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Checking references for intended status: Informational ---------------------------------------------------------------------------- -- Obsolete informational reference (is this intentional?): RFC 2460 (Obsoleted by RFC 8200) -- Obsolete informational reference (is this intentional?): RFC 3315 (Obsoleted by RFC 8415) -- Obsolete informational reference (is this intentional?): RFC 5246 (Obsoleted by RFC 8446) -- Obsolete informational reference (is this intentional?): RFC 6961 (Obsoleted by RFC 8446) == Outdated reference: A later version (-04) exists of draft-zuniga-lpwan-sigfox-system-description-02 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 5 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 lpwan S. Farrell, Ed. 3 Internet-Draft Trinity College Dublin 4 Intended status: Informational May 14, 2017 5 Expires: November 15, 2017 7 LPWAN Overview 8 draft-ietf-lpwan-overview-02 10 Abstract 12 Low Power Wide Area Networks (LPWAN) are wireless technologies with 13 characteristics such as large coverage areas, low bandwidth, possibly 14 very small packet and application layer data sizes and long battery 15 life operation. This memo is an informational overview of the set of 16 LPWAN technologies being considered in the IETF and of the gaps that 17 exist between the needs of those technologies and the goal of running 18 IP in LPWANs. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at http://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on November 15, 2017. 37 Copyright Notice 39 Copyright (c) 2017 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (http://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 55 2. LPWAN Technologies . . . . . . . . . . . . . . . . . . . . . 3 56 2.1. LoRaWAN . . . . . . . . . . . . . . . . . . . . . . . . . 4 57 2.1.1. Provenance and Documents . . . . . . . . . . . . . . 4 58 2.1.2. Characteristics . . . . . . . . . . . . . . . . . . . 4 59 2.2. Narrowband IoT (NB-IoT) . . . . . . . . . . . . . . . . . 11 60 2.2.1. Provenance and Documents . . . . . . . . . . . . . . 11 61 2.2.2. Characteristics . . . . . . . . . . . . . . . . . . . 11 62 2.3. SIGFOX . . . . . . . . . . . . . . . . . . . . . . . . . 15 63 2.3.1. Provenance and Documents . . . . . . . . . . . . . . 15 64 2.3.2. Characteristics . . . . . . . . . . . . . . . . . . . 15 65 2.4. Wi-SUN Alliance Field Area Network (FAN) . . . . . . . . 19 66 2.4.1. Provenance and Documents . . . . . . . . . . . . . . 20 67 2.4.2. Characteristics . . . . . . . . . . . . . . . . . . . 20 68 3. Generic Terminology . . . . . . . . . . . . . . . . . . . . . 23 69 4. Gap Analysis . . . . . . . . . . . . . . . . . . . . . . . . 24 70 4.1. Naive application of IPv6 . . . . . . . . . . . . . . . . 24 71 4.2. 6LoWPAN . . . . . . . . . . . . . . . . . . . . . . . . . 25 72 4.2.1. Header Compression . . . . . . . . . . . . . . . . . 25 73 4.2.2. Address Autoconfiguration . . . . . . . . . . . . . . 26 74 4.2.3. Fragmentation . . . . . . . . . . . . . . . . . . . . 26 75 4.2.4. Neighbor Discovery . . . . . . . . . . . . . . . . . 27 76 4.3. 6lo . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 77 4.4. 6tisch . . . . . . . . . . . . . . . . . . . . . . . . . 28 78 4.5. RoHC . . . . . . . . . . . . . . . . . . . . . . . . . . 28 79 4.6. ROLL . . . . . . . . . . . . . . . . . . . . . . . . . . 28 80 4.7. CoAP . . . . . . . . . . . . . . . . . . . . . . . . . . 29 81 4.8. Mobility . . . . . . . . . . . . . . . . . . . . . . . . 29 82 4.9. DNS and LPWAN . . . . . . . . . . . . . . . . . . . . . . 29 83 5. Security Considerations . . . . . . . . . . . . . . . . . . . 29 84 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30 85 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 30 86 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 33 87 9. Informative References . . . . . . . . . . . . . . . . . . . 33 88 Appendix A. Changes . . . . . . . . . . . . . . . . . . . . . . 38 89 A.1. From -00 to -01 . . . . . . . . . . . . . . . . . . . . . 38 90 A.2. From -01 to -02 . . . . . . . . . . . . . . . . . . . . . 39 91 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 39 93 1. Introduction 95 [[Ed: Editor comments/queries are in double square brackets like 96 this.]] 98 This document provides background material and an overview of the 99 technologies being considered in the IETF's Low Power Wide-Area 100 Networking (LPWAN) working group. We also provide a gap analysis 101 between the needs of these technologies and currently available IETF 102 specifications. 104 Most technologies in this space aim for similar goals of supporting 105 large numbers of low-cost, low-throughput devices at very low-cost 106 and with very-low power consumption, so that even battery-powered 107 devices can be deployed for years. LPWAN devices also tend to be 108 constrained in their use of bandwidth, for example with limited 109 frequencies being allowed to be used within limited duty-cycles 110 (usually expressed as a percentage of time per-hour that the device 111 is allowed to transmit.) And as the name implies, coverage of large 112 areas is also a common goal. So, by and large, the different 113 technologies aim for deployment in very similar circumstances. 115 Existing pilot deployments have shown huge potential and created much 116 industrial interest in these technolgies. As of today, essentially 117 no LPWAN devices have IP capabilities. Connecting LPWANs to the 118 Internet would provide significant benefits to these networks in 119 terms of interoperability, application deployment, and management, 120 among others. The goal of the LPWAN WG is to, where necessary, adapt 121 IETF defined protocols, addressing schemes and naming to this 122 particular constrained environment. 124 This document is largely the work of the people listed in Section 7. 125 Discussion of this document should take place on the lp-wan@ietf.org 126 list. 128 2. LPWAN Technologies 130 This section provides an overview of the set of LPWAN technologies 131 that are being considered in the LPWAN working group. The text for 132 each was mainly contributed by proponents of each technology. 134 Note that this text is not intended to be normative in any sesne, but 135 simply to help the reader in finding the relevant layer 2 136 specifications and in understanding how those integrate with IETF- 137 defined technologies. Similarly, there is no attempt here to set out 138 the pros and cons of the relevant technologies. 140 2.1. LoRaWAN 142 Text here is largely from [I-D.farrell-lpwan-lora-overview] which may 143 have been updated since this was published. 145 2.1.1. Provenance and Documents 147 LoRaWAN is a wireless technology for long-range low-power low-data- 148 rate applications developed by the LoRa Alliance, a membership 149 consortium. This draft is based on 150 version 1.0.2 [LoRaSpec] of the LoRa specification. Version 1.0, 151 which has also seen some deployment, is available at [LoRaSpec1.0]. 153 2.1.2. Characteristics 155 LoRaWAN networks are typically organized in a star-of-stars topology 156 in which gateways relay messages between end-devices and a central 157 "network server" in the backend. Gateways are connected to the 158 network server via IP links while end-devices use single-hop LoRaWAN 159 communication that can be received at one or more gateways. All 160 communication is generally bi-directional, although uplink 161 communication from end-devices to the network server are favoured in 162 terms of overall bandwidth availability. 164 Figure 1 shows the entities involved in a LoRaWAN network. 166 +----------+ 167 |End-device| * * * 168 +----------+ * +---------+ 169 * | Gateway +---+ 170 +----------+ * +---------+ | +---------+ 171 |End-device| * * * +---+ Network +--- Application 172 +----------+ * | | Server | 173 * +---------+ | +---------+ 174 +----------+ * | Gateway +---+ 175 |End-device| * * * * +---------+ 176 +----------+ 177 Key: * LoRaWAN Radio 178 +---+ IP connectivity 180 Figure 1: LoRaWAN architecture 182 o End-device: a LoRa client device, sometimes called a mote. 183 Communicates with gateways. 185 o Gateway: a radio on the infrastructure-side, sometimes called a 186 concentrator or base-station. Communicates with end-devices and, 187 via IP, with a network server. 189 o Network Server: The Network Server (NS) terminates the LoRaWAN MAC 190 layer for the end-devices connected to the network. It is the 191 center of the star topology. 193 o Uplink message: refers to communications from end-device to 194 network server or appliction via one or more gateways. 196 o Downlink message: refers to communications from network server or 197 application via one gateway to a single end-device or a group of 198 end-devices (considering multicasting). 200 o Application: refers to application layer code both on the end- 201 device and running "behind" the network server. For LoRaWAN, 202 there will generally only be one application running on most end- 203 devices. Interfaces between the network server and application 204 are not further described here. 206 In LoRaWAN networks, end-device transmissions may be received at 207 multiple gateways, so during nominal operation a network server may 208 see multiple instances of the same uplink message from an end-device. 210 The LoRaWAN network infrastructure manages the data rate and RF 211 output power for each end-device individually by means of an adaptive 212 data rate (ADR) scheme. End-devices may transmit on any channel 213 allowed by local regulation at any time. 215 LoRaWAN radios make use of industrial, scientific and medical (ISM) 216 bands, for example, 433MHz and 868MHz within the European Union and 217 915MHz in the Americas. 219 The end-device changes channel in a pseudo-random fashion for every 220 transmission to help make the system more robust to interference and/ 221 or to conform to local regulations. 223 Figure 2 below shows that after a transmission slot a Class A device 224 turns on its receiver for two short receive windows that are offset 225 from the end of the transmission window. End-devices can only 226 transmit a subsequent uplink frame after the end of the associated 227 receive windows. When a device joins a LoRaWAN network, there are 228 similar timeouts on parts of that process. 230 |----------------------------| |--------| |--------| 231 | Tx | | Rx | | Rx | 232 |----------------------------| |--------| |--------| 233 |---------| 234 Rx delay 1 235 |------------------------| 236 Rx delay 2 238 Figure 2: LoRaWAN Class A transmission and reception window 240 Given the different regional requirements the detailed specification 241 for the LoRaWAN physical layer (taking up more than 30 pages of the 242 specification) is not reproduced here. Instead and mainly to 243 illustrate the kinds of issue encountered, in Table 1 we present some 244 of the default settings for one ISM band (without fully explaining 245 those here) and in Table 2 we describe maxima and minima for some 246 parameters of interest to those defining ways to use IETF protocols 247 over the LoRaWAN MAC layer. 249 +------------------------+------------------------------------------+ 250 | Parameters | Default Value | 251 +------------------------+------------------------------------------+ 252 | Rx delay 1 | 1 s | 253 | | | 254 | Rx delay 2 | 2 s (must be RECEIVE_DELAY1 + 1s) | 255 | | | 256 | join delay 1 | 5 s | 257 | | | 258 | join delay 2 | 6 s | 259 | | | 260 | 868MHz Default | 3 (868.1,868.2,868.3), data rate: 0.3-5 | 261 | channels | kbps | 262 +------------------------+------------------------------------------+ 264 Table 1: Default settings for EU868MHz band 266 +-----------------------------------------------+--------+----------+ 267 | Parameter/Notes | Min | Max | 268 +-----------------------------------------------+--------+----------+ 269 | Duty Cycle: some but not all ISM bands impose | 1% | no-limit | 270 | a limit in terms of how often an end-device | | | 271 | can transmit. In some cases LoRaWAN is more | | | 272 | stringent in an attempt to avoid congestion. | | | 273 | | | | 274 | EU 868MHz band data rate/frame-size | 250 | 50000 | 275 | | bits/s | bits/s : | 276 | | : 59 | 250 | 277 | | octets | octets | 278 | | | | 279 | US 915MHz band data rate/frame-size | 980 | 21900 | 280 | | bits/s | bits/s : | 281 | | : 19 | 250 | 282 | | octets | octets | 283 +-----------------------------------------------+--------+----------+ 285 Table 2: Minima and Maxima for various LoRaWAN Parameters 287 Note that in the case of the smallest frame size (19 octets), 8 288 octets are required for LoRa MAC layer headers leaving only 11 octets 289 for payload (including MAC layer options). However, those settings 290 do not apply for the join procedure - end-devices are required to use 291 a channel and data rate that can send the 23 byte Join-request 292 message for the join procedure. 294 Uplink and downlink higher layer data is carried in a MACPayload. 295 There is a concept of "ports" (an optional 8 bit value) to handle 296 different applications on an end-device. Port zero is reserved for 297 LoRaWAN specific messaging, such as the configuration of device's 298 network parameters (available channels, data rates, ADR parameters, 299 RX1/2 delay, etc.). 301 In addition to carrying higher layer PDUs there are Join-Request and 302 Join-Response (aka Join-Accept) messages for handling network access. 303 And so-called "MAC commands" (see below) up to 15 bytes long can be 304 piggybacked in an options field ("FOpts"). 306 There are a number of MAC commands for: link and device status 307 checking, ADR and duty-cycle negotiation, managing the RX windows and 308 radio channel settings. For example, the link check response message 309 allows the network server (in response to a request from an end- 310 device) to inform an end-device about the signal attenuation seen 311 most recently at a gateway, and to also tell the end-device how many 312 gateways received the corresponding link request MAC command. 314 Some MAC commands are initiated by the network server. For example, 315 one command allows the network server to ask an end-device to reduce 316 its duty-cycle to only use a proportion of the maximum allowed in a 317 region. Another allows the network server to query the end-device's 318 power status with the response from the end-device specifying whether 319 it has an external power source or is battery powered (in which case 320 a relative battery level is also sent to the network server). 322 A LoRaWAN network has a short network identifier ("NwkID") which is a 323 seven bit value. A private network (common for LoRaWAN) can use the 324 value zero. If a network wishes to support "foreign" end-devices 325 then the NwkID needs to be registered with the LoRA Alliance, in 326 which case the NwkID is the seven least significant bits of a 327 registered 24-bit NetID. (Note however, that the methods for 328 "roaming" are defined in the upcoming LoRaWAN 1.1 specification.) 330 In order to operate nominally on a LoRaWAN network, a device needs a 331 32-bit device address, which is the catentation of the NwkID and a 332 25-bit device-specific network address that is assigned when the 333 device "joins" the network (see below for the join procedure) or that 334 is pre-provisioned into the device. 336 End-devices are assumed to work with one or a quite limited number of 337 applications, identified by a 64-bit AppEUI, which is assumed to be a 338 registered IEEE EUI64 value. In addition, a device needs to have two 339 symmetric session keys, one for protecting network artefacts 340 (port=0), the NwkSKey, and another for protecting application layer 341 traffic, the AppSKey. Both keys are used for 128 bit AES 342 cryptographic operations. So, one option is for an end-device to 343 have all of the above, plus channel information, somehow 344 (pre-)provisioned, in which case the end-device can simply start 345 transmitting. This is achievable in many cases via out-of-band means 346 given the nature of LoRaWAN networks. Table 3 summarises these 347 values. 349 +---------+---------------------------------------------------------+ 350 | Value | Description | 351 +---------+---------------------------------------------------------+ 352 | DevAddr | DevAddr (32-bits) = NwkId (7-bits) + device-specific | 353 | | network address (25 bits) | 354 | | | 355 | AppEUI | IEEE EUI64 naming the application | 356 | | | 357 | NwkSKey | 128 bit network session key for use with AES | 358 | | | 359 | AppSKey | 128 bit application session key for use with AES | 360 +---------+---------------------------------------------------------+ 362 Table 3: Values required for nominal operation 364 As an alternative, end-devices can use the LoRaWAN join procedure in 365 order to setup some of these values and dynamically gain access to 366 the network. To use the join procedure, an end-device must still 367 know the AppEUI, and in addition, a different (long-term) symmetric 368 key that is bound to the AppEUI - this is the application key 369 (AppKey), and is distinct from the application session key (AppSKey). 370 The AppKey is required to be specific to the device, that is, each 371 end-device should have a different AppKey value. And finally, the 372 end-device also needs a long-term identifier for itself, 373 syntactically also an EUI-64, and known as the device EUI or DevEUI. 374 Table 4 summarises these values. 376 +---------+----------------------------------------------------+ 377 | Value | Description | 378 +---------+----------------------------------------------------+ 379 | DevEUI | IEEE EUI64 naming the device | 380 | | | 381 | AppEUI | IEEE EUI64 naming the application | 382 | | | 383 | AppKey | 128 bit long term application key for use with AES | 384 +---------+----------------------------------------------------+ 386 Table 4: Values required for join procedure 388 The join procedure involves a special exchange where the end-device 389 asserts the AppEUI and DevEUI (integrity protected with the long-term 390 AppKey, but not encrypted) in a Join-request uplink message. This is 391 then routed to the network server which interacts with an entity that 392 knows that AppKey to verify the Join-request. All going well, a 393 Join-accept downlink message is returned from the network server to 394 the end-device that specifies the 24-bit NetID, 32-bit DevAddr and 395 channel information and from which the AppSKey and NwkSKey can be 396 derived based on knowledge of the AppKey. This provides the end- 397 device with all the values listed in Table 3. 399 All payloads are encrypted and have data integrity. MAC commands, 400 when sent as a payload (port zero), are therefore protected. MAC 401 commands piggy-backed as frame options ("FOpts") are however sent in 402 clear. Any MAC commands sent as frame options and not only as 403 payload, are visible to a passive attacker but are not malleable for 404 an active attacker due to the use of the MIC. 406 For LoRaWAN version 1.0.x, the NWkSkey session key is used to provide 407 data integrity between the end-device and the network server. The 408 AppSKey is used to provide data confidentiality between the end- 409 device and network server, or to the application "behind" the network 410 server, depending on the implementation of the network. 412 All MAC layer messages have an outer 32-bit Message Integrity Code 413 (MIC) calculated using AES-CMAC calculated over the ciphertext 414 payload and other headers and using the NwkSkey. Payloads are 415 encrypted using AES-128, with a counter-mode derived from IEEE 416 802.15.4 using the AppSKey. Gateways are not expected to be provided 417 with the AppSKey or NwkSKey, all of the infrastructure-side 418 cryptography happens in (or "behind") the network server. When 419 session keys are derived from the AppKey as a result of the join 420 procedure the Join-accept message payload is specially handled. 422 The long-term AppKey is directly used to protect the Join-accept 423 message content, but the function used is not an aes-encrypt 424 operation, but rather an aes-decrypt operation. The justification is 425 that this means that the end-device only needs to implement the aes- 426 encrypt operation. (The counter mode variant used for payload 427 decryption means the end-device doesn't need an aes-decrypt 428 primitive.) 430 The Join-accept plaintext is always less than 16 bytes long, so 431 electronic code book (ECB) mode is used for protecting Join-accept 432 messages. The Join-accept contains an AppNonce (a 24 bit value) that 433 is recovered on the end-device along with the other Join-accept 434 content (e.g. DevAddr) using the aes-encrypt operation. Once the 435 Join-accept payload is available to the end-device the session keys 436 are derived from the AppKey, AppNonce and other values, again using 437 an ECB mode aes-encrypt operation, with the plaintext input being a 438 maximum of 16 octets. 440 2.2. Narrowband IoT (NB-IoT) 442 Text here is largely from [I-D.ratilainen-lpwan-nb-iot] which may 443 have been updated since this was published. 445 2.2.1. Provenance and Documents 447 Narrowband Internet of Things (NB-IoT) is developed and standardized 448 by 3GPP. The standardization of NB-IoT was finalized with 3GPP 449 Release-13 in June 2016, but further enhancements for NB-IoT are 450 worked on in the following releases, for example in the form of 451 multicast support. For more information of what has been specified 452 for NB-IoT, 3GPP specification 36.300 [TGPP36300] provides an 453 overview and overall description of the E-UTRAN radio interface 454 protocol architecture, while specifications 36.321 [TGPP36321], 455 36.322 [TGPP36322], 36.323 [TGPP36323] and 36.331 [TGPP36331] give 456 more detailed description of MAC, RLC, PDCP and RRC protocol layers 457 respectively. Note that the description below assumes familiarity 458 with numerous 3GPP terms. 460 2.2.2. Characteristics 462 [[Ed: Not clear what minimum/worst-case MTU might be.]] 464 Specific targets for NB-IoT include: Less than US$5 module cost, 465 extended coverage of 164 dB maximum coupling loss, battery life of 466 over 10 years, ~55000 devices per cell and uplink reporting latency 467 of less than 10 seconds. 469 NB-IoT supports Half Duplex FDD operation mode with 60 kbps peak rate 470 in uplink and 30 kbps peak rate in downlink, and a maximum size MTU 471 of 1600 bytes. As the name suggests, NB-IoT uses narrowbands with 472 the bandwidth of 180 kHz in both, downlink and uplink. The multiple 473 access scheme used in the downlink is OFDMA with 15 kHz sub-carrier 474 spacing. On uplink multi-tone SC-FDMA is used with 15 kHz tone 475 spacing or as a special case of SC-FDMA single tone with either 15kHz 476 or 3.75 kHz tone spacing may be used. 478 NB-IoT can be deployed in three ways. In-band deployment means that 479 the narrowband is multiplexed within normal LTE carrier. In Guard- 480 band deployment the narrowband uses the unused resource blocks 481 between two adjacent LTE carriers. Also standalone deployment is 482 supported, where the narrowband can be located alone in dedicated 483 spectrum, which makes it possible for example to refarm the GSM 484 carrier at 850/900 MHz for NB-IoT. All three deployment modes are 485 meant to be used in licensed bands. The maximum transmission power 486 is either 20 or 23 dBm for uplink transmissions, while for downlink 487 transmission the eNodeB may use higher transmission power, up to 46 488 dBm depending on the deployment. 490 For signaling optimization, two options are introduced in addition to 491 legacy RRC connection setup, mandatory Data-over-NAS (Control Plane 492 optimization, solution 2 in [TGPP23720]) and optional RRC Suspend/ 493 Resume (User Plane optimization, solution 18 in [TGPP23720]). In the 494 control plane optimization the data is sent over Non Access Stratum, 495 directly from Mobility Management Entity (MME) in core network to the 496 UE without interaction from base station. This means there are no 497 Access Stratum security or header compression, as the Access Stratum 498 is bypassed, and only limited RRC procedures. 500 The RRC Suspend/Resume procedures reduce the signaling overhead 501 required for UE state transition from Idle to Connected mode in order 502 to have a user plane transaction with the network and back to Idle 503 state by reducing the signaling messages required compared to legacy 504 operation 506 With extended DRX the RRC Connected mode DRX cycle is up to 10.24 507 seconds and in RRC Idle the DRX cycle can be up to 3 hours. 509 NB-IoT has no channel access restrictions allowing up to a 100% duty- 510 cycle. 512 3GPP access security is specified in [TGPP33203]. 514 +--+ 515 |UE| \ +------+ +------+ 516 +--+ \ | MME |------| HSS | 517 \ / +------+ +------+ 518 +--+ \+-----+ / | 519 |UE| ----| eNB |- | 520 +--+ /+-----+ \ | 521 / \ +--------+ 522 / \| | +------+ Service PDN 523 +--+ / | S-GW |----| P-GW |---- e.g. Internet 524 |UE| | | +------+ 525 +--+ +--------+ 527 Figure 3: 3GPP network architecture 529 Mobility Management Entity (MME) is responsible for handling the 530 mobility of the UE. MME tasks include tracking and paging UEs, 531 session management, choosing the Serving gateway for the UE during 532 initial attachment and authenticating the user. At MME, the Non 533 Access Stratum (NAS) signaling from the UE is terminated. 535 Serving Gateway (S-GW) routes and forwards the user data packets 536 through the access network and acts as a mobility anchor for UEs 537 during handover between base stations known as eNodeBs and also 538 during handovers between other 3GPP technologies. 540 Packet Data Node Gateway (P-GW) works as an interface between 3GPP 541 network and external networks. 543 Home Subscriber Server (HSS) contains user-related and subscription- 544 related information. It is a database, which performs mobility 545 management, session establishment support, user authentication and 546 access authorization. 548 E-UTRAN consists of components of a single type, eNodeB. eNodeB is a 549 base station, which controls the UEs in one or several cells. 551 The illustration of 3GPP radio protocol architecture can be seen from 552 Figure 4. 554 +---------+ +---------+ 555 | NAS |----|-----------------------------|----| NAS | 556 +---------+ | +---------+---------+ | +---------+ 557 | RRC |----|----| RRC | S1-AP |----|----| S1-AP | 558 +---------+ | +---------+---------+ | +---------+ 559 | PDCP |----|----| PDCP | SCTP |----|----| SCTP | 560 +---------+ | +---------+---------+ | +---------+ 561 | RLC |----|----| RLC | IP |----|----| IP | 562 +---------+ | +---------+---------+ | +---------+ 563 | MAC |----|----| MAC | L2 |----|----| L2 | 564 +---------+ | +---------+---------+ | +---------+ 565 | PHY |----|----| PHY | PHY |----|----| PHY | 566 +---------+ +---------+---------+ +---------+ 567 LTE-Uu S1-MME 568 UE eNodeB MME 570 Figure 4: 3GPP radio protocol architecture 572 The radio protocol architecture of NB-IoT (and LTE) is separated into 573 control plane and user plane. Control plane consists of protocols 574 which control the radio access bearers and the connection between the 575 UE and the network. The highest layer of control plane is called 576 Non-Access Stratum (NAS), which conveys the radio signaling between 577 the UE and the EPC, passing transparently through radio network. It 578 is responsible for authentication, security control, mobility 579 management and bearer management. 581 Access Stratum (AS) is the functional layer below NAS, and in control 582 plane it consists of Radio Resource Control protocol (RRC) 584 [TGPP36331], which handles connection establishment and release 585 functions, broadcast of system information, radio bearer 586 establishment, reconfiguration and release. RRC configures the user 587 and control planes according to the network status. There exists two 588 RRC states, RRC_Idle or RRC_Connected, and RRC entity controls the 589 switching between these states. In RRC_Idle, the network knows that 590 the UE is present in the network and the UE can be reached in case of 591 incoming call. In this state the UE monitors paging, performs cell 592 measurements and cell selection and acquires system information. 593 Also the UE can receive broadcast and multicast data, but it is not 594 expected to transmit or receive singlecast data. In RRC_Connected 595 the UE has a connection to the eNodeB, the network knows the UE 596 location on cell level and the UE may receive and transmit singlecast 597 data. RRC_Connected mode is established, when the UE is expected to 598 be active in the network, to transmit or receive data. Connection is 599 released, switching to RRC_Idle, when there is no traffic to save the 600 UE battery and radio resources. However, a new feature was 601 introduced for NB-IoT, as mentioned earlier, which allows data to be 602 transmitted from the MME directly to the UE, while the UE is in 603 RRC_Idle transparently to the eNodeB. 605 Packet Data Convergence Protocol's (PDCP) [TGPP36323] main services 606 in control plane are transfer of control plane data, ciphering and 607 integrity protection. 609 Radio Link Control protocol (RLC) [TGPP36322] performs transfer of 610 upper layer PDUs and optionally error correction with Automatic 611 Repeat reQuest (ARQ), concatenation, segmentation and reassembly of 612 RLC SDUs, in-sequence delivery of upper layer PDUs, duplicate 613 detection, RLC SDU discard, RLC-re-establishment and protocol error 614 detection and recovery. 616 Medium Access Control protocol (MAC) [TGPP36321] provides mapping 617 between logical channels and transport channels, multiplexing of MAC 618 SDUs, scheduling information reporting, error correction with HARQ, 619 priority handling and transport format selection. 621 Physical layer [TGPP36201] provides data transport services to higher 622 layers. These include error detection and indication to higher 623 layers, FEC encoding, HARQ soft-combining. Rate matching and mapping 624 of the transport channels onto physical channels, power weighting and 625 modulation of physical channels, frequency and time synchronization 626 and radio characteristics measurements. 628 User plane is responsible for transferring the user data through the 629 Access Stratum. It interfaces with IP and consists of PDCP, which in 630 user plane performs header compression using Robust Header 631 Compression (RoHC), transfer of user plane data between eNodeB and 632 UE, ciphering and integrity protection. Lower layers in user plane 633 are similarly RLC, MAC and physical layer performing tasks mentioned 634 above. 636 Under worst-case conditions, NB-IoT may achieve data rate of roughly 637 200 bps. For downlink with 164 dB coupling loss, NB-IoT may achieve 638 higher data rates, depending on the deployment mode. Stand-alone 639 operation may achieve the highest data rates, up to few kbps, while 640 in-band and guard-band operations may reach several hundreds of bps. 641 NB-IoT may even operate with higher maximum coupling loss than 170 dB 642 with very low bit rates. 644 2.3. SIGFOX 646 Text here is largely from 647 [I-D.zuniga-lpwan-sigfox-system-description] which may have been 648 updated since this was published. 650 2.3.1. Provenance and Documents 652 The SIGFOX LPWAN is in line with the terminology and specifications 653 being defined by the ETSI ERM TG28 Low Throughput Networks (LTN) 654 group [etsi_ltn]. As of today, SIGFOX's network has been fully 655 deployed in 6 countries, with ongoing deployments on 18 other 656 countries, in total a geography containing 397M people. 658 2.3.2. Characteristics 660 SIGFOX LPWAN autonomous battery-operated devices send only a few 661 bytes per day, week or month, in principle allowing them to remain on 662 a single battery for up to 10-15 years. The capacity of a SIGFOX 663 base station mainly depends on the number of messages generated by 664 the devices, and not on the number of devices. The battery life of 665 devices also depends on the number of messages generated by the 666 device, but it is important to keep in mind that these devices are 667 designed to last several years, some of them even buried underground. 668 The coverage of the cell also depends on the link budget and on the 669 type of deployment (urban, rural, etc.), which can vary from sending 670 less than one message per device per day to dozens of messages per 671 device per day. 673 The radio interface is compliant with the following regulations: 675 Spectrum allocation in the USA [fcc_ref] 677 Spectrum allocation in Europe [etsi_ref] 679 Spectrum allocation in Japan [arib_ref] 681 The SIGFOX LTN radio interface is also compliant with the local 682 regulations of the following countries: Australia, Brazil, Canada, 683 Kenya, Lebanon, Mauritius, Mexico, New Zealand, Oman, Peru, 684 Singapore, South Africa, South Korea, and Thailand. 686 The radio interface is based on Ultra Narrow Band (UNB) 687 communications, which allow an increased transmission range by 688 spending a limited amount of energy at the device. Moreover, UNB 689 allows a large number of devices to coexist in a given cell without 690 significantly increasing the spectrum interference. 692 Both uplink and downlink communications are possible with the UNB 693 solution. Due to spectrum optimizations, different uplink and 694 downlink frames and time synchronization methods are needed. 696 The main radio characteristics of the UNB uplink transmission are: 698 o Channelization mask: 100 Hz (600 Hz in the USA) 700 o Uplink baud rate: 100 baud (600 baud in the USA) 702 o Modulation scheme: DBPSK 704 o Uplink transmission power: compliant with local regulation 706 o Link budget: 155 dB (or better) 708 o Central frequency accuracy: not relevant, provided there is no 709 significant frequency drift within an uplink packet 711 In Europe, the UNB uplink frequency band is limited to 868,00 to 712 868,60 MHz, with a maximum output power of 25 mW and a maximum mean 713 transmission time of 1%. 715 The format of the uplink frame is the following: 717 +--------+--------+--------+------------------+-------------+-----+ 718 |Preamble| Frame | Dev ID | Payload |Msg Auth Code| FCS | 719 | | Sync | | | | | 720 +--------+--------+--------+------------------+-------------+-----+ 722 Figure 5: Uplink Frame Format 724 The uplink frame is composed of the following fields: 726 o Preamble: 19 bits 727 o Frame sync and header: 29 bits 729 o Device ID: 32 bits 731 o Payload: 0-96 bits 733 o Authentication: 16-40 bits 735 o Frame check sequence: 16 bits (CRC) 737 The main radio characteristics of the UNB downlink transmission are: 739 o Channelization mask: 1.5 kHz 741 o Downlink baud rate: 600 baud 743 o Modulation scheme: GFSK 745 o Downlink transmission power: 500 mW (4W in the USA) 747 o Link budget: 153 dB (or better) 749 o Central frequency accuracy: Centre frequency of downlink 750 transmission are set by the network according to the corresponding 751 uplink transmission. 753 In Europe, the UNB downlink frequency band is limited to 869,40 to 754 869,65 MHz, with a maximum output power of 500 mW with 10% duty 755 cycle. 757 The format of the downlink frame is the following: 759 +------------+-----+---------+------------------+-------------+-----+ 760 | Preamble |Frame| ECC | Payload |Msg Auth Code| FCS | 761 | |Sync | | | | | 762 +------------+-----+---------+------------------+-------------+-----+ 764 Figure 6: Downlink Frame Format 766 The downlink frame is composed of the following fields: 768 o Preamble: 91 bits 770 o Frame sync and header: 13 bits 772 o Error Correcting Code (ECC): 32 bits 773 o Payload: 0-64 bits 775 o Authentication: 16 bits 777 o Frame check sequence: 8 bits (CRC) 779 The radio interface is optimized for uplink transmissions, which are 780 asynchronous. Downlink communications are achieved by querying the 781 network for existing data from the device. 783 A device willing to receive downlink messages opens a fixed window 784 for reception after sending an uplink transmission. The delay and 785 duration of this window have fixed values. The LTN transmits the 786 downlink message for a given device during the reception window. The 787 LTN selects the base station (BS) for transmitting the corresponding 788 downlink message. 790 Uplink and downlink transmissions are unbalanced due to the 791 regulatory constraints on the ISM bands. Under the strictest 792 regulations, the system can allow a maximum of 140 uplink messages 793 and 4 downlink messages per device per day. These restrictions can 794 be slightly relaxed depending on system conditions and the specific 795 regulatory domain of operation. 797 +--+ 798 |EP| * +------+ 799 +--+ * | RA | 800 * +------+ 801 +--+ * | 802 |EP| * * * * | 803 +--+ * +----+ | 804 * | BS | \ +--------+ 805 +--+ * +----+ \ | | 806 DA -----|EP| * * * | SC |----- NA 807 +--+ * / | | 808 * +----+ / +--------+ 809 +--+ * | BS |/ 810 |EP| * * * * +----+ 811 +--+ * 812 * 813 +--+ * 814 |EP| * * 815 +--+ 817 Figure 7: SIGFOX architecture 819 Figure 7 depicts the different elements of the SIGFOX architecture. 821 SIGFOX has a "one-contract one-network" model allowing devices to 822 connect in any country, without any notion of roaming. 824 The architecture consists of a single core network, which allows 825 global connectivity with minimal impact on the end device and radio 826 access network. The core network elements are the Service Center 827 (SC) and the Registration Authority (RA). The SC is in charge of the 828 data connectivity between the Base Station (BS) and the Internet, as 829 well as the control and management of the BSs and End Points. The RA 830 is in charge of the End Point network access authorization. 832 The radio access network is comprised of several BSs connected 833 directly to the SC. Each BS performs complex L1/L2 functions, 834 leaving some L2 and L3 functionalities to the SC. 836 The devices or End Points (EPs) are the objects that communicate 837 application data between local device applications (DAs) and network 838 applications (NAs). 840 EPs (or devices) can be static or nomadic, as they associate with the 841 SC and they do not attach to a specific BS. Hence, they can 842 communicate with the SC through one or many BSs. 844 Due to constraints in the complexity of the EP, it is assumed that 845 EPs host only one or very few device applications, which communicate 846 to one single network application at a time. 848 The radio protocol provides mechanisms to authenticate and ensure 849 integrity of the message. This is achieved by using a unique device 850 ID and a message authentication code, which allow ensuring that the 851 message has been generated and sent by the device with the ID claimed 852 in the message. 854 Security keys are independent for each device. These keys are 855 associated with the device ID and they are pre-provisioned. 856 Application data can be encrypted by the application provider. 858 2.4. Wi-SUN Alliance Field Area Network (FAN) 860 [[Ed: Text here is via personal communication from Bob Heile 861 (bheile@ieee.org) and was authored by Bob and Sum Chin Sean. The 862 editor thanks Paul Duffy (paduffy@cisco.com) for forwarding updated 863 text from Bob and additional comments/input on this section. ]] 865 2.4.1. Provenance and Documents 867 The Wi-SUN Alliance is an industry alliance 868 for smart city, smart grid, smart utility, and a broad set of general 869 IoT applications. The Wi-SUN Alliance Field Area Network (FAN) 870 profile is open standards based (primarily on IETF and IEEE802 871 standards) and was developed to address applications like smart 872 municipality/city infrastructure monitoring and management, electric 873 vehicle (EV) infrastructure, advanced metering infrastructure (AMI), 874 distribution automation (DA), supervisory control and data 875 acquisition (SCADA) protection/management, distributed generation 876 monitoring and management, and many more IoT applications. 877 Additionally, the Alliance has created a certification program to 878 promote global multi-vendor interoperability. 880 The FAN profiile is currently being specified within ANSI/TIA as an 881 extension of work previously done on Smart Utility Networks. 882 [ANSI-4957-000]. Updates to those specifications intended to be 883 published in 2017 will contain details of the FAN profile. A current 884 snapshot of the work to produce that profile is presented in 885 [wisun-pressie1] [wisun-pressie2] . 887 2.4.2. Characteristics 889 The FAN profile is an IPv6 frequency hopping wireless mesh network 890 with support for enterprise level security. The frequency hopping 891 wireless mesh topology aims to offer superior network robustness, 892 reliability due to high redundancy, good scalability due to the 893 flexible mesh configuration and good resilience to interference. 894 Very low power modes are in development permitting long term battery 895 operation of network nodes. 897 The core architecture of Wi-SUN FAN is a mesh network. A FAN 898 contains one or more networks. Within a network, nodes assume one of 899 three operational roles. First, each network contains a Border 900 Router providing Wide Area Network (WAN) connectivity to the network. 901 The Border Router maintains source routing tables for all nodes 902 within its network, provides node authentication and key management 903 services, and disseminates network-wide information such as broadcast 904 schedules. Secondly, Router nodes, which provide upward and downward 905 packet forwarding (within a network). A Router also provides 906 services for relaying security and address management protocols. 907 Lastly, Leaf nodes provide minimum capabilities: discovering and 908 joining a network, send/receive IPv6 packets, etc. A low power 909 network may contain a mesh topology with Routers at the edges that 910 construct star topology with Leaf nodes. 912 The FAN profile is based on various open standards developed by the 913 IETF (including [RFC0768], [RFC2460], [RFC4443] and [RFC6282]), 914 IEEE802 (including [IEEE-802-15-4] and [IEEE-802-15-9]) and ANSI/TIA 915 [ANSI-4957-210] for low power and lossy networks. 917 The FAN profile specification provides an application-independent 918 IPv6-based transport service for both connectionless (i.e. UDP) and 919 connection-oriented (i.e. TCP) services. There are two possible 920 methods for establishing the IPv6 packet routing: mandatory Routing 921 Protocol for Low-Power and Lossy Networks (RPL) at the Network layer 922 or optional Multi-Hop Delivery Service (MHDS) at the Data Link layer. 923 Table 5 provides an overview of the FAN network stack. 925 The Transport service is based on User Datagram Protocol (UDP) 926 defined in RFC768 or Transmission Control Protocol (TCP) defined in 927 RFC793. 929 The Network service is provided by IPv6 defined in RFC2460 with 930 6LoWPAN adaptation as defined in RC4944 and RFC6282. Additionally, 931 ICMPv6 as defined in RFC4443 is used for control plane in information 932 exchange. 934 The Data Link service provides both control/management of the 935 Physical layer and data transfer/management services to the Network 936 layer. These services are divided into Media Access Control (MAC) 937 and Logical Link Control (LLC) sub-layers. The LLC sub-layer 938 provides a protocol dispatch service which supports 6LoWPAN and an 939 optional MAC sub-layer mesh service. The MAC sub-layer is 940 constructed using data structures defined in IEEE802.15.4-2015. 941 Multiple modes of frequency hopping are defined. The entire MAC 942 payload is encapsulated in an IEEE802.15.9 Information Element to 943 enable LLC protocol dispatch between upper layer 6LoWPAN processing, 944 MAC sublayer mesh processing, etc. These areas will be expanded once 945 IEEE802.15.12 is completed 947 The PHY service is derived from a sub-set of the SUN FSK 948 specification in IEEE802.15.4-2015. The 2-FSK modulation schemes, 949 with channel spacing range from 200 to 600 kHz, are defined to 950 provide data rates from 50 to 300 kbps, with Forward Error Coding 951 (FEC) as an optional feature. Towards enabling ultra-low-power 952 applications, the PHY layer design is also extendable to low energy 953 and critical infrastructure monitoring networks. 955 +------------------------------+------------------------------------+ 956 | Layer | Description | 957 +------------------------------+------------------------------------+ 958 | IPv6 protocol suite | TCP/UDP | 959 | | | 960 | | 6LoWPAN Adaptation + Header | 961 | | Compression | 962 | | | 963 | | DHCPv6 for IP address management. | 964 | | | 965 | | Routing using RPL. | 966 | | | 967 | | ICMPv6. | 968 | | | 969 | | Unicast and Multicast forwarding. | 970 | | | 971 | MAC based on IEEE 802.15.4e | Frequency hopping | 972 | + IE extensions | | 973 | | | 974 | | Discovery and Join | 975 | | | 976 | | Protocol Dispatch (IEEE 802.15.9) | 977 | | | 978 | | Several Frame Exchange patterns | 979 | | | 980 | | Optional Mesh Under routing (ANSI | 981 | | 4957.210). | 982 | | | 983 | PHY based on 802.15.4g | Various data rates and regions | 984 | | | 985 | Security | 802.1X/EAP-TLS/PKI | 986 | | Authentication. | 987 | | | 988 | | 802.11i Group Key Management | 989 | | | 990 | | Optional ETSI-TS-102-887-2 Node 2 | 991 | | Node Key Management | 992 +------------------------------+------------------------------------+ 994 Table 5: Wi-SUN Stack Overview 996 The FAN security supports Data Link layer network access control, 997 mutual authentication, and establishment of a secure pairwise link 998 between a FAN node and its Border Router, which is implemented with 999 an adaptation of IEEE802.1X and EAP-TLS as described in [RFC5216] 1000 using secure device identity as described in IEEE802.1AR. 1001 Certificate formats are based upon [RFC5280]. A secure group link 1002 between a Border Router and a set of FAN nodes is established using 1003 an adaptation of the IEEE802.11 Four-Way Handshake. A set of 4 group 1004 keys are maintained within the network, one of which is the current 1005 transmit key. Secure node to node links are supported between one- 1006 hop FAN neighbors using an adaptation of ETSI-TS-102-887-2. FAN 1007 nodes implement Frame Security as specified in IEEE802.15.4-2015. 1009 3. Generic Terminology 1011 LPWAN technologies, such as those discussed above, have similar 1012 architectures but different terminology. We can identify different 1013 types of entities in a typical LPWAN network: 1015 o End-Devices are the devices or the "things" (e.g. sensors, 1016 actuators, etc.), they are named differently in each technology 1017 (End Device, User Equipment or End Point). There can be a high 1018 density of end devices per radio gateway. 1020 o The Radio Gateway, which is the end point of the constrained link. 1021 It is known as: Gateway, Evolved Node B or Base station. 1023 o The Network Gateway or Router is the interconnection node between 1024 the Radio Gateway and the Internet. It is known as: Network 1025 Server, Serving GW or Service Center. 1027 o AAA Server, which controls the user authentication, the 1028 applications. It is known as: Join-Server, Home Subscriber Server 1029 or Registration Authority. [[Ed: I'm not clear that AAA server is 1030 the right generic term here.]] 1032 o At last we have the Application Server, known also as Packet Data 1033 Node Gateway or Network Application. 1035 +---------------------------------------------------------------------+ 1036 | Function/ | | | | | 1037 | Technology | LORAWAN | NB-IOT | SIGFOX | IETF | 1038 +--------------+-----------+------------+-------------+---------------+ 1039 | Sensor, | | | | | 1040 | Actuator, | End | User | End | Thing | 1041 |device, object| Device | Equipment | Point | (HOST) | 1042 +--------------+-----------+------------+-------------+---------------+ 1043 | Transceiver | | Evolved | Base | RADIO | 1044 | Antenna | Gateway | Node B | Station | GATEWAY | 1045 +--------------+-----------+------------+-------------+---------------+ 1046 | Server | Network | Serving- | Service |Network Gateway| 1047 | | Server | Gateway | Center | (ROUTER) | 1048 +--------------+-----------+------------+-------------+---------------+ 1049 | Security | Join | Home |Registration | | 1050 | Server | Server | Subscriber | Authority | AAA | 1051 | | | Server | | SERVER | 1052 +--------------+-----------+------------+-------------+---------------+ 1053 | Application |Application| Packet Data| Network | APPLICATION | 1054 | | Server |Node Gateway| Application | SERVER | 1055 +---------------------------------------------------------------------+ 1057 Figure 8: LPWAN Architecture Terminology 1059 () () () | +------+ 1060 () () () () / \ +---------+ | AAA | 1061 () () () () () () / \========| /\ |====|Server| +-----------+ 1062 () () () | | <--|--> | +------+ |Application| 1063 () () () () / \============| v |==============| Server | 1064 () () () / \ +---------+ +-----------+ 1065 HOSTS Radio Gateways Network Gateway 1067 Figure 9: LPWAN Architecture 1069 In addition to the names of entities, LPWANs are also subject to 1070 possibly regional frequency band regulations. Those may include 1071 restrictions on the duty-cycle, for example requiring that hosts only 1072 transmit for a certain percentage of each hour. 1074 4. Gap Analysis 1076 4.1. Naive application of IPv6 1078 IPv6 [RFC2460] has been designed to allocate addresses to all the 1079 nodes connected to the Internet. Nevertheless, the header overhead 1080 of at least 40 bytes introduced by the protocol is incompatible with 1081 LPWAN constraints. If IPv6 with no further optimization were used, 1082 several LPWAN frames would be needed just to carry the IP header. 1084 Another problem arises from IPv6 MTU requirements, which require the 1085 layer below to support at least 1280 byte packets [RFC2460]. 1087 IPv6 has a configuration protocol - neighbor discovery protocol, 1088 (NDP) [RFC4861]). For a node to learn network parameters NDP 1089 generates regular traffic with a relatively large message size that 1090 does not fit LPWAN constraints. 1092 In some LPWAN technologies, layer two multicast is not supported. In 1093 that case, if the network topology is a star, the solution and 1094 considerations of section 3.2.5 of [RFC7668] may be applied. 1096 Other key protocols such as DHCPv6 [RFC3315], IPsec [RFC4301] and TLS 1097 [RFC5246] have similarly problematic properties in this context. 1098 Each of those require relatively frequent round-trips between the 1099 host and some other host on the network. In the case of 1100 cryptographic protocols such as IPsec and TLS, in addition to the 1101 round-trips required for secure session establishment, cryptographic 1102 operations can require padding and addition of authenticators that 1103 are problematic when considering LPWAN lower layers. 1105 4.2. 6LoWPAN 1107 Several technologies that exhibit significant constraints in various 1108 dimensions have exploited the 6LoWPAN suite of specifications 1109 [RFC4944], [RFC6282], [RFC6775] to support IPv6 [I-D.hong-6lo-use- 1110 cases]. However, the constraints of LPWANs, often more extreme than 1111 those typical of technologies that have (re)used 6LoWPAN, constitute 1112 a challenge for the 6LoWPAN suite in order to enable IPv6 over LPWAN. 1113 LPWANs are characterised by device constraints (in terms of 1114 processing capacity, memory, and energy availability), and specially, 1115 link constraints, such as: 1117 o very low layer two payload size (from ~10 to ~100 bytes), 1119 o very low bit rate (from ~10 bit/s to ~100 kbit/s), and 1121 o in some specific technologies, further message rate constraints 1122 (e.g. between ~0.1 message/minute and ~1 message/minute) due to 1123 regional regulations that limit the duty cycle. 1125 4.2.1. Header Compression 1127 6LoWPAN header compression reduces IPv6 (and UDP) header overhead by 1128 eliding header fields when they can be derived from the link layer, 1129 and by assuming that some of the header fields will frequently carry 1130 expected values. 6LoWPAN provides both stateless and stateful header 1131 compression. In the latter, all nodes of a 6LoWPAN are assumed to 1132 share compression context. In the best case, the IPv6 header for 1133 link-local communication can be reduced to only 2 bytes. For global 1134 communication, the IPv6 header may be compressed down to 3 bytes in 1135 the most extreme case. However, in more practical situations, the 1136 smallest IPv6 header size may be 11 bytes (one address prefix 1137 compressed) or 19 bytes (both source and destination prefixes 1138 compressed). These headers are large considering the link layer 1139 payload size of LPWAN technologies, and in some cases are even bigger 1140 than the LPWAN PDUs. 6LoWPAN has been initially designed for IEEE 1141 802.15.4 networks with a frame size up to 127 bytes and a throughput 1142 of up to 250 kb/s, which may or may not be duty-cycled. 1144 4.2.2. Address Autoconfiguration 1146 Traditionally, Interface Identifiers (IIDs) have been derived from 1147 link layer identifiers [RFC4944] . This allows optimisations such as 1148 header compression. Nevertheless, recent guidance has given advice 1149 on the fact that, due to privacy concerns, 6LoWPAN devices should not 1150 be configured to embed their link layer addresses in the IID by 1151 default. 1153 4.2.3. Fragmentation 1155 As stated above, IPv6 requires the layer below to support an MTU of 1156 1280 bytes [RFC2460]. Therefore, given the low maximum payload size 1157 of LPWAN technologies, fragmentation is needed. 1159 If a layer of an LPWAN technology supports fragmentation, proper 1160 analysis has to be carried out to decide whether the fragmentation 1161 functionality provided by the lower layer or fragmentation at the 1162 adaptation layer should be used. Otherwise, fragmentation 1163 functionality shall be used at the adaptation layer. 1165 6LoWPAN defined a fragmentation mechanism and a fragmentation header 1166 to support the transmission of IPv6 packets over IEEE 802.15.4 1167 networks [RFC4944]. While the 6LoWPAN fragmentation header is 1168 appropriate for IEEE 802.15.4-2003 (which has a frame payload size of 1169 81-102 bytes), it is not suitable for several LPWAN technologies, 1170 many of which have a maximum payload size that is one order of 1171 magnitude below that of IEEE 802.15.4-2003. The overhead of the 1172 6LoWPAN fragmentation header is high, considering the reduced payload 1173 size of LPWAN technologies and the limited energy availability of the 1174 devices using such technologies. Furthermore, its datagram offset 1175 field is expressed in increments of eight octets. In some LPWAN 1176 technologies, the 6LoWPAN fragmentation header plus eight octets from 1177 the original datagram exceeds the available space in the layer two 1178 payload. In addition, the MTU in the LPWAN networks could be 1179 variable which implies a variable fragmentation solution. 1181 4.2.4. Neighbor Discovery 1183 6LoWPAN Neighbor Discovery [RFC6775] defined optimizations to IPv6 1184 Neighbor Discovery [RFC4861], in order to adapt functionality of the 1185 latter for networks of devices using IEEE 802.15.4 or similar 1186 technologies. The optimizations comprise host-initiated interactions 1187 to allow for sleeping hosts, replacement of multicast-based address 1188 resolution for hosts by an address registration mechanism, multihop 1189 extensions for prefix distribution and duplicate address detection 1190 (note that these are not needed in a star topology network), and 1191 support for 6LoWPAN header compression. 1193 6LoWPAN Neighbor Discovery may be used in not so severely constrained 1194 LPWAN networks. The relative overhead incurred will depend on the 1195 LPWAN technology used (and on its configuration, if appropriate). In 1196 certain LPWAN setups (with a maximum payload size above ~60 bytes, 1197 and duty-cycle-free or equivalent operation), an RS/RA/NS/NA exchange 1198 may be completed in a few seconds, without incurring packet 1199 fragmentation. 1201 In other LPWANs (with a maximum payload size of ~10 bytes, and a 1202 message rate of ~0.1 message/minute), the same exchange may take 1203 hours or even days, leading to severe fragmentation and consuming a 1204 significant amount of the available network resources. 6LoWPAN 1205 Neighbor Discovery behavior may be tuned through the use of 1206 appropriate values for the default Router Lifetime, the Valid 1207 Lifetime in the PIOs, and the Valid Lifetime in the 6CO, as well as 1208 the address Registration Lifetime. However, for the latter LPWANs 1209 mentioned above, 6LoWPAN Neighbor Discovery is not suitable. 1211 4.3. 6lo 1213 The 6lo WG has been reusing and adapting 6LoWPAN to enable IPv6 1214 support over link layer technologies such as Bluetooth Low Energy 1215 (BTLE), ITU-T G.9959, DECT-ULE, MS/TP-RS485, NFC IEEE 802.11ah. (See 1216 for details.) These technologies are 1217 similar in several aspects to IEEE 802.15.4, which was the original 1218 6LoWPAN target technology. 1220 6lo has mostly used the subset of 6LoWPAN techniques best suited for 1221 each lower layer technology, and has provided additional 1222 optimizations for technologies where the star topology is used, such 1223 as BTLE or DECT-ULE. 1225 The main constraint in these networks comes from the nature of the 1226 devices (constrained devices), whereas in LPWANs it is the network 1227 itself that imposes the most stringent constraints. 1229 4.4. 6tisch 1231 The 6tisch solution is dedicated to mesh networks that operate using 1232 802.15.4e MAC with a deterministic slotted channel. The time slot 1233 channel (TSCH) can help to reduce collisions and to enable a better 1234 balance over the channels. It improves the battery life by avoiding 1235 the idle listening time for the return channel. 1237 A key element of 6tisch is the use of synchronization to enable 1238 determinism. TSCH and 6TiSCH may provide a standard scheduling 1239 function. The LPWAN networks probably will not support 1240 synchronization like the one used in 6tisch. 1242 4.5. RoHC 1244 Robust header compression (RoHC) is a header compression mechanism 1245 [RFC3095] developed for multimedia flows in a point to point channel. 1246 RoHC uses 3 levels of compression, each level having its own header 1247 format. In the first level, RoHC sends 52 bytes of header, in the 1248 second level the header could be from 34 to 15 bytes and in the third 1249 level header size could be from 7 to 2 bytes. The level of 1250 compression is managed by a sequence number, which varies in size 1251 from 2 bytes to 4 bits in the minimal compression. SN compression is 1252 done with an algorithm called W-LSB (Window- Least Signifiant Bits). 1253 This window has a 4 bit size representing 15 packets, so every 15 1254 packets RoHC needs to slide the window in order to receive the 1255 correct sequence number, and sliding the window implies a reduction 1256 of the level of compression. When packets are lost or errored, the 1257 decompressor loses context and drops packets until a bigger header is 1258 sent with more complete information. To estimate the performance of 1259 RoHC, an average header size is used. This average depends on the 1260 transmission conditions, but most of the time is between 3 and 4 1261 bytes. 1263 RoHC has not been adapted specifically to the constrained hosts and 1264 networks of LPWANs: it does not take into account energy limitations 1265 nor the transmission rate, and RoHC context is synchronised during 1266 transmission, which does not allow better compression. 1268 4.6. ROLL 1270 Most technologies considered by the lpwan WG are based on a star 1271 topology, which eliminates the need for routing at that layer. 1272 Future work may address additional use-cases that may require 1273 adaptation of existing routing protocols or the definition of new 1274 ones. As of the time of writing, work similar to that done in the 1275 ROLL WG and other routing protocols are out of scope of the LPWAN WG. 1277 4.7. CoAP 1279 CoAP [RFC7252] provides a RESTful framework for applications intended 1280 to run on constrained IP networks. It may be necessary to adapt CoAP 1281 or related protocols to take into account for the extreme duty cycles 1282 and the potentially extremely limited throughput of LPWANs. 1284 For example, some of the timers in CoAP may need to be redefined. 1285 Taking into account CoAP acknowledgements may allow the reduction of 1286 L2 acknowledgements. On the other hand, the current work in progress 1287 in the CoRE WG where the COMI/CoOL network management interface 1288 which, uses Structured Identifiers (SID) to reduce payload size over 1289 CoAP proves to be a good solution for the LPWAN technologies. The 1290 overhead is reduced by adding a dictionary which matches a URI to a 1291 small identifier and a compact mapping of the YANG model into the 1292 CBOR binary representation. 1294 4.8. Mobility 1296 LPWANs nodes can be mobile. However, LPWAN mobility is different 1297 from the one specified for Mobile IP. LPWAN implies sporadic traffic 1298 and will rarely be used for high-frequency, real-time communications. 1299 The applications do not generate a flow, they need to save energy and 1300 most of the time the node will be down. The mobility will imply most 1301 of the time a group of devices, which represent a network itself. 1302 The mobility concerns more the gateway than the devices. 1304 NEMO [RFC3963] Mobility solutions may be used in the case where some 1305 hosts belonging to the same Network gateway will move from one point 1306 to another and that they are not aware of this mobility. 1308 4.9. DNS and LPWAN 1310 The Domain Name System (DNS) DNS [RFC1035], enables applications to 1311 name things with a globallly resolvable name. Many protocols use the 1312 DNS to identify hosts for example applications using CoAP. 1314 The DNS query/answer protocol as a pre-cursor to other communication 1315 within the time-to-live (TTL) of a DNS answer is clearly problematic 1316 in an LPWAN, say where only one round-trip per hour can be used, and 1317 with a TTL that is less than 3600. It is currently unclear whether 1318 and how DNS-like functionality might be provided in LPWANs. 1320 5. Security Considerations 1322 Most LPWAN technologies integrate some authentication or encryption 1323 mechanisms that were defined outside the IETF. The working group may 1324 need to do work to integrate these mechanisms to unify management. A 1325 standardized Authentication, Accounting and Authorization (AAA) 1326 infrastructure [RFC2904] may offer a scalable solution for some of 1327 the security and management issues for LPWANs. AAA offers 1328 centralized management that may be of use in LPWANs, for example 1329 [I-D.garcia-dime-diameter-lorawan] and 1330 [I-D.garcia-radext-radius-lorawan] suggest possible security 1331 processes for a LoRaWAN network. Similar mechanisms may be useful to 1332 explore for other LPWAN technologies. 1334 Some applications using LPWANs may raise few or no privacy 1335 considerations. For example, temperature sensors in a large office 1336 building may not raise privacy issues. However, the same sensors, if 1337 deployed in a home environment and especially if triggered due to 1338 human presence, can raise significant privacy issues - if an end- 1339 device emits (an encrypted) packet every time someone enters a room 1340 in a home, then that traffic is privacy sensitive. And the more that 1341 the existence of that traffic is visible to network entities, the 1342 more privacy sensitivities arise. At this point, it is not clear 1343 whether there are workable mitigations for problems like this - in a 1344 more typical network, one would cosider defining padding mechanisms 1345 and allowing for cover traffic. In some LPWANs, those mechanisms may 1346 not be feasible. Nonetheless, the privacy challenges do exist and 1347 can be real and so some solutions will be needed. Note that many 1348 aspects of solutions in this space may not be visible in IETF 1349 specifications, but can be e.g. implementation or deployment 1350 specific. 1352 Another challenge for LPWANs will be how to handle key management and 1353 associated protocols. In a more traditional network (e.g. the web), 1354 servers can stable OCSP responses in order to allow browsers to check 1355 revocation status for presented certificates. [RFC6961] While the 1356 "stapling" approach is likely something that would help in an LPWAN, 1357 as it avoids an RTT, certificates and OCSP responses are bulky items 1358 and will prove challenging to handle in LPWANs with bounded 1359 bandwidth. 1361 6. IANA Considerations 1363 There are no IANA considerations related to this memo. 1365 7. Contributors 1367 As stated above this document is mainly a collection of content 1368 developed by the full set of contributors listed below. The main 1369 input documents and their authors were: 1371 o Text for Section 2.1 was provieded by Alper Yegin and Stephen 1372 Farrell in [I-D.farrell-lpwan-lora-overview]. 1374 o Text for Section 2.2 was provided by Antti Ratilainen in 1375 [I-D.ratilainen-lpwan-nb-iot]. 1377 o Text for Section 2.3 was provided by Juan Carlos Zuniga and Benoit 1378 Ponsard in [I-D.zuniga-lpwan-sigfox-system-description]. 1380 o Text for Section 2.4 was provided via personal communication from 1381 Bob Heile (bheile@ieee.org) and was authored by Bob and Sum Chin 1382 Sean. There is no Internet draft for that at present. 1384 o Text for Section 4 was provided by Ana Minabiru, Carles Gomez, 1385 Laurent Toutain, Josep Paradells and Jon Crowcroft in 1386 [I-D.minaburo-lpwan-gap-analysis]. Additional text from that 1387 draft is also used elsewhere above. 1389 The full list of contributors are: 1391 Jon Crowcroft 1392 University of Cambridge 1393 JJ Thomson Avenue 1394 Cambridge, CB3 0FD 1395 United Kingdom 1397 Email: jon.crowcroft@cl.cam.ac.uk 1399 Carles Gomez 1400 UPC/i2CAT 1401 C/Esteve Terradas, 7 1402 Castelldefels 08860 1403 Spain 1405 Email: carlesgo@entel.upc.edu 1407 Bob Heile 1408 Wi-Sun Alliance 1409 11 Robert Toner Blvd, Suite 5-301 1410 North Attleboro, MA 02763 1411 USA 1413 Phone: +1-781-929-4832 1414 Email: bheile@ieee.org 1416 Ana Minaburo 1417 Acklio 1418 2bis rue de la Chataigneraie 1419 35510 Cesson-Sevigne Cedex 1420 France 1422 Email: ana@ackl.io 1424 Josep PAradells 1425 UPC/i2CAT 1426 C/Jordi Girona, 1-3 1427 Barcelona 08034 1428 Spain 1430 Email: josep.paradells@entel.upc.edu 1432 Benoit Ponsard 1433 SIGFOX 1434 425 rue Jean Rostand 1435 Labege 31670 1436 France 1438 Email: Benoit.Ponsard@sigfox.com 1439 URI: http://www.sigfox.com/ 1441 Antti Ratilainen 1442 Ericsson 1443 Hirsalantie 11 1444 Jorvas 02420 1445 Finland 1447 Email: antti.ratilainen@ericsson.com 1449 Chin-Sean SUM 1450 Wi-Sun Alliance 1451 20, Science Park Rd 1452 Singapore 117674 1454 Phone: +65 6771 1011 1455 Email: sum@wi-sun.org 1457 Laurent Toutain 1458 Institut MINES TELECOM ; TELECOM Bretagne 1459 2 rue de la Chataigneraie 1460 CS 17607 1461 35576 Cesson-Sevigne Cedex 1462 France 1464 Email: Laurent.Toutain@telecom-bretagne.eu 1466 Alper Yegin 1467 Actility 1468 Paris, Paris 1469 FR 1471 Email: alper.yegin@actility.com 1473 Juan Carlos Zuniga 1474 SIGFOX 1475 425 rue Jean Rostand 1476 Labege 31670 1477 France 1479 Email: JuanCarlos.Zuniga@sigfox.com 1480 URI: http://www.sigfox.com/ 1482 8. Acknowledgements 1484 Thanks to all those listed in Section 7 for the excellent text. 1485 Errors in the handling of that are solely the editor's fault. 1487 In addition to the contributors above, thanks are due to Jiazi Yi, 1488 [your name here] for comments. 1490 Stephen Farrell's work on this memo was supported by the Science 1491 Foundation Ireland funded CONNECT centre . 1493 9. Informative References 1495 [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, 1496 DOI 10.17487/RFC0768, August 1980, 1497 . 1499 [RFC1035] Mockapetris, P., "Domain names - implementation and 1500 specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, 1501 November 1987, . 1503 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1504 (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, 1505 December 1998, . 1507 [RFC2904] Vollbrecht, J., Calhoun, P., Farrell, S., Gommans, L., 1508 Gross, G., de Bruijn, B., de Laat, C., Holdrege, M., and 1509 D. Spence, "AAA Authorization Framework", RFC 2904, 1510 DOI 10.17487/RFC2904, August 2000, 1511 . 1513 [RFC3095] Bormann, C., Burmeister, C., Degermark, M., Fukushima, H., 1514 Hannu, H., Jonsson, L-E., Hakenberg, R., Koren, T., Le, 1515 K., Liu, Z., Martensson, A., Miyazaki, A., Svanbro, K., 1516 Wiebke, T., Yoshimura, T., and H. Zheng, "RObust Header 1517 Compression (ROHC): Framework and four profiles: RTP, UDP, 1518 ESP, and uncompressed", RFC 3095, DOI 10.17487/RFC3095, 1519 July 2001, . 1521 [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, 1522 C., and M. Carney, "Dynamic Host Configuration Protocol 1523 for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July 1524 2003, . 1526 [RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. 1527 Thubert, "Network Mobility (NEMO) Basic Support Protocol", 1528 RFC 3963, DOI 10.17487/RFC3963, January 2005, 1529 . 1531 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 1532 Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, 1533 December 2005, . 1535 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet 1536 Control Message Protocol (ICMPv6) for the Internet 1537 Protocol Version 6 (IPv6) Specification", RFC 4443, 1538 DOI 10.17487/RFC4443, March 2006, 1539 . 1541 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 1542 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 1543 DOI 10.17487/RFC4861, September 2007, 1544 . 1546 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 1547 "Transmission of IPv6 Packets over IEEE 802.15.4 1548 Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, 1549 . 1551 [RFC5216] Simon, D., Aboba, B., and R. Hurst, "The EAP-TLS 1552 Authentication Protocol", RFC 5216, DOI 10.17487/RFC5216, 1553 March 2008, . 1555 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 1556 (TLS) Protocol Version 1.2", RFC 5246, 1557 DOI 10.17487/RFC5246, August 2008, 1558 . 1560 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., 1561 Housley, R., and W. Polk, "Internet X.509 Public Key 1562 Infrastructure Certificate and Certificate Revocation List 1563 (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008, 1564 . 1566 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 1567 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 1568 DOI 10.17487/RFC6282, September 2011, 1569 . 1571 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 1572 Bormann, "Neighbor Discovery Optimization for IPv6 over 1573 Low-Power Wireless Personal Area Networks (6LoWPANs)", 1574 RFC 6775, DOI 10.17487/RFC6775, November 2012, 1575 . 1577 [RFC6961] Pettersen, Y., "The Transport Layer Security (TLS) 1578 Multiple Certificate Status Request Extension", RFC 6961, 1579 DOI 10.17487/RFC6961, June 2013, 1580 . 1582 [RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained 1583 Application Protocol (CoAP)", RFC 7252, 1584 DOI 10.17487/RFC7252, June 2014, 1585 . 1587 [RFC7668] Nieminen, J., Savolainen, T., Isomaki, M., Patil, B., 1588 Shelby, Z., and C. Gomez, "IPv6 over BLUETOOTH(R) Low 1589 Energy", RFC 7668, DOI 10.17487/RFC7668, October 2015, 1590 . 1592 [I-D.farrell-lpwan-lora-overview] 1593 Farrell, S. and A. Yegin, "LoRaWAN Overview", draft- 1594 farrell-lpwan-lora-overview-01 (work in progress), October 1595 2016. 1597 [I-D.minaburo-lpwan-gap-analysis] 1598 Minaburo, A., Gomez, C., Toutain, L., Paradells, J., and 1599 J. Crowcroft, "LPWAN Survey and GAP Analysis", draft- 1600 minaburo-lpwan-gap-analysis-02 (work in progress), October 1601 2016. 1603 [I-D.zuniga-lpwan-sigfox-system-description] 1604 Zuniga, J. and B. PONSARD, "SIGFOX System Description", 1605 draft-zuniga-lpwan-sigfox-system-description-02 (work in 1606 progress), March 2017. 1608 [I-D.ratilainen-lpwan-nb-iot] 1609 Ratilainen, A., "NB-IoT characteristics", draft- 1610 ratilainen-lpwan-nb-iot-00 (work in progress), July 2016. 1612 [I-D.garcia-dime-diameter-lorawan] 1613 Garcia, D., Lopez, R., Kandasamy, A., and A. Pelov, 1614 "LoRaWAN Authentication in Diameter", draft-garcia-dime- 1615 diameter-lorawan-00 (work in progress), May 2016. 1617 [I-D.garcia-radext-radius-lorawan] 1618 Garcia, D., Lopez, R., Kandasamy, A., and A. Pelov, 1619 "LoRaWAN Authentication in RADIUS", draft-garcia-radext- 1620 radius-lorawan-03 (work in progress), May 2017. 1622 [TGPP36300] 1623 3GPP, "TS 36.300 v13.4.0 Evolved Universal Terrestrial 1624 Radio Access (E-UTRA) and Evolved Universal Terrestrial 1625 Radio Access Network (E-UTRAN); Overall description; Stage 1626 2", 2016, 1627 . 1629 [TGPP36321] 1630 3GPP, "TS 36.321 v13.2.0 Evolved Universal Terrestrial 1631 Radio Access (E-UTRA); Medium Access Control (MAC) 1632 protocol specification", 2016. 1634 [TGPP36322] 1635 3GPP, "TS 36.322 v13.2.0 Evolved Universal Terrestrial 1636 Radio Access (E-UTRA); Radio Link Control (RLC) protocol 1637 specification", 2016. 1639 [TGPP36323] 1640 3GPP, "TS 36.323 v13.2.0 Evolved Universal Terrestrial 1641 Radio Access (E-UTRA); Packet Data Convergence Protocol 1642 (PDCP) specification (Not yet available)", 2016. 1644 [TGPP36331] 1645 3GPP, "TS 36.331 v13.2.0 Evolved Universal Terrestrial 1646 Radio Access (E-UTRA); Radio Resource Control (RRC); 1647 Protocol specification", 2016. 1649 [TGPP36201] 1650 3GPP, "TS 36.201 v13.2.0 - Evolved Universal Terrestrial 1651 Radio Access (E-UTRA); LTE physical layer; General 1652 description", 2016. 1654 [TGPP23720] 1655 3GPP, "TR 23.720 v13.0.0 - Study on architecture 1656 enhancements for Cellular Internet of Things", 2016. 1658 [TGPP33203] 1659 3GPP, "TS 33.203 v13.1.0 - 3G security; Access security 1660 for IP-based services", 2016. 1662 [etsi_ltn] 1663 "ETSI Technical Committee on EMC and Radio Spectrum 1664 Matters (ERM) TG28 Low Throughput Networks (LTN)", 1665 February 2015. 1667 [fcc_ref] "FCC CFR 47 Part 15.247 Telecommunication Radio Frequency 1668 Devices - Operation within the bands 902-928 MHz, 1669 2400-2483.5 MHz, and 5725-5850 MHz.", June 2016. 1671 [etsi_ref] 1672 "ETSI EN 300-220 (Parts 1 and 2): Electromagnetic 1673 compatibility and Radio spectrum Matters (ERM); Short 1674 Range Devices (SRD); Radio equipment to be used in the 25 1675 MHz to 1 000 MHz frequency range with power levels ranging 1676 up to 500 mW", May 2016. 1678 [arib_ref] 1679 "ARIB STD-T108 (Version 1.0): 920MHz-Band Telemeter, 1680 Telecontrol and data transmission radio equipment.", 1681 February 2012. 1683 [LoRaSpec] 1684 LoRa Alliance, "LoRaWAN Specification Version V1.0.2", 1685 July 2016, . 1689 [LoRaSpec1.0] 1690 LoRa Alliance, "LoRaWAN Specification Version V1.0", Jan 1691 2015, . 1694 [ANSI-4957-000] 1695 ANSI, TIA-4957.000, "Architecture Overview for the Smart 1696 Utility Network", May 2013, . 1699 [ANSI-4957-210] 1700 ANSI, TIA-4957.210, "Multi-Hop Delivery Specification of a 1701 Data Link Sub-Layer", May 2013, . 1704 [wisun-pressie1] 1705 Phil Beecher, Chair, Wi-SUN Alliance, "Wi-SUN Alliance 1706 Overview", March 2017, . 1710 [wisun-pressie2] 1711 Bob Heile, Director of Standards, Wi-SUN Alliance, "IETF97 1712 Wi-SUN Alliance Field Area Network (FAN) Overview", 1713 November 2016, 1714 . 1717 [IEEE-802-15-4] 1718 "IEEE Standard for Low-Rate Wireless Personal Area 1719 Networks (WPANs)", IEEE Standard 802.15.4, 2015, 1720 . 1723 [IEEE-802-15-9] 1724 "IEEE Recommended Practice for Transport of Key Management 1725 Protocol (KMP) Datagrams", IEEE Standard 802.15.9, 2016, 1726 . 1729 Appendix A. Changes 1731 A.1. From -00 to -01 1733 o WG have stated they want this to be an RFC. 1735 o WG clearly want to keep the RF details. 1737 o Various changes made to remove/resolve a number of editorial notes 1738 from -00 (in some cases as per suggestions from Ana Minaburo) 1740 o Merged PR's: #1... 1742 o Rejected PR's: #2 (change was made to .txt not .xml but was 1743 replicated manually by editor) 1745 o Github repo is at: https://github.com/sftcd/lpwan-ov 1747 A.2. From -01 to -02 1749 o WG seem to agree with editor suggestions in slides 13-24 of the 1750 presentation on this topic given at IETF98 (See: 1751 https://www.ietf.org/proceedings/98/slides/slides-98-lpwan- 1752 aggregated-slides-07.pdf) 1754 o Got new text wrt Wi-SUN via email from Paul Duffy and merged that 1755 in 1757 o Reflected list discussion wrt terminology and "end-device" 1759 o Merged PR's: #3... 1761 Author's Address 1763 Stephen Farrell (editor) 1764 Trinity College Dublin 1765 Dublin 2 1766 Ireland 1768 Phone: +353-1-896-2354 1769 Email: stephen.farrell@cs.tcd.ie