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2 lpwan S. Farrell, Ed.
3 Internet-Draft Trinity College Dublin
4 Intended status: Informational January 30, 2018
5 Expires: August 3, 2018
7 LPWAN Overview
8 draft-ietf-lpwan-overview-08
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 August 3, 2018.
37 Copyright Notice
39 Copyright (c) 2018 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 . . . . . . . . . . . . . . . . . . . 16
65 2.4. Wi-SUN Alliance Field Area Network (FAN) . . . . . . . . 20
66 2.4.1. Provenance and Documents . . . . . . . . . . . . . . 20
67 2.4.2. Characteristics . . . . . . . . . . . . . . . . . . . 21
68 3. Generic Terminology . . . . . . . . . . . . . . . . . . . . . 24
69 4. Gap Analysis . . . . . . . . . . . . . . . . . . . . . . . . 25
70 4.1. Naive application of IPv6 . . . . . . . . . . . . . . . . 26
71 4.2. 6LoWPAN . . . . . . . . . . . . . . . . . . . . . . . . . 26
72 4.2.1. Header Compression . . . . . . . . . . . . . . . . . 27
73 4.2.2. Address Autoconfiguration . . . . . . . . . . . . . . 27
74 4.2.3. Fragmentation . . . . . . . . . . . . . . . . . . . . 27
75 4.2.4. Neighbor Discovery . . . . . . . . . . . . . . . . . 28
76 4.3. 6lo . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
77 4.4. 6tisch . . . . . . . . . . . . . . . . . . . . . . . . . 29
78 4.5. RoHC . . . . . . . . . . . . . . . . . . . . . . . . . . 29
79 4.6. ROLL . . . . . . . . . . . . . . . . . . . . . . . . . . 30
80 4.7. CoAP . . . . . . . . . . . . . . . . . . . . . . . . . . 30
81 4.8. Mobility . . . . . . . . . . . . . . . . . . . . . . . . 30
82 4.9. DNS and LPWAN . . . . . . . . . . . . . . . . . . . . . . 31
83 5. Security Considerations . . . . . . . . . . . . . . . . . . . 31
84 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32
85 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 32
86 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 35
87 9. Informative References . . . . . . . . . . . . . . . . . . . 35
88 Appendix A. Changes . . . . . . . . . . . . . . . . . . . . . . 40
89 A.1. From -00 to -01 . . . . . . . . . . . . . . . . . . . . . 40
90 A.2. From -01 to -02 . . . . . . . . . . . . . . . . . . . . . 41
91 A.3. From -02 to -03 . . . . . . . . . . . . . . . . . . . . . 41
92 A.4. From -03 to -04 . . . . . . . . . . . . . . . . . . . . . 41
93 A.5. From -04 to -05 . . . . . . . . . . . . . . . . . . . . . 41
94 A.6. From -05 to -06 . . . . . . . . . . . . . . . . . . . . . 42
95 A.7. From -06 to -07 . . . . . . . . . . . . . . . . . . . . . 42
96 A.8. From -07 to -08 . . . . . . . . . . . . . . . . . . . . . 42
98 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 42
100 1. Introduction
102 This document provides background material and an overview of the
103 technologies being considered in the IETF's Low Power Wide-Area
104 Networking (LPWAN) working group. We also provide a gap analysis
105 between the needs of these technologies and currently available IETF
106 specifications.
108 Most technologies in this space aim for similar goals of supporting
109 large numbers of very low-cost, low-throughput devices with very-low
110 power consumption, so that even battery-powered devices can be
111 deployed for years. LPWAN devices also tend to be constrained in
112 their use of bandwidth, for example with limited frequencies being
113 allowed to be used within limited duty-cycles (usually expressed as a
114 percentage of time per-hour that the device is allowed to transmit.)
115 And as the name implies, coverage of large areas is also a common
116 goal. So, by and large, the different technologies aim for
117 deployment in very similar circumstances.
119 What mainly distinguishes LPWANs from other constrained networks is
120 that in LPWANs the balancing act related to power consumption/battery
121 life, cost and bandwidth tends to prioritise doing better with
122 respect to power and cost and we are more willing to live with
123 extremely low bandwidth and constrained duty-cycles when making the
124 various trade-offs required, in order to get the multiple-kilometre
125 radio links implied by the "wide area" aspect of the LPWAN term.
127 Existing pilot deployments have shown huge potential and created much
128 industrial interest in these technologies. As of today, essentially
129 no LPWAN end-devices (other than for Wi-SUN) have IP capabilities.
130 Connecting LPWANs to the Internet would provide significant benefits
131 to these networks in terms of interoperability, application
132 deployment, and management, among others. The goal of the IETF LPWAN
133 working group is to, where necessary, adapt IETF-defined protocols,
134 addressing schemes and naming to this particular constrained
135 environment.
137 This document is largely the work of the people listed in Section 7.
139 2. LPWAN Technologies
141 This section provides an overview of the set of LPWAN technologies
142 that are being considered in the LPWAN working group. The text for
143 each was mainly contributed by proponents of each technology.
145 Note that this text is not intended to be normative in any sense, but
146 simply to help the reader in finding the relevant layer 2
147 specifications and in understanding how those integrate with IETF-
148 defined technologies. Similarly, there is no attempt here to set out
149 the pros and cons of the relevant technologies.
151 Note that some of the technology-specific drafts referenced below may
152 have been updated since publication of this document.
154 2.1. LoRaWAN
156 2.1.1. Provenance and Documents
158 LoRaWAN is an ISM-based wireless technology for long-range low-power
159 low-data-rate applications developed by the LoRa Alliance, a
160 membership consortium. This draft
161 is based on version 1.0.2 [LoRaSpec] of the LoRa specification. That
162 specification is publicly available and has already seen several
163 deployments across the globe.
165 2.1.2. Characteristics
167 LoRaWAN aims to support end-devices operating on a single battery for
168 an extended period of time (e.g., 10 years or more), extended
169 coverage through 155 dB maximum coupling loss, and reliable and
170 efficient file download (as needed for remote software/firmware
171 upgrade).
173 LoRaWAN networks are typically organized in a star-of-stars topology
174 in which gateways relay messages between end-devices and a central
175 "network server" in the backend. Gateways are connected to the
176 network server via IP links while end-devices use single-hop LoRaWAN
177 communication that can be received at one or more gateways.
178 Communication is generally bi-directional; uplink communication from
179 end-devices to the network server is favored in terms of overall
180 bandwidth availability.
182 Figure 1 shows the entities involved in a LoRaWAN network.
184 +----------+
185 |End-device| * * *
186 +----------+ * +---------+
187 * | Gateway +---+
188 +----------+ * +---------+ | +---------+
189 |End-device| * * * +---+ Network +--- Application
190 +----------+ * | | Server |
191 * +---------+ | +---------+
192 +----------+ * | Gateway +---+
193 |End-device| * * * * +---------+
194 +----------+
195 Key: * LoRaWAN Radio
196 +---+ IP connectivity
198 Figure 1: LoRaWAN architecture
200 o End-device: a LoRa client device, sometimes called a mote.
201 Communicates with gateways.
203 o Gateway: a radio on the infrastructure-side, sometimes called a
204 concentrator or base-station. Communicates with end-devices and,
205 via IP, with a network server.
207 o Network Server: The Network Server (NS) terminates the LoRaWAN MAC
208 layer for the end-devices connected to the network. It is the
209 center of the star topology.
211 o Join Server: The Join Server (JS) is a server on the Internet side
212 of an NS that processes join requests from an end-devices.
214 o Uplink message: refers to communications from an end-device to a
215 network server or application via one or more gateways.
217 o Downlink message: refers to communications from a network server
218 or application via one gateway to a single end-device or a group
219 of end-devices (considering multicasting).
221 o Application: refers to application layer code both on the end-
222 device and running "behind" the network server. For LoRaWAN,
223 there will generally only be one application running on most end-
224 devices. Interfaces between the network server and application
225 are not further described here.
227 In LoRaWAN networks, end-device transmissions may be received at
228 multiple gateways, so during nominal operation a network server may
229 see multiple instances of the same uplink message from an end-device.
231 The LoRaWAN network infrastructure manages the data rate and RF
232 output power for each end-device individually by means of an adaptive
233 data rate (ADR) scheme. End-devices may transmit on any channel
234 allowed by local regulation at any time.
236 LoRaWAN radios make use of industrial, scientific and medical (ISM)
237 bands, for example, 433MHz and 868MHz within the European Union and
238 915MHz in the Americas.
240 The end-device changes channel in a pseudo-random fashion for every
241 transmission to help make the system more robust to interference and/
242 or to conform to local regulations.
244 Figure 2 below shows that after a transmission slot a Class A device
245 turns on its receiver for two short receive windows that are offset
246 from the end of the transmission window. End-devices can only
247 transmit a subsequent uplink frame after the end of the associated
248 receive windows. When a device joins a LoRaWAN network, there are
249 similar timeouts on parts of that process.
251 |----------------------------| |--------| |--------|
252 | Tx | | Rx | | Rx |
253 |----------------------------| |--------| |--------|
254 |---------|
255 Rx delay 1
256 |------------------------|
257 Rx delay 2
259 Figure 2: LoRaWAN Class A transmission and reception window
261 Given the different regional requirements the detailed specification
262 for the LoRaWAN physical layer (taking up more than 30 pages of the
263 specification) is not reproduced here. Instead and mainly to
264 illustrate the kinds of issue encountered, in Table 1 we present some
265 of the default settings for one ISM band (without fully explaining
266 those here) and in Table 2 we describe maxima and minima for some
267 parameters of interest to those defining ways to use IETF protocols
268 over the LoRaWAN MAC layer.
270 +------------------------+------------------------------------------+
271 | Parameters | Default Value |
272 +------------------------+------------------------------------------+
273 | Rx delay 1 | 1 s |
274 | | |
275 | Rx delay 2 | 2 s (must be RECEIVE_DELAY1 + 1s) |
276 | | |
277 | join delay 1 | 5 s |
278 | | |
279 | join delay 2 | 6 s |
280 | | |
281 | 868MHz Default | 3 (868.1,868.2,868.3), data rate: 0.3-5 |
282 | channels | kbps |
283 +------------------------+------------------------------------------+
285 Table 1: Default settings for EU 868MHz band
287 +-----------------------------------------------+--------+----------+
288 | Parameter/Notes | Min | Max |
289 +-----------------------------------------------+--------+----------+
290 | Duty Cycle: some but not all ISM bands impose | 1% | no-limit |
291 | a limit in terms of how often an end-device | | |
292 | can transmit. In some cases LoRaWAN is more | | |
293 | restrictive in an attempt to avoid | | |
294 | congestion. | | |
295 | | | |
296 | EU 868MHz band data rate/frame-size | 250 | 50000 |
297 | | bits/s | bits/s : |
298 | | : 59 | 250 |
299 | | octets | octets |
300 | | | |
301 | US 915MHz band data rate/frame-size | 980 | 21900 |
302 | | bits/s | bits/s : |
303 | | : 19 | 250 |
304 | | octets | octets |
305 +-----------------------------------------------+--------+----------+
307 Table 2: Minima and Maxima for various LoRaWAN Parameters
309 Note that in the case of the smallest frame size (19 octets), 8
310 octets are required for LoRa MAC layer headers leaving only 11 octets
311 for payload (including MAC layer options). However, those settings
312 do not apply for the join procedure - end-devices are required to use
313 a channel and data rate that can send the 23-byte Join-request
314 message for the join procedure.
316 Uplink and downlink higher layer data is carried in a MACPayload.
317 There is a concept of "ports" (an optional 8-bit value) to handle
318 different applications on an end-device. Port zero is reserved for
319 LoRaWAN specific messaging, such as the configuration of the end
320 device's network parameters (available channels, data rates, ADR
321 parameters, RX1/2 delay, etc.).
323 In addition to carrying higher layer PDUs there are Join-Request and
324 Join-Response (aka Join-Accept) messages for handling network access.
325 And so-called "MAC commands" (see below) up to 15 bytes long can be
326 piggybacked in an options field ("FOpts").
328 There are a number of MAC commands for link and device status
329 checking, ADR and duty-cycle negotiation, managing the RX windows and
330 radio channel settings. For example, the link check response message
331 allows the network server (in response to a request from an end-
332 device) to inform an end-device about the signal attenuation seen
333 most recently at a gateway, and to also tell the end-device how many
334 gateways received the corresponding link request MAC command.
336 Some MAC commands are initiated by the network server. For example,
337 one command allows the network server to ask an end-device to reduce
338 its duty-cycle to only use a proportion of the maximum allowed in a
339 region. Another allows the network server to query the end-device's
340 power status with the response from the end-device specifying whether
341 it has an external power source or is battery powered (in which case
342 a relative battery level is also sent to the network server).
344 In order to operate nominally on a LoRaWAN network, a device needs a
345 32-bit device address, that is assigned when the device "joins" the
346 network (see below for the join procedure) or that is pre-provisioned
347 into the device. In case of roaming devices, the device address is
348 assigned based on the 24-bit network identifier (NetID) that is
349 allocated to the network by the LoRa Alliance. Non-roaming devices
350 can be assigned device addresses by the network without relying on a
351 LoRa Alliance-assigned NetID.
353 End-devices are assumed to work with one or a quite limited number of
354 applications, identified by a 64-bit AppEUI, which is assumed to be a
355 registered IEEE EUI64 value. In addition, a device needs to have two
356 symmetric session keys, one for protecting network artifacts
357 (port=0), the NwkSKey, and another for protecting application layer
358 traffic, the AppSKey. Both keys are used for 128-bit AES
359 cryptographic operations. So, one option is for an end-device to
360 have all of the above, plus channel information, somehow
361 (pre-)provisioned, in which case the end-device can simply start
362 transmitting. This is achievable in many cases via out-of-band means
363 given the nature of LoRaWAN networks. Table 3 summarizes these
364 values.
366 +---------+---------------------------------------------------------+
367 | Value | Description |
368 +---------+---------------------------------------------------------+
369 | DevAddr | DevAddr (32-bits) = device-specific network address |
370 | | generated from the NetID |
371 | | |
372 | AppEUI | IEEE EUI64 corresponding to the join server for an |
373 | | application |
374 | | |
375 | NwkSKey | 128-bit network session key used with AES-CMAC |
376 | | |
377 | AppSKey | 128-bit application session key used with AES-CTR |
378 | | |
379 | AppKey | 128-bit application session key used with AES-ECB |
380 +---------+---------------------------------------------------------+
382 Table 3: Values required for nominal operation
384 As an alternative, end-devices can use the LoRaWAN join procedure
385 with a join server behind the NS in order to setup some of these
386 values and dynamically gain access to the network. To use the join
387 procedure, an end-device must still know the AppEUI, and in addition,
388 a different (long-term) symmetric key that is bound to the AppEUI -
389 this is the application key (AppKey), and is distinct from the
390 application session key (AppSKey). The AppKey is required to be
391 specific to the device, that is, each end-device should have a
392 different AppKey value. And finally, the end-device also needs a
393 long-term identifier for itself, syntactically also an EUI-64, and
394 known as the device EUI or DevEUI. Table 4 summarizes these values.
396 +---------+----------------------------------------------------+
397 | Value | Description |
398 +---------+----------------------------------------------------+
399 | DevEUI | IEEE EUI64 naming the device |
400 | | |
401 | AppEUI | IEEE EUI64 naming the application |
402 | | |
403 | AppKey | 128-bit long term application key for use with AES |
404 +---------+----------------------------------------------------+
406 Table 4: Values required for join procedure
408 The join procedure involves a special exchange where the end-device
409 asserts the AppEUI and DevEUI (integrity protected with the long-term
410 AppKey, but not encrypted) in a Join-request uplink message. This is
411 then routed to the network server which interacts with an entity that
412 knows that AppKey to verify the Join-request. All going well, a
413 Join-accept downlink message is returned from the network server to
414 the end-device that specifies the 24-bit NetID, 32-bit DevAddr and
415 channel information and from which the AppSKey and NwkSKey can be
416 derived based on knowledge of the AppKey. This provides the end-
417 device with all the values listed in Table 3.
419 All payloads are encrypted and have data integrity. MAC commands,
420 when sent as a payload (port zero), are therefore protected. MAC
421 commands piggy-backed as frame options ("FOpts") are however sent in
422 clear. Any MAC commands sent as frame options and not only as
423 payload, are visible to a passive attacker but are not malleable for
424 an active attacker due to the use of the Message Integrity Check
425 (MIC) described below.
427 For LoRaWAN version 1.0.x, the NWkSkey session key is used to provide
428 data integrity between the end-device and the network server. The
429 AppSKey is used to provide data confidentiality between the end-
430 device and network server, or to the application "behind" the network
431 server, depending on the implementation of the network.
433 All MAC layer messages have an outer 32-bit MIC calculated using AES-
434 CMAC calculated over the ciphertext payload and other headers and
435 using the NwkSkey. Payloads are encrypted using AES-128, with a
436 counter-mode derived from IEEE 802.15.4 using the AppSKey. Gateways
437 are not expected to be provided with the AppSKey or NwkSKey, all of
438 the infrastructure-side cryptography happens in (or "behind") the
439 network server. When session keys are derived from the AppKey as a
440 result of the join procedure the Join-accept message payload is
441 specially handled.
443 The long-term AppKey is directly used to protect the Join-accept
444 message content, but the function used is not an AES-encrypt
445 operation, but rather an AES-decrypt operation. The justification is
446 that this means that the end-device only needs to implement the AES-
447 encrypt operation. (The counter mode variant used for payload
448 decryption means the end-device doesn't need an AES-decrypt
449 primitive.)
451 The Join-accept plaintext is always less than 16 bytes long, so
452 electronic code book (ECB) mode is used for protecting Join-accept
453 messages. The Join-accept contains an AppNonce (a 24 bit value) that
454 is recovered on the end-device along with the other Join-accept
455 content (e.g. DevAddr) using the AES-encrypt operation. Once the
456 Join-accept payload is available to the end-device the session keys
457 are derived from the AppKey, AppNonce and other values, again using
458 an ECB mode AES-encrypt operation, with the plaintext input being a
459 maximum of 16 octets.
461 2.2. Narrowband IoT (NB-IoT)
463 2.2.1. Provenance and Documents
465 Narrowband Internet of Things (NB-IoT) is developed and standardized
466 by 3GPP. The standardization of NB-IoT was finalized with 3GPP
467 Release 13 in June 2016, and further enhancements for NB-IoT are
468 specified in 3GPP Release 14 in 2017, for example in the form of
469 multicast support. Further features and improvements will be
470 developed in the following releases, but NB-IoT has been ready to be
471 deployed since 2016, and is rather simple to deploy especially in the
472 existing LTE networks with a software upgrade in the operator's base
473 stations. For more information of what has been specified for NB-
474 IoT, 3GPP specification 36.300 [TGPP36300] provides an overview and
475 overall description of the E-UTRAN radio interface protocol
476 architecture, while specifications 36.321 [TGPP36321], 36.322
477 [TGPP36322], 36.323 [TGPP36323] and 36.331 [TGPP36331] give more
478 detailed description of MAC, Radio Link Control (RLC), Packet Data
479 Convergence Protocol (PDCP) and Radio Resource Control (RRC) protocol
480 layers, respectively. Note that the description below assumes
481 familiarity with numerous 3GPP terms.
483 For a general overview of NB-IoT, see [nbiot-ov].
485 2.2.2. Characteristics
487 Specific targets for NB-IoT include: Less than US$5 module cost,
488 extended coverage of 164 dB maximum coupling loss, battery life of
489 over 10 years, ~55000 devices per cell and uplink reporting latency
490 of less than 10 seconds.
492 NB-IoT supports Half Duplex FDD operation mode with 60 kbps peak rate
493 in uplink and 30 kbps peak rate in downlink, and a maximum
494 transmission unit (MTU) size of 1600 bytes limited by PDCP layer (see
495 Figure 4 for the protocol structure), which is the highest layer in
496 the user plane, as explained later. Any packet size up to the said
497 MTU size can be passed to the NB-IoT stack from higher layers,
498 segmentation of the packet is performed in the RLC layer, which can
499 segment the data to transmission blocks with size as small as 16
500 bits. As the name suggests, NB-IoT uses narrowbands with bandwidth
501 of 180 kHz in both downlink and uplink. The multiple access scheme
502 used in the downlink is OFDMA with 15 kHz sub-carrier spacing. In
503 uplink, SC-FDMA single tone with either 15kHz or 3.75 kHz tone
504 spacing is used, or optionally multi-tone SC- FDMA can be used with
505 15 kHz tone spacing.
507 NB-IoT can be deployed in three ways. In-band deployment means that
508 the narrowband is deployed inside the LTE band and radio resources
509 are flexibly shared between NB-IoT and normal LTE carrier. In Guard-
510 band deployment the narrowband uses the unused resource blocks
511 between two adjacent LTE carriers. Standalone deployment is also
512 supported, where the narrowband can be located alone in dedicated
513 spectrum, which makes it possible for example to reframe a GSM
514 carrier at 850/900 MHz for NB-IoT. All three deployment modes are
515 used in licensed frequency bands. The maximum transmission power is
516 either 20 or 23 dBm for uplink transmissions, while for downlink
517 transmission the eNodeB may use higher transmission power, up to 46
518 dBm depending on the deployment.
520 A maximum coupling loss (MCL) target for NB-IoT coverage enhancements
521 defined by 3GPP is 164 dB. With this MCL, the performance of NB-IoT
522 in downlink varies between 200 bps and 2-3 kbps, depending on the
523 deployment mode. Stand-alone operation may achieve the highest data
524 rates, up to few kbps, while in-band and guard-band operations may
525 reach several hundreds of bps. NB-IoT may even operate with MCL
526 higher than 170 dB with very low bit rates.
528 For signaling optimization, two options are introduced in addition to
529 legacy LTE RRC connection setup; mandatory Data-over-NAS (Control
530 Plane optimization, solution 2 in [TGPP23720]) and optional RRC
531 Suspend/Resume (User Plane optimization, solution 18 in [TGPP23720]).
532 In the control plane optimization the data is sent over Non-Access
533 Stratum, directly to/from Mobility Management Entity (MME) (see
534 Figure 3 for the network architecture) in the core network to the
535 User Equipment (UE) without interaction from the base station. This
536 means there are no Access Stratum security or header compression
537 provided by the PDCP layer in the eNodeB, as the Access Stratum is
538 bypassed, and only limited RRC procedures. RoHC based header
539 compression may still optionally be provided and terminated in MME.
541 The RRC Suspend/Resume procedures reduce the signaling overhead
542 required for UE state transition from RRC Idle to RRC Connected mode
543 compared to legacy LTE operation in order to have quicker user plane
544 transaction with the network and return to RRC Idle mode faster.
546 In order to prolong device battery life, both power-saving mode (PSM)
547 and extended DRX (eDRX) are available to NB-IoT. With eDRX the RRC
548 Connected mode DRX cycle is up to 10.24 seconds and in RRC Idle the
549 eDRX cycle can be up to 3 hours. In PSM the device is in a deep
550 sleep state and only wakes up for uplink reporting, after which there
551 is a window, configured by the network, during which the device
552 receiver is open for downlink connectivity, of for periodical "keep-
553 alive" signaling (PSM uses periodic TAU signaling with additional
554 reception window for downlink reachability).
556 Since NB-IoT operates in licensed spectrum, it has no channel access
557 restrictions allowing up to a 100% duty-cycle.
559 3GPP access security is specified in [TGPP33203].
561 +--+
562 |UE| \ +------+ +------+
563 +--+ \ | MME |------| HSS |
564 \ / +------+ +------+
565 +--+ \+-----+ / |
566 |UE| ----| eNB |- |
567 +--+ /+-----+ \ |
568 / \ +--------+
569 / \| | +------+ Service PDN
570 +--+ / | S-GW |----| P-GW |---- e.g. Internet
571 |UE| | | +------+
572 +--+ +--------+
574 Figure 3: 3GPP network architecture
576 Figure 3 shows the 3GPP network architecture, which applies to NB-
577 IoT. Mobility Management Entity (MME) is responsible for handling
578 the mobility of the UE. MME tasks include tracking and paging UEs,
579 session management, choosing the Serving gateway for the UE during
580 initial attachment and authenticating the user. At MME, the Non-
581 Access Stratum (NAS) signaling from the UE is terminated.
583 Serving Gateway (S-GW) routes and forwards the user data packets
584 through the access network and acts as a mobility anchor for UEs
585 during handover between base stations known as eNodeBs and also
586 during handovers between NB-IoT and other 3GPP technologies.
588 Packet Data Network Gateway (P-GW) works as an interface between 3GPP
589 network and external networks.
591 The Home Subscriber Server (HSS) contains user-related and
592 subscription- related information. It is a database, which performs
593 mobility management, session establishment support, user
594 authentication and access authorization.
596 E-UTRAN consists of components of a single type, eNodeB. eNodeB is a
597 base station, which controls the UEs in one or several cells.
599 The 3GPP radio protocol architecture is illustrated in Figure 4.
601 +---------+ +---------+
602 | NAS |----|-----------------------------|----| NAS |
603 +---------+ | +---------+---------+ | +---------+
604 | RRC |----|----| RRC | S1-AP |----|----| S1-AP |
605 +---------+ | +---------+---------+ | +---------+
606 | PDCP |----|----| PDCP | SCTP |----|----| SCTP |
607 +---------+ | +---------+---------+ | +---------+
608 | RLC |----|----| RLC | IP |----|----| IP |
609 +---------+ | +---------+---------+ | +---------+
610 | MAC |----|----| MAC | L2 |----|----| L2 |
611 +---------+ | +---------+---------+ | +---------+
612 | PHY |----|----| PHY | PHY |----|----| PHY |
613 +---------+ +---------+---------+ +---------+
614 LTE-Uu S1-MME
615 UE eNodeB MME
617 Figure 4: 3GPP radio protocol architecture for control plane
619 Control plane protocol stack
621 The radio protocol architecture of NB-IoT (and LTE) is separated into
622 control plane and user plane. The control plane consists of
623 protocols which control the radio access bearers and the connection
624 between the UE and the network. The highest layer of control plane
625 is called Non-Access Stratum (NAS), which conveys the radio signaling
626 between the UE and the Evolved Packet Core (EPC), passing
627 transparently through the radio network. NAS responsible for
628 authentication, security control, mobility management and bearer
629 management.
631 Access Stratum (AS) is the functional layer below NAS, and in the
632 control plane it consists of Radio Resource Control protocol (RRC)
633 [TGPP36331], which handles connection establishment and release
634 functions, broadcast of system information, radio bearer
635 establishment, reconfiguration and release. RRC configures the user
636 and control planes according to the network status. There exists two
637 RRC states, RRC_Idle or RRC_Connected, and RRC entity controls the
638 switching between these states. In RRC_Idle, the network knows that
639 the UE is present in the network and the UE can be reached in case of
640 incoming call/downlink data. In this state, the UE monitors paging,
641 performs cell measurements and cell selection and acquires system
642 information. Also the UE can receive broadcast and multicast data,
643 but it is not expected to transmit or receive unicast data. In
644 RRC_Connected the UE has a connection to the eNodeB, the network
645 knows the UE location on the cell level and the UE may receive and
646 transmit unicast data. An RRC connection is established when the UE
647 is expected to be active in the network, to transmit or receive data.
648 The RRC connection is released, switching back to RRC_Idle, when
649 there is no more traffic in order to preserve UE battery life and
650 radio resources. However, a new feature was introduced for NB-IoT,
651 as mentioned earlier, which allows data to be transmitted from the
652 MME directly to the UE transparently to the eNodeB, thus bypassing AS
653 functions.
655 Packet Data Convergence Protocol's (PDCP) [TGPP36323] main services
656 in control plane are transfer of control plane data, ciphering and
657 integrity protection.
659 Radio Link Control protocol (RLC) [TGPP36322] performs transfer of
660 upper layer PDUs and optionally error correction with Automatic
661 Repeat reQuest (ARQ), concatenation, segmentation, and reassembly of
662 RLC SDUs, in-sequence delivery of upper layer PDUs, duplicate
663 detection, RLC SDU discard, RLC-re-establishment and protocol error
664 detection and recovery.
666 Medium Access Control protocol (MAC) [TGPP36321] provides mapping
667 between logical channels and transport channels, multiplexing of MAC
668 SDUs, scheduling information reporting, error correction with HARQ,
669 priority handling and transport format selection.
671 Physical layer [TGPP36201] provides data transport services to higher
672 layers. These include error detection and indication to higher
673 layers, FEC encoding, HARQ soft-combining, rate matching and mapping
674 of the transport channels onto physical channels, power weighting and
675 modulation of physical channels, frequency and time synchronization
676 and radio characteristics measurements.
678 User plane is responsible for transferring the user data through the
679 Access Stratum. It interfaces with IP and the highest layer of user
680 plane is PDCP, which in user plane performs header compression using
681 Robust Header Compression (RoHC), transfer of user plane data between
682 eNodeB and UE, ciphering and integrity protection. Similar to
683 control plane, lower layers in user plane include RLC, MAC and
684 physical layer performing the same tasks as in control plane.
686 2.3. SIGFOX
688 2.3.1. Provenance and Documents
690 The SIGFOX LPWAN is in line with the terminology and specifications
691 being defined by ETSI [etsi_unb]. As of today, SIGFOX's network has
692 been fully deployed in 12 countries, with ongoing deployments on 26
693 other countries, giving in total a geography of 2 million square
694 kilometers, containing 512 million people.
696 2.3.2. Characteristics
698 SIGFOX LPWAN autonomous battery-operated devices send only a few
699 bytes per day, week or month, in principle allowing them to remain on
700 a single battery for up to 10-15 years. Hence, the system is
701 designed as to allow devices to last several years, sometimes even
702 buried underground.
704 Since the radio protocol is connection-less and optimized for uplink
705 communications, the capacity of a SIGFOX base station depends on the
706 number of messages generated by devices, and not on the actual number
707 of devices. Likewise, the battery life of devices depends on the
708 number of messages generated by the device. Depending on the use
709 case, devices can vary from sending less than one message per device
710 per day, to dozens of messages per device per day.
712 The coverage of the cell depends on the link budget and on the type
713 of deployment (urban, rural, etc.). The radio interface is compliant
714 with the following regulations:
716 Spectrum allocation in the USA [fcc_ref]
718 Spectrum allocation in Europe [etsi_ref]
720 Spectrum allocation in Japan [arib_ref]
722 The SIGFOX radio interface is also compliant with the local
723 regulations of the following countries: Australia, Brazil, Canada,
724 Kenya, Lebanon, Mauritius, Mexico, New Zealand, Oman, Peru,
725 Singapore, South Africa, South Korea, and Thailand.
727 The radio interface is based on Ultra Narrow Band (UNB)
728 communications, which allow an increased transmission range by
729 spending a limited amount of energy at the device. Moreover, UNB
730 allows a large number of devices to coexist in a given cell without
731 significantly increasing the spectrum interference.
733 Both uplink and downlink are supported, although the system is
734 optimized for uplink communications. Due to spectrum optimizations,
735 different uplink and downlink frames and time synchronization methods
736 are needed.
738 The main radio characteristics of the UNB uplink transmission are:
740 o Channelization mask: 100 Hz / 600 Hz (depending on the region)
742 o Uplink baud rate: 100 baud / 600 baud (depending on the region)
743 o Modulation scheme: DBPSK
745 o Uplink transmission power: compliant with local regulation
747 o Link budget: 155 dB (or better)
749 o Central frequency accuracy: not relevant, provided there is no
750 significant frequency drift within an uplink packet transmission
752 For example, in Europe the UNB uplink frequency band is limited to
753 868.00 to 868.60 MHz, with a maximum output power of 25 mW and a duty
754 cycle of 1%.
756 The format of the uplink frame is the following:
758 +--------+--------+--------+------------------+-------------+-----+
759 |Preamble| Frame | Dev ID | Payload |Msg Auth Code| FCS |
760 | | Sync | | | | |
761 +--------+--------+--------+------------------+-------------+-----+
763 Figure 5: Uplink Frame Format
765 The uplink frame is composed of the following fields:
767 o Preamble: 19 bits
769 o Frame sync and header: 29 bits
771 o Device ID: 32 bits
773 o Payload: 0-96 bits
775 o Authentication: 16-40 bits
777 o Frame check sequence: 16 bits (CRC)
779 The main radio characteristics of the UNB downlink transmission are:
781 o Channelization mask: 1.5 kHz
783 o Downlink baud rate: 600 baud
785 o Modulation scheme: GFSK
787 o Downlink transmission power: 500 mW / 4W (depending on the region)
789 o Link budget: 153 dB (or better)
790 o Central frequency accuracy: the center frequency of downlink
791 transmission is set by the network according to the corresponding
792 uplink transmission
794 For example, in Europe the UNB downlink frequency band is limited to
795 869.40 to 869.65 MHz, with a maximum output power of 500 mW with 10%
796 duty cycle.
798 The format of the downlink frame is the following:
800 +------------+-----+---------+------------------+-------------+-----+
801 | Preamble |Frame| ECC | Payload |Msg Auth Code| FCS |
802 | |Sync | | | | |
803 +------------+-----+---------+------------------+-------------+-----+
805 Figure 6: Downlink Frame Format
807 The downlink frame is composed of the following fields:
809 o Preamble: 91 bits
811 o Frame sync and header: 13 bits
813 o Error Correcting Code (ECC): 32 bits
815 o Payload: 0-64 bits
817 o Authentication: 16 bits
819 o Frame check sequence: 8 bits (CRC)
821 The radio interface is optimized for uplink transmissions, which are
822 asynchronous. Downlink communications are achieved by devices
823 querying the network for available data.
825 A device willing to receive downlink messages opens a fixed window
826 for reception after sending an uplink transmission. The delay and
827 duration of this window have fixed values. The network transmits the
828 downlink message for a given device during the reception window, and
829 the network also selects the base station (BS) for transmitting the
830 corresponding downlink message.
832 Uplink and downlink transmissions are unbalanced due to the
833 regulatory constraints on ISM bands. Under the strictest
834 regulations, the system can allow a maximum of 140 uplink messages
835 and 4 downlink messages per device per day. These restrictions can
836 be slightly relaxed depending on system conditions and the specific
837 regulatory domain of operation.
839 +---+
840 |DEV| * +------+
841 +---+ * | RA |
842 * +------+
843 +---+ * |
844 |DEV| * * * * |
845 +---+ * +----+ |
846 * | BS | \ +--------+
847 +---+ * +----+ \ | |
848 DA -----|DEV| * * * | SC |----- NA
849 +---+ * / | |
850 * +----+ / +--------+
851 +---+ * | BS |/
852 |DEV| * * * * +----+
853 +---+ *
854 *
855 +---+ *
856 |DEV| * *
857 +---+
859 Figure 7: SIGFOX network architecture
861 Figure 7 depicts the different elements of the SIGFOX network
862 architecture.
864 SIGFOX has a "one-contract one-network" model allowing devices to
865 connect in any country, without any need or notion of either roaming
866 or handover.
868 The architecture consists of a single cloud-based core network, which
869 allows global connectivity with minimal impact on the end device and
870 radio access network. The core network elements are the Service
871 Center (SC) and the Registration Authority (RA). The SC is in charge
872 of the data connectivity between the Base Station (BS) and the
873 Internet, as well as the control and management of the BSs and End
874 Points. The RA is in charge of the End Point network access
875 authorization.
877 The radio access network is comprised of several BSs connected
878 directly to the SC. Each BS performs complex L1/L2 functions,
879 leaving some L2 and L3 functionalities to the SC.
881 The Devices (DEVs) or End Points (EPs) are the objects that
882 communicate application data between local device applications (DAs)
883 and network applications (NAs).
885 Devices (or EPs) can be static or nomadic, as they associate with the
886 SC and they do not attach to any specific BS. Hence, they can
887 communicate with the SC through one or multiple BSs.
889 Due to constraints in the complexity of the Device, it is assumed
890 that Devices host only one or very few device applications, which
891 most of the time communicate each to a single network application at
892 a time.
894 The radio protocol authenticates and ensures the integrity of each
895 message. This is achieved by using a unique device ID and an AES-128
896 based message authentication code, ensuring that the message has been
897 generated and sent by the device with the ID claimed in the message.
898 Application data can be encrypted at the application level or not,
899 depending on the criticality of the use case, to provide a balance
900 between cost and effort vs. risk. AES-128 in counter mode is used
901 for encryption. Cryptographic keys are independent for each device.
902 These keys are associated with the device ID and separate integrity
903 and confidentiality keys are pre-provisioned. A confidentiality key
904 is only provisioned if confidentiality is to be used. At the time of
905 writing the algorithms and keying details for this are not published.
907 2.4. Wi-SUN Alliance Field Area Network (FAN)
909 Text here is via personal communication from Bob Heile
910 (bheile@ieee.org) and was authored by Bob and Sum Chin Sean. Duffy
911 (paduffy@cisco.com) also provided additional comments/input on this
912 section.
914 2.4.1. Provenance and Documents
916 The Wi-SUN Alliance is an industry alliance
917 for smart city, smart grid, smart utility, and a broad set of general
918 IoT applications. The Wi-SUN Alliance Field Area Network (FAN)
919 profile is open standards based (primarily on IETF and IEEE802
920 standards) and was developed to address applications like smart
921 municipality/city infrastructure monitoring and management, electric
922 vehicle (EV) infrastructure, advanced metering infrastructure (AMI),
923 distribution automation (DA), supervisory control and data
924 acquisition (SCADA) protection/management, distributed generation
925 monitoring and management, and many more IoT applications.
926 Additionally, the Alliance has created a certification program to
927 promote global multi-vendor interoperability.
929 The FAN profile is specified within ANSI/TIA as an extension of work
930 previously done on Smart Utility Networks. [ANSI-4957-000]. Updates
931 to those specifications intended to be published in 2017 will contain
932 details of the FAN profile. A current snapshot of the work to
933 produce that profile is presented in [wisun-pressie1]
934 [wisun-pressie2] .
936 2.4.2. Characteristics
938 The FAN profile is an IPv6 wireless mesh network with support for
939 enterprise level security. The frequency hopping wireless mesh
940 topology aims to offer superior network robustness, reliability due
941 to high redundancy, good scalability due to the flexible mesh
942 configuration and good resilience to interference. Very low power
943 modes are in development permitting long term battery operation of
944 network nodes.
946 The following list contains some overall characteristics of Wi-SUN
947 that are relevant to LPWAN applications.
949 o Coverage: The range of Wi-SUN FAN is typically 2 -- 3 km in line
950 of sight, matching the needs of neighborhood area networks, campus
951 area networks, or corporate area networks. The range can also be
952 extended via multi-hop networking.
954 o High bandwidth, low link latency: Wi-SUN supports relatively high
955 bandwidth, i.e. up to 300 kbps [FANTPS], enables remote update and
956 upgrade of devices so that they can handle new applications,
957 extending their working life. Wi-SUN supports LPWAN IoT
958 applications that require on-demand control by providing low link
959 latency (0.02s) and bi-directional communication.
961 o Low power consumption: FAN devices draw less than 2 uA when
962 resting and only 8 mA when listening. Such devices can maintain a
963 long lifetime even if they are frequently listening. For
964 instance, suppose the device transmits data for 10 ms once every
965 10 s; theoretically, a battery of 1000 mAh can last more than 10
966 years.
968 o Scalability: Tens of millions Wi-SUN FAN devices have been
969 deployed in urban, suburban and rural environments, including
970 deployments with more than 1 million devices.
972 A FAN contains one or more networks. Within a network, nodes assume
973 one of three operational roles. First, each network contains a
974 Border Router providing Wide Area Network (WAN) connectivity to the
975 network. The Border Router maintains source routing tables for all
976 nodes within its network, provides node authentication and key
977 management services, and disseminates network-wide information such
978 as broadcast schedules. Secondly, Router nodes, which provide upward
979 and downward packet forwarding (within a network). A Router also
980 provides services for relaying security and address management
981 protocols. Lastly, Leaf nodes provide minimum capabilities:
982 discovering and joining a network, send/receive IPv6 packets, etc. A
983 low power network may contain a mesh topology with Routers at the
984 edges that construct a star topology with Leaf nodes.
986 The FAN profile is based on various open standards developed by the
987 IETF (including [RFC0768], [RFC2460], [RFC4443] and [RFC6282]),
988 IEEE802 (including [IEEE-802-15-4] and [IEEE-802-15-9]) and ANSI/TIA
989 [ANSI-4957-210] for low power and lossy networks.
991 The FAN profile specification provides an application-independent
992 IPv6-based transport service. There are two possible methods for
993 establishing the IPv6 packet routing: Routing Protocol for Low-Power
994 and Lossy Networks (RPL) at the Network layer is mandatory, and
995 Multi-Hop Delivery Service (MHDS) is optional at the Data Link layer.
996 Table 5 provides an overview of the FAN network stack.
998 The Transport service is based on User Datagram Protocol (UDP)
999 defined in RFC768 or Transmission Control Protocol (TCP) defined in
1000 RFC793.
1002 The Network service is provided by IPv6 as defined in RFC2460 with
1003 6LoWPAN adaptation as defined in RFC4944 and RFC6282. ICMPv6, as
1004 defined in RFC4443, is used for the control plane during information
1005 exchange.
1007 The Data Link service provides both control/management of the
1008 Physical layer and data transfer/management services to the Network
1009 layer. These services are divided into Media Access Control (MAC)
1010 and Logical Link Control (LLC) sub-layers. The LLC sub-layer
1011 provides a protocol dispatch service which supports 6LoWPAN and an
1012 optional MAC sub-layer mesh service. The MAC sub-layer is
1013 constructed using data structures defined in IEEE802.15.4-2015.
1014 Multiple modes of frequency hopping are defined. The entire MAC
1015 payload is encapsulated in an IEEE802.15.9 Information Element to
1016 enable LLC protocol dispatch between upper layer 6LoWPAN processing,
1017 MAC sublayer mesh processing, etc. These areas will be expanded once
1018 IEEE802.15.12 is completed.
1020 The PHY service is derived from a sub-set of the SUN FSK
1021 specification in IEEE802.15.4-2015. The 2-FSK modulation schemes,
1022 with channel spacing range from 200 to 600 kHz, are defined to
1023 provide data rates from 50 to 300 kbps, with Forward Error Coding
1024 (FEC) as an optional feature. Towards enabling ultra-low-power
1025 applications, the PHY layer design is also extendable to low energy
1026 and critical infrastructure monitoring networks.
1028 +----------------------+--------------------------------------------+
1029 | Layer | Description |
1030 +----------------------+--------------------------------------------+
1031 | IPv6 protocol suite | TCP/UDP |
1032 | | |
1033 | | 6LoWPAN Adaptation + Header Compression |
1034 | | |
1035 | | DHCPv6 for IP address management. |
1036 | | |
1037 | | Routing using RPL. |
1038 | | |
1039 | | ICMPv6. |
1040 | | |
1041 | | Unicast and Multicast forwarding. |
1042 | | |
1043 | MAC based on IEEE | Frequency hopping |
1044 | 802.15.4e + IE | |
1045 | extensions | |
1046 | | |
1047 | | Discovery and Join |
1048 | | |
1049 | | Protocol Dispatch (IEEE 802.15.9) |
1050 | | |
1051 | | Several Frame Exchange patterns |
1052 | | |
1053 | | Optional Mesh Under routing (ANSI |
1054 | | 4957.210). |
1055 | | |
1056 | PHY based on | Various data rates and regions |
1057 | 802.15.4g | |
1058 | | |
1059 | Security | 802.1X/EAP-TLS/PKI Authentication. |
1060 | | TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8 |
1061 | | required for EAP-TLS. |
1062 | | |
1063 | | 802.11i Group Key Management |
1064 | | |
1065 | | Frame security is implemented as AES-CCM* |
1066 | | as specified in IEEE 802.15.4 |
1067 | | |
1068 | | Optional ETSI-TS-102-887-2 Node 2 Node Key |
1069 | | Management |
1070 +----------------------+--------------------------------------------+
1072 Table 5: Wi-SUN Stack Overview
1074 The FAN security supports Data Link layer network access control,
1075 mutual authentication, and establishment of a secure pairwise link
1076 between a FAN node and its Border Router, which is implemented with
1077 an adaptation of IEEE802.1X and EAP-TLS as described in [RFC5216]
1078 using secure device identity as described in IEEE802.1AR.
1079 Certificate formats are based upon [RFC5280]. A secure group link
1080 between a Border Router and a set of FAN nodes is established using
1081 an adaptation of the IEEE802.11 Four-Way Handshake. A set of 4 group
1082 keys are maintained within the network, one of which is the current
1083 transmit key. Secure node to node links are supported between one-
1084 hop FAN neighbors using an adaptation of ETSI-TS-102-887-2. FAN
1085 nodes implement Frame Security as specified in IEEE802.15.4-2015.
1087 3. Generic Terminology
1089 LPWAN technologies, such as those discussed above, have similar
1090 architectures but different terminology. We can identify different
1091 types of entities in a typical LPWAN network:
1093 o End-Devices are the devices or the "things" (e.g. sensors,
1094 actuators, etc.); they are named differently in each technology
1095 (End Device, User Equipment or End Point). There can be a high
1096 density of end devices per radio gateway.
1098 o The Radio Gateway, which is the end point of the constrained link.
1099 It is known as: Gateway, Evolved Node B or Base station.
1101 o The Network Gateway or Router is the interconnection node between
1102 the Radio Gateway and the Internet. It is known as: Network
1103 Server, Serving GW or Service Center.
1105 o LPWAN-AAA Server, which controls the user authentication, the
1106 applications. It is known as: Join-Server, Home Subscriber Server
1107 or Registration Authority. (We use the term LPWAN-AAA server
1108 because we're not assuming that this entity speaks RADIUS or
1109 Diameter as many/most AAA servers do, but equally we don't want to
1110 rule that out, as the functionality will be similar.
1112 o At last we have the Application Server, known also as Packet Data
1113 Node Gateway or Network Application.
1115 +---------------------------------------------------------------------+
1116 | Function/ | | | | | |
1117 |Technology | LORAWAN | NB-IOT | SIGFOX | Wi-SUN | IETF |
1118 +-----------+-----------+-----------+------------+--------+-----------+
1119 | Sensor, | | | | | |
1120 |Actuator, | End | User | End | Leaf | Device |
1121 |device, | Device | Equipment | Point | Node | (Dev) |
1122 | object | | | | | |
1123 +-----------+-----------+-----------+------------+--------+-----------+
1124 |Transceiver| | Evolved | Base | Router | RADIO |
1125 | Antenna | Gateway | Node B | Station | Node | Gateway |
1126 +-----------+-----------+-----------+------------+--------+-----------+
1127 | Server | Network | PDN GW/ | Service | Border | Network |
1128 | | Server | SCEF | Center | Router | Gateway |
1129 | | | | | | (NGW) |
1130 +-----------+-----------+-----------+------------+--------+-----------+
1131 | Security | Join | Home |Registration|Authent.| LPWAN- |
1132 | Server | Server | Subscriber| Authority | Server | AAA |
1133 | | | Server | | | SERVER |
1134 +-----------+-----------+-----------+------------+--------+-----------+
1135 |Application|Application|Application| Network |Appli- |Application|
1136 | | Server | Server | Application| cation | (App) |
1137 +---------------------------------------------------------------------+
1139 Figure 8: LPWAN Architecture Terminology
1141 +------+
1142 () () () | |LPWAN-|
1143 () () () () / \ +---------+ | AAA |
1144 () () () () () () / \========| /\ |====|Server| +-----------+
1145 () () () | | <--|--> | +------+ |APPLICATION|
1146 () () () () / \============| v |==============| (App) |
1147 () () () / \ +---------+ +-----------+
1148 Dev Radio Gateways NGW
1150 Figure 9: LPWAN Architecture
1152 In addition to the names of entities, LPWANs are also subject to
1153 possibly regional frequency band regulations. Those may include
1154 restrictions on the duty-cycle, for example requiring that hosts only
1155 transmit for a certain percentage of each hour.
1157 4. Gap Analysis
1159 This section considers some of the gaps between current LPWAN
1160 technologies and the goals of the LPWAN working group. Many of the
1161 generic considerations described in [RFC7452] will also apply in
1162 LPWANs, as end-devices can also be considered as a subclass of (so-
1163 called) "smart objects." In addition, LPWAN device implementers will
1164 also need to consider the issues relating to firmware updates
1165 described in [RFC8240].
1167 4.1. Naive application of IPv6
1169 IPv6 [RFC8200] has been designed to allocate addresses to all the
1170 nodes connected to the Internet. Nevertheless, the header overhead
1171 of at least 40 bytes introduced by the protocol is incompatible with
1172 LPWAN constraints. If IPv6 with no further optimization were used,
1173 several LPWAN frames could be needed just to carry the IP header.
1174 Another problem arises from IPv6 MTU requirements, which require the
1175 layer below to support at least 1280 byte packets [RFC2460].
1177 IPv6 has a configuration protocol - neighbor discovery protocol,
1178 (NDP) [RFC4861]). For a node to learn network parameters NDP
1179 generates regular traffic with a relatively large message size that
1180 does not fit LPWAN constraints.
1182 In some LPWAN technologies, layer two multicast is not supported. In
1183 that case, if the network topology is a star, the solution and
1184 considerations of section 3.2.5 of [RFC7668] may be applied.
1186 Other key protocols such as DHCPv6 [RFC3315], IPsec [RFC4301] and TLS
1187 [RFC5246] have similarly problematic properties in this context.
1188 Each of those require relatively frequent round-trips between the
1189 host and some other host on the network. In the case of
1190 cryptographic protocols such as IPsec and TLS, in addition to the
1191 round-trips required for secure session establishment, cryptographic
1192 operations can require padding and addition of authenticators that
1193 are problematic when considering LPWAN lower layers. Note that mains
1194 powered Wi-SUN mesh router nodes will typically be more resource
1195 capable than the other LPWAN techs discussed. This can enable use of
1196 more "chatty" protocols for some aspects of Wi-SUN.
1198 4.2. 6LoWPAN
1200 Several technologies that exhibit significant constraints in various
1201 dimensions have exploited the 6LoWPAN suite of specifications
1202 [RFC4944], [RFC6282], [RFC6775] to support IPv6 [I-D.hong-6lo-use-
1203 cases]. However, the constraints of LPWANs, often more extreme than
1204 those typical of technologies that have (re)used 6LoWPAN, constitute
1205 a challenge for the 6LoWPAN suite in order to enable IPv6 over LPWAN.
1206 LPWANs are characterized by device constraints (in terms of
1207 processing capacity, memory, and energy availability), and specially,
1208 link constraints, such as:
1210 o very low layer two payload size (from ~10 to ~100 bytes),
1211 o very low bit rate (from ~10 bit/s to ~100 kbit/s), and
1213 o in some specific technologies, further message rate constraints
1214 (e.g. between ~0.1 message/minute and ~1 message/minute) due to
1215 regional regulations that limit the duty cycle.
1217 4.2.1. Header Compression
1219 6LoWPAN header compression reduces IPv6 (and UDP) header overhead by
1220 eliding header fields when they can be derived from the link layer,
1221 and by assuming that some of the header fields will frequently carry
1222 expected values. 6LoWPAN provides both stateless and stateful header
1223 compression. In the latter, all nodes of a 6LoWPAN are assumed to
1224 share compression context. In the best case, the IPv6 header for
1225 link-local communication can be reduced to only 2 bytes. For global
1226 communication, the IPv6 header may be compressed down to 3 bytes in
1227 the most extreme case. However, in more practical situations, the
1228 smallest IPv6 header size may be 11 bytes (one address prefix
1229 compressed) or 19 bytes (both source and destination prefixes
1230 compressed). These headers are large considering the link layer
1231 payload size of LPWAN technologies, and in some cases are even bigger
1232 than the LPWAN PDUs. 6LoWPAN has been initially designed for IEEE
1233 802.15.4 networks with a frame size up to 127 bytes and a throughput
1234 of up to 250 kb/s, which may or may not be duty-cycled.
1236 4.2.2. Address Autoconfiguration
1238 Traditionally, Interface Identifiers (IIDs) have been derived from
1239 link layer identifiers [RFC4944] . This allows optimizations such as
1240 header compression. Nevertheless, recent guidance has given advice
1241 on the fact that, due to privacy concerns, 6LoWPAN devices should not
1242 be configured to embed their link layer addresses in the IID by
1243 default.
1245 4.2.3. Fragmentation
1247 As stated above, IPv6 requires the layer below to support an MTU of
1248 1280 bytes [RFC2460]. Therefore, given the low maximum payload size
1249 of LPWAN technologies, fragmentation is needed.
1251 If a layer of an LPWAN technology supports fragmentation, proper
1252 analysis has to be carried out to decide whether the fragmentation
1253 functionality provided by the lower layer or fragmentation at the
1254 adaptation layer should be used. Otherwise, fragmentation
1255 functionality shall be used at the adaptation layer.
1257 6LoWPAN defined a fragmentation mechanism and a fragmentation header
1258 to support the transmission of IPv6 packets over IEEE 802.15.4
1259 networks [RFC4944]. While the 6LoWPAN fragmentation header is
1260 appropriate for IEEE 802.15.4-2003 (which has a frame payload size of
1261 81-102 bytes), it is not suitable for several LPWAN technologies,
1262 many of which have a maximum payload size that is one order of
1263 magnitude below that of IEEE 802.15.4-2003. The overhead of the
1264 6LoWPAN fragmentation header is high, considering the reduced payload
1265 size of LPWAN technologies and the limited energy availability of the
1266 devices using such technologies. Furthermore, its datagram offset
1267 field is expressed in increments of eight octets. In some LPWAN
1268 technologies, the 6LoWPAN fragmentation header plus eight octets from
1269 the original datagram exceeds the available space in the layer two
1270 payload. In addition, the MTU in the LPWAN networks could be
1271 variable which implies a variable fragmentation solution.
1273 4.2.4. Neighbor Discovery
1275 6LoWPAN Neighbor Discovery [RFC6775] defined optimizations to IPv6
1276 Neighbor Discovery [RFC4861], in order to adapt functionality of the
1277 latter for networks of devices using IEEE 802.15.4 or similar
1278 technologies. The optimizations comprise host-initiated interactions
1279 to allow for sleeping hosts, replacement of multicast-based address
1280 resolution for hosts by an address registration mechanism, multihop
1281 extensions for prefix distribution and duplicate address detection
1282 (note that these are not needed in a star topology network), and
1283 support for 6LoWPAN header compression.
1285 6LoWPAN Neighbor Discovery may be used in not so severely constrained
1286 LPWAN networks. The relative overhead incurred will depend on the
1287 LPWAN technology used (and on its configuration, if appropriate). In
1288 certain LPWAN setups (with a maximum payload size above ~60 bytes,
1289 and duty-cycle-free or equivalent operation), an RS/RA/NS/NA exchange
1290 may be completed in a few seconds, without incurring packet
1291 fragmentation.
1293 In other LPWANs (with a maximum payload size of ~10 bytes, and a
1294 message rate of ~0.1 message/minute), the same exchange may take
1295 hours or even days, leading to severe fragmentation and consuming a
1296 significant amount of the available network resources. 6LoWPAN
1297 Neighbor Discovery behavior may be tuned through the use of
1298 appropriate values for the default Router Lifetime, the Valid
1299 Lifetime in the PIOs, and the Valid Lifetime in the 6LoWPAN Context
1300 Option (6CO), as well as the address Registration Lifetime. However,
1301 for the latter LPWANs mentioned above, 6LoWPAN Neighbor Discovery is
1302 not suitable.
1304 4.3. 6lo
1306 The 6lo WG has been reusing and adapting 6LoWPAN to enable IPv6
1307 support over link layer technologies such as Bluetooth Low Energy
1308 (BTLE), ITU-T G.9959, DECT-ULE, MS/TP-RS485, NFC IEEE 802.11ah. (See
1309 for details.) These technologies are
1310 similar in several aspects to IEEE 802.15.4, which was the original
1311 6LoWPAN target technology.
1313 6lo has mostly used the subset of 6LoWPAN techniques best suited for
1314 each lower layer technology, and has provided additional
1315 optimizations for technologies where the star topology is used, such
1316 as BTLE or DECT-ULE.
1318 The main constraint in these networks comes from the nature of the
1319 devices (constrained devices), whereas in LPWANs it is the network
1320 itself that imposes the most stringent constraints.
1322 4.4. 6tisch
1324 The 6tisch solution is dedicated to mesh networks that operate using
1325 802.15.4e MAC with a deterministic slotted channel. The time slot
1326 channel (TSCH) can help to reduce collisions and to enable a better
1327 balance over the channels. It improves the battery life by avoiding
1328 the idle listening time for the return channel.
1330 A key element of 6tisch is the use of synchronization to enable
1331 determinism. TSCH and 6TiSCH may provide a standard scheduling
1332 function. The LPWAN networks probably will not support
1333 synchronization like the one used in 6tisch.
1335 4.5. RoHC
1337 Robust header compression (RoHC) is a header compression mechanism
1338 [RFC3095] developed for multimedia flows in a point to point channel.
1339 RoHC uses 3 levels of compression, each level having its own header
1340 format. In the first level, RoHC sends 52 bytes of header, in the
1341 second level the header could be from 34 to 15 bytes and in the third
1342 level header size could be from 7 to 2 bytes. The level of
1343 compression is managed by a sequence number, which varies in size
1344 from 2 bytes to 4 bits in the minimal compression. SN compression is
1345 done with an algorithm called W-LSB (Window- Least Significant Bits).
1346 This window has a 4-bit size representing 15 packets, so every 15
1347 packets RoHC needs to slide the window in order to receive the
1348 correct sequence number, and sliding the window implies a reduction
1349 of the level of compression. When packets are lost or errored, the
1350 decompressor loses context and drops packets until a bigger header is
1351 sent with more complete information. To estimate the performance of
1352 RoHC, an average header size is used. This average depends on the
1353 transmission conditions, but most of the time is between 3 and 4
1354 bytes.
1356 RoHC has not been adapted specifically to the constrained hosts and
1357 networks of LPWANs: it does not take into account energy limitations
1358 nor the transmission rate, and RoHC context is synchronised during
1359 transmission, which does not allow better compression.
1361 4.6. ROLL
1363 Most technologies considered by the lpwan WG are based on a star
1364 topology, which eliminates the need for routing at that layer.
1365 Future work may address additional use-cases that may require
1366 adaptation of existing routing protocols or the definition of new
1367 ones. As of the time of writing, work similar to that done in the
1368 ROLL WG and other routing protocols are out of scope of the LPWAN WG.
1370 4.7. CoAP
1372 CoAP [RFC7252] provides a RESTful framework for applications intended
1373 to run on constrained IP networks. It may be necessary to adapt CoAP
1374 or related protocols to take into account for the extreme duty cycles
1375 and the potentially extremely limited throughput of LPWANs.
1377 For example, some of the timers in CoAP may need to be redefined.
1378 Taking into account CoAP acknowledgments may allow the reduction of
1379 L2 acknowledgments. On the other hand, the current work in progress
1380 in the CoRE WG where the COMI/CoOL network management interface
1381 which, uses Structured Identifiers (SID) to reduce payload size over
1382 CoAP may prove to be a good solution for the LPWAN technologies. The
1383 overhead is reduced by adding a dictionary which matches a URI to a
1384 small identifier and a compact mapping of the YANG model into the
1385 CBOR binary representation.
1387 4.8. Mobility
1389 LPWAN nodes can be mobile. However, LPWAN mobility is different from
1390 the one specified for Mobile IP. LPWAN implies sporadic traffic and
1391 will rarely be used for high-frequency, real-time communications.
1392 The applications do not generate a flow, they need to save energy and
1393 most of the time the node will be down.
1395 In addition, LPWAN mobility may mostly apply to groups of devices,
1396 that represent a network in which case mobility is more a concern for
1397 the gateway than the devices. NEMO [RFC3963] Mobility or other
1398 mobile gateway solutions (such as a gateway with an LTE uplink) may
1399 be used in the case where some end-devices belonging to the same
1400 network gateway move from one point to another such that they are not
1401 aware of being mobile.
1403 4.9. DNS and LPWAN
1405 The Domain Name System (DNS) DNS [RFC1035], enables applications to
1406 name things with a globally resolvable name. Many protocols use the
1407 DNS to identify hosts, for example applications using CoAP.
1409 The DNS query/answer protocol as a pre-cursor to other communication
1410 within the time-to-live (TTL) of a DNS answer is clearly problematic
1411 in an LPWAN, say where only one round-trip per hour can be used, and
1412 with a TTL that is less than 3600. It is currently unclear whether
1413 and how DNS-like functionality might be provided in LPWANs.
1415 5. Security Considerations
1417 Most LPWAN technologies integrate some authentication or encryption
1418 mechanisms that were defined outside the IETF. The working group may
1419 need to do work to integrate these mechanisms to unify management. A
1420 standardized Authentication, Accounting, and Authorization (AAA)
1421 infrastructure [RFC2904] may offer a scalable solution for some of
1422 the security and management issues for LPWANs. AAA offers
1423 centralized management that may be of use in LPWANs, for example
1424 [I-D.garcia-dime-diameter-lorawan] and
1425 [I-D.garcia-radext-radius-lorawan] suggest possible security
1426 processes for a LoRaWAN network. Similar mechanisms may be useful to
1427 explore for other LPWAN technologies.
1429 Some applications using LPWANs may raise few or no privacy
1430 considerations. For example, temperature sensors in a large office
1431 building may not raise privacy issues. However, the same sensors, if
1432 deployed in a home environment and especially if triggered due to
1433 human presence, can raise significant privacy issues - if an end-
1434 device emits (an encrypted) packet every time someone enters a room
1435 in a home, then that traffic is privacy sensitive. And the more that
1436 the existence of that traffic is visible to network entities, the
1437 more privacy sensitivities arise. At this point, it is not clear
1438 whether there are workable mitigations for problems like this - in a
1439 more typical network, one would consider defining padding mechanisms
1440 and allowing for cover traffic. In some LPWANs, those mechanisms may
1441 not be feasible. Nonetheless, the privacy challenges do exist and
1442 can be real and so some solutions will be needed. Note that many
1443 aspects of solutions in this space may not be visible in IETF
1444 specifications, but can be e.g. implementation or deployment
1445 specific.
1447 Another challenge for LPWANs will be how to handle key management and
1448 associated protocols. In a more traditional network (e.g. the web),
1449 servers can "staple" Online Certificate Status Protocol (OCSP)
1450 responses in order to allow browsers to check revocation status for
1451 presented certificates. [RFC6961] While the stapling approach is
1452 likely something that would help in an LPWAN, as it avoids an RTT,
1453 certificates and OCSP responses are bulky items and will prove
1454 challenging to handle in LPWANs with bounded bandwidth.
1456 6. IANA Considerations
1458 There are no IANA considerations related to this memo.
1460 7. Contributors
1462 As stated above this document is mainly a collection of content
1463 developed by the full set of contributors listed below. The main
1464 input documents and their authors were:
1466 o Text for Section 2.1 was provided by Alper Yegin and Stephen
1467 Farrell in [I-D.farrell-lpwan-lora-overview].
1469 o Text for Section 2.2 was provided by Antti Ratilainen in
1470 [I-D.ratilainen-lpwan-nb-iot].
1472 o Text for Section 2.3 was provided by Juan Carlos Zuniga and Benoit
1473 Ponsard in [I-D.zuniga-lpwan-sigfox-system-description].
1475 o Text for Section 2.4 was provided via personal communication from
1476 Bob Heile (bheile@ieee.org) and was authored by Bob and Sum Chin
1477 Sean. There is no Internet draft for that at present.
1479 o Text for Section 4 was provided by Ana Minabiru, Carles Gomez,
1480 Laurent Toutain, Josep Paradells and Jon Crowcroft in
1481 [I-D.minaburo-lpwan-gap-analysis]. Additional text from that
1482 draft is also used elsewhere above.
1484 The full list of contributors are:
1486 Jon Crowcroft
1487 University of Cambridge
1488 JJ Thomson Avenue
1489 Cambridge, CB3 0FD
1490 United Kingdom
1492 Email: jon.crowcroft@cl.cam.ac.uk
1493 Carles Gomez
1494 UPC/i2CAT
1495 C/Esteve Terradas, 7
1496 Castelldefels 08860
1497 Spain
1499 Email: carlesgo@entel.upc.edu
1501 Bob Heile
1502 Wi-Sun Alliance
1503 11 Robert Toner Blvd, Suite 5-301
1504 North Attleboro, MA 02763
1505 USA
1507 Phone: +1-781-929-4832
1508 Email: bheile@ieee.org
1510 Ana Minaburo
1511 Acklio
1512 2bis rue de la Chataigneraie
1513 35510 Cesson-Sevigne Cedex
1514 France
1516 Email: ana@ackl.io
1518 Josep PAradells
1519 UPC/i2CAT
1520 C/Jordi Girona, 1-3
1521 Barcelona 08034
1522 Spain
1524 Email: josep.paradells@entel.upc.edu
1526 Benoit Ponsard
1527 SIGFOX
1528 425 rue Jean Rostand
1529 Labege 31670
1530 France
1532 Email: Benoit.Ponsard@sigfox.com
1533 URI: http://www.sigfox.com/
1535 Antti Ratilainen
1536 Ericsson
1537 Hirsalantie 11
1538 Jorvas 02420
1539 Finland
1541 Email: antti.ratilainen@ericsson.com
1543 Chin-Sean SUM
1544 Wi-Sun Alliance
1545 20, Science Park Rd
1546 Singapore 117674
1548 Phone: +65 6771 1011
1549 Email: sum@wi-sun.org
1551 Laurent Toutain
1552 Institut MINES TELECOM ; TELECOM Bretagne
1553 2 rue de la Chataigneraie
1554 CS 17607
1555 35576 Cesson-Sevigne Cedex
1556 France
1558 Email: Laurent.Toutain@telecom-bretagne.eu
1560 Alper Yegin
1561 Actility
1562 Paris, Paris
1563 FR
1565 Email: alper.yegin@actility.com
1567 Juan Carlos Zuniga
1568 SIGFOX
1569 425 rue Jean Rostand
1570 Labege 31670
1571 France
1573 Email: JuanCarlos.Zuniga@sigfox.com
1574 URI: http://www.sigfox.com/
1576 8. Acknowledgments
1578 Thanks to all those listed in Section 7 for the excellent text.
1579 Errors in the handling of that are solely the editor's fault.
1581 [[RFC editor: Please surnames below for I18N, at least Mirja's does
1582 need fixing.]]
1584 In addition to the contributors above, thanks are due to (in
1585 alphabetical order): Abdussalam Baryun, Andy Malis, Arun
1586 (arun@acklio.com), Behcet SariKaya, Dan Garcia Carrillo, Jiazi Yi,
1587 Mirja Kuehlewind, Paul Duffy, Russ Housley, Thad Guidry, Warren
1588 Kumari, for comments.
1590 Alexander Pelov and Pascal Thubert were the LPWAN WG chairs while
1591 this document was developed.
1593 Stephen Farrell's work on this memo was supported by Pervasive
1594 Nation, the Science Foundation Ireland's CONNECT centre national IoT
1595 network.
1597 9. Informative References
1599 [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
1600 DOI 10.17487/RFC0768, August 1980, .
1603 [RFC1035] Mockapetris, P., "Domain names - implementation and
1604 specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
1605 November 1987, .
1607 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
1608 (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
1609 December 1998, .
1611 [RFC2904] Vollbrecht, J., Calhoun, P., Farrell, S., Gommans, L.,
1612 Gross, G., de Bruijn, B., de Laat, C., Holdrege, M., and
1613 D. Spence, "AAA Authorization Framework", RFC 2904,
1614 DOI 10.17487/RFC2904, August 2000, .
1617 [RFC3095] Bormann, C., Burmeister, C., Degermark, M., Fukushima, H.,
1618 Hannu, H., Jonsson, L-E., Hakenberg, R., Koren, T., Le,
1619 K., Liu, Z., Martensson, A., Miyazaki, A., Svanbro, K.,
1620 Wiebke, T., Yoshimura, T., and H. Zheng, "RObust Header
1621 Compression (ROHC): Framework and four profiles: RTP, UDP,
1622 ESP, and uncompressed", RFC 3095, DOI 10.17487/RFC3095,
1623 July 2001, .
1625 [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
1626 C., and M. Carney, "Dynamic Host Configuration Protocol
1627 for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
1628 2003, .
1630 [RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P.
1631 Thubert, "Network Mobility (NEMO) Basic Support Protocol",
1632 RFC 3963, DOI 10.17487/RFC3963, January 2005,
1633 .
1635 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the
1636 Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
1637 December 2005, .
1639 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
1640 Control Message Protocol (ICMPv6) for the Internet
1641 Protocol Version 6 (IPv6) Specification", STD 89,
1642 RFC 4443, DOI 10.17487/RFC4443, March 2006,
1643 .
1645 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
1646 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
1647 DOI 10.17487/RFC4861, September 2007, .
1650 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
1651 "Transmission of IPv6 Packets over IEEE 802.15.4
1652 Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,
1653 .
1655 [RFC5216] Simon, D., Aboba, B., and R. Hurst, "The EAP-TLS
1656 Authentication Protocol", RFC 5216, DOI 10.17487/RFC5216,
1657 March 2008, .
1659 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
1660 (TLS) Protocol Version 1.2", RFC 5246,
1661 DOI 10.17487/RFC5246, August 2008, .
1664 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
1665 Housley, R., and W. Polk, "Internet X.509 Public Key
1666 Infrastructure Certificate and Certificate Revocation List
1667 (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
1668 .
1670 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
1671 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
1672 DOI 10.17487/RFC6282, September 2011, .
1675 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
1676 Bormann, "Neighbor Discovery Optimization for IPv6 over
1677 Low-Power Wireless Personal Area Networks (6LoWPANs)",
1678 RFC 6775, DOI 10.17487/RFC6775, November 2012,
1679 .
1681 [RFC6961] Pettersen, Y., "The Transport Layer Security (TLS)
1682 Multiple Certificate Status Request Extension", RFC 6961,
1683 DOI 10.17487/RFC6961, June 2013, .
1686 [RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
1687 Application Protocol (CoAP)", RFC 7252,
1688 DOI 10.17487/RFC7252, June 2014, .
1691 [RFC7452] Tschofenig, H., Arkko, J., Thaler, D., and D. McPherson,
1692 "Architectural Considerations in Smart Object Networking",
1693 RFC 7452, DOI 10.17487/RFC7452, March 2015,
1694 .
1696 [RFC7668] Nieminen, J., Savolainen, T., Isomaki, M., Patil, B.,
1697 Shelby, Z., and C. Gomez, "IPv6 over BLUETOOTH(R) Low
1698 Energy", RFC 7668, DOI 10.17487/RFC7668, October 2015,
1699 .
1701 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
1702 (IPv6) Specification", STD 86, RFC 8200,
1703 DOI 10.17487/RFC8200, July 2017, .
1706 [RFC8240] Tschofenig, H. and S. Farrell, "Report from the Internet
1707 of Things Software Update (IoTSU) Workshop 2016",
1708 RFC 8240, DOI 10.17487/RFC8240, September 2017,
1709 .
1711 [I-D.farrell-lpwan-lora-overview]
1712 Farrell, S. and A. Yegin, "LoRaWAN Overview", draft-
1713 farrell-lpwan-lora-overview-01 (work in progress), October
1714 2016.
1716 [I-D.minaburo-lpwan-gap-analysis]
1717 Minaburo, A., Gomez, C., Toutain, L., Paradells, J., and
1718 J. Crowcroft, "LPWAN Survey and GAP Analysis", draft-
1719 minaburo-lpwan-gap-analysis-02 (work in progress), October
1720 2016.
1722 [I-D.zuniga-lpwan-sigfox-system-description]
1723 Zuniga, J. and B. PONSARD, "SIGFOX System Description",
1724 draft-zuniga-lpwan-sigfox-system-description-04 (work in
1725 progress), December 2017.
1727 [I-D.ratilainen-lpwan-nb-iot]
1728 Ratilainen, A., "NB-IoT characteristics", draft-
1729 ratilainen-lpwan-nb-iot-00 (work in progress), July 2016.
1731 [I-D.garcia-dime-diameter-lorawan]
1732 Garcia, D., Lopez, R., Kandasamy, A., and A. Pelov,
1733 "LoRaWAN Authentication in Diameter", draft-garcia-dime-
1734 diameter-lorawan-00 (work in progress), May 2016.
1736 [I-D.garcia-radext-radius-lorawan]
1737 Garcia, D., Lopez, R., Kandasamy, A., and A. Pelov,
1738 "LoRaWAN Authentication in RADIUS", draft-garcia-radext-
1739 radius-lorawan-03 (work in progress), May 2017.
1741 [TGPP36300]
1742 3GPP, "TS 36.300 v13.4.0 Evolved Universal Terrestrial
1743 Radio Access (E-UTRA) and Evolved Universal Terrestrial
1744 Radio Access Network (E-UTRAN); Overall description; Stage
1745 2", 2016,
1746 .
1748 [TGPP36321]
1749 3GPP, "TS 36.321 v13.2.0 Evolved Universal Terrestrial
1750 Radio Access (E-UTRA); Medium Access Control (MAC)
1751 protocol specification", 2016.
1753 [TGPP36322]
1754 3GPP, "TS 36.322 v13.2.0 Evolved Universal Terrestrial
1755 Radio Access (E-UTRA); Radio Link Control (RLC) protocol
1756 specification", 2016.
1758 [TGPP36323]
1759 3GPP, "TS 36.323 v13.2.0 Evolved Universal Terrestrial
1760 Radio Access (E-UTRA); Packet Data Convergence Protocol
1761 (PDCP) specification (Not yet available)", 2016.
1763 [TGPP36331]
1764 3GPP, "TS 36.331 v13.2.0 Evolved Universal Terrestrial
1765 Radio Access (E-UTRA); Radio Resource Control (RRC);
1766 Protocol specification", 2016.
1768 [TGPP36201]
1769 3GPP, "TS 36.201 v13.2.0 - Evolved Universal Terrestrial
1770 Radio Access (E-UTRA); LTE physical layer; General
1771 description", 2016.
1773 [TGPP23720]
1774 3GPP, "TR 23.720 v13.0.0 - Study on architecture
1775 enhancements for Cellular Internet of Things", 2016.
1777 [TGPP33203]
1778 3GPP, "TS 33.203 v13.1.0 - 3G security; Access security
1779 for IP-based services", 2016.
1781 [fcc_ref] "FCC CFR 47 Part 15.247 Telecommunication Radio Frequency
1782 Devices - Operation within the bands 902-928 MHz,
1783 2400-2483.5 MHz, and 5725-5850 MHz.", June 2016.
1785 [etsi_ref]
1786 "ETSI EN 300-220 (Parts 1 and 2): Electromagnetic
1787 compatibility and Radio spectrum Matters (ERM); Short
1788 Range Devices (SRD); Radio equipment to be used in the 25
1789 MHz to 1 000 MHz frequency range with power levels ranging
1790 up to 500 mW", May 2016.
1792 [arib_ref]
1793 "ARIB STD-T108 (Version 1.0): 920MHz-Band Telemeter,
1794 Telecontrol and data transmission radio equipment.",
1795 February 2012.
1797 [LoRaSpec]
1798 LoRa Alliance, "LoRaWAN Specification Version V1.0.2",
1799 July 2016, .
1803 [ANSI-4957-000]
1804 ANSI, TIA-4957.000, "Architecture Overview for the Smart
1805 Utility Network", May 2013, .
1808 [ANSI-4957-210]
1809 ANSI, TIA-4957.210, "Multi-Hop Delivery Specification of a
1810 Data Link Sub-Layer", May 2013, .
1813 [wisun-pressie1]
1814 Phil Beecher, Chair, Wi-SUN Alliance, "Wi-SUN Alliance
1815 Overview", March 2017, .
1819 [wisun-pressie2]
1820 Bob Heile, Director of Standards, Wi-SUN Alliance, "IETF97
1821 Wi-SUN Alliance Field Area Network (FAN) Overview",
1822 November 2016,
1823 .
1826 [IEEE-802-15-4]
1827 "IEEE Standard for Low-Rate Wireless Personal Area
1828 Networks (WPANs)", IEEE Standard 802.15.4, 2015,
1829 .
1832 [IEEE-802-15-9]
1833 "IEEE Recommended Practice for Transport of Key Management
1834 Protocol (KMP) Datagrams", IEEE Standard 802.15.9, 2016,
1835 .
1838 [etsi_unb]
1839 "ETSI TR 103 435 System Reference document (SRdoc); Short
1840 Range Devices (SRD); Technical characteristics for Ultra
1841 Narrow Band (UNB) SRDs operating in the UHF spectrum below
1842 1 GHz", February 2017.
1844 [nbiot-ov]
1845 Beyene, Yihenew Dagne, et al., "NB-IoT technology overview
1846 and experience from cloud-RAN implementation", IEEE
1847 Wireless Communications 24,3 (2017): 26-32, June 2017.
1849 Appendix A. Changes
1851 A.1. From -00 to -01
1853 o WG have stated they want this to be an RFC.
1855 o WG clearly want to keep the RF details.
1857 o Various changes made to remove/resolve a number of editorial notes
1858 from -00 (in some cases as per suggestions from Ana Minaburo)
1860 o Merged PR's: #1...
1862 o Rejected PR's: #2 (change was made to .txt not .xml but was
1863 replicated manually by editor)
1865 o Github repo is at: https://github.com/sftcd/lpwan-ov
1867 A.2. From -01 to -02
1869 o WG seem to agree with editor suggestions in slides 13-24 of the
1870 presentation on this topic given at IETF98 (See:
1871 https://www.ietf.org/proceedings/98/slides/slides-98-lpwan-
1872 aggregated-slides-07.pdf)
1874 o Got new text wrt Wi-SUN via email from Paul Duffy and merged that
1875 in
1877 o Reflected list discussion wrt terminology and "end-device"
1879 o Merged PR's: #3...
1881 A.3. From -02 to -03
1883 o Editorial changes and typo fixes thanks to Fred Baker running
1884 something called Grammerly and sending me it's report.
1886 o Merged PR's: #4, #6, #7...
1888 o Editor did an editing pass on the lot.
1890 A.4. From -03 to -04
1892 o Picked up a PR that had been wrongly applied that expands UE
1894 o Editorial changes wrt LoRa suggested by Alper
1896 o Editorial changes wrt SIGFOX provided by Juan-Carlos
1898 A.5. From -04 to -05
1900 o Handled Russ Housley's WGLC review.
1902 o Handled Alper Yegin's WGLC review.
1904 A.6. From -05 to -06
1906 o More Alper comments:-)
1908 o Added some more detail about sigfox security.
1910 o Added Wi-SUN changes from Charlie Perkins
1912 A.7. From -06 to -07
1914 Yet more Alper comments:-)
1916 Comments from Behcet Sarikaya
1918 A.8. From -07 to -08
1920 various typos
1922 Last call and directorate comments from Abdussalam Baryun (AB) and
1923 Andy Malis
1925 20180118 IESG ballot comments from Warren: nits handled, two
1926 possible bits of text still needed.
1928 Some more AB comments handled. Still need to check over 7452 and
1929 8240 to see if issues from those need to be discussed here.
1931 Corrected "no IP capabilities - Wi-SUN devices do v6 (thanks Paul
1932 Duffy:-)
1934 Mirja's AD ballot comments handled.
1936 Added a sentence in intro trying to say what's "special" about
1937 LPWAN compared to other constrained networks. (As suggested by
1938 Warren.)
1940 Added text @ start of gap analysis referring to RFCs 7252 and
1941 8240, as suggested by a few folks (AB, Warren, Mirja)
1943 Added nbiot-ov reference for those who'd like a more polished
1944 presentation of NB-IoT
1946 Author's Address
1947 Stephen Farrell (editor)
1948 Trinity College Dublin
1949 Dublin 2
1950 Ireland
1952 Phone: +353-1-896-2354
1953 Email: stephen.farrell@cs.tcd.ie