t>
					 <!--In Route Over topologies, IP forwarding is used,
					while link-layer addresses in the mesh-header defined by RFC 4944 <xref target="RFC4944"/> 
					are used for transmission in Mesh Under topologies .-->
				</t>
				<t>
					<!--In Mesh Under, more than one LMs are selected for multi-hop transmission. 
					The nodes MAY also play role in handling multi-point traffic (multicast) by duplicate unicasting to the connected nodes.
					In Route Over, LRs
					will handle multicast traffic to their LoWPAN links.-->
				</t>
				<t>
					The data volume is usually not so large in this case, but is sensitive to delay. 
					Data aggregators can be installed for each storage room, or just one data aggregator
					can collect all data. To make a light transmission, UDP is likely to be chosen, 
					but secure transmission and security mechanism MUST be added. 
					To increase security, link-layer mechanisms and/or additional security
					mechanisms SHOULD be used.
				</t>
				<t>
					Because a failure of a LoWPAN node can critically affect the storage of the blood
					packs, network management is important in this use-case. A light weight management 
					mechanism MUST be provided for the management.
				</t>
				<t>
					When a container is moved out from the storage room, and connected to the other hospital
					system (if the hospital buildings are fully or partly covered with LoWPANs), 
					a mechanism to rebind to a new parent node and a new LoWPAN MUST be supported.  
					In the case that it is moved by an ambulance, it will be connected to an LBR
					in the vehicle. This type of mobility is supported by 6LoWPAN ND and routing mechanism. 
				</t>
				<t>				
					LoWPANs MUST be provided with low installation and management
					costs, providing benefits such as reduced inventory, and precise location tracking
					of containers, and mobile equipment (moving beds at the hospital or ambulances).
				</t>

				<figure title="Storage rooms with a simple star topology" anchor="fig.storage">
					<preamble></preamble>
					<artwork><![CDATA[
                     LBR 
                      |                     LBR: LoWPAN Border Router  
          LC----------LC----------LC        LC: Local Controller node
         / | \       / | \       / | \          (Data Aggregator)
        n  n  n     n  n  n     n  n  n      n: LoWPAN node 
				]]></artwork>
					<postamble></postamble>
				</figure>

				<figure title="Storage rooms with a mesh topology" anchor="fig.Ext-storage">
					<preamble></preamble>
					<artwork><![CDATA[
                        
          +------------+-----------+         
          |            |           |         LBR: LoWPAN Border Router 
         LBR          LBR         LBR(LC)     LC: Local Controller node
          |            |           |             (Data Aggregator)
         LC - n       LC - n      n            n: LoWPAN Node        
       /  |   |        |   |     / \        
      n   n - LC   n - n - n    n - n
      |       | \          |    |\           			
      n       n  n - n     n    n n         
				]]></artwork>
					<postamble></postamble>
				</figure>
			</section>	
		</section>
	
	
    	<!-- STRUCTURAL MONITORING -->	
		
		<section anchor="scenario1" title="Structural Monitoring">
		
			<t>
				Intelligent monitoring in facility management can make safety checks and periodic
				monitoring of the architecture status highly efficient. Mains-powered nodes can be
				included in the design phase of a construction or battery-equipped nodes can be
				added afterwards. All nodes are static and manually deployed. Some data is not
				critical for security protection (such as normal room temperature), but event-driven
				emergency data (such as a fire alarm) MUST be handled in a very critical manner.
			</t>
	
			<section title="A Use Case and its Requirements">
				<t>
					Example: Bridge Safety Monitoring
				</t>
				<t>
					A 1000m long concrete bridge with 10 pillars is described. Each pillar and the
					bridge body contain 5 sensors to measure the water level, and 5 vibration sensors
					are used to monitor its structural health. The LoWPAN nodes are deployed to have
					100m line-of-sight distance from each other. All nodes are placed statically and
					manually configured with a single-hop connection to the local coordinator. All
					LoWPAN nodes are immobile while the service is provided. Except from the pillars,
					there are no special obstacles of attenuation to the node signals, but careful
					configuration is needed to prevent signal interference between LoWPAN nodes.
				</t>
				<t>
					The physical network topology is changed in case of node failure. On the
					top part of each pillar, an sink node is placed to collect the sensed data.
					The sink nodes of each pillar become data gathering point of the LoWPAN hosts
					at the pillar as local coordinators.
				</t>
				<t>
					This use case can be extended to medium or large size sensor networks to monitor
					a building or for instance the safety status of highways and tunnels. Larger
					networks of the same kind still have similar characteristics such as static
					node placement, manual deployment and dependent on the blue print of
					the structure, mesh topologies will be built with mains-powered relay points.
					Periodic and event-driven real-time data gathering is performed and the
					emergency event-driven data MUST be delivered without delay.
				</t>
				<t>
					Dominant parameters in structural monitoring applications:
					<list style='symbols'>
						<t>Deployment: static, organized, pre-planned</t>
						<t>Mobility: none</t>
						<t>Network Size: small (dozens of nodes) to large </t>
						<t>Power Source: mains-powered nodes are mixed with battery powered 
							(mains-power nodes will be used for local coordination or relays).</t>
						<t>Security Level: safety-critical. Secure transmission must be guaranteed. 
							Only authenticated users must be able to access and handle the data.</t>
						<t>Multi-hop communication: multi-hop mesh networking is recommended to be supported.</t>
						<t>Connectivity: always connected or intermittent by sleeping mode scheduling.</t>
						<t>QoS: Emergency notification (fire, over-threshold vibrations, water level, etc.)
							is required to have priority of delivery and must be transmitted in a
							highly reliable manner.</t>
						<t>Traffic Pattern: MP2P (data collection), P2P (localized querying)</t>
						<t>Other Issues: accurate sensing and reliable transmission are important.
							In addition, sensor status reports should be maintained in a reliable
							monitoring system.</t>
					</list>
				</t>
			</section>
			
		    <!-- (structural monitoring applicability) -->	
		    
			<section title="6LoWPAN Applicability">
				<t>
					The network configuration of this use case can be done by simple topologies, 
					however, there are many extended use cases for more complex structures. 
					The example bridge monitoring case may be the simplest case
					(an example topology is illustrated in <xref target="fig.bridge"/>). 					
				</t> 
				<t>
					The LoWPAN Nodes are installed on the place after manual optimization of their location.
					As the communication of the leaf LoWPAN nodes may be limited to the data gathering points, 
					both 16-bit and 64-bit can be used for IPv6 link-local addresses <xref target="RFC4944"/>.
					<!--Static data paths to data gathering points can be set in the commissioning phase. 
					Address configuration and LoWPAN formation are achieved by 6LoWPAN HC <xref target="I-D.ietf-6lowpan-hc"/> 
					and 6LoWPAN ND <xref target="I-D.ietf-6lowpan-nd"/>. 
					Each pillar network may be built as a stub network, 
					so that 16-bit addresses can be utilized (see Section 3 in <xref target="I-D.ietf-6lowpan-hc"/>).
					Globally routable addresses must be allocated to communicate with other LoWPAN nodes.
				</t>
				<!--t>
					If the network does not use a Route Over mechanism, the 6LoWPAN mesh-header
					described in RFC 4944 <xref target="RFC4944"/> may be used for static data forwarding,
					unless other mesh under mechanisms are provided. 
				</t>
				<t-->
					Each pillar may have one LC for data collection from each pillar.
					<!--The logical entity for data gathering can be implemented as a separate node or in a LR or LM.--> 
					Communication schedules should be set up between leaf nodes and their LC to efficiently gather
					the different types of sensed data. Each data packet may include meta-information
					about its data, or the type of sensors could be encoded in its address during
					the address allocation. 
				</t>
				<t>	
					This type of application works based on both periodic and
					event-driven notifications. The data over or under a pre-defined threshold is
					meaningful to report. Event-driven data sensed on abnormal occurrences is
					time-critical and requires secure and reliable transmission. For energy
					conservation, all nodes may have periodic and long sleep modes but wake up on
					certain events. The data gathering entity can be programmed to trigger
					actuators installed in the infrastructure, when a certain threshold value has
					been reached. 
				</t>
				<t>
					Due to the safety-critical data of the structure, authentication and security
					are important issues here. Only authenticated users MUST be allowed to
					access the data. Additional security SHOULD be provided at the LBR 
					for restricting the access from outside of the LoWPAN. The LBR may take
					charge of authentication of LoWPAN nodes. Reliable and secure data transmission
					must be guaranteed. 
				</t>		

				<figure title="A bridge monitoring scenario" anchor="fig.bridge">
					<preamble></preamble>
					<artwork><![CDATA[
LBR - LC ----- LC ------ LC           LBR: LoWPAN Border Router
      /|        |        |            LC: Local Controller node
     n n    n - n - n    n - n        n: LoWPAN Node
       /\       |   |    |   |        
      n  n      n - n    n - n - n   
				]]>
				    </artwork> 
					<postamble></postamble>
				</figure>
			</section>
		</section>
	
	
    	<!-- CONNECTED HOME -->	
    	
		<section title="Connected Home">
			<t>
				The "Connected" Home or "Smart" home is with no doubt an area where LoWPANs
				can be used to support an increasing number of services:
			</t>
			<t>
				<list style='symbols'>
					<t>Home safety/security</t>
					<t>Home Automation and Control</t>
					<t>Healthcare (see above section)</t>
					<t>Smart appliances and home entertainment systems</t>
				</list>
			</t>
			<t>
				In home environments LoWPAN networks typically comprise a few dozen and probably in
				the near future a few hundreds of nodes of various nature: sensors, actuators and
				connected objects.
			</t>
	
			<section title="A Use Case and its Requirements">
				<t>
					Example: Home Automation
				</t>
				<t>
					The home automation and control system LoWPAN offers a wide range of services: local
					or remote access from the Internet (via a secured edge router) to monitor the home (temperature,
					humidity, activation of remote video surveillance, status of the doors (locked or open), etc.) but also for
					home control (activate the air conditioning/heating, door locks, sprinkler systems, etc.). Fairly
					sophisticated systems can also optimize the level of energy consumption thanks to a wide range
					of input from various sensors connected to the LoWPAN: light sensors, presence detection,
					temperature, etc. in order to control electric window shades, chillers, air flow control, air conditioning
					and heating with the objective to optimize energy consumption.
				</t>
				<t>
					With the emergence of “Smart Grid” applications, the LoWPAN	
					may also have direct interactions with the Grid itself via the Internet
					to report the amount of KWatts that could be load shed (Home to Grid) 
					and to receive dynamic load shedding information if/when required (Grid to 
					home): this application is also referred to as Demand-Response application. 
					Another service known as Demand Side Management (DSM) could be provided 
					by utilities to monitor and report to the user its energy consumption with a 
					fine granularity (on a per device basis). Other inputs such as dynamic pricing 
					can also be received by the user from the utility that can then turn on and off 
					some appliances according to its local policy in order to reduce its energy bill.
				</t>
				<t>
				    In terms of home safety and security, the LoWPAN is made of motion- 
				    and audio-sensors, sensors at doors and windows, and video cameras to 
				    which additional sensors can be added for safety (gas, water, CO, 
				    Radon, smoke detection).  The LoWPAN typically comprises a few dozen 
				    nodes forming an ad-hoc network with multi-hop routing since the 
				    nodes may not be in direct range.  It is worth mentioning that the number of 
				    devices tends to grow considering the number of new applications for the home. 
				    In its most simple form, all nodes are static and communicate with 
				    a central control module but more sophisticated scenarios may also 
				    involve inter-device communication. For example, a motion/presence sensor 
				    may send a multicast message to a group of lights to be switched on, 
				    or a video camera will be activated sending a video stream to a gateway 
				    that can be received on a cell phone.
				</t>
				<t>
					Ergonomics in Connected Homes is a key and the LoWPAN must be self-managed and easy to install.
					Traffic patterns may greatly vary depending on the applicability and so does the level of reliability
					and QoS expected from the LoWPAN. Humidity sensing is typically not critical and requires no immediate
					action whereas tele-assistance or gas leak detection is critical and requires a high degree of reliability.
					Furthermore, although some actions may not involve critical data, still the response time and network
					delays must be on the order of a few hundreds of milliseconds to preserve the user experience (e.g. use
					a remote control to switch a light on). A minority of nodes are mobile (with slow motion). 
					With the emergence of energy related applications it becomes crucial to preserve 
					data confidentiality. Connected Home LoWPAN usually do not require multi-topology 
					or QoS routing and fairly simple QoS mechanisms must be
					supported by the LoWPAN (the number of Class of Services is usually limited).
				</t>
				<t>
					Dominant parameters for home automation applications:
					<list style='symbols'>
						<t>Deployment: multi-hop topologies</t>
						<t>Mobility: some degree of mobility</t>
						<t>Network Size: medium number of nodes, potentially high density</t>
						<t>Power Source: mix of battery and mains-powered devices</t>
						<t>Security Level: authentication and encryption required</t>
						<t>Multi-hop communication: no requirement for multi-topology or QoS routing</t>
						<t>Connectivity: intermittent (usage-dependent sleep modes)</t>
						<t>QoS: support of limited QoS (small number of Class of Service)</t>
						<t>Traffic Pattern: P2P (inter-device), P2MP and MP2P (polling)</t>
					</list>
				</t>
			</section>
			
		    <!-- (home automation)-->		
			
			<section title="6LoWPAN Applicability">
				<t>
					In the home automation use case, the network topology is made of a mix of 
					a battery operated and mains-powered nodes that both communication with 
					each other and a LBR provides connectivity to the outside of world for control management 
					(<xref target="fig.home"/>). 			
				</t>
				<t>
					In home network, installation and management must as extremely simple for the user. 
					Link local IPv6 addresses can be used by nodes with no external communication 
					and the LBR allocates routable addresses to communicate with other LoWPAN nodes 
					not reachable over a single radio transmission.
				</t>
				<figure title="Home Automation scenario" anchor="fig.home">
					<preamble></preamble>
					<artwork><![CDATA[				
				
                           n --- n              I: Internet
                           |     |             LBR: LoWPAN Border Router
Internet/ ------- LBR/LC -- n --- n ---- LC     LC: Local controller node
Utility network     |      |            /|\     n: LoWPAN Node
                    n ---- n           n n n    

   (outside)       (home automation system) ]]></artwork>
					<postamble></postamble>
				</figure>
				<t>
					In some scenarios, the traffic will be sent to a LC for processing that 
					may in turn decide of local actions (switch a light on, …). In other scenarios, 
					all devices will send their data to the LCs that may also act as the LBR 
					for data processing and potential relay of data to outside of the LoWPAN. 
					It does not mean that every device gets through the LC and LBR for communicating each other. 
					For the sake of illustration, some of the data may be processed to trigger 
					local action (e.g. switch off an appliance), simply store and sent once 
					enough data has been accumulated (e.g. energy consumption for the past 6 hours 
					for a set of appliances) or could trigger an alarm immediately sent to 
					a datacenter (e.g. gas leak detection).
				</t>
				<t> 
				    Although in the majority of cases nodes within the LoWPAN will be in direct range, 
				    some nodes will reach the LBR/LC  with a 2-3 hops path <!--using Mesh Under 
				    or very likely a Route Over solution -->(with the emergence of several 
				    low power media such as low power PLC) in which case LoWPAN routers will be deployed 
				    in the home to interconnect the various IPv6 links.
				</t>
				<t> 
					The home LoWPAN must be able to provide extremely reliable communication 
					in support of some specific application (e.g. fire, gas leak detection, 
					health monitoring) whereas other application may not be critical at all (e.g humidity monitoring).
					Similarly some information may require the use of security mechanisms 
					for authentication, confidentiality.
				</t>
			</section>

		</section>

	    <!-- HEALTHCARE-->	
	
		<section title="Healthcare">
		
			<t>
				LoWPANs are envisioned to be heavily used in healthcare environments. They have a
				big potential to ease the deployment of new services by getting rid of cumbersome
				wires and simplify patient care in hospitals and for home care. In healthcare
				environments, delayed or lost information may be a matter of life or death.
			</t>
			<t>
				Various systems, ranging from simple wearable remote controls for tele-assistance
				or intermediate systems with wearable sensor nodes monitoring various metrics to
				more complex systems for studying life dynamics, can be supported by LoWPANs. In the
				latter category, a large amount of data from various LoWPAN nodes can be collected:
				movement pattern observation, checks that medicaments have been taken, object
				tracking, and more. An example of such a deployment is described in
				<xref target="refs.hartog"/> using the concept of Personal Networks. 
			</t>

			<section title="A Use Case and its Requirements">
				<t>
					Example: healthcare at home by tele-assistance
				</t>
				<t>
					A senior citizen who lives alone wears one to few wearable LoWPAN nodes to
					measure heartbeat, pulse rate, etc. Dozens of LoWPAN nodes are densely installed
					at home for movement detection. A LBR at home will send the sensed
					information to a connected healthcare center. Portable base stations with LCDs
					may be used to check the data at home, as well. The different roles of devices
					have different duty-cycles, which affect node management.
				</t>
				<t>
					Multipath interference may often occur due to the mobility of the patients at home, 
					where there are many walls and obstacles. Even during sleeping, the change of
					the body position may affect the radio propagation.
				</t>	
				<t>
					Data is gathered both periodically and event-driven. In this application, 
					event-driven data can be very time-critical. Thus, real-time and reliable
					transmission must be guaranteed.
				</t>			
				<t>
					Privacy also becomes an serious issue in this case, as the sensed data is very personal.
					In addition, different data will be provided to the hospital system from what is
					given to a patient's family members. Role-based access control is needed to
					support such services, thus support of authorization and authentication is important.
				</t>
				<t>
					Dominant parameters in healthcare applications:
					<list style='symbols'>
						<t>Deployment: pre-planned</t>
						<t>Mobility: moderate (patient's mobility)</t>
						<t>Network Size: small, high node density </t>
						<t>Power Source: hybrid</t>
						<t>Security Level: Data privacy and security MUST be provided. Encryption is required. 
							Role based access control is required to be supported by light weight authentication mechanism</t>
						<t>Multi-hop communication: multi-hop for homecare devices, star topology on patients body. 
							Multipath interference due to walls and obstacles at home must be considered.</t>
						<t>Connectivity: always on</t>
						<t>QoS: high level of support (life and death implication), role-based </t>
						<t>Traffic Pattern: MP2P/P2MP (data collection), P2P (local diagnostic)</t>
						<t>Other issues: Plug-and-play configuration is required for mainly non-technical end-users.
							Real-time data acquisition and analysis are important. 
							Efficient data management is needed for various devices which have different
							duty-cycles, and for role-based data control. 
							Reliability and robustness of the network are also essential.</t>
					</list>
				</t>
			</section>
			
		    <!-- (health care applicability) -->
		
			<section title="6LoWPAN Applicability">
				<t>
					In this use case, the local network size is rather small (less than 10s of nodes).
					The home care system is statically configured with multi-hop paths and the
					patient’s body network can be built as a star topology. The LBR
					at home is the sink node in the routing path from sources on the patient's body.
					A plug-and-play configuration is required. As the communication of the system is limited
					to a home environment, both 16-bit and 64-bit can be used for IPv6 link-local
					addresses <xref target="RFC4944"/>. An example topology is provided in <xref target="fig.healthcare"/>.
				</t>
				<!--t>
					Multi-hop communication can be achieved by either Mesh Under or Route Over 
					mechanisms. When a Route Over routing mechanism is used, the routers deployed in the home
					environment will form a mesh of IPv6 links. In Mesh Under, more than one LMs 
					in the LoWPAN play role in multi-hop transmission in link layer 
					and in transmission multi-point
					traffic (multicast) to unicast method. In Route Over, LRs will handle
					multicast traffic to their LoWPAN link.
				</t-->
				<t>
					The patient’s body network can be simply configured as a star topology with a LC
					dealing with data aggregation and dynamic network attachment when the patient
					moves around at home. As multipath interference may often occur due to the
					patients' mobility at home, the deployment of LoWPAN nodes and transmission
					paths should be well considered. At home, some nodes can be installed with
					power-affluence status, and those LoWPAN nodes can be used for relaying points
					or data aggregation points. 
				</t>
				<t>
					The sensed information MUST be maintained with the identification of the patient 
					no matter if the patient visits the connected hospital or stays at home.
					If the patient's LoWPAN uses globally unique IPv6 address, the address can be
					used for the identification. However, it causes cost for privacy and security.
					The hospital LoWPAN where the patient's information is transferring needs to 
					operate additional identification system together with strong authority and authentication mechanism.
					The connection between the LBR at home and the LBR at Hospital must be 
					reliable and secure, as the data is privacy-critical. To achieve this, additional
					policy for security is recommended between the two LoWPAN.
				</t>					
	
				<figure title="A mobile healthcare scenario." anchor="fig.healthcare">
					<preamble></preamble>
					<artwork><![CDATA[
                      n - n               I: Internet
                      |   |             LBR: Edge Router
   LBR --- I -- LBR - n - n - LC         LC: Local controller node
   /|\           |    |       /|\         n: LoWPAN Node
 .. . ..         n -- n      n n n       

(hospital)       (home system)  (patient)  
			 ]]></artwork>
					<postamble></postamble>
				</figure>
			</section>
		
		</section>
	
		
        <!-- VEHICLE TELEMATICS -->	

		<section title="Vehicle Telematics">
			<t>
				LoWPANs play an important role in intelligent transportation systems. Incorporated
				in roads, vehicles, and traffic signals, they contribute to the improvement of safety
				of transporting systems. Through traffic or air-quality monitoring, they increase
				the possibilities in terms of traffic flow optimization and help reducing road congestion.
			</t>
			
			<section title="A Use Case and its Requirements">
				<t>
					Example: Telematics
				</t>
				<t>
					As shown in <xref target="fig.telematics"/>, scattered LoWPAN Nodes are included
					in roads during their construction for motion monitoring. When a car passes over
					these nodes, the possibility is then given to track the trajectory and velocity
					of cars for safety purposes. 
				</t>
				<t>
					The lifetime of the LoWPAN Nodes incorporated into
					roads is expected to be as long as the life time of the roads (about 10 years). 
					Multi-hop communication is possible between LoWPAN Nodes, and the network should
					be able to cope with the deterioration over time of the node density due to power
					fails. Sink nodes placed at the side of road are most likely mains-powered,  LoWPAN Nodes in
					the roads run on battery. Power saving schemes might intermittently disconnect
					the nodes. A rough estimate of 4 nodes per square meter is needed. Other
					applications may involve car-to-car communication for increased road safety.
				</t>
				<t>
					Dominant parameters in vehicle telematics applications:
					<list style='symbols'>
						<t>Deployment: scattered, pre-planned</t>
						<t>Mobility: none (road infrastructure), high (vehicle)</t>
						<t>Network Size: large (road infrastructure), small (vehicle)</t>
						<t>Power Source: hybrid </t>
						<t>Security Level: low</t>
						<t>Multi-hop communication: multi-hop, especially ad-hoc</t>
						<t>Connectivity: intermittent</t>
						<t>QoS: support of limited QoS</t>
						<t>Traffic Pattern: mostly Point-to-Point (P2P), Point-to-Multi-Point (P2MP)</t>
					</list>
				</t>
			</section>
			
			<!-- (vehicle telematics) -->
			
			<section title="6LoWPAN Applicability">
				<t>
					For this use case, the network topology includes fixed LBRs that
					are mains-powered and have a connection to high speed networks (e.g., Internet) 
					in order to reach the transportation control center (<xref target="fig.telematics"/>). 
					These LBRs may be logically combined with LC as a data sink to gather sensed data 
					from a number of LoWPAN Nodes inserted in the tarmac of the road. 
					In the road infrastructure, a LoWPAN with one LBR forms a fixed network and 
					the LoWPAN nodes are installed by manual optimization of their location. 
					<!--Static data paths to the data gathering point can be set in the commissioning phase. 	
					If the network does not use a Route Over mechanism, the 6LoWPAN mesh under forwarding 
					is used. Forwarding/Routing tables are not changed unless a node failure occurs.-->
				</t>
	
				<figure title="Telematics scenario." anchor="fig.telematics">
					<preamble></preamble>

				 <artwork><![CDATA[
	+-----+
	| LBR |----------------------------- LBR ...
	+-----+    (at the road side)                               
 -------|------------------------------
		|	                                
   n -- n --- n --- n   +---|---+       LBR: LoWPAN Border Router   
       / \          |   | n-n-n |        n: LoWPAN Node
      n  n          n   +---|---+             
                          (cars)                                                          
 --------------------------------------   
				 ]]></artwork>
					<postamble></postamble>
				</figure>
			</section>
            
		</section>


    <!-- AGRICULTURAL MONITORING -->
			
		<section anchor="scenario2" title="Agricultural Monitoring">
			<t>
				Accurate temporal and spatial monitoring can significantly increase agricultural productivity. Due to natural
				limitations, such as a farmers' inability to check the crop at all times of day or inadequate measurement tools,
				luck often plays a too large role in the success of harvests. Using a network of strategically placed sensors,
				indicators such as temperature, humidity, soil condition, can be automatically monitored without labor
				intensive field measurements. For example, sensor networks could provide precise information about crops in real time,
				enabling businesses to reduce water, energy, and pesticide usage and enhancing environment protection.
				The sensing data can be used to find optimal environments for the plants. In addition, the data on the planting
				condition can be saved by sensor tags, which can be used in supply chain management.
			</t>
		<!------------------------------------------------------------>		
			<section title="A Use Case and its Requirements">
				<t>	
					Example: Automated Vineyard 
				</t>
				<t>
					In a vineyard with medium to large geographical size, a number of 50 to 100 LC
					nodes are manually deployed in order to provide full signal coverage over the
					study area. An additional number of 100 to 1000 leaf nodes with (possibly
					heterogeneous) specialized sensors (i.e., humidity, temperature, soil condition,
					sunlight) are attached to the LCs in local wireless star topologies, periodically
					reporting measurements to the associated LCs. For example, in a 20-acre
					vineyard with 8 parcels of land, 10 LoWPAN Nodes are placed within each parcel
					to provide readings on temperature and soil moisture. The LoWPAN Nodes are able
					to support a multi-hop forwarding/routing scheme to enable data transmission to a
					sink node at the edge of the vineyard. Each of the 8 parcels contains one data
					aggregator to collect the sensed data. 
				</t>
				<t>
					Localization is important for this type of LoWPAN where installed in a geographically large area, 
					for pinning down where an
					event occurred, and for combining gathered data with their actual position. Using
					manual deployment, device addresses can be used for identifying the position and localization. 
					For randomly deployed nodes, a localization algorithm needs to be applied.
				</t>
				<t>
					There might be various types of sensor devices deployed in a single LoWPAN, each
					providing raw data with different semantics. Thus, an additional method is
					required to correctly interpret sensor readings. Each data packet may include
					meta-information about its data, or a type of a sensor could be encoded in its
					address during address allocation.
				</t>
				<t>
					Dominant parameters in agricultural monitoring:
					<list style='symbols'>
						<t>
							Deployment: pre-planned
							<vspace blankLines='1' />
							The nodes are installed outdoors or in a greenhouse with high exposure
							to water, soil, dust, in dynamic environments of moving people and
							machinery, with growing crop and foliage. LoWPAN nodes can be deployed
							in a pre-defined manner, considering the harsh environment.
						</t>
						<t>Mobility: all static</t>
						<t>Network Size: medium to large, low to medium density</t>
						<t>Power Source: all nodes are battery-powered except the sink, or energy harvesting</t>
						<t>Security Level: business-critical. 
						Light-weight security or a global key management can be used depending on the business purpose.</t>
						<t>Multi-hop communication: mesh topology with local star connections.</t>
						<t>Connectivity: intermittent (many sleeping nodes)</t>
						<t>QoS: support of limited QoS (small number of Class of Service) </t>
						<t>Traffic Pattern: Mainly MP2P/P2MP. P2P actuator triggering.</t>
						<t>Other issues: Time synchronization among sensors are required, but the traffic interval
						   may not be frequent (e.g. once in 30 minutes to 1 hour).</t>
					</list>
				</t>

			</section>
	
			<section title="6LoWPAN Applicability">
				<t>
					The network configuration in this use case might, in the most simple case, look
					like illustrated in <xref target="fig.vineyard"/>. This static scenario consists
					of one or more fixed LBR that are mains-powered and have a high-bandwidth
					connection to a backbone link, which might be placed in a control
					center, or connect to the Internet. The LBRs are strategically located at
					the border of vineyard parcels, acting as data sinks. A number of LCs are
					placed along a row of plants with individual LoWPAN nodes spread around them.
				</t>
				<t>
					While the LBRs implement the IPv6 Neighbor Discovery protocol (RFC 4861) 
					to connect the outside of the LoWPAN,
					the LoWPAN Nodes operate a more energy-considering ND described in
					<xref target="I-D.ietf-6lowpan-nd"/>, which includes basic bootstrapping and
					address assignment. Each LBR can have predefined forward management information 
					to a central data aggregation point, if necessary.
				</t>
				<!--t>
					The intermediate nodes must implement a multi-hop forwarding/routing protocol 
					and they are responsible to transmit the measured data 
					at the LoWPAN nodes to the LBRs. In this simplest case, the LRs or LMs 
					can build static forwarding/routing paths, 
					and all end-nodes can be placed in one radio hop distance from its forwarder.
					In more advanced setups, mesh routing is used for data distribution.
                </t-->
				<t>
					LoWPAN nodes may send event-driven notifications when readings exceed certain
					thresholds, such as low soil humidity; which may automatically trigger a water
					sprinkler in the local environment. For increased energy efficiency, all LoWPAN
					Nodes are in periodic sleep state. However, the LCs need to be aware of
					sudden events from the leaf nodes. Their sleep periods should therefore be set
					to shorter intervals. Communication schedules must be set up between master and
					leaf nodes, and global time synchronization is needed to account for clock drift.
				</t>
				<t>
					Also, the result of data collection may activate actuators. Context-awareness,
					node identification and data collection on the application level are necessary.
				</t>	
				<figure title="Automated vineyard scenario." anchor="fig.vineyard">
					<preamble></preamble>
					<artwork><![CDATA[
     I                            
     |
     |    n n n   n n n   n n n         I: Internet
     |     \|/     \|/     \|/        LBR: LoWPAN Border Router 
    LBR----LC------LC------LC          LC: Local Controller node  
     |     /|\     /|\     /|\          n: LoWPAN node 
     |    n n n   n n n   n n n      
     |
LBR
    ...	 ]]></artwork>
					<postamble></postamble>
				</figure>
			</section>

		</section>
	
	</section> <!-- end of main section "Application Scenarios" -->


<!-- SECURITY CONSIDERATIONS -->		

	<section title="Security Considerations">
		<t>
			Security requirements differ by use case. For example, industrial and structural
			monitoring applications are safety-critical. Secure transmission MUST be guaranteed, and
			only authenticated users MUST be able to access and handle the data. Lightweight key
			mechanisms can be used.	In health care system, data privacy is an important issue. 
			Encryption is required, and role-based access control is required to be supported by a
			proper authentication mechanism.
		</t>
	</section>

	<section title="IANA Considerations">
		<t>
			This document contains no actions for IANA.
		</t>
	</section>
	
	<section title="Acknowledgements">
		<t>
			Thanks for David Cypher for giving more insight on the IEEE 802.15.4 standard, 
			and Irene Fernandez, Shoichi Sakane and Paul Chilton for intensive review and valuable comments.
		</t>
	</section>

</middle>

<back>

	<references title='Normative References'>&RFC2119;&RFC4919;&RFC4944;
		<reference anchor="refs.ieee802.15.4">
		 	<front>
			   <title>IEEE Std. 802.15.4-2006 (as amended)</title>
			   <author><organization>IEEE Computer Society</organization></author>
			   <date month="" year="2007"/>
		  	</front>
		</reference>
	</references>
		
	<references title='Informative References'>

&I-D.ietf-6lowpan-nd;

&I-D.ietf-6lowpan-hc;

&I-D.ietf-6lowpan-routing-requirements;

        <!-- [DK] removed because out of date:
		<reference anchor="refs.bulusu">
			<front>
				<title>Wireless Sensor Networks</title>
				<author initials="N." surname="Bulusu" fullname="Nirupama Bulusu"></author>
				<author initials="S." surname="Jha" fullname="Sanjay Jha"></author>
				<date month="July" year="2005"/>
			</front>
		</reference>
		-->

		<reference anchor="refs.roemer">
			<front>
				<title>The Design Space of Wireless Sensor Networks</title>
				<author initials="K." surname="Roemer" fullname="Kay Roemer"></author>
				<author initials="F." surname="Mattern" fullname="Friedemann Mattern"></author>

				<date month="December" year="2004"/>
			</front>
		</reference>
	
        <reference anchor="refs.hartog">
			<front>
				<title>On the Potential of Personal Networks for Hospitals</title>
				<author initials="F." surname="den Hartog" fullname="Frank den Hartog"></author>
				<author initials="J." surname="Schmidt" fullname="J. Schmidt"></author>
                <author initials="A." surname="de Vries" fullname="Arnoud de Vries"></author>
				<date month="May" year="2006"/>
			</front>
		</reference>

	</references>

</back>

</rfc>

PAFTECH AB 2003-20262026-04-23 14:32:41