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Internet Engineering Task Force (IETF)                   S. Farrell, Ed.Request for Comments: 8376                        Trinity College DublinCategory: Informational                                         May 2018ISSN: 2070-1721Low-Power Wide Area Network (LPWAN) OverviewAbstract   Low-Power Wide Area Networks (LPWANs) are wireless technologies with   characteristics such as large coverage areas, low bandwidth, possibly   very small packet and application-layer data sizes, and long battery   life operation.  This memo is an informational overview of the set of   LPWAN technologies being considered in the IETF and of the gaps that   exist between the needs of those technologies and the goal of running   IP in LPWANs.Status of This Memo   This document is not an Internet Standards Track specification; it is   published for informational purposes.   This document is a product of the Internet Engineering Task Force   (IETF).  It represents the consensus of the IETF community.  It has   received public review and has been approved for publication by the   Internet Engineering Steering Group (IESG).  Not all documents   approved by the IESG are candidates for any level of Internet   Standard; seeSection 2 of RFC 7841.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttps://www.rfc-editor.org/info/rfc8376.Copyright Notice   Copyright (c) 2018 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 78 and the IETF Trust's Legal   Provisions Relating to IETF Documents   (https://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.Farrell                       Informational                     [Page 1]

RFC 8376                     LPWAN Overview                     May 2018Table of Contents1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .22.  LPWAN Technologies  . . . . . . . . . . . . . . . . . . . . .32.1.  LoRaWAN . . . . . . . . . . . . . . . . . . . . . . . . .42.1.1.  Provenance and Documents  . . . . . . . . . . . . . .42.1.2.  Characteristics . . . . . . . . . . . . . . . . . . .42.2.  Narrowband IoT (NB-IoT) . . . . . . . . . . . . . . . . .102.2.1.  Provenance and Documents  . . . . . . . . . . . . . .102.2.2.  Characteristics . . . . . . . . . . . . . . . . . . .112.3.  Sigfox  . . . . . . . . . . . . . . . . . . . . . . . . .152.3.1.  Provenance and Documents  . . . . . . . . . . . . . .152.3.2.  Characteristics . . . . . . . . . . . . . . . . . . .162.4.  Wi-SUN Alliance Field Area Network (FAN)  . . . . . . . .202.4.1.  Provenance and Documents  . . . . . . . . . . . . . .202.4.2.  Characteristics . . . . . . . . . . . . . . . . . . .213.  Generic Terminology . . . . . . . . . . . . . . . . . . . . .244.  Gap Analysis  . . . . . . . . . . . . . . . . . . . . . . . .264.1.  Naive Application of IPv6 . . . . . . . . . . . . . . . .264.2.  6LoWPAN . . . . . . . . . . . . . . . . . . . . . . . . .264.2.1.  Header Compression  . . . . . . . . . . . . . . . . .274.2.2.  Address Autoconfiguration . . . . . . . . . . . . . .274.2.3.  Fragmentation . . . . . . . . . . . . . . . . . . . .274.2.4.  Neighbor Discovery  . . . . . . . . . . . . . . . . .284.3.  6lo . . . . . . . . . . . . . . . . . . . . . . . . . . .294.4.  6tisch  . . . . . . . . . . . . . . . . . . . . . . . . .294.5.  RoHC  . . . . . . . . . . . . . . . . . . . . . . . . . .294.6.  ROLL  . . . . . . . . . . . . . . . . . . . . . . . . . .304.7.  CoAP  . . . . . . . . . . . . . . . . . . . . . . . . . .304.8.  Mobility  . . . . . . . . . . . . . . . . . . . . . . . .314.9.  DNS and LPWAN . . . . . . . . . . . . . . . . . . . . . .315.  Security Considerations . . . . . . . . . . . . . . . . . . .316.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .327.  Informative References  . . . . . . . . . . . . . . . . . . .32   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .39   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .40   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .431.  Introduction   This document provides background material and an overview of the   technologies being considered in the IETF's IPv6 over Low Power Wide-   Area Networks (LPWAN) Working Group (WG).  It also provides a gap   analysis between the needs of these technologies and currently   available IETF specifications.Farrell                       Informational                     [Page 2]

RFC 8376                     LPWAN Overview                     May 2018   Most technologies in this space aim for a similar goal of supporting   large numbers of very low-cost, low-throughput devices with very low   power consumption, so that even battery-powered devices can be   deployed for years.  LPWAN devices also tend to be constrained in   their use of bandwidth, for example, with limited frequencies being   allowed to be used within limited duty cycles (usually expressed as a   percentage of time per hour that the device is allowed to transmit).   As the name implies, coverage of large areas is also a common goal.   So, by and large, the different technologies aim for deployment in   very similar circumstances.   While all constrained networks must balance power consumption /   battery life, cost, and bandwidth, LPWANs prioritize power and cost   benefits by accepting severe bandwidth and duty cycle constraints   when making the required trade-offs.  This prioritization is made in   order to get the multiple-kilometer radio links implied by "Wide   Area" in LPWAN's name.   Existing pilot deployments have shown huge potential and created much   industrial interest in these technologies.  At the time of writing,   essentially no LPWAN end devices (other than for Wi-SUN) have IP   capabilities.  Connecting LPWANs to the Internet would provide   significant benefits to these networks in terms of interoperability,   application deployment, and management (among others).  The goal of   the LPWAN WG is to, where necessary, adapt IETF-defined protocols,   addressing schemes, and naming conventions to this particular   constrained environment.   This document is largely the work of the people listed in the   Contributors section.2.  LPWAN Technologies   This section provides an overview of the set of LPWAN technologies   that are being considered in the LPWAN WG.  The text for each was   mainly contributed by proponents of each technology.   Note that this text is not intended to be normative in any sense; it   simply exists to help the reader in finding the relevant Layer 2 (L2)   specifications and in understanding how those integrate with IETF-   defined technologies.  Similarly, there is no attempt here to set out   the pros and cons of the relevant technologies.Farrell                       Informational                     [Page 3]

RFC 8376                     LPWAN Overview                     May 20182.1.  LoRaWAN2.1.1.  Provenance and Documents   LoRaWAN is a wireless technology based on Industrial, Scientific, and   Medical (ISM) that is used for long-range low-power low-data-rate   applications developed by the LoRa Alliance, a membership consortium   <https://www.lora-alliance.org/>.  This document is based on Version   1.0.2 of the LoRa specification [LoRaSpec].  That specification is   publicly available and has already seen several deployments across   the globe.2.1.2.  Characteristics   LoRaWAN aims to support end devices operating on a single battery for   an extended period of time (e.g., 10 years or more), extended   coverage through 155 dB maximum coupling loss, and reliable and   efficient file download (as needed for remote software/firmware   upgrade).   LoRaWAN networks are typically organized in a star-of-stars topology   in which Gateways relay messages between end devices and a central   "network server" in the backend.  Gateways are connected to the   network server via IP links while end devices use single-hop LoRaWAN   communication that can be received at one or more Gateways.   Communication is generally bidirectional; uplink communication from   end devices to the network server is favored in terms of overall   bandwidth availability.   Figure 1 shows the entities involved in a LoRaWAN network.   +----------+   |End Device| * * *   +----------+       *   +---------+                        * | Gateway +---+   +----------+       *   +---------+   |   +---------+   |End Device| * * *                   +---+ Network +--- Application   +----------+       *                 |   | Server  |                        * +---------+   |   +---------+   +----------+       *   | Gateway +---+   |End Device| * * *   * +---------+   +----------+       Key: *      LoRaWAN Radio            +---+  IP connectivity                      Figure 1: LoRaWAN ArchitectureFarrell                       Informational                     [Page 4]

RFC 8376                     LPWAN Overview                     May 2018   o  End Device: a LoRa client device, sometimes called a "mote".      Communicates with Gateways.   o  Gateway: a radio on the infrastructure side, sometimes called a      "concentrator" or "base station".  Communicates with end devices      and, via IP, with a network server.   o  Network Server: The Network Server (NS) terminates the LoRaWAN      Medium Access Control (MAC) layer for the end devices connected to      the network.  It is the center of the star topology.   o  Join Server: The Join Server (JS) is a server on the Internet side      of an NS that processes join requests from an end devices.   o  Uplink message: refers to communications from an end device to a      network server or application via one or more Gateways.   o  Downlink message: refers to communications from a network server      or application via one Gateway to a single end device or a group      of end devices (considering multicasting).   o  Application: refers to application-layer code both on the end      device and running "behind" the NS.  For LoRaWAN, there will      generally only be one application running on most end devices.      Interfaces between the NS and the application are not further      described here.   In LoRaWAN networks, end device transmissions may be received at   multiple Gateways, so, during nominal operation, a network server may   see multiple instances of the same uplink message from an end device.   The LoRaWAN network infrastructure manages the data rate and Radio   Frequency (RF) output power for each end device individually by means   of an Adaptive Data Rate (ADR) scheme.  End devices may transmit on   any channel allowed by local regulation at any time.   LoRaWAN radios make use of ISM bands, for example, 433 MHz and 868   MHz within the European Union and 915 MHz in the Americas.   The end device changes channels in a pseudorandom fashion for every   transmission to help make the system more robust to interference and/   or to conform to local regulations.Farrell                       Informational                     [Page 5]

RFC 8376                     LPWAN Overview                     May 2018   Figure 2 shows that after a transmission slot, a Class A device turns   on its receiver for two short receive windows that are offset from   the end of the transmission window.  End devices can only transmit a   subsequent uplink frame after the end of the associated receive   windows.  When a device joins a LoRaWAN network, there are similar   timeouts on parts of that process.   |----------------------------|         |--------|     |--------|   |             Tx             |         |   Rx   |     |   Rx   |   |----------------------------|         |--------|     |--------|                                |---------|                                 Rx delay 1                                |------------------------|                                 Rx delay 2        Figure 2: LoRaWAN Class A Transmission and Reception Window   Given the different regional requirements, the detailed specification   for the LoRaWAN Physical layer (PHY) (taking up more than 30 pages of   the specification) is not reproduced here.  Instead, and mainly to   illustrate the kinds of issue encountered, Table 1 presents some of   the default settings for one ISM band (without fully explaining those   here); Table 2 describes maxima and minima for some parameters of   interest to those defining ways to use IETF protocols over the   LoRaWAN MAC layer.   +-----------------------+-------------------------------------------+   |       Parameters      |               Default Value               |   +-----------------------+-------------------------------------------+   |       Rx delay 1      |                    1 s                    |   |                       |                                           |   |       Rx delay 2      |     2 s (must be RECEIVE_DELAY1 + 1 s)    |   |                       |                                           |   |      join delay 1     |                    5 s                    |   |                       |                                           |   |      join delay 2     |                    6 s                    |   |                       |                                           |   |     868MHz Default    |  3 (868.1,868.2,868.3), data rate: 0.3-50 |   |        channels       |                   kbit/s                  |   +-----------------------+-------------------------------------------+               Table 1: Default Settings for EU 868 MHz BandFarrell                       Informational                     [Page 6]

RFC 8376                     LPWAN Overview                     May 2018   +------------------------------------------------+--------+---------+   | Parameter/Notes                                |  Min   |   Max   |   +------------------------------------------------+--------+---------+   | Duty Cycle: some but not all ISM bands impose  |   1%   |    no   |   | a limit in terms of how often an end device    |        |  limit  |   | can transmit.  In some cases, LoRaWAN is more  |        |         |   | restrictive in an attempt to avoid congestion. |        |         |   |                                                |        |         |   | EU 868 MHz band data rate/frame size           |  250   |  50000  |   |                                                | bits/s |  bits/s |   |                                                |  : 59  |  : 250  |   |                                                | octets |  octets |   |                                                |        |         |   | US 915 MHz band data rate/frame size           |  980   |  21900  |   |                                                | bits/s |  bits/s |   |                                                |  : 19  |  : 250  |   |                                                | octets |  octets |   +------------------------------------------------+--------+---------+         Table 2: Minima and Maxima for Various LoRaWAN Parameters   Note that, in the case of the smallest frame size (19 octets), 8   octets are required for LoRa MAC layer headers, leaving only 11   octets for payload (including MAC layer options).  However, those   settings do not apply for the join procedure -- end devices are   required to use a channel and data rate that can send the 23-byte   Join-Request message for the join procedure.   Uplink and downlink higher-layer data is carried in a MACPayload.   There is a concept of "ports" (an optional 8-bit value) to handle   different applications on an end device.  Port zero is reserved for   LoRaWAN-specific messaging, such as the configuration of the end   device's network parameters (available channels, data rates, ADR   parameters, Rx Delay 1 and 2, etc.).   In addition to carrying higher-layer PDUs, there are Join-Request and   Join-Response (aka Join-Accept) messages for handling network access.   And so-called "MAC commands" (see below) up to 15 bytes long can be   piggybacked in an options field ("FOpts").   There are a number of MAC commands for link and device status   checking, ADR and duty cycle negotiation, and managing the RX windows   and radio channel settings.  For example, the link check response   message allows the NS (in response to a request from an end device)   to inform an end device about the signal attenuation seen most   recently at a Gateway and to tell the end device how many Gateways   received the corresponding link request MAC command.Farrell                       Informational                     [Page 7]

RFC 8376                     LPWAN Overview                     May 2018   Some MAC commands are initiated by the network server.  For example,   one command allows the network server to ask an end device to reduce   its duty cycle to only use a proportion of the maximum allowed in a   region.  Another allows the network server to query the end device's   power status with the response from the end device specifying whether   it has an external power source or is battery powered (in which case,   a relative battery level is also sent to the network server).   In order to operate nominally on a LoRaWAN network, a device needs a   32-bit device address, which is assigned when the device "joins" the   network (see below for the join procedure) or that is pre-provisioned   into the device.  In case of roaming devices, the device address is   assigned based on the 24-bit network identifier (NetID) that is   allocated to the network by the LoRa Alliance.  Non-roaming devices   can be assigned device addresses by the network without relying on a   NetID assigned by the LoRa Alliance.   End devices are assumed to work with one or quite a limited number of   applications, identified by a 64-bit AppEUI, which is assumed to be a   registered IEEE EUI64 value [EUI64].  In addition, a device needs to   have two symmetric session keys, one for protecting network artifacts   (port=0), the NwkSKey, and another for protecting application-layer   traffic, the AppSKey.  Both keys are used for 128-bit AES   cryptographic operations.  So, one option is for an end device to   have all of the above plus channel information, somehow   (pre-)provisioned; in that case, the end device can simply start   transmitting.  This is achievable in many cases via out-of-band means   given the nature of LoRaWAN networks.  Table 3 summarizes these   values.   +---------+---------------------------------------------------------+   | Value   | Description                                             |   +---------+---------------------------------------------------------+   | DevAddr | DevAddr (32 bits) =  device-specific network address    |   |         | generated from the NetID                                |   |         |                                                         |   | AppEUI  | IEEE EUI64 value corresponding to the join server for   |   |         | an application                                          |   |         |                                                         |   | NwkSKey | 128-bit network session key used with AES-CMAC          |   |         |                                                         |   | AppSKey | 128-bit application session key used with AES-CTR       |   |         |                                                         |   | AppKey  | 128-bit application session key used with AES-ECB       |   +---------+---------------------------------------------------------+              Table 3: Values Required for Nominal OperationFarrell                       Informational                     [Page 8]

RFC 8376                     LPWAN Overview                     May 2018   As an alternative, end devices can use the LoRaWAN join procedure   with a join server behind the NS in order to set up some of these   values and dynamically gain access to the network.  To use the join   procedure, an end device must still know the AppEUI and a different   (long-term) symmetric key that is bound to the AppEUI (this is the   application key (AppKey), and it is distinct from the application   session key (AppSKey)).  The AppKey is required to be specific to the   device; that is, each end device should have a different AppKey   value.  Finally, the end device also needs a long-term identifier for   itself, which is syntactically also an EUI-64 and is known as the   device EUI or DevEUI.  Table 4 summarizes these values.     +---------+----------------------------------------------------+     | Value   | Description                                        |     +---------+----------------------------------------------------+     | DevEUI  | IEEE EUI64 naming the device                       |     |         |                                                    |     | AppEUI  | IEEE EUI64 naming the application                  |     |         |                                                    |     | AppKey  | 128-bit long-term application key for use with AES |     +---------+----------------------------------------------------+                Table 4: Values Required for Join Procedure   The join procedure involves a special exchange where the end device   asserts the AppEUI and DevEUI (integrity protected with the long-term   AppKey, but not encrypted) in a Join-Request uplink message.  This is   then routed to the network server, which interacts with an entity   that knows that AppKey to verify the Join-Request.  If all is going   well, a Join-Accept downlink message is returned from the network   server to the end device.  That message specifies the 24-bit NetID,   32-bit DevAddr, and channel information and from which the AppSKey   and NwkSKey can be derived based on knowledge of the AppKey.  This   provides the end device with all the values listed in Table 3.   All payloads are encrypted and have data integrity.  MAC commands,   when sent as a payload (port zero), are therefore protected.   However, MAC commands piggybacked as frame options ("FOpts") are sent   in clear.  Any MAC commands sent as frame options and not only as   payload, are visible to a passive attacker, but they are not   malleable for an active attacker due to the use of the Message   Integrity Check (MIC) described below.   For LoRaWAN version 1.0.x, the NwkSKey session key is used to provide   data integrity between the end device and the network server.  The   AppSKey is used to provide data confidentiality between the end   device and network server, or to the application "behind" the network   server, depending on the implementation of the network.Farrell                       Informational                     [Page 9]

RFC 8376                     LPWAN Overview                     May 2018   All MAC-layer messages have an outer 32-bit MIC calculated using AES-   CMAC with the input being the ciphertext payload and other headers   and using the NwkSkey.  Payloads are encrypted using AES-128, with a   counter-mode derived from [IEEE.802.15.4] using the AppSKey.   Gateways are not expected to be provided with the AppSKey or NwkSKey,   all of the infrastructure-side cryptography happens in (or "behind")   the network server.  When session keys are derived from the AppKey as   a result of the join procedure, the Join-Accept message payload is   specially handled.   The long-term AppKey is directly used to protect the Join-Accept   message content, but the function used is not an AES-encrypt   operation, but rather an AES-decrypt operation.  The justification is   that this means that the end device only needs to implement the AES-   encrypt operation.  (The counter-mode variant used for payload   decryption means the end device doesn't need an AES-decrypt   primitive.)   The Join-Accept plaintext is always less than 16 bytes long, so   Electronic Code Book (ECB) mode is used for protecting Join-Accept   messages.  The Join-Accept message contains an AppNonce (a 24-bit   value) that is recovered on the end device along with the other Join-   Accept content (e.g., DevAddr) using the AES-encrypt operation.  Once   the Join-Accept payload is available to the end device, the session   keys are derived from the AppKey, AppNonce, and other values, again   using an ECB mode AES-encrypt operation, with the plaintext input   being a maximum of 16 octets.2.2.  Narrowband IoT (NB-IoT)2.2.1.  Provenance and Documents   Narrowband Internet of Things (NB-IoT) has been developed and   standardized by 3GPP.  The standardization of NB-IoT was finalized   with 3GPP Release 13 in June 2016, and further enhancements for   NB-IoT are specified in 3GPP Release 14 in 2017 (for example, in the   form of multicast support).  Further features and improvements will   be developed in the following releases, but NB-IoT has been ready to   be deployed since 2016; it is rather simple to deploy, especially in   the existing LTE networks with a software upgrade in the operator's   base stations.  For more information of what has been specified for   NB-IoT, 3GPP specification 36.300 [TGPP36300] provides an overview   and overall description of the Evolved Universal Terrestrial Radio   Access Network (E-UTRAN) radio interface protocol architecture, while   specifications 36.321 [TGPP36321], 36.322 [TGPP36322], 36.323   [TGPP36323], and 36.331 [TGPP36331] give more detailed descriptionsFarrell                       Informational                    [Page 10]

RFC 8376                     LPWAN Overview                     May 2018   of MAC, Radio Link Control (RLC), Packet Data Convergence Protocol   (PDCP), and Radio Resource Control (RRC) protocol layers,   respectively.  Note that the description below assumes familiarity   with numerous 3GPP terms.   For a general overview of NB-IoT, see [nbiot-ov].2.2.2.  Characteristics   Specific targets for NB-IoT include: module cost that is Less than US   $5, extended coverage of 164 dB maximum coupling loss, battery life   of over 10 years, ~55000 devices per cell, and uplink reporting   latency of less than 10 seconds.   NB-IoT supports Half Duplex Frequency Division Duplex (FDD) operation   mode with 60 kbit/s peak rate in uplink and 30 kbit/s peak rate in   downlink, and a Maximum Transmission Unit (MTU) size of 1600 bytes,   limited by PDCP layer (see Figure 4 for the protocol structure),   which is the highest layer in the user plane, as explained later.   Any packet size up to the said MTU size can be passed to the NB-IoT   stack from higher layers, segmentation of the packet is performed in   the RLC layer, which can segment the data to transmission blocks with   a size as small as 16 bits.  As the name suggests, NB-IoT uses   narrowbands with bandwidth of 180 kHz in both downlink and uplink.   The multiple access scheme used in the downlink is Orthogonal   Frequency-Division Multiplex (OFDMA) with 15 kHz sub-carrier spacing.   In uplink, Sub-Carrier Frequency-Division Multiplex (SC-FDMA) single   tone with either 15kHz or 3.75 kHz tone spacing is used, or   optionally multi-tone SC-FDMA can be used with 15 kHz tone spacing.   NB-IoT can be deployed in three ways.  In-band deployment means that   the narrowband is deployed inside the LTE band and radio resources   are flexibly shared between NB-IoT and normal LTE carrier.  In Guard-   band deployment, the narrowband uses the unused resource blocks   between two adjacent LTE carriers.  Standalone deployment is also   supported, where the narrowband can be located alone in dedicated   spectrum, which makes it possible, for example, to reframe a GSM   carrier at 850/900 MHz for NB-IoT.  All three deployment modes are   used in licensed frequency bands.  The maximum transmission power is   either 20 or 23 dBm for uplink transmissions, while for downlink   transmission the eNodeB may use higher transmission power, up to 46   dBm depending on the deployment.   A Maximum Coupling Loss (MCL) target for NB-IoT coverage enhancements   defined by 3GPP is 164 dB.  With this MCL, the performance of NB-IoT   in downlink varies between 200 bps and 2-3 kbit/s, depending on the   deployment mode.  Stand-alone operation may achieve the highest dataFarrell                       Informational                    [Page 11]

RFC 8376                     LPWAN Overview                     May 2018   rates, up to a few kbit/s, while in-band and guard-band operations   may reach several hundreds of bps.  NB-IoT may even operate with an   MCL higher than 170 dB with very low bit rates.   For signaling optimization, two options are introduced in addition to   the legacy LTE RRC connection setup; mandatory Data-over-NAS (Control   Plane optimization, solution 2 in [TGPP23720]) and optional RRC   Suspend/Resume (User Plane optimization, solution 18 in [TGPP23720]).   In the control-plane optimization, the data is sent over Non-Access   Stratum (NAS), directly to/from the Mobile Management Entity (MME)   (see Figure 3 for the network architecture) in the core network to   the User Equipment (UE) without interaction from the base station.   This means there is no Access Stratum security or header compression   provided by the PDCP layer in the eNodeB, as the Access Stratum is   bypassed, and only limited RRC procedures.  Header compression based   on Robust Header Compression (RoHC) may still optionally be provided   and terminated in the MME.   The RRC Suspend/Resume procedures reduce the signaling overhead   required for UE state transition from RRC Idle to RRC Connected mode   compared to a legacy LTE operation in order to have quicker user-   plane transaction with the network and return to RRC Idle mode   faster.   In order to prolong device battery life, both Power-Saving Mode (PSM)   and extended DRX (eDRX) are available to NB-IoT.  With eDRX, the RRC   Connected mode DRX cycle is up to 10.24 seconds; in RRC Idle, the   eDRX cycle can be up to 3 hours.  In PSM, the device is in a deep   sleep state and only wakes up for uplink reporting.  After the   reporting, there is a window (configured by the network) during which   the device receiver is open for downlink connectivity or for   periodical "keep-alive" signaling (PSM uses periodic TAU signaling   with additional reception windows for downlink reachability).   Since NB-IoT operates in a licensed spectrum, it has no channel   access restrictions allowing up to a 100% duty cycle.   3GPP access security is specified in [TGPP33203].Farrell                       Informational                    [Page 12]

RFC 8376                     LPWAN Overview                     May 2018   +--+   |UE| \                 +------+      +------+   +--+  \                | MME  |------| HSS  |          \             / +------+      +------+   +--+    \+--------+ /      |   |UE| ----| eNodeB |-       |   +--+    /+--------+ \      |          /             \ +--------+         /               \|        |    +------+     Service Packet   +--+ /                 |  S-GW  |----| P-GW |---- Data Network (PDN)   |UE|                   |        |    +------+     e.g., Internet   +--+                   +--------+                    Figure 3: 3GPP Network Architecture   Figure 3 shows the 3GPP network architecture, which applies to   NB-IoT.  The MME is responsible for handling the mobility of the UE.   The MME tasks include tracking and paging UEs, session management,   choosing the Serving Gateway for the UE during initial attachment and   authenticating the user.  At the MME, the NAS signaling from the UE   is terminated.   The Serving Gateway (S-GW) routes and forwards the user data packets   through the access network and acts as a mobility anchor for UEs   during handover between base stations known as eNodeBs and also   during handovers between NB-IoT and other 3GPP technologies.   The Packet Data Network Gateway (P-GW) works as an interface between   the 3GPP network and external networks.   The Home Subscriber Server (HSS) contains user-related and   subscription-related information.  It is a database that performs   mobility management, session-establishment support, user   authentication, and access authorization.   E-UTRAN consists of components of a single type, eNodeB. eNodeB is a   base station that controls the UEs in one or several cells.   The 3GPP radio protocol architecture is illustrated in Figure 4.Farrell                       Informational                    [Page 13]

RFC 8376                     LPWAN Overview                     May 2018   +---------+                                       +---------+   | NAS     |----|-----------------------------|----| NAS     |   +---------+    |    +---------+---------+    |    +---------+   | RRC     |----|----| RRC     | S1-AP   |----|----| S1-AP   |   +---------+    |    +---------+---------+    |    +---------+   | PDCP    |----|----| PDCP    | SCTP    |----|----| SCTP    |   +---------+    |    +---------+---------+    |    +---------+   | RLC     |----|----| RLC     | IP      |----|----| IP      |   +---------+    |    +---------+---------+    |    +---------+   | MAC     |----|----| MAC     | L2      |----|----| L2      |   +---------+    |    +---------+---------+    |    +---------+   | PHY     |----|----| PHY     | PHY     |----|----| PHY     |   +---------+         +---------+---------+         +---------+               LTE-Uu                         S1-MME       UE                     eNodeB                     MME     Figure 4: 3GPP Radio Protocol Architecture for the Control Plane   The radio protocol architecture of NB-IoT (and LTE) is separated into   the control plane and the user plane.  The control plane consists of   protocols that control the radio-access bearers and the connection   between the UE and the network.  The highest layer of control plane   is called the Non-Access Stratum (NAS), which conveys the radio   signaling between the UE and the Evolved Packet Core (EPC), passing   transparently through the radio network.  The NAS is responsible for   authentication, security control, mobility management, and bearer   management.   The Access Stratum (AS) is the functional layer below the NAS; in the   control plane, it consists of the Radio Resource Control (RRC)   protocol [TGPP36331], which handles connection establishment and   release functions, broadcast of system information, radio-bearer   establishment, reconfiguration, and release.  The RRC configures the   user and control planes according to the network status.  There exist   two RRC states, RRC_Idle or RRC_Connected, and the RRC entity   controls the switching between these states.  In RRC_Idle, the   network knows that the UE is present in the network, and the UE can   be reached in case of an incoming call/downlink data.  In this state,   the UE monitors paging, performs cell measurements and cell   selection, and acquires system information.  Also, the UE can receive   broadcast and multicast data, but it is not expected to transmit or   receive unicast data.  In RRC_Connected state, the UE has a   connection to the eNodeB, the network knows the UE location on the   cell level, and the UE may receive and transmit unicast data.  An RRC   connection is established when the UE is expected to be active in the   network, to transmit or receive data.  The RRC connection is   released, switching back to RRC_Idle, when there is no more traffic;   this is in order to preserve UE battery life and radio resources.Farrell                       Informational                    [Page 14]

RFC 8376                     LPWAN Overview                     May 2018   However, as mentioned earlier, a new feature was introduced for   NB-IoT that allows data to be transmitted from the MME directly to   the UE and then transparently to the eNodeB, thus bypassing AS   functions.   The PDCP's [TGPP36323] main services in the control plane are   transfer of control-plane data, ciphering, and integrity protection.   The RLC protocol [TGPP36322] performs transfer of upper-layer PDUs   and, optionally, error correction with Automatic Repeat reQuest   (ARQ), concatenation, segmentation, and reassembly of RLC Service   Data Units (SDUs), in-sequence delivery of upper-layer PDUs,   duplicate detection, RLC SDU discarding, RLC-re-establishment, and   protocol error detection and recovery.   The MAC protocol [TGPP36321] provides mapping between logical   channels and transport channels, multiplexing of MAC SDUs, scheduling   information reporting, error correction with Hybrid ARQ (HARQ),   priority handling, and transport format selection.   The PHY [TGPP36201] provides data-transport services to higher   layers.  These include error detection and indication to higher   layers, Forward Error Correction (FEC) encoding, HARQ soft-combining,   rate-matching, mapping of the transport channels onto physical   channels, power-weighting and modulation of physical channels,   frequency and time synchronization, and radio characteristics   measurements.   The user plane is responsible for transferring the user data through   the Access Stratum.  It interfaces with IP and the highest layer of   the user plane is the PDCP, which, in the user plane, performs header   compression using RoHC, transfer of user-plane data between eNodeB   and the UE, ciphering, and integrity protection.  Similar to the   control plane, lower layers in the user plane include RLC, MAC, and   the PHY performing the same tasks as they do in the control plane.2.3.  Sigfox2.3.1.  Provenance and Documents   The Sigfox LPWAN is in line with the terminology and specifications   being defined by ETSI [etsi_unb].  As of today, Sigfox's network has   been fully deployed in 12 countries, with ongoing deployments in 26   other countries, giving in total a geography of 2 million square   kilometers, containing 512 million people.Farrell                       Informational                    [Page 15]

RFC 8376                     LPWAN Overview                     May 20182.3.2.  Characteristics   Sigfox LPWAN autonomous battery-operated devices send only a few   bytes per day, week, or month, in principle, allowing them to remain   on a single battery for up to 10-15 years.  Hence, the system is   designed as to allow devices to last several years, sometimes even   buried underground.   Since the radio protocol is connectionless and optimized for uplink   communications, the capacity of a Sigfox base station depends on the   number of messages generated by devices, and not on the actual number   of devices.  Likewise, the battery life of devices depends on the   number of messages generated by the device.  Depending on the use   case, devices can vary from sending less than one message per device   per day to dozens of messages per device per day.   The coverage of the cell depends on the link budget and on the type   of deployment (urban, rural, etc.).  The radio interface is compliant   with the following regulations:      Spectrum allocation in the USA [fcc_ref]      Spectrum allocation in Europe [etsi_ref1] [etsi_ref2]      Spectrum allocation in Japan [arib_ref]   The Sigfox radio interface is also compliant with the local   regulations of the following countries: Australia, Brazil, Canada,   Kenya, Lebanon, Mauritius, Mexico, New Zealand, Oman, Peru,   Singapore, South Africa, South Korea, and Thailand.   The radio interface is based on Ultra Narrow Band (UNB)   communications, which allow an increased transmission range by   spending a limited amount of energy at the device.  Moreover, UNB   allows a large number of devices to coexist in a given cell without   significantly increasing the spectrum interference.   Both uplink and downlink are supported, although the system is   optimized for uplink communications.  Due to spectrum optimizations,   different uplink and downlink frames and time synchronization methods   are needed.   The main radio characteristics of the UNB uplink transmission are:   o  Channelization mask: 100 Hz / 600 Hz (depending on the region)   o  Uplink baud rate: 100 baud / 600 baud (depending on the region)Farrell                       Informational                    [Page 16]

RFC 8376                     LPWAN Overview                     May 2018   o  Modulation scheme: DBPSK   o  Uplink transmission power: compliant with local regulation   o  Link budget: 155 dB (or better)   o  Central frequency accuracy: not relevant, provided there is no      significant frequency drift within an uplink packet transmission   For example, in Europe, the UNB uplink frequency band is limited to   868.00 to 868.60 MHz, with a maximum output power of 25 mW and a duty   cycle of 1%.   The format of the uplink frame is the following:   +--------+--------+--------+------------------+-------------+-----+   |Preamble|  Frame | Dev ID |     Payload      |Msg Auth Code| FCS |   |        |  Sync  |        |                  |             |     |   +--------+--------+--------+------------------+-------------+-----+                       Figure 5: Uplink Frame Format   The uplink frame is composed of the following fields:   o  Preamble: 19 bits   o  Frame sync and header: 29 bits   o  Device ID: 32 bits   o  Payload: 0-96 bits   o  Authentication: 16-40 bits   o  Frame check sequence: 16 bits (Cyclic Redundancy Check (CRC))   The main radio characteristics of the UNB downlink transmission are:   o  Channelization mask: 1.5 kHz   o  Downlink baud rate: 600 baud   o  Modulation scheme: GFSK   o  Downlink transmission power: 500 mW / 4W (depending on the region)   o  Link budget: 153 dB (or better)Farrell                       Informational                    [Page 17]

RFC 8376                     LPWAN Overview                     May 2018   o  Central frequency accuracy: the center frequency of downlink      transmission is set by the network according to the corresponding      uplink transmission.   For example, in Europe, the UNB downlink frequency band is limited to   869.40 to 869.65 MHz, with a maximum output power of 500 mW with 10%   duty cycle.   The format of the downlink frame is the following:   +------------+-----+---------+------------------+-------------+-----+   |  Preamble  |Frame|   ECC   |     Payload      |Msg Auth Code| FCS |   |            |Sync |         |                  |             |     |   +------------+-----+---------+------------------+-------------+-----+                      Figure 6: Downlink Frame Format   The downlink frame is composed of the following fields:   o  Preamble: 91 bits   o  Frame sync and header: 13 bits   o  Error Correcting Code (ECC): 32 bits   o  Payload: 0-64 bits   o  Authentication: 16 bits   o  Frame check sequence: 8 bits (CRC)   The radio interface is optimized for uplink transmissions, which are   asynchronous.  Downlink communications are achieved by devices   querying the network for available data.   A device willing to receive downlink messages opens a fixed window   for reception after sending an uplink transmission.  The delay and   duration of this window have fixed values.  The network transmits the   downlink message for a given device during the reception window, and   the network also selects the BS for transmitting the corresponding   downlink message.   Uplink and downlink transmissions are unbalanced due to the   regulatory constraints on ISM bands.  Under the strictest   regulations, the system can allow a maximum of 140 uplink messagesFarrell                       Informational                    [Page 18]

RFC 8376                     LPWAN Overview                     May 2018   and 4 downlink messages per device per day.  These restrictions can   be slightly relaxed depending on system conditions and the specific   regulatory domain of operation.                +---+                |DEV| *                    +------+                +---+   *                  |  RA  |                          *                +------+                +---+       *                 |                |DEV| * * *   *               |                +---+       *   +----+        |                              * | BS | \  +--------+                +---+       *   +----+  \ |        |        DA -----|DEV| * * *               |   SC   |----- NA                +---+       *           / |        |                              * +----+ /  +--------+                +---+       *   | BS |/                |DEV| * * *   * +----+                +---+         *                            *                +---+     *                |DEV| * *                +---+                   Figure 7: Sigfox Network Architecture   Figure 7 depicts the different elements of the Sigfox network   architecture.   Sigfox has a "one-contract one-network" model allowing devices to   connect in any country, without any need or notion of either roaming   or handover.   The architecture consists of a single cloud-based core network, which   allows global connectivity with minimal impact on the end device and   radio access network.  The core network elements are the Service   Center (SC) and the Registration Authority (RA).  The SC is in charge   of the data connectivity between the BS and the Internet, as well as   the control and management of the BSs and End Points (EPs).  The RA   is in charge of the EP network access authorization.   The radio access network is comprised of several BSs connected   directly to the SC.  Each BS performs complex L1/L2 functions,   leaving some L2 and L3 functionalities to the SC.   The Devices (DEVs) or EPs are the objects that communicate   application data between local Device Applications (DAs) and Network   Applications (NAs).Farrell                       Informational                    [Page 19]

RFC 8376                     LPWAN Overview                     May 2018   Devices (or EPs) can be static or nomadic, as they associate with the   SC and they do not attach to any specific BS.  Hence, they can   communicate with the SC through one or multiple BSs.   Due to constraints in the complexity of the Device, it is assumed   that Devices host only one or very few device applications, which   most of the time communicate each to a single network application at   a time.   The radio protocol authenticates and ensures the integrity of each   message.  This is achieved by using a unique device ID and an   AES-128-based message authentication code, ensuring that the message   has been generated and sent by the device with the ID claimed in the   message.  Application data can be encrypted at the application level   or not, depending on the criticality of the use case, to provide a   balance between cost and effort versus risk.  AES-128 in counter mode   is used for encryption.  Cryptographic keys are independent for each   device.  These keys are associated with the device ID and separate   integrity and confidentiality keys are pre-provisioned.  A   confidentiality key is only provisioned if confidentiality is to be   used.  At the time of writing, the algorithms and keying details for   this are not published.2.4.  Wi-SUN Alliance Field Area Network (FAN)   Text here is via personal communication from Bob Heile   (bheile@ieee.org) and was authored by Bob and Sum Chin Sean.  Paul   Duffy (paduffy@cisco.com) also provided additional comments/input on   this section.2.4.1.  Provenance and Documents   The Wi-SUN Alliance <https://www.wi-sun.org/> is an industry alliance   for smart city, smart grid, smart utility, and a broad set of general   IoT applications.  The Wi-SUN Alliance Field Area Network (FAN)   profile is open-standards based (primarily on IETF and IEEE 802   standards) and was developed to address applications like smart   municipality/city infrastructure monitoring and management, Electric   Vehicle (EV) infrastructure, Advanced Metering Infrastructure (AMI),   Distribution Automation (DA), Supervisory Control and Data   Acquisition (SCADA) protection/management, distributed generation   monitoring and management, and many more IoT applications.   Additionally, the Alliance has created a certification program to   promote global multi-vendor interoperability.   The FAN profile is specified within ANSI/TIA as an extension of work   previously done on Smart Utility Networks [ANSI-4957-000].  Updates   to those specifications intended to be published in 2017 will containFarrell                       Informational                    [Page 20]

RFC 8376                     LPWAN Overview                     May 2018   details of the FAN profile.  A current snapshot of the work to   produce that profile is presented in [wisun-pressie1] and   [wisun-pressie2].2.4.2.  Characteristics   The FAN profile is an IPv6 wireless mesh network with support for   enterprise-level security.  The frequency-hopping wireless mesh   topology aims to offer superior network robustness, reliability due   to high redundancy, good scalability due to the flexible mesh   configuration, and good resilience to interference.  Very low power   modes are in development permitting long-term battery operation of   network nodes.   The following list contains some overall characteristics of Wi-SUN   that are relevant to LPWAN applications.   o  Coverage: The range of Wi-SUN FAN is typically 2 - 3 km in line of      sight, matching the needs of neighborhood area networks, campus      area networks, or corporate area networks.  The range can also be      extended via multi-hop networking.   o  High-bandwidth, low-link latency: Wi-SUN supports relatively high      bandwidth, i.e., up to 300 kbit/s [FANOV], enables remote update      and upgrade of devices so that they can handle new applications,      extending their working life.  Wi-SUN supports LPWAN IoT      applications that require on-demand control by providing low link      latency (0.02 s) and bidirectional communication.   o  Low-power consumption: FAN devices draw less than 2 uA when      resting and only 8 mA when listening.  Such devices can maintain a      long lifetime, even if they are frequently listening.  For      instance, suppose the device transmits data for 10 ms once every      10 s; theoretically, a battery of 1000 mAh can last more than 10      years.   o  Scalability: Tens of millions of Wi-SUN FAN devices have been      deployed in urban, suburban, and rural environments, including      deployments with more than 1 million devices.   A FAN contains one or more networks.  Within a network, nodes assume   one of three operational roles.  First, each network contains a   Border Router providing WAN connectivity to the network.  The Border   Router maintains source-routing tables for all nodes within its   network, provides node authentication and key management services,   and disseminates network-wide information such as broadcast   schedules.  Second, Router nodes, which provide upward and downward   packet forwarding (within a network).  A Router also providesFarrell                       Informational                    [Page 21]

RFC 8376                     LPWAN Overview                     May 2018   services for relaying security and address management protocols.   Finally, Leaf nodes provide minimum capabilities: discovering and   joining a network, sending/receiving IPv6 packets, etc.  A low-power   network may contain a mesh topology with Routers at the edges that   construct a star topology with Leaf nodes.   The FAN profile is based on various open standards developed by the   IETF (including [RFC768], [RFC2460], [RFC4443], and [RFC6282]).   Related IEEE 802 standards include [IEEE.802.15.4] and   [IEEE.802.15.9].  For Low-Power and Lossy Networks (LLNs), see ANSI/   TIA [ANSI-4957-210].   The FAN profile specification provides an application-independent   IPv6-based transport service.  There are two possible methods for   establishing IPv6 packet routing: the Routing Protocol for Low-Power   and Lossy Networks (RPL) at the Network layer is mandatory, and   Multi-Hop Delivery Service (MHDS) is optional at the Data Link layer.   Figure 8 provides an overview of the FAN network stack.   The Transport service is based on UDP (defined in [RFC768]) or TCP   (defined in [RFC793].   The Network service is provided by IPv6 as defined in [RFC2460] with   an IPv6 over Low-Power Wireless Personal Area Networks (6LoWPAN)   adaptation as defined in [RFC4944] and [RFC6282].  ICMPv6, as defined   in [RFC4443], is used for the control plane during information   exchange.   The Data Link service provides both control/management of the PHY and   data transfer/management services to the Network layer.  These   services are divided into MAC and Logical Link Control (LLC) sub-   layers.  The LLC sub-layer provides a protocol dispatch service that   supports 6LoWPAN and an optional MAC sub-layer mesh service.  The MAC   sub-layer is constructed using data structures defined in   [IEEE.802.15.4].  Multiple modes of frequency hopping are defined.   The entire MAC payload is encapsulated in an [IEEE.802.15.9]   Information Element to enable LLC protocol dispatch between upper-   layer 6LoWPAN processing and MAC sub-layer mesh processing, etc.   These areas will be expanded once [IEEE.802.15.12] is completed.   The PHY service is derived from a subset of the SUN FSK specification   in [IEEE.802.15.4].  The 2-FSK modulation schemes, with a channel-   spacing range from 200 to 600 kHz, are defined to provide data rates   from 50 to 300 kbit/s, with FEC as an optional feature.  Towards   enabling ultra-low-power applications, the PHY layer design is also   extendable to low-energy and critical infrastructure-monitoring   networks.Farrell                       Informational                    [Page 22]

RFC 8376                     LPWAN Overview                     May 2018   +----------------------+--------------------------------------------+   | Layer                | Description                                |   +----------------------+--------------------------------------------+   | IPv6 protocol suite  | TCP/UDP                                    |   |                      |                                            |   |                      | 6LoWPAN Adaptation + Header Compression    |   |                      |                                            |   |                      | DHCPv6 for IP address management           |   |                      |                                            |   |                      | Routing using RPL                          |   |                      |                                            |   |                      | ICMPv6                                     |   |                      |                                            |   |                      | Unicast and Multicast forwarding           |   +----------------------+--------------------------------------------+   | MAC based on         | Frequency hopping                          |   | [IEEE.802.15.4e] +   |                                            |   | IE extensions        | Discovery and Join                         |   |                      |                                            |   |                      | Protocol Dispatch ([IEEE.802.15.9])        |   |                      |                                            |   |                      | Several Frame Exchange patterns            |   |                      |                                            |   |                      | Optional Mesh Under routing                |   |                      | ([ANSI-4957-210])                          |   +----------------------+--------------------------------------------+   | PHY based on         | Various data rates and regions             |   | [IEEE.802.15.4g]     |                                            |   +----------------------+--------------------------------------------+   | Security             | [IEEE.802.1x]/EAP-TLS/PKI Authentication   |   |                      | TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8         |   |                      | required for EAP-TLS                       |   |                      |                                            |   |                      | 802.11i Group Key Management               |   |                      |                                            |   |                      | Frame security is implemented as AES-CCM*  |   |                      | as specified in [IEEE.802.15.4]            |   |                      |                                            |   |                      | Optional [ETSI-TS-102-887-2] Node 2 Node   |   |                      | Key Management                             |   +----------------------+--------------------------------------------+                      Figure 8: Wi-SUN Stack OverviewFarrell                       Informational                    [Page 23]

RFC 8376                     LPWAN Overview                     May 2018   The FAN security supports Data Link layer network access control,   mutual authentication, and establishment of a secure pairwise link   between a FAN node and its Border Router, which is implemented with   an adaptation of [IEEE.802.1x] and EAP-TLS as described in [RFC5216]   using secure device identity as described in [IEEE.802.1AR].   Certificate formats are based upon [RFC5280].  A secure group link   between a Border Router and a set of FAN nodes is established using   an adaptation of the [IEEE.802.11] Four-Way Handshake.  A set of four   group keys are maintained within the network, one of which is the   current transmit key.  Secure node-to-node links are supported   between one-hop FAN neighbors using an adaptation of   [ETSI-TS-102-887-2].  FAN nodes implement Frame Security as specified   in [IEEE.802.15.4].3.  Generic Terminology   LPWAN technologies, such as those discussed above, have similar   architectures but different terminology.  We can identify different   types of entities in a typical LPWAN network:   o  End devices are the devices or the "things" (e.g., sensors,      actuators, etc.); they are named differently in each technology      (End Device, User Equipment, or EP).  There can be a high density      of end devices per Radio Gateway.   o  The Radio Gateway, which is the EP of the constrained link.  It is      known as: Gateway, Evolved Node B or base station.   o  The Network Gateway or Router is the interconnection node between      the Radio Gateway and the Internet.  It is known as the Network      Server, Serving GW, or Service Center.   o  LPWAN-AAA server, which controls user authentication.  It is known      as the Join-Server, Home Subscriber Server, or Registration      Authority.  (We use the term LPWAN-AAA server because we're not      assuming that this entity speaks RADIUS or Diameter as many/most      AAA servers do; but, equally, we don't want to rule that out, as      the functionality will be similar.)   o  At last we have the Application Server, known also as Packet Data      Node Gateway or Network Application.Farrell                       Informational                    [Page 24]

RFC 8376                     LPWAN Overview                     May 2018 +---------------------------------------------------------------------+ | Function/ |           |           |            |        |           | |Technology |  LoRaWAN  |   NB-IoT  |   Sigfox   | Wi-SUN |    IETF   | +-----------+-----------+-----------+------------+--------+-----------+ |Sensor,    |           |           |            |        |           | |Actuator,  |    End    |    User   |     End    |  Leaf  |   Device  | |device,    |  Device   | Equipment |    Point   |  Node  |   (DEV)   | |object     |           |           |            |        |           | +-----------+-----------+-----------+------------+--------+-----------+ |Transceiver|           |  Evolved  |    Base    | Router |   Radio   | |Antenna    |  Gateway  |  Node B   |   Station  |  Node  |  Gateway  | +-----------+-----------+-----------+------------+--------+-----------+ |Server     |  Network  |  PDN GW/  |   Service  | Border |  Network  | |           |  Server   |   SCEF*   |   Center   | Router |  Gateway  | |           |           |           |            |        |   (NGW)   | +-----------+-----------+-----------+------------+--------+-----------+ |Security   |   Join    |    Home   |Registration|Authent.|  LPWAN-   | |Server     |  Server   | Subscriber| Authority  | Server |   AAA     | |           |           |   Server  |            |        |  Server   | +-----------+-----------+-----------+------------+--------+-----------+ |Application|Application|Application|  Network   |Appli-  |Application| |           |   Server  |  Server   | Application| cation |   (App)   | +---------------------------------------------------------------------+ * SCEF = Service Capability Exposure Function                 Figure 9: LPWAN Architecture Terminology                                                 +------+ ()    ()   ()         |                         |LPWAN-|   ()  () () ()       / \         +---------+    | AAA  |() () () () () ()    /   \========|    /\   |====|Server|  +-----------+ ()  ()   ()        |             | <--|--> |    +------+  |APPLICATION|()  ()  ()  ()     / \============|    v    |==============|    (App)  |  ()  ()  ()      /   \           +---------+              +-----------+ DEV         Radio Gateways           NGW                       Figure 10: LPWAN Architecture   In addition to the names of entities, LPWANs are also subject to   possibly regional frequency-band regulations.  Those may include   restrictions on the duty cycle, for example, requiring that hosts   only transmit for a certain percentage of each hour.Farrell                       Informational                    [Page 25]

RFC 8376                     LPWAN Overview                     May 20184.  Gap Analysis   This section considers some of the gaps between current LPWAN   technologies and the goals of the LPWAN WG.  Many of the generic   considerations described in [RFC7452] will also apply in LPWANs, as   end devices can also be considered to be a subclass of (so-called)   "smart objects".  In addition, LPWAN device implementers will also   need to consider the issues relating to firmware updates described in   [RFC8240].4.1.  Naive Application of IPv6   IPv6 [RFC8200] has been designed to allocate addresses to all the   nodes connected to the Internet.  Nevertheless, the header overhead   of at least 40 bytes introduced by the protocol is incompatible with   LPWAN constraints.  If IPv6 with no further optimization were used,   several LPWAN frames could be needed just to carry the IP header.   Another problem arises from IPv6 MTU requirements, which require the   layer below to support at least 1280 byte packets [RFC2460].   IPv6 has a configuration protocol: Neighbor Discovery Protocol (NDP)   [RFC4861]).  For a node to learn network parameters, NDP generates   regular traffic with a relatively large message size that does not   fit LPWAN constraints.   In some LPWAN technologies, L2 multicast is not supported.  In that   case, if the network topology is a star, the solution and   considerations fromSection 3.2.5 of [RFC7668] may be applied.   Other key protocols (such as DHCPv6 [RFC3315], IPsec [RFC4301] and   TLS [RFC5246]) have similarly problematic properties in this context.   Each protocol requires relatively frequent round-trips between the   host and some other host on the network.  In the case of   cryptographic protocols (such as IPsec and TLS), in addition to the   round-trips required for secure session establishment, cryptographic   operations can require padding and addition of authenticators that   are problematic when considering LPWAN lower layers.  Note that mains   powered Wi-SUN mesh router nodes will typically be more resource   capable than the other LPWAN technologies discussed.  This can enable   use of more "chatty" protocols for some aspects of Wi-SUN.4.2.  6LoWPAN   Several technologies that exhibit significant constraints in various   dimensions have exploited the 6LoWPAN suite of specifications   ([RFC4944], [RFC6282], and [RFC6775]) to support IPv6 [USES-6LO].   However, the constraints of LPWANs, often more extreme than those   typical of technologies that have (re-)used 6LoWPAN, constitute aFarrell                       Informational                    [Page 26]

RFC 8376                     LPWAN Overview                     May 2018   challenge for the 6LoWPAN suite in order to enable IPv6 over LPWAN.   LPWANs are characterized by device constraints (in terms of   processing capacity, memory, and energy availability), and   especially, link constraints, such as:   o  tiny L2 payload size (from ~10 to ~100 bytes),   o  very low bit rate (from ~10 bit/s to ~100 kbit/s), and   o  in some specific technologies, further message rate constraints      (e.g., between ~0.1 message/minute and ~1 message/minute) due to      regional regulations that limit the duty cycle.4.2.1.  Header Compression   6LoWPAN header compression reduces IPv6 (and UDP) header overhead by   eliding header fields when they can be derived from the link layer   and by assuming that some of the header fields will frequently carry   expected values. 6LoWPAN provides both stateless and stateful header   compression.  In the latter, all nodes of a 6LoWPAN are assumed to   share compression context.  In the best case, the IPv6 header for   link-local communication can be reduced to only 2 bytes.  For global   communication, the IPv6 header may be compressed down to 3 bytes in   the most extreme case.  However, in more practical situations, the   smallest IPv6 header size may be 11 bytes (one address prefix   compressed) or 19 bytes (both source and destination prefixes   compressed).  These headers are large considering the link-layer   payload size of LPWAN technologies, and in some cases, are even   bigger than the LPWAN PDUs. 6LoWPAN was initially designed for   [IEEE.802.15.4] networks with a frame size up to 127 bytes and a   throughput of up to 250 kbit/s, which may or may not be duty cycled.4.2.2.  Address Autoconfiguration   Traditionally, Interface Identifiers (IIDs) have been derived from   link-layer identifiers [RFC4944].  This allows optimizations such as   header compression.  Nevertheless, recent guidance has given advice   on the fact that, due to privacy concerns, 6LoWPAN devices should not   be configured to embed their link-layer addresses in the IID by   default.  [RFC8065] provides guidance on better methods for   generating IIDs.4.2.3.  Fragmentation   As stated above, IPv6 requires the layer below to support an MTU of   1280 bytes [RFC8200].  Therefore, given the low maximum payload size   of LPWAN technologies, fragmentation is needed.Farrell                       Informational                    [Page 27]

RFC 8376                     LPWAN Overview                     May 2018   If a layer of an LPWAN technology supports fragmentation, proper   analysis has to be carried out to decide whether the fragmentation   functionality provided by the lower layer or fragmentation at the   adaptation layer should be used.  Otherwise, fragmentation   functionality shall be used at the adaptation layer.   6LoWPAN defined a fragmentation mechanism and a fragmentation header   to support the transmission of IPv6 packets over IEEE.802.15.4   networks [RFC4944].  While the 6LoWPAN fragmentation header is   appropriate for the 2003 version of [IEEE.802.15.4] (which has a   frame payload size of 81-102 bytes), it is not suitable for several   LPWAN technologies, many of which have a maximum payload size that is   one order of magnitude below that of the 2003 version of   [IEEE.802.15.4].  The overhead of the 6LoWPAN fragmentation header is   high, considering the reduced payload size of LPWAN technologies, and   the limited energy availability of the devices using such   technologies.  Furthermore, its datagram offset field is expressed in   increments of eight octets.  In some LPWAN technologies, the 6LoWPAN   fragmentation header plus eight octets from the original datagram   exceeds the available space in the layer two payload.  In addition,   the MTU in the LPWAN networks could be variable, which implies a   variable fragmentation solution.4.2.4.  Neighbor Discovery   6LoWPAN Neighbor Discovery [RFC6775] defines optimizations to IPv6 ND   [RFC4861], in order to adapt functionality of the latter for networks   of devices using [IEEE.802.15.4] or similar technologies.  The   optimizations comprise host-initiated interactions to allow for   sleeping hosts, replacement of multicast-based address resolution for   hosts by an address registration mechanism, multihop extensions for   prefix distribution and duplicate address detection (note that these   are not needed in a star topology network), and support for 6LoWPAN   header compression.   6LoWPAN ND may be used in not so severely constrained LPWAN networks.   The relative overhead incurred will depend on the LPWAN technology   used (and on its configuration, if appropriate).  In certain LPWAN   setups (with a maximum payload size above ~60 bytes and duty-cycle-   free or equivalent operation), an RS/RA/NS/NA exchange may be   completed in a few seconds, without incurring packet fragmentation.   In other LPWANs (with a maximum payload size of ~10 bytes and a   message rate of ~0.1 message/minute), the same exchange may take   hours or even days, leading to severe fragmentation and consuming a   significant amount of the available network resources.  6LoWPAN ND   behavior may be tuned through the use of appropriate values for the   default Router Lifetime, the Valid Lifetime in the PIOs, and theFarrell                       Informational                    [Page 28]

RFC 8376                     LPWAN Overview                     May 2018   Valid Lifetime in the 6LoWPAN Context Option (6CO), as well as the   address Registration Lifetime.  However, for the latter LPWANs   mentioned above, 6LoWPAN ND is not suitable.4.3.  6lo   The 6lo WG has been reusing and adapting 6LoWPAN to enable IPv6   support over link-layer technologies such as Bluetooth Low Energy   (BTLE), ITU-T G.9959 [G9959], Digital Enhanced Cordless   Telecommunications (DECT) Ultra Low Energy (ULE), MS/TP-RS485, Near   Field Communication (NFC) IEEE 802.11ah.  (See   <https://datatracker.ietf.org/wg/6lo/> for details on the 6lo WG.)   These technologies are similar in several aspects to [IEEE.802.15.4],   which was the original 6LoWPAN target technology.   6lo has mostly used the subset of 6LoWPAN techniques best suited for   each lower-layer technology and has provided additional optimizations   for technologies where the star topology is used, such as BTLE or   DECT-ULE.   The main constraint in these networks comes from the nature of the   devices (constrained devices); whereas, in LPWANs, it is the network   itself that imposes the most stringent constraints.4.4.  6tisch   The IPv6 over the TSCH mode of IEEE 802.15.4e (6tisch) solution is   dedicated to mesh networks that operate using [IEEE.802.15.4e] MAC   with a deterministic slotted channel.  Time-Slotted Channel Hopping   (TSCH) can help to reduce collisions and to enable a better balance   over the channels.  It improves the battery life by avoiding the idle   listening time for the return channel.   A key element of 6tisch is the use of synchronization to enable   determinism.  TSCH and 6tisch may provide a standard scheduling   function.  The LPWAN networks probably will not support   synchronization like the one used in 6tisch.4.5.  RoHC   RoHC is a header compression mechanism [RFC3095] developed for   multimedia flows in a point-to-point channel.  RoHC uses three levels   of compression, each level having its own header format.  In the   first level, RoHC sends 52 bytes of header; in the second level, the   header could be from 34 to 15 bytes; and in the third level, header   size could be from 7 to 2 bytes.  The level of compression is managed   by a Sequence Number (SN), which varies in size from 2 bytes to 4   bits in the minimal compression.  SN compression is done with anFarrell                       Informational                    [Page 29]

RFC 8376                     LPWAN Overview                     May 2018   algorithm called Window-Least Significant Bits (W-LSB).  This window   has a 4-bit size representing 15 packets, so every 15 packets, RoHC   needs to slide the window in order to receive the correct SN, and   sliding the window implies a reduction of the level of compression.   When packets are lost or errored, the decompressor loses context and   drops packets until a bigger header is sent with more complete   information.  To estimate the performance of RoHC, an average header   size is used.  This average depends on the transmission conditions,   but most of the time is between 3 and 4 bytes.   RoHC has not been adapted specifically to the constrained hosts and   networks of LPWANs: it does not take into account energy limitations   nor the transmission rate.  Additionally, RoHC context is   synchronized during transmission, which does not allow better   compression.4.6.  ROLL   Most technologies considered by the LPWAN WG are based on a star   topology, which eliminates the need for routing at that layer.   Future work may address additional use cases that may require   adaptation of existing routing protocols or the definition of new   ones.  As of the time of writing, work similar to that done in the   Routing Over Low-Power and Lossy Network (ROLL) WG and other routing   protocols are out of scope of the LPWAN WG.4.7.  CoAP   The Constrained Application Protocol (CoAP) [RFC7252] provides a   RESTful framework for applications intended to run on constrained IP   networks.  It may be necessary to adapt CoAP or related protocols to   take into account the extreme duty cycles and the potentially   extremely limited throughput of LPWANs.   For example, some of the timers in CoAP may need to be redefined.   Taking into account CoAP acknowledgments may allow the reduction of   L2 acknowledgments.  On the other hand, the current work in progress   in the CoRE WG where the Constrained Management Interface (COMI) /   Constrained Objects Language (CoOL) network management interface   which, uses Structured Identifiers (SIDs) to reduce payload size over   CoAP may prove to be a good solution for the LPWAN technologies.  The   overhead is reduced by adding a dictionary that matches a URI to a   small identifier and a compact mapping of the YANG data model into   the Concise Binary Object Representation (CBOR).Farrell                       Informational                    [Page 30]

RFC 8376                     LPWAN Overview                     May 20184.8.  Mobility   LPWAN nodes can be mobile.  However, LPWAN mobility is different from   the one specified for Mobile IP.  LPWAN implies sporadic traffic and   will rarely be used for high-frequency, real-time communications.   The applications do not generate a flow; they need to save energy   and, most of the time, the node will be down.   In addition, LPWAN mobility may mostly apply to groups of devices   that represent a network; in which case, mobility is more a concern   for the Gateway than the devices.  Network Mobility (NEMO) [RFC3963]   or other mobile Gateway solutions (such as a Gateway with an LTE   uplink) may be used in the case where some end devices belonging to   the same network Gateway move from one point to another such that   they are not aware of being mobile.4.9.  DNS and LPWAN   The Domain Name System (DNS) [RFC1035], enables applications to name   things with a globally resolvable name.  Many protocols use the DNS   to identify hosts, for example, applications using CoAP.   The DNS query/answer protocol as a precursor to other communication   within the Time-To-Live (TTL) of a DNS answer is clearly problematic   in an LPWAN, say where only one round-trip per hour can be used, and   with a TTL that is less than 3600 seconds.  It is currently unclear   whether and how DNS-like functionality might be provided in LPWANs.5.  Security Considerations   Most LPWAN technologies integrate some authentication or encryption   mechanisms that were defined outside the IETF.  The LPWAN WG may need   to do work to integrate these mechanisms to unify management.  A   standardized Authentication, Authorization, and Accounting (AAA)   infrastructure [RFC2904] may offer a scalable solution for some of   the security and management issues for LPWANs.  AAA offers   centralized management that may be of use in LPWANs, for example   [LoRaWAN-AUTH] and [LoRaWAN-RADIUS] suggest possible security   processes for a LoRaWAN network.  Similar mechanisms may be useful to   explore for other LPWAN technologies.   Some applications using LPWANs may raise few or no privacy   considerations.  For example, temperature sensors in a large office   building may not raise privacy issues.  However, the same sensors, if   deployed in a home environment, and especially if triggered due to   human presence, can raise significant privacy issues: if an end   device emits a (encrypted) packet every time someone enters a room in   a home, then that traffic is privacy sensitive.  And the more thatFarrell                       Informational                    [Page 31]

RFC 8376                     LPWAN Overview                     May 2018   the existence of that traffic is visible to network entities, the   more privacy sensitivities arise.  At this point, it is not clear   whether there are workable mitigations for problems like this.  In a   more typical network, one would consider defining padding mechanisms   and allowing for cover traffic.  In some LPWANs, those mechanisms may   not be feasible.  Nonetheless, the privacy challenges do exist and   can be real; therefore, some solutions will be needed.  Note that   many aspects of solutions in this space may not be visible in IETF   specifications but can be, e.g., implementation or deployment   specific.   Another challenge for LPWANs will be how to handle key management and   associated protocols.  In a more traditional network (e.g., the Web),   servers can "staple" Online Certificate Status Protocol (OCSP)   responses in order to allow browsers to check revocation status for   presented certificates [RFC6961].  While the stapling approach is   likely something that would help in an LPWAN, as it avoids an RTT,   certificates and OCSP responses are bulky items and will prove   challenging to handle in LPWANs with bounded bandwidth.6.  IANA Considerations   This document has no IANA actions.7.  Informative References   [ANSI-4957-000]              ANSI/TIA, "Architecture Overview for the Smart Utility              Network", ANSI/TIA-4957.0000 , May 2013.   [ANSI-4957-210]              ANSI/TIA, "Multi-Hop Delivery Specification of a Data Link              Sub-Layer", ANSI/TIA-4957.210 , May 2013.   [arib_ref] ARIB, "920MHz-Band Telemeter, Telecontrol and Data              Transmission Radio Equipment", ARIB STD-T108 Version 1.0,              February 2012.   [ETSI-TS-102-887-2]              ETSI, "Electromagnetic compatibility and Radio spectrum              Matters (ERM); Short Range Devices; Smart Metering              Wireless Access Protocol; Part 2: Data Link Layer (MAC              Sub-layer)", ETSI TS 102 887-2, Version V1.1.1, September              2013.Farrell                       Informational                    [Page 32]

RFC 8376                     LPWAN Overview                     May 2018   [etsi_ref1]              ETSI, "Short Range Devices (SRD) operating in the              frequency range 25 MHz to 1 000 MHz; Part 1: Technical              characteristics and methods of measurement", Draft ETSI              EN 300-220-1, Version V3.1.0, May 2016.   [etsi_ref2]              ETSI, "Short Range Devices (SRD) operating in the              frequency range 25 MHz to 1 000 MHz; Part 2: Harmonised              Standard covering the essential requirements of article              3.2 of Directive 2014/53/EU for non specific radio              equipment", Final draft ETSI EN 300-220-2 P300-220-2,              Version V3.1.1, November 2016.   [etsi_unb] ETSI ERM, "System Reference document (SRdoc); Short Range              Devices (SRD); Technical characteristics for Ultra Narrow              Band (UNB) SRDs operating in the UHF spectrum below 1              GHz", ETSI TR 103 435, Version V1.1.1, February 2017.   [EUI64]    IEEE, "Guidelines for 64-bit Global Identifier              (EUI),Organizationally Unique Identifier (OUI), and              Company ID (CID)", August 2017,              <http://standards.ieee.org/develop/regauth/tut/eui.pdf>.   [FANOV]    IETF, "Wi-SUN Alliance Field Area Network (FAN) Overview",              IETF 97, November 2016,              <https://www.ietf.org/proceedings/97/slides/slides-97-lpwan-35-wi-sun-presentation-00.pdf>.   [fcc_ref]  "Telecommunication Radio Frequency Devices - Operation              within the bands 902-928 MHz, 2400-2483.5 MHz, and              5725-5850 MHz.", FCC CFR 47 15.247, June 2016.   [G9959]    ITU-T, "Short range narrow-band digital radiocommunication              transceivers - PHY, MAC, SAR and LLC layer              specifications", ITU-T Recommendation G.9959, January              2015, <http://www.itu.int/rec/T-REC-G.9959>.   [IEEE.802.11]              IEEE, "IEEE Standard for Information technology--              Telecommunications and information exchange between              systems Local and metropolitan area networks--Specific              requirements Part 11: Wireless LAN Medium Access Control              (MAC) and Physical Layer (PHY) Specifications",              IEEE 802.11.Farrell                       Informational                    [Page 33]

RFC 8376                     LPWAN Overview                     May 2018   [IEEE.802.15.12]              IEEE, "Upper Layer Interface (ULI) for IEEE 802.15.4 Low-              Rate Wireless Networks", IEEE 802.15.12.   [IEEE.802.15.4]              IEEE, "IEEE Standard for Low-Rate Wireless Networks",              IEEE 802.15.4, <https://standards.ieee.org/findstds/standard/802.15.4-2015.html>.   [IEEE.802.15.4e]              IEEE, "IEEE Standard for Local and metropolitan area              networks--Part 15.4: Low-Rate Wireless Personal Area              Networks (LR-WPANs) Amendment 1: MAC sublayer",              IEEE 802.15.4e.   [IEEE.802.15.4g]              IEEE, "IEEE Standard for Local and metropolitan area              networks--Part 15.4: Low-Rate Wireless Personal Area              Networks (LR-WPANs) Amendment 3: Physical Layer (PHY)              Specifications for Low-Data-Rate, Wireless, Smart Metering              Utility Networks", IEEE 802.15.4g.   [IEEE.802.15.9]              IEEE, "IEEE Recommended Practice for Transport of Key              Management Protocol (KMP) Datagrams", IEEE Standard              802.15.9, 2016, <https://standards.ieee.org/findstds/standard/802.15.9-2016.html>.   [IEEE.802.1AR]              ANSI/IEEE, "IEEE Standard for Local and metropolitan area              networks - Secure Device Identity", IEEE 802.1AR.   [IEEE.802.1x]              IEEE, "Port Based Network Access Control", IEEE 802.1x.   [LoRaSpec] LoRa Alliance, "LoRaWAN Specification Version V1.0.2",              July 2016, <https://lora-alliance.org/sites/default/files/2018-05/lorawan1_0_2-20161012_1398_1.pdf>.   [LoRaWAN]  Farrell, S. and A. Yegin,"LoRaWAN Overview", Work in              Progress,draft-farrell-lpwan-lora-overview-01, October              2016.   [LoRaWAN-AUTH]              Garcia, D., Marin, R., Kandasamy, A., and A. Pelov,              "LoRaWAN Authentication in Diameter", Work in Progress,draft-garcia-dime-diameter-lorawan-00, May 2016.Farrell                       Informational                    [Page 34]

RFC 8376                     LPWAN Overview                     May 2018   [LoRaWAN-RADIUS]              Garcia, D., Lopez, R., Kandasamy, A., and A. Pelov,              "LoRaWAN Authentication in RADIUS", Work in Progress,draft-garcia-radext-radius-lorawan-03, May 2017.   [LPWAN-GAP]              Minaburo, A., Ed., Gomez, C., Ed., Toutain, L., Paradells,              J., and J. Crowcroft, "LPWAN Survey and GAP Analysis",              Work in Progress,draft-minaburo-lpwan-gap-analysis-02,              October 2016.   [NB-IoT]   Ratilainen, A.,"NB-IoT characteristics", Work in              Progress,draft-ratilainen-lpwan-nb-iot-00, July 2016.   [nbiot-ov] IEEE, "NB-IoT Technology Overview and Experience from              Cloud-RAN Implementation", Volume 24, Issue 3 Pages 26-32,              DOI 10.1109/MWC.2017.1600418, June 2017.   [RFC768]   Postel, J., "User Datagram Protocol", STD 6,RFC 768,              DOI 10.17487/RFC0768, August 1980,              <https://www.rfc-editor.org/info/rfc768>.   [RFC793]   Postel, J., "Transmission Control Protocol", STD 7,RFC 793, DOI 10.17487/RFC0793, September 1981,              <https://www.rfc-editor.org/info/rfc793>.   [RFC1035]  Mockapetris, P., "Domain names - implementation and              specification", STD 13,RFC 1035, DOI 10.17487/RFC1035,              November 1987, <https://www.rfc-editor.org/info/rfc1035>.   [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6              (IPv6) Specification",RFC 2460, DOI 10.17487/RFC2460,              December 1998, <https://www.rfc-editor.org/info/rfc2460>.   [RFC2904]  Vollbrecht, J., Calhoun, P., Farrell, S., Gommans, L.,              Gross, G., de Bruijn, B., de Laat, C., Holdrege, M., and              D. Spence, "AAA Authorization Framework",RFC 2904,              DOI 10.17487/RFC2904, August 2000,              <https://www.rfc-editor.org/info/rfc2904>.   [RFC3095]  Bormann, C., Burmeister, C., Degermark, M., Fukushima, H.,              Hannu, H., Jonsson, L-E., Hakenberg, R., Koren, T., Le,              K., Liu, Z., Martensson, A., Miyazaki, A., Svanbro, K.,              Wiebke, T., Yoshimura, T., and H. Zheng, "RObust Header              Compression (ROHC): Framework and four profiles: RTP, UDP,              ESP, and uncompressed",RFC 3095, DOI 10.17487/RFC3095,              July 2001, <https://www.rfc-editor.org/info/rfc3095>.Farrell                       Informational                    [Page 35]

RFC 8376                     LPWAN Overview                     May 2018   [RFC3315]  Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,              C., and M. Carney, "Dynamic Host Configuration Protocol              for IPv6 (DHCPv6)",RFC 3315, DOI 10.17487/RFC3315, July              2003, <https://www.rfc-editor.org/info/rfc3315>.   [RFC3963]  Devarapalli, V., Wakikawa, R., Petrescu, A., and P.              Thubert, "Network Mobility (NEMO) Basic Support Protocol",RFC 3963, DOI 10.17487/RFC3963, January 2005,              <https://www.rfc-editor.org/info/rfc3963>.   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the              Internet Protocol",RFC 4301, DOI 10.17487/RFC4301,              December 2005, <https://www.rfc-editor.org/info/rfc4301>.   [RFC4443]  Conta, A., Deering, S., and M. Gupta, Ed., "Internet              Control Message Protocol (ICMPv6) for the Internet              Protocol Version 6 (IPv6) Specification", STD 89,RFC 4443, DOI 10.17487/RFC4443, March 2006,              <https://www.rfc-editor.org/info/rfc4443>.   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,              "Neighbor Discovery for IP version 6 (IPv6)",RFC 4861,              DOI 10.17487/RFC4861, September 2007,              <https://www.rfc-editor.org/info/rfc4861>.   [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,              <https://www.rfc-editor.org/info/rfc4944>.   [RFC5216]  Simon, D., Aboba, B., and R. Hurst, "The EAP-TLS              Authentication Protocol",RFC 5216, DOI 10.17487/RFC5216,              March 2008, <https://www.rfc-editor.org/info/rfc5216>.   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security              (TLS) Protocol Version 1.2",RFC 5246,              DOI 10.17487/RFC5246, August 2008,              <https://www.rfc-editor.org/info/rfc5246>.   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,              Housley, R., and W. Polk, "Internet X.509 Public Key              Infrastructure Certificate and Certificate Revocation List              (CRL) Profile",RFC 5280, DOI 10.17487/RFC5280, May 2008,              <https://www.rfc-editor.org/info/rfc5280>.Farrell                       Informational                    [Page 36]

RFC 8376                     LPWAN Overview                     May 2018   [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,              <https://www.rfc-editor.org/info/rfc6282>.   [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,              <https://www.rfc-editor.org/info/rfc6775>.   [RFC6961]  Pettersen, Y., "The Transport Layer Security (TLS)              Multiple Certificate Status Request Extension",RFC 6961,              DOI 10.17487/RFC6961, June 2013,              <https://www.rfc-editor.org/info/rfc6961>.   [RFC7252]  Shelby, Z., Hartke, K., and C. Bormann, "The Constrained              Application Protocol (CoAP)",RFC 7252,              DOI 10.17487/RFC7252, June 2014,              <https://www.rfc-editor.org/info/rfc7252>.   [RFC7452]  Tschofenig, H., Arkko, J., Thaler, D., and D. McPherson,              "Architectural Considerations in Smart Object Networking",RFC 7452, DOI 10.17487/RFC7452, March 2015,              <https://www.rfc-editor.org/info/rfc7452>.   [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,              <https://www.rfc-editor.org/info/rfc7668>.   [RFC8065]  Thaler, D., "Privacy Considerations for IPv6 Adaptation-              Layer Mechanisms",RFC 8065, DOI 10.17487/RFC8065,              February 2017, <https://www.rfc-editor.org/info/rfc8065>.   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6              (IPv6) Specification", STD 86,RFC 8200,              DOI 10.17487/RFC8200, July 2017,              <https://www.rfc-editor.org/info/rfc8200>.   [RFC8240]  Tschofenig, H. and S. Farrell, "Report from the Internet              of Things Software Update (IoTSU) Workshop 2016",RFC 8240, DOI 10.17487/RFC8240, September 2017,              <https://www.rfc-editor.org/info/rfc8240>.Farrell                       Informational                    [Page 37]

RFC 8376                     LPWAN Overview                     May 2018   [Sigfox]   Zuniga, J. and B. PONSARD,"Sigfox System Description",              Work in Progress,draft-zuniga-lpwan-sigfox-system-description-04, December              2017.   [TGPP23720]              3GPP, "Study on architecture enhancements for Cellular              Internet of Things", 3GPP TS 23.720 13.0.0, 2016.   [TGPP33203]              3GPP, "3G security; Access security for IP-based              services", 3GPP TS 23.203 13.1.0, 2016.   [TGPP36201]              3GPP, "Evolved Universal Terrestrial Radio Access              (E-UTRA); LTE physical layer; General description", 3GPP              TS 36.201 13.2.0, 2016.   [TGPP36300]              3GPP, "Evolved Universal Terrestrial Radio Access (E-UTRA)              and Evolved Universal Terrestrial Radio Access Network              (E-UTRAN); Overall description; Stage 2", 3GPP TS 36.300              13.4.0, 2016,              <http://www.3gpp.org/ftp/Specs/2016-09/Rel-14/36_series/>.   [TGPP36321]              3GPP, "Evolved Universal Terrestrial Radio Access              (E-UTRA); Medium Access Control (MAC) protocol              specification", 3GPP TS 36.321 13.2.0, 2016.   [TGPP36322]              3GPP, "Evolved Universal Terrestrial Radio Access              (E-UTRA); Radio Link Control (RLC) protocol              specification", 3GPP TS 36.322 13.2.0, 2016.   [TGPP36323]              3GPP, "Evolved Universal Terrestrial Radio Access              (E-UTRA); Packet Data Convergence Protocol (PDCP)              specification (Not yet available)", 3GPP TS 36.323 13.2.0,              2016.   [TGPP36331]              3GPP, "Evolved Universal Terrestrial Radio Access              (E-UTRA); Radio Resource Control (RRC); Protocol              specification", 3GPP TS 36.331 13.2.0, 2016.Farrell                       Informational                    [Page 38]

RFC 8376                     LPWAN Overview                     May 2018   [USES-6LO] Hong, Y., Gomez, C., Choi, Y-H., and D-Y. Ko, "IPv6 over              Constrained Node Networks(6lo) Applicability & Use cases",              Work in Progress,draft-hong-6lo-use-cases-03, October              2016.   [wisun-pressie1]              Beecher, P., "Wi-SUN Alliance", March 2017,              <http://indiasmartgrid.org/event2017/10-03-2017/4.%20Roundtable%20on%20Communication%20and%20Cyber%20Security/1.%20Phil%20Beecher.pdf>.   [wisun-pressie2]              Heile, B., "Wi-SUN Alliance Field Area Network              (FAN)Overview", As presented at IETF 97, November 2016,              <https://www.ietf.org/proceedings/97/slides/slides-97-lpwan-35-wi-sun-presentation-00.pdf>.Acknowledgments   Thanks to all those listed in the Contributors section for the   excellent text.  Errors in the handling of that are solely the   editor's fault.   In addition to those in the Contributors section, thanks are due to   (in alphabetical order) the following for comments:   Abdussalam Baryun   Andy Malis   Arun (arun@acklio.com)   Behcet SariKaya   Dan Garcia Carrillo   Jiazi Yi   Mirja Kuhlewind   Paul Duffy   Russ Housley   Samita Chakrabarti   Thad Guidry   Warren Kumari   Alexander Pelov and Pascal Thubert were the LPWAN WG Chairs while   this document was developed.   Stephen Farrell's work on this memo was supported by Pervasive   Nation, the Science Foundation Ireland's CONNECT centre national IoT   network <https://connectcentre.ie/pervasive-nation/>.Farrell                       Informational                    [Page 39]

RFC 8376                     LPWAN Overview                     May 2018Contributors   As stated above, this document is mainly a collection of content   developed by the full set of contributors listed below.  The main   input documents and their authors were:   o  Text forSection 2.1 was provided by Alper Yegin and Stephen      Farrell in [LoRaWAN].   o  Text forSection 2.2 was provided by Antti Ratilainen in [NB-IoT].   o  Text forSection 2.3 was provided by Juan Carlos Zuniga and Benoit      Ponsard in [Sigfox].   o  Text forSection 2.4 was provided via personal communication from      Bob Heile and was authored by Bob and Sum Chin Sean.  There is no      Internet-Draft for that at the time of writing.   o  Text forSection 4 was provided by Ana Minabiru, Carles Gomez,      Laurent Toutain, Josep Paradells, and Jon Crowcroft in      [LPWAN-GAP].  Additional text from that document is also used      elsewhere above.   The full list of contributors is as follows:      Jon Crowcroft      University of Cambridge      JJ Thomson Avenue      Cambridge, CB3 0FD      United Kingdom      Email: jon.crowcroft@cl.cam.ac.uk      Carles Gomez      UPC/i2CAT      C/Esteve Terradas, 7      Castelldefels 08860      Spain      Email: carlesgo@entel.upc.eduFarrell                       Informational                    [Page 40]

RFC 8376                     LPWAN Overview                     May 2018      Bob Heile      Wi-Sun Alliance      11 Robert Toner Blvd, Suite 5-301      North Attleboro, MA  02763      United States of America      Phone: +1-781-929-4832      Email: bheile@ieee.org      Ana Minaburo      Acklio      2bis rue de la Chataigneraie      35510 Cesson-Sevigne Cedex      France      Email: ana@ackl.io      Josep PAradells      UPC/i2CAT      C/Jordi Girona, 1-3      Barcelona 08034      Spain      Email: josep.paradells@entel.upc.edu      Charles E. Perkins      Futurewei      2330 Central Expressway      Santa Clara, CA 95050      United States of America      Email: charliep@computer.org      Benoit Ponsard      Sigfox      425 rue Jean Rostand      Labege  31670      France      Email: Benoit.Ponsard@sigfox.com      URI:http://www.sigfox.com/Farrell                       Informational                    [Page 41]

RFC 8376                     LPWAN Overview                     May 2018      Antti Ratilainen      Ericsson      Hirsalantie 11      Jorvas  02420      Finland      Email: antti.ratilainen@ericsson.com      Chin-Sean SUM      Wi-Sun Alliance      20, Science Park Rd 117674      Singapore      Phone: +65 6771 1011      Email: sum@wi-sun.org      Laurent Toutain      Institut MINES TELECOM ; TELECOM Bretagne      2 rue de la Chataigneraie      CS 17607      35576 Cesson-Sevigne Cedex      France      Email: Laurent.Toutain@telecom-bretagne.eu      Alper Yegin      Actility      Paris      France      Email: alper.yegin@actility.com      Juan Carlos Zuniga      Sigfox      425 rue Jean Rostand      Labege  31670      France      Email: JuanCarlos.Zuniga@sigfox.com      URI:http://www.sigfox.com/Farrell                       Informational                    [Page 42]

RFC 8376                     LPWAN Overview                     May 2018Author's Address   Stephen Farrell (editor)   Trinity College Dublin   Dublin  2   Ireland   Phone: +353-1-896-2354   Email: stephen.farrell@cs.tcd.ieFarrell                       Informational                    [Page 43]