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6Lo Working Group                                              Y-G. Hong
Internet-Draft                                                      ETRI
Intended status: Standards Track                                C. Gomez
Expires: September 22, 2016                                    UPC/i2cat
                                                               Y-H. Choi
                                                                    ETRI
                                                                 D-Y. Ko
                                                               SKtelecom
                                                          March 21, 2016


     Use cases for IPv6 over Networks of Resource-constrained Nodes
                      draft-hong-6lo-use-cases-01

Abstract

   This document describes the characteristics of link layer
   technologies that are used at constrained node networks and typical
   use cases of IPv6 over networks of resource-constrained nodes.  In
   addition to IEEE 802.15.4, various link layer technologies such as
   BLE, ITU-T G.9959 (Z-Wave), DECT-ULE, MS/TP, NFC, and LTE MTC are
   widely used at constrained node networks for typical services.  Based
   on these link layer technologies, IPv6 over networks of resource-
   constrained nodes has various and practical use cases.  To
   efficiently implement typical services, the applicability and
   consideration of several design spaces are described.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 22, 2016.








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Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Terminology . . . . . . . . . . . . . . . . .   4
   3.  6lo Link layer technologies . . . . . . . . . . . . . . . . .   4
     3.1.  ITU-T G.9959  . . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  Bluetooth Low Energy  . . . . . . . . . . . . . . . . . .   4
     3.3.  DECT-ULE  . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.4.  Master-Slave/Token-Passing  . . . . . . . . . . . . . . .   5
     3.5.  NFC . . . . . . . . . . . . . . . . . . . . . . . . . . .   6
     3.6.  LTE MTC . . . . . . . . . . . . . . . . . . . . . . . . .   6
   4.  Design Space  . . . . . . . . . . . . . . . . . . . . . . . .   7
   5.  6lo Use Cases . . . . . . . . . . . . . . . . . . . . . . . .   8
     5.1.  Use case of NFC: Alternative Secure Transfer  . . . . . .   8
     5.2.  Use case of ITU-T G.9959: Smart Home  . . . . . . . . . .  10
     5.3.  Use case of Bluetooth Low Energy: Smartphone-Based
           Interaction with Constrained Devices  . . . . . . . . . .  12
     5.4.  Use case of DECT-ULE: Smart Home  . . . . . . . . . . . .  13
     5.5.  Use case of LTE MTC . . . . . . . . . . . . . . . . . . .  14
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  16
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  16
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  17
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  18
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  19

1.  Introduction

   Running IPv6 on constrained node networks has different features due
   to the characteristics of constrained node networks such as small
   packet size, short link-layer address, low bandwidth, network
   topology, low power, low cost, and large number of devices [RFC4919].



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   For example, because some IEEE 802.15.4 link layers have a frame size
   of 127 octets and IPv6 requires an MTU of 1280 bytes, an appropriate
   fragmentation and reassembly adaptation layer must be provided at the
   layer of below IPv6.  Also, the limited size of IEEE 802.15.4 frame,
   the length shortage of data delivery, and low energy consumption
   requirements make the need for header compression.  IETF 6lowpan
   (IPv6 over Low powerWPAN) working group published [RFC4944], an
   adaptation layer for sending IPv6 packets over IEEE 802.15.4,
   [RFC6282], compression format for IPv6 datagrams over IEEE
   802.15.4-based networks, and [RFC6775], Neighbor Discovery
   Optimization for 6lowpan.

   As IoT (Internet of Things) services become more popular, various
   link layer technologies such as Bluetooth Low Energy (Bluetooth LE),
   ITU-T G.9959 (Z-Wave), Digital Enhanced Cordless Telecommunications -
   Ultra Low Energy (DECT-ULE), Master-Slave/Token Passing (MS/TP), and
   Near Field Communication (NFC) are actively used.  And the need of
   transmission of IPv6 packets over these link layer technologies is
   required.  A number of IPv6-over-foo documents have been developed in
   the IETF 6lo (IPv6 over Networks of Resource-constrained Nodes) and
   6tisch (IPv6 over the TSCH mode of IEEE 802.15.4e) working group.

   In the 6lowpan working group, the [RFC6568], "Design and Application
   Spaces for 6LoWPANs" was published and it describes potential
   application scenarios and use cases for low-power wireless personal
   area networks.  In this document, various design space dimension such
   as deployment, network size, power source, connectivity, multi-hop
   communication, traffic pattern, security level, mobility, and QoS
   were analyzed.  And it described a fundamental set of 6lowpan
   application scenarios and use cases: Industrial monitoring-Hospital
   storage rooms, Structural monitoring-Bridge safety monitoring,
   Connected home-Home Automation, Healthcare-Healthcare at home by
   tele-assistance, Vehicle telematics-telematics, and Agricultural
   monitoring-Automated vineyard.

   Even though the [RFC6568] describes some potential application
   scenarios and use cases and it lists the design space in the context
   of 6lowpan, it does not cover the different use cases and design
   space in the context of the 6lo working group.  This document
   provides the use cases of 6lo, considering the following:

   o  6lo use cases MAY be uniquely different to the 6lowpan use cases.

   o  6lo use cases SHOULD cover various IoT related wire/wireless link
      layer technologies providing practical information of such
      technologies.





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   o  6lo use cases MAY describe characteristics and typical use cases
      of each link layer technology, and then 6lo use cases's
      applicability.

2.  Conventions and Terminology

   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 [RFC2119].

3.  6lo Link layer technologies

3.1.  ITU-T G.9959

   The ITU-T G.9959 recommendation [G.9959] targets low-power Personal
   Area Networks (PANs).  G.9959 defines how a unique 32-bit HomeID
   network identifier is assigned by a network controller and how an
   8-bit NodeID host identifier is allocated to each node.  NodeIDs are
   unique within the network identified by the HomeID.  The G.9959
   HomeID represents an IPv6 subnet that is identified by one or more
   IPv6 prefixes [RFC7428].

3.2.  Bluetooth Low Energy

   Bluetooth LE was introduced in Bluetooth 4.0, enhanced in Bluetooth
   4.1, and developed even further in successive versions.  Bluetooth
   SIG has also published Internet Protocol Support Profile (IPSP),
   which includes Internet Protocol Support Service (IPSS).  The IPSP
   enables discovery of IP-enabled devices and establishment of link-
   layer connection for transporting IPv6 packets.  IPv6 over Bluetooth
   LE is dependent on both Bluetooth 4.1 and IPSP 1.0 or newer.

   Devices such as mobile phones, notebooks, tablets and other handheld
   computing devices which will include Bluetooth 4.1 chipsets will also
   have the low-energy variant of Bluetooth.  Bluetooth LE will also be
   included in many different types of accessories that collaborate with
   mobile devices such as phones, tablets and notebook computers.  An
   example of a use case for a Bluetooth LE accessory is a heart rate
   monitor that sends data via the mobile phone to a server on the
   Internet [RFC7668].

3.3.  DECT-ULE

   DECT ULE is a low power air interface technology that is designed to
   support both circuit switched services, such as voice communication,
   and packet mode data services at modest data rate.





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   The DECT ULE protocol stack consists of the PHY layer operating at
   frequencies in the 1880 - 1920 MHz frequency band depending on the
   region and uses a symbol rate of 1.152 Mbps.  Radio bearers are
   allocated by use of FDMA/TDMA/TDD technics.

   In its generic network topology, DECT is defined as a cellular
   network technology.  However, the most common configuration is a star
   network with a single Fixed Parts (FP) defining the network with a
   number of PP attached.  The MAC layer supports traditional DECT as
   this is used for services like discovery, pairing, security features
   etc.  All these features have been reused from DECT.

   The DECT ULE device can switch to the ULE mode of operation,
   utilizing the new ULE MAC layer features.  The DECT ULE Data Link
   Control (DLC) provides multiplexing as well as segmentation and re-
   assembly for larger packets from layers above.  The DECT ULE layer
   also implements per-message authentication and encryption.  The DLC
   layer ensures packet integrity and preserves packet order, but
   delivery is based on best effort.

   The current DECT ULE MAC layer standard supports low bandwidth data
   broadcast.  However the usage of this broadcast service has not yet
   been standardized for higher layers [I-D.ietf-6lo-dect-ule].

3.4.  Master-Slave/Token-Passing

   MS/TP is a contention-free access method for the RS-485 physical
   layer, which is used extensively in building automation networks.
   This specification defines the frame format for transmission of IPv6
   [RFC2460] packets and the method of forming link-local and
   statelessly autoconfigured IPv6 addresses on MS/TP networks.  The
   general approach is to adapt elements of the 6LoWPAN [RFC4944]
   specification to constrained wired networks.

   An MS/TP device is typically based on a low-cost microcontroller with
   limited processing power and memory.  Together with low data rates
   and a small address space, these constraints are similar to those
   faced in 6LoWPAN networks and suggest some elements of that solution
   might be leveraged.  MS/TP differs significantly from 6LoWPAN in at
   least three respects: a) MS/TP devices typically have a continuous
   source of power, b) all MS/TP devices on a segment can communicate
   directly so there are no hidden node or mesh routing issues, and c)
   recent changes to MS/TP provide support for large payloads,
   eliminating the need for link-layer fragmentation and reassembly.

   MS/TP is designed to enable multidrop networks over shielded twisted
   pair wiring.  It can support a data rate of 115,200 baud on segments
   up to 1000 meters in length, or segments up to 1200 meters in length



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   at lower baud rates.  An MS/TP link requires only a UART, an RS-485
   transceiver with a driver that can be disabled, and a 5ms resolution
   timer.  These features make MS/TP a cost-effective field bus for the
   most numerous and least expensive devices in a building automation
   network [I-D.ietf-6lo-6lobac].

3.5.  NFC

   NFC technology enables simple and safe two-way interactions between
   electronic devices, allowing consumers to perform contactless
   transactions, access digital content, and connect electronic devices
   with a single touch.  NFC complements many popular consumer level
   wireless technologies, by utilizing the key elements in existing
   standards for contactless card technology (ISO/IEC 14443 A&B and
   JIS-X 6319-4).  NFC can be compatible with existing contactless card
   infrastructure and it enables a consumer to utilize one device across
   different systems.

   Extending the capability of contactless card technology, NFC also
   enables devices to share information at a distance that is less than
   10 cm with a maximum communication speed of 424 kbps.  Users can
   share business cards, make transactions, access information from a
   smart poster or provide credentials for access control systems with a
   simple touch.

   NFC's bidirectional communication ability is ideal for establishing
   connections with other technologies by the simplicity of touch.  In
   addition to the easy connection and quick transactions, simple data
   sharing is also available [I-D.ietf-6lo-nfc].

3.6.  LTE MTC

   LTE category defines the overall performance and capabilities of the
   UE(User Equipment).  For example, the maximum down rate of category 1
   UE and category 2 UE are 10.3 Mbit/s and 51.0 Mbit/s respectively.
   There are many categories in LTE standard. 3GPP standards defined the
   category 0 to be used for low rate IoT service in release 12.  Since
   category 1 and category 0 could be used for low rate IoT service, we
   call LTE MTC[LTE_MTC].

   LTE MTC have the advantages compared to above category 2 to be used
   for low rate IoT service such as low power and low cost.

   The below figure shows the primary characteristics of LTE MTC.







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         +------------+---------------------+-------------------+
         |  Category  | Max. Date Rate Down | Max. Date Rate Up |
         +------------+---------------------+-------------------+
         | Category 0 |      1.0 Mbit/s     |     1.0 Mbit/s    |
         |            |                     |                   |
         | Category 1 |     10.3 Mbit/s     |     5.2 Mbit/s    |
         +------------+---------------------+-------------------+

                Table 1: Primary characteristics of LTE MTC

4.  Design Space

   The [RFC6568] 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).  In the RFC 6558, the following design space dimensions are
   described; Deployment, Network size, Power source, Connectivity,
   Multi-hop communication, Traffic pattern, Mobility, Quality of
   Service (QoS).

   The design space dimensions of 6lo are a little different to those of
   the RFC 6558 due to the different characteristics of 6lo link layer
   technologies.  The following design space dimensions can be
   considered.

   o  Deployment/Bootstrapping: 6lo nodes can be connected randomly, or
      in an organized manner.  The bootstrapping has different
      characteristics of each link layer technologies.

   o  Topology: Topology of 6lo networks may inherently follow the
      characteristics of each link layer technology.  Point-to-point,
      star, tree or mesh topologies can be configured.

   o  L2-Mesh or L3-Mesh: L2-mesh and L3-mesh may inherently follow the
      characteristics of each link layer technologies.  Some link layer
      technologies may support L2-mesh and some may not support.

   o  Multi-link subnet, single subnet: The selection of multi-link
      subnet and single subnet depends on connectivity and the number of
      6lo nodes.

   o  Data rate: Originally, the link layer technologies of 6lo have low
      rate of data transmission.  But, by adjusting the MTU, it can
      deliver higher data rate.






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   o  Buffering requirements: Some 6lo use case may require more data
      rate than the link layer technology support.  In this case, a
      buffering mechanism to manage the date is required.

   o  Security Requirements: Some 6lo use case can transfer some
      important and personal data between 6lo nodes.  In this case,
      high-level security support is required.

   o  Mobility across 6lo networks and subnets: The movement of 6lo
      nodes is dependent on the 6lo use case.  If the 6lo nodes can move
      or moved around, it requires the mobility management mechanism.

   o  Time synchronization requirements: The requirement of time
      synchronization of the upper layer service is dependent on the 6lo
      use case.  For some 6lo use case related to health service, the
      measured data must be recorded with exact time and must be
      transferred with time synchronization.

   o  Reliability and QoS: Some 6lo use case requires high reliability,
      for example real-time service or health-related services.

   o  Traffic patterns: 6lo use case may various traffic patterns.  Some
      6lo use case may require short data length and randomly.  Some 6lo
      use case may require continuous data and periodic data
      transmission.

   o  Security Bootstrapping: Without the external operations, 6lo nodes
      must have the security bootstrapping mechanism.

   o  Power use strategy: to enable certain use cases, there may be
      requirements on the class of energy availability and the strategy
      followed for using power for communication [RFC7228].  Each link
      layer technology defines a particular power use strategy which may
      be tuned [I-D.ietf-lwig-energy-efficient].

   o  Energy limitation: The energy limitation class [RFC7228] is
      specific to each use case, and may or may not be related to the
      power use strategy.

5.  6lo Use Cases

5.1.  Use case of NFC: Alternative Secure Transfer

   According to applications, various secured data can be handled and
   transferred.  Depending on security level of the data, methods for
   transfer can be alternatively selected.  The personal data having
   serious issues should be transferred securely, but data transfer by
   using Wi-Fi and Bluetooth connections cannot always be secure because



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   of their a little long radio frequency range.  Hackers can overhear
   the personal data transfer behind hidden areas.  Therefore, methods
   need to be alternatively selected to transfer secured data.  Voice
   and video data, which are not respectively secure and requires long
   transmission range, can be transferred by 3G/4G technologies, such as
   WCDMA, GSM, and LTE.  Big size data, which are not secure and
   requires high speed and broad bandwidth, can be transferred by Wi-Fi
   and wired network technologies.  However, the person data, which are
   serious issues so requires secure transfer in wireless area, can be
   securely transferred by NFC technology.  It has very short frequency
   range ? nearly single touch communication.

   Example: Secure Transfer by Using NFC in Healthcare Services with
   Tele-Assistance

   A senior citizen who lives alone wears one to several wearable 6lo
   devices to measure heartbeat, pulse rate, etc.  The 6lo devices are
   densely installed at home for movement detection.  An LoWPAN Border
   Router (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.  Data is gathered in both periodic
   and event-driven fashion.  In this application, event-driven data can
   be very time-critical.  In addition, privacy also becomes a serious
   issue in this case, as the sensed data is very personal.

   While the senior citizen is provided audio and video healthcare
   services by a tele-assistance based on LTE connections, the senior
   citizen can alternatively use NFC connections to transfer the
   personal sensed data to the tele-assistance.  At this moment, hidden
   hackers can overhear the data based on the LTE connection, but they
   cannot gather the personal data over the NFC connection.


       +-------------+                              +-------------+
       |voice & video|....... LTE connection ......>|voice & video|
       |     data    |<...... LTE connection .......|    data     |
       +-------------+                              +-------------+
       | sensed data |....... NFC connection ......>|             |
       |             |<...... NFC connection .......|   personal  |
       |             |                              | result data |
       +-------------+                              +-------------+
          (patient)                                (tele-assistance)


       Figure 1: Alternative Secure Transfer in Healthcare Services

   Dominant parameters in secure transfer by using NFC in healthcare
   services:



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   o  Deployment/Bootstrapping: Pre-planned.  MP2P/P2MP (data
      collection), P2P (local diagnostic).

   o  Topology: Small, NFC-enabled device connected to the Internet.

   o  L2-mesh or L3-mesh: NFC does not support L2-mesh, L3-mesh can be
      configured.

   o  Multi-link subnet, single subnet: a Single-hop for gateway;
      patient's body network is mesh topology.

   o  Data rate: Small data rate.

   o  Buffering requirements: Low requirement.

   o  Security requirements: Data privacy and security must be provided.
      Encryption is required.

   o  Mobility: Moderate (patient's mobility).

   o  Time Synchronization: Highly required.

   o  Reliability and QoS: High level of reliability support (life-or-
      death implication), role-based.

   o  Traffic patterns: Short data length and periodic (randomly).

   o  Security Bootstrapping: Highly required.

   o  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 that have different duty cycles, and for role-based data
      control.  Reliability and robustness of the network are also
      essential.

5.2.  Use case of ITU-T G.9959: Smart Home

   Z-Wave is one of the main technologies that may be used to enable
   smart home applications.  Born as a proprietary technology, Z-Wave
   was specifically designed for this use case.  Recently, the Z-Wave
   radio interface (physical and MAC layers) has been standardized as
   the ITU-T G.9959 specification.

   Example: Use of ITU-T G.9959 for Home Automation

   Variety of home devices (e.g. light dimmers/switches, plugs,
   thermostats,blinds/curtains and remote controls) are augmented with



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   ITU-T G.9959 interfaces.  A user may turn on/off or may control home
   appliances by pressing a wall switch or by pressing a button in a
   remote control.  Scenes may be programmed, so that after a given
   event, the home devices adopt a specific configuration.  Sensors may
   also periodically send measurements of several parameters (e.g. gas
   presence, light, temperature, humidity, etc.) which are collected at
   a sink device, or may generate commands for actuators (e.g. a smoke
   sensor may send an alarm message to a safety system).

   The devices involved in the described scenario are nodes of a network
   that follows the mesh topology, which is suitable for path diversity
   to face indoor multipath propagation issues.  The multihop paradigm
   allows end-to-end connectivity when direct range communication is not
   possible.  Security support is required, specially for safety-related
   communication.  When a user interaction (e.g. a button press)
   triggers a message that encapsulates a command, if the message is
   lost, the user may have to perform further interactions to achieve
   the desired effect (e.g. a light is turned off).  A reaction to a
   user interaction will be perceived by the user as immediate as long
   as the reaction takes place after less than 0.5 seconds [RFC5826].

   Dominant parameters in home automation scenarios with ITU-T G.9959:

   o  Deployment/Bootstrapping: Pre-planned.

   o  Topology: Mesh topology.

   o  L2-mesh or L3-mesh: ITU-T G.9959 provides support for L2-mesh, and
      L3-mesh can also be used (the latter requires an IP-based routing
      protocol).

   o  Multi-link subnet, single subnet: Multi-link subnet.

   o  Data rate: Small data rate, infrequent transmissions.

   o  Buffering requirements: Low requirement.

   o  Security requirements: Data privacy and security must be provided.
      Encryption is required.

   o  Mobility: Most devices are static.  A few devices (e.g. remote
      control) are portable.

   o  Time Synchronization: TBD.

   o  Reliability and QoS: Moderate to high level of reliability
      support.  Actions as a result of human-generated traffic should
      occur after less than 0.5 seconds.



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   o  Traffic patterns: Periodic (sensor readings) and aperiodic (user-
      triggered interaction).

   o  Security Bootstrapping: Required.

5.3.  Use case of Bluetooth Low Energy: Smartphone-Based Interaction
      with Constrained Devices

   The key feature behind the current high Bluetooth LE momentum is its
   support in a large majority of smartphones in the market.  Bluetooth
   LE can be used to allow the interaction between the smartphone and
   surrounding sensors or actuators.  Furthermore, Bluetooth LE is also
   the main radio interface currently available in wearables.  Since a
   smartphone typically has several radio interfaces that provide
   Internet access, such as Wi-Fi or 4G, the smartphone can act as a
   gateway for nearby devices such as sensors, actuators or wearables.
   Bluetooth LE may be used in several domains, including healthcare,
   sports/wellness and home automation.

   Example: Bluetooth LE-based Body Area Network for fitness

   A person wears a smartwatch for fitness purposes.  The smartwatch has
   several sensors (e.g. heart rate, accelerometer, gyrometer, GPS,
   temperature, etc.), a display, and a Bluetooth LE radio interface.
   The smartwatch can show fitness-related statistics on its display.
   However, when a paired smartphone is in the range of the smartwatch,
   the latter can report almost real-time measurements of its sensors to
   the smartphone, which can forward the data to a cloud service on the
   Internet.  In addition, the smartwatch can receive notifications
   (e.g. alarm signals) from the cloud service via the smartphone.  On
   the other hand, the smartphone may locally generate messages for the
   smartwatch, such as e-mail reception or calendar notifications.

   The functionality supported by the smartwatch may be complemented by
   other devices such as other on-body sensors, wireless headsets or
   head-mounted displays.  All such devices may connect to the
   smartphone creating a star topology network whereby the smartphone is
   the central component.

   Dominant parameters in home automation scenarios with Bluetooth LE:

   o  Deployment/Bootstrapping: Pre-planned.

   o  Topology: Star topology.

   o  L2-mesh or L3-mesh: No.

   o  Multi-link subnet, single subnet: Multi-link subnet.



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   o  Data rate: TBD.

   o  Buffering requirements: Low requirement.

   o  Security requirements: For health-critical information, data
      privacy and security must be provided.  Encryption is required.
      Some types of notifications sent by the smartphone may not need.

   o  Mobility: Low.

   o  Time Synchronization: the link layer, which is based on TDMA,
      provides a basis for time synchronization.

   o  Reliability and QoS: a relatively low ratio of message losses is
      acceptable for periodic sensor readings.  End-to-end latency of
      sensor readings is not subject to stringent requirements.  The
      latency of should be low for critical notifications or alarms,
      generated by either the smartphone or an Internet cloud service.

   o  Traffic patterns: periodic (sensor readings) and aperiodic
      (smartphone-generated notifications).

   o  Security Bootstrapping: Required.

5.4.  Use case of DECT-ULE: Smart Home

   DECT is a technology widely used for wireless telephone communicatio
   s in residential scenarios.  Since DECT-ULE is a low-power variant of
   DECT, DECT-ULE can be used to connect constrained devices such as
   sensors and actuators to a Fixed Part, a device that typically acts
   as a base station for wireless telephones.  Therefore, DECT-ULE is
   specially suitable for the connected home space in application areas
   such as home automation, smart metering, safety, healthcare, etc.

   Example: use of DECT-ULE for Smart Metering

   The smart electricity meter of a home is equipped with a DECT-ULE
   transceiver.  This device is in the coverage range of the Fixed Part
   of the home.  The Fixed Part can act as a router connected to the
   Internet.  This way, the smart meter can transmit electricity
   consumption readings through the DECT-ULE link with the Fixed Part,
   and the latter can forward such readings to the utility company using
   Wide Area Network (WAN) links.  The meter can also receive queries
   from the utility company or from an advanced energy control system
   controlled by the user, which may also be connected to the Fixed Part
   via DECT-ULE.

   Dominant parameters in smart metering scenarios with DECT-ULE:



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   o  Deployment/Bootstrapping: Pre-planned.

   o  Topology: Star topology.

   o  L2-mesh or L3-mesh: No.

   o  Multi-link subnet, single subnet: Multi-link subnet.

   o  Data rate: Small data rate, infrequent transmissions.

   o  Buffering requirements: Low requirement.

   o  Security requirements: Data privacy and security must be provided.
      Encryption is required.

   o  Mobility: No.

   o  Time Synchronization: TBD.

   o  Reliability and QoS: bounded latency, stringent reliability
      service agreements [I-D.ietf-roll-applicability-ami].

   o  Traffic patterns: Periodic (meter reading notifications sent by
      the meter) and aperiodic (user- or company-triggered queries to
      the meter, and messages triggered by local events such as power
      outage or leak detection [I-D.ietf-roll-applicability-ami]).

   o  Security Bootstrapping: required.

5.5.  Use case of LTE MTC

   Wireless link layer technologies can be divided short range
   connectivity and long range connectivity.  BLE, ITU-T G.9959
   (Z-Wave), DECT-ULE, MS/TP, NFC are used for short range connectivity.
   LTE MTC is used for long range connectivity.  And there is another
   long range connectivity technology.  It is LPWAN(Low Power Wide Area
   Network) technology such as LoRa, Sigfox and etc.  Therefore, the use
   case of LTE MTC should be compared to LPWAN.

   Example: Use of wireless backhaul for LoRa gateway

   LoRa is the most promising technology of LPWAN.  LoRa network
   architecture has a star of stat topology.  LoRa gateway relay the
   messages from LoRa end device to application server and vice versa.
   LoRa gateway can has two types of backhaul, wired and wireless
   backhaul.





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   If LoRa gateway has wireless backhaul, it should have LTE modem.
   Since the modem cost of LTE MTC is cheaper than the modem cost of
   above LTE category 2, it is helpful to design to use LTE MTC.  Since
   the maximum date rate of LoRa end device is 50kbps, it is sufficient
   to use LTE MTC without using category 2.

   Dominant parameters in LoRa gateway scenarios with above example:

   o  Deployment/Bootstrapping: Pre-planned.

   o  Topology: Star topology.

   o  L2-mesh or L3-mesh: No.

   o  Multi-link subnet, single subnet: Single subnet.

   o  Data rate: depends on 3GPP specification.

   o  Buffering requirements: High requirement.

   o  Security requirements: No, because data security is already
      provided in LoRa specification.

   o  Mobility: Static.

   o  Time Synchronization: Highly required.

   o  Reliability and QoS: TBD.

   o  Traffic patterns: Random.

   o  Security Bootstrapping: required.

   Example: Use of controlling car

   Car sharing service becomes more popular.  Customers wish to control
   the car with smart phone application.  For example, customers wish to
   lock/unlock the car door with smart phone application, because
   customers may not have a car key.  Customers wish to blow with smart
   phone application to locate the car easily.

   Therefore, rental car should have a long range connectivity capable
   modem such as LoRa end device and LTE UE.  However, LoRa may not be
   used because LoRa has low reliability and may not is supported in
   indoor environment such as basement parking lot.  And since the
   message of controlling car is very small, it is sufficient to use LTE
   MTC but above category 2.




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   Dominant parameters in controlling car scenarios with above example:

   o  Deployment/Bootstrapping: Pre-planned.

   o  Topology: Star topology.

   o  L2-mesh or L3-mesh: No.

   o  Multi-link subnet, single subnet: Single subnet.

   o  Data rate: depends on 3GPP specification.

   o  Buffering requirements: High requirement.

   o  Security requirements: High requirement.

   o  Mobility: Always dynamic .

   o  Time Synchronization: Highly required.

   o  Reliability and QoS: TBD.

   o  Traffic patterns: Random.

   o  Security Bootstrapping: required.

6.  IANA Considerations

   There are no IANA considerations related to this document.

7.  Security Considerations

   [TBD]

8.  Acknowledgements

   Carles Gomez has been funded in part by the Spanish Government
   (Ministerio de Educacion, Cultura y Deporte) through the Jose
   Castillejo grant CAS15/00336.  His contribution to this work has been
   carried out during his stay as a visiting scholar at the Computer
   Laboratory of the University of Cambridge.

9.  References








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9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC4919]  Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6
              over Low-Power Wireless Personal Area Networks (6LoWPANs):
              Overview, Assumptions, Problem Statement, and Goals",
              RFC 4919, DOI 10.17487/RFC4919, August 2007,
              <http://www.rfc-editor.org/info/rfc4919>.

   [RFC4944]  Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
              "Transmission of IPv6 Packets over IEEE 802.15.4
              Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,
              <http://www.rfc-editor.org/info/rfc4944>.

   [RFC5826]  Brandt, A., Buron, J., and G. Porcu, "Home Automation
              Routing Requirements in Low-Power and Lossy Networks",
              RFC 5826, DOI 10.17487/RFC5826, April 2010,
              <http://www.rfc-editor.org/info/rfc5826>.

   [RFC6282]  Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
              Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
              DOI 10.17487/RFC6282, September 2011,
              <http://www.rfc-editor.org/info/rfc6282>.

   [RFC6568]  Kim, E., Kaspar, D., and JP. Vasseur, "Design and
              Application Spaces for IPv6 over Low-Power Wireless
              Personal Area Networks (6LoWPANs)", RFC 6568,
              DOI 10.17487/RFC6568, April 2012,
              <http://www.rfc-editor.org/info/rfc6568>.

   [RFC6775]  Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
              Bormann, "Neighbor Discovery Optimization for IPv6 over
              Low-Power Wireless Personal Area Networks (6LoWPANs)",
              RFC 6775, DOI 10.17487/RFC6775, November 2012,
              <http://www.rfc-editor.org/info/rfc6775>.

   [RFC7228]  Bormann, C., Ersue, M., and A. Keranen, "Terminology for
              Constrained-Node Networks", RFC 7228,
              DOI 10.17487/RFC7228, May 2014,
              <http://www.rfc-editor.org/info/rfc7228>.







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   [RFC7428]  Brandt, A. and J. Buron, "Transmission of IPv6 Packets
              over ITU-T G.9959 Networks", RFC 7428,
              DOI 10.17487/RFC7428, February 2015,
              <http://www.rfc-editor.org/info/rfc7428>.

   [RFC7668]  Nieminen, J., Savolainen, T., Isomaki, M., Patil, B.,
              Shelby, Z., and C. Gomez, "IPv6 over BLUETOOTH(R) Low
              Energy", RFC 7668, DOI 10.17487/RFC7668, October 2015,
              <http://www.rfc-editor.org/info/rfc7668>.

9.2.  Informative References

   [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
              December 1998, <http://www.rfc-editor.org/info/rfc2460>.

   [I-D.ietf-6lo-dect-ule]
              Mariager, P., Petersen, J., Shelby, Z., Logt, M., and D.
              Barthel, "Transmission of IPv6 Packets over DECT Ultra Low
              Energy", draft-ietf-6lo-dect-ule-03 (work in progress),
              September 2015.

   [I-D.ietf-6lo-6lobac]
              Lynn, K., Martocci, J., Neilson, C., and S. Donaldson,
              "Transmission of IPv6 over MS/TP Networks", draft-ietf-
              6lo-6lobac-02 (work in progress), July 2015.

   [I-D.ietf-6lo-nfc]
              Youn, J. and Y. Hong, "Transmission of IPv6 Packets over
              Near Field Communication", draft-ietf-6lo-nfc-01 (work in
              progress), July 2015.

   [I-D.ietf-lwig-energy-efficient]
              Gomez, C., Kovatsch, M., Tian, H., and Z. Cao, "Energy-
              Efficient Features of Internet of Things Protocols",
              draft-ietf-lwig-energy-efficient-04 (work in progress),
              February 2016.

   [I-D.ietf-roll-applicability-ami]
              Popa, D., Gillmore, M., Toutain, L., Hui, J., Salazar, R.,
              Monden, K., and N. Cam-Winget, "Applicability Statement
              for the Routing Protocol for Low Power and Lossy Networks
              (RPL) in AMI Networks", draft-ietf-roll-applicability-
              ami-11 (work in progress), August 2015.







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   [G.9959]   "International Telecommunication Union, "Short range
              narrow-band digital radiocommunication transceivers - PHY
              and MAC layer specifications", ITU-T Recommendation",
              January 2015.

   [LTE_MTC]  "3GPP TS 36.306 V13.0.0, 3rd Generation Partnership
              Project; Technical Specification Group Radio Access
              Network; Evolved Universal Terrestrial Radio Access
              (E-UTRA); User Equipment (UE) radio access capabilities
              (Release 13)", December 2015.

Authors' Addresses

   Yong-Geun Hong
   ETRI
   161 Gajeong-Dong Yuseung-Gu
   Daejeon  305-700
   Korea

   Phone: +82 42 860 6557
   Email: yghong@etri.re.kr


   Carles Gomez
   Universitat Politecnica de Catalunya/Fundacio i2cat
   C/Esteve Terradas, 7
   Castelldefels  08860
   Spain

   Email: carlesgo@entel.upc.edu


   Younghwan Choi
   ETRI
   218 Gajeongno, Yuseong
   Daejeon  305-700
   Korea

   Phone: +82 42 860 1429
   Email: yhc@etri.re.kr











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   Deoknyong Ko
   SKtelecom
   9-1 Byundang-gu Sunae-dong, Seongnam-si
   Gyeonggi-do  13595
   Korea

   Phone: +82 10 3356 8052
   Email: engineer@sk.com











































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