Internet Engineering Task Force (IETF) S. Farrell, Ed.
Request for Comments: 8376 Trinity College Dublin
Category: Informational May 2018
ISSN: 2070-1721
Low-Power Wide Area Network (LPWAN) Overview
Abstract
Low-Power Wide Area Networks (LPWANs) are wireless technologies with
characteristics such as large coverage areas, low bandwidth, possibly
very small packet and application-layer data sizes, and long battery
life operation. This memo is an informational overview of the set of
LPWAN technologies being considered in the IETF and of the gaps that
exist between the needs of those technologies and the goal of running
IP in LPWANs.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are candidates for any level of Internet
Standard; see Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8376.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. LPWAN Technologies . . . . . . . . . . . . . . . . . . . . . 3
2.1. LoRaWAN . . . . . . . . . . . . . . . . . . . . . . . . . 3 4
2.1.1. Provenance and Documents . . . . . . . . . . . . . . 3 4
2.1.2. Characteristics . . . . . . . . . . . . . . . . . . . 4
2.2. Narrowband IoT (NB-IoT) . . . . . . . . . . . . . . . . . 10
2.2.1. Provenance and Documents . . . . . . . . . . . . . . 10
2.2.2. Characteristics . . . . . . . . . . . . . . . . . . . 11
2.3. Sigfox . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.3.1. Provenance and Documents . . . . . . . . . . . . . . 15
2.3.2. Characteristics . . . . . . . . . . . . . . . . . . . 16
2.4. Wi-SUN Alliance Field Area Network (FAN) . . . . . . . . 20
2.4.1. Provenance and Documents . . . . . . . . . . . . . . 20
2.4.2. Characteristics . . . . . . . . . . . . . . . . . . . 21
3. Generic Terminology . . . . . . . . . . . . . . . . . . . . . 24
4. Gap Analysis . . . . . . . . . . . . . . . . . . . . . . . . 26
4.1. Naive Application of IPv6 . . . . . . . . . . . . . . . . 26
4.2. 6LoWPAN . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.2.1. Header Compression . . . . . . . . . . . . . . . . . 27
4.2.2. Address Autoconfiguration . . . . . . . . . . . . . . 27
4.2.3. Fragmentation . . . . . . . . . . . . . . . . . . . . 27
4.2.4. Neighbor Discovery . . . . . . . . . . . . . . . . . 28
4.3. 6lo . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.4. 6tisch . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.5. RoHC . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.6. ROLL . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.7. CoAP . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.8. Mobility . . . . . . . . . . . . . . . . . . . . . . . . 31
4.9. DNS and LPWAN . . . . . . . . . . . . . . . . . . . . . . 31
5. Security Considerations . . . . . . . . . . . . . . . . . . . 31
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32
7. Informative References . . . . . . . . . . . . . . . . . . . 32
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 39
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 43
1. Introduction
This document provides background material and an overview of the
technologies being considered in the IETF's IPv6 over Low Power Wide-
Area Networks (LPWAN) Working Group (WG). It also provides a gap
analysis between the needs of these technologies and currently
available IETF specifications.
Most technologies in this space aim for a similar goal of supporting
large numbers of very low-cost, low-throughput devices with very low
power consumption, so that even battery-powered devices can be
deployed for years. LPWAN devices also tend to be constrained in
their use of bandwidth, for example, with limited frequencies being
allowed to be used within limited duty cycles (usually expressed as a
percentage of time per hour that the device is allowed to transmit).
As the name implies, coverage of large areas is also a common goal.
So, by and large, the different technologies aim for deployment in
very similar circumstances.
While all constrained networks must balance power consumption /
battery life, cost, and bandwidth, LPWANs prioritize power and cost
benefits by accepting severe bandwidth and duty cycle constraints
when making the required trade-offs. This prioritization is made in
order to get the multiple-kilometer radio links implied by "Wide
Area" in LPWAN's name.
Existing pilot deployments have shown huge potential and created much
industrial interest in these technologies. At the time of writing,
essentially no LPWAN end devices (other than for Wi-SUN) have IP
capabilities. Connecting LPWANs to the Internet would provide
significant benefits to these networks in terms of interoperability,
application deployment, and management (among others). The goal of
the LPWAN WG is to, where necessary, adapt IETF-defined protocols,
addressing schemes, and naming conventions to this particular
constrained environment.
This document is largely the work of the people listed in the
Contributors section.
2. LPWAN Technologies
This section provides an overview of the set of LPWAN technologies
that are being considered in the LPWAN WG. The text for each was
mainly contributed by proponents of each technology.
Note that this text is not intended to be normative in any sense; it
simply exists to help the reader in finding the relevant Layer 2 (L2)
specifications and in understanding how those integrate with IETF-
defined technologies. Similarly, there is no attempt here to set out
the pros and cons of the relevant technologies.
2.1. LoRaWAN
2.1.1. Provenance and Documents
LoRaWAN is a wireless technology based on Industrial, Scientific, and
Medical (ISM) that is used for long-range low-power low-data-rate
applications developed by the LoRa Alliance, a membership consortium
<https://www.lora-alliance.org/>. This document is based on Version
1.0.2 of the LoRa specification [LoRaSpec]. That specification is
publicly available and has already seen several deployments across
the globe.
2.1.2. Characteristics
LoRaWAN aims to support end devices operating on a single battery for
an extended period of time (e.g., 10 years or more), extended
coverage through 155 dB maximum coupling loss, and reliable and
efficient file download (as needed for remote software/firmware
upgrade).
LoRaWAN networks are typically organized in a star-of-stars topology
in which Gateways relay messages between end devices and a central
"network server" in the backend. Gateways are connected to the
network server via IP links while end devices use single-hop LoRaWAN
communication that can be received at one or more Gateways.
Communication is generally bidirectional; uplink communication from
end devices to the network server is favored in terms of overall
bandwidth availability.
Figure 1 shows the entities involved in a LoRaWAN network.
+----------+
|End Device| * * *
+----------+ * +---------+
* | Gateway +---+
+----------+ * +---------+ | +---------+
|End Device| * * * +---+ Network +--- Application
+----------+ * | | Server |
* +---------+ | +---------+
+----------+ * | Gateway +---+
|End Device| * * * * +---------+
+----------+
Key: * LoRaWAN Radio
+---+ IP connectivity
Figure 1: LoRaWAN Architecture
o End Device: a LoRa client device, sometimes called a "mote".
Communicates with Gateways.
o Gateway: a radio on the infrastructure side, sometimes called a
"concentrator" or "base station". Communicates with end devices
and, via IP, with a network server.
o Network Server: The Network Server (NS) terminates the LoRaWAN
Medium Access Control (MAC) layer for the end devices connected to
the network. It is the center of the star topology.
o Join Server: The Join Server (JS) is a server on the Internet side
of an NS that processes join requests from an end devices.
o Uplink message: refers to communications from an end device to a
network server or application via one or more Gateways.
o Downlink message: refers to communications from a network server
or application via one Gateway to a single end device or a group
of end devices (considering multicasting).
o Application: refers to application-layer code both on the end
device and running "behind" the NS. For LoRaWAN, there will
generally only be one application running on most end devices.
Interfaces between the NS and the application are not further
described here.
In LoRaWAN networks, end device transmissions may be received at
multiple Gateways, so, during nominal operation, a network server may
see multiple instances of the same uplink message from an end device.
The LoRaWAN network infrastructure manages the data rate and Radio
Frequency (RF) output power for each end device individually by means
of an Adaptive Data Rate (ADR) scheme. End devices may transmit on
any channel allowed by local regulation at any time.
LoRaWAN radios make use of ISM bands, for example, 433 MHz and 868
MHz within the European Union and 915 MHz in the Americas.
The end device changes channels in a pseudorandom fashion for every
transmission to help make the system more robust to interference and/
or to conform to local regulations.
Figure 2 shows that after a transmission slot, a Class A device turns
on its receiver for two short receive windows that are offset from
the end of the transmission window. End devices can only transmit a
subsequent uplink frame after the end of the associated receive
windows. When a device joins a LoRaWAN network, there are similar
timeouts on parts of that process.
|----------------------------| |--------| |--------|
| Tx | | Rx | | Rx |
|----------------------------| |--------| |--------|
|---------|
Rx delay 1
|------------------------|
Rx delay 2
Figure 2: LoRaWAN Class A Transmission and Reception Window
Given the different regional requirements, the detailed specification
for the LoRaWAN Physical layer (PHY) (taking up more than 30 pages of
the specification) is not reproduced here. Instead, and mainly to
illustrate the kinds of issue encountered, Table 1 presents some of
the default settings for one ISM band (without fully explaining those
here); Table 2 describes maxima and minima for some parameters of
interest to those defining ways to use IETF protocols over the
LoRaWAN MAC layer.
+-----------------------+-------------------------------------------+
| Parameters | Default Value |
+-----------------------+-------------------------------------------+
| Rx delay 1 | 1 s |
| | |
| Rx delay 2 | 2 s (must be RECEIVE_DELAY1 + 1 s) |
| | |
| join delay 1 | 5 s |
| | |
| join delay 2 | 6 s |
| | |
| 868MHz Default | 3 (868.1,868.2,868.3), data rate: 0.3-50 |
| channels | kbit/s |
+-----------------------+-------------------------------------------+
Table 1: Default Settings for EU 868 MHz Band
+------------------------------------------------+--------+---------+
| Parameter/Notes | Min | Max |
+------------------------------------------------+--------+---------+
| Duty Cycle: some but not all ISM bands impose | 1% | no |
| a limit in terms of how often an end device | | limit |
| can transmit. In some cases, LoRaWAN is more | | |
| restrictive in an attempt to avoid congestion. | | |
| | | |
| EU 868 MHz band data rate/frame size | 250 | 50000 |
| | bits/s | bits/s |
| | : 59 | : 250 |
| | octets | octets |
| | | |
| US 915 MHz band data rate/frame size | 980 | 21900 |
| | bits/s | bits/s |
| | : 19 | : 250 |
| | octets | octets |
+------------------------------------------------+--------+---------+
Table 2: Minima and Maxima for Various LoRaWAN Parameters
Note that, in the case of the smallest frame size (19 octets), 8
octets are required for LoRa MAC layer headers, leaving only 11
octets for payload (including MAC layer options). However, those
settings do not apply for the join procedure -- end devices are
required to use a channel and data rate that can send the 23-byte
Join-Request message for the join procedure.
Uplink and downlink higher-layer data is carried in a MACPayload.
There is a concept of "ports" (an optional 8-bit value) to handle
different applications on an end device. Port zero is reserved for
LoRaWAN-specific messaging, such as the configuration of the end
device's network parameters (available channels, data rates, ADR
parameters, Rx Delay 1 and 2, etc.).
In addition to carrying higher-layer PDUs, there are Join-Request and
Join-Response (aka Join-Accept) messages for handling network access.
And so-called "MAC commands" (see below) up to 15 bytes long can be
piggybacked in an options field ("FOpts").
There are a number of MAC commands for link and device status
checking, ADR and duty cycle negotiation, and managing the RX windows
and radio channel settings. For example, the link check response
message allows the NS (in response to a request from an end device)
to inform an end device about the signal attenuation seen most
recently at a Gateway and to tell the end device how many Gateways
received the corresponding link request MAC command.
Some MAC commands are initiated by the network server. For example,
one command allows the network server to ask an end device to reduce
its duty cycle to only use a proportion of the maximum allowed in a
region. Another allows the network server to query the end device's
power status with the response from the end device specifying whether
it has an external power source or is battery powered (in which case,
a relative battery level is also sent to the network server).
In order to operate nominally on a LoRaWAN network, a device needs a
32-bit device address, which is assigned when the device "joins" the
network (see below for the join procedure) or that is pre-provisioned
into the device. In case of roaming devices, the device address is
assigned based on the 24-bit network identifier (NetID) that is
allocated to the network by the LoRa Alliance. Non-roaming devices
can be assigned device addresses by the network without relying on a
NetID assigned by the LoRa Alliance.
End devices are assumed to work with one or quite a limited number of
applications, identified by a 64-bit AppEUI, which is assumed to be a
registered IEEE EUI64 value [EUI64]. In addition, a device needs to
have two symmetric session keys, one for protecting network artifacts
(port=0), the NwkSKey, and another for protecting application-layer
traffic, the AppSKey. Both keys are used for 128-bit AES
cryptographic operations. So, one option is for an end device to
have all of the above plus channel information, somehow
(pre-)provisioned; in that case, the end device can simply start
transmitting. This is achievable in many cases via out-of-band means
given the nature of LoRaWAN networks. Table 3 summarizes these
values.
+---------+---------------------------------------------------------+
| Value | Description |
+---------+---------------------------------------------------------+
| DevAddr | DevAddr (32 bits) = device-specific network address |
| | generated from the NetID |
| | |
| AppEUI | IEEE EUI64 value corresponding to the join server for |
| | an application |
| | |
| NwkSKey | 128-bit network session key used with AES-CMAC |
| | |
| AppSKey | 128-bit application session key used with AES-CTR |
| | |
| AppKey | 128-bit application session key used with AES-ECB |
+---------+---------------------------------------------------------+
Table 3: Values Required for Nominal Operation
As an alternative, end devices can use the LoRaWAN join procedure
with a join server behind the NS in order to set up some of these
values and dynamically gain access to the network. To use the join
procedure, an end device must still know the AppEUI and a different
(long-term) symmetric key that is bound to the AppEUI (this is the
application key (AppKey), and it is distinct from the application
session key (AppSKey)). The AppKey is required to be specific to the
device; that is, each end device should have a different AppKey
value. Finally, the end device also needs a long-term identifier for
itself, which is syntactically also an EUI-64 and is known as the
device EUI or DevEUI. Table 4 summarizes these values.
+---------+----------------------------------------------------+
| Value | Description |
+---------+----------------------------------------------------+
| DevEUI | IEEE EUI64 naming the device |
| | |
| AppEUI | IEEE EUI64 naming the application |
| | |
| AppKey | 128-bit long-term application key for use with AES |
+---------+----------------------------------------------------+
Table 4: Values Required for Join Procedure
The join procedure involves a special exchange where the end device
asserts the AppEUI and DevEUI (integrity protected with the long-term
AppKey, but not encrypted) in a Join-Request uplink message. This is
then routed to the network server, which interacts with an entity
that knows that AppKey to verify the Join-Request. If all is going
well, a Join-Accept downlink message is returned from the network
server to the end device. That message specifies the 24-bit NetID,
32-bit DevAddr, and channel information and from which the AppSKey
and NwkSKey can be derived based on knowledge of the AppKey. This
provides the end device with all the values listed in Table 3.
All payloads are encrypted and have data integrity. MAC commands,
when sent as a payload (port zero), are therefore protected.
However, MAC commands piggybacked as frame options ("FOpts") are sent
in clear. Any MAC commands sent as frame options and not only as
payload, are visible to a passive attacker, but they are not
malleable for an active attacker due to the use of the Message
Integrity Check (MIC) described below.
For LoRaWAN version 1.0.x, the NwkSKey session key is used to provide
data integrity between the end device and the network server. The
AppSKey is used to provide data confidentiality between the end
device and network server, or to the application "behind" the network
server, depending on the implementation of the network.
All MAC-layer messages have an outer 32-bit MIC calculated using AES-
CMAC with the input being the ciphertext payload and other headers
and using the NwkSkey. Payloads are encrypted using AES-128, with a
counter-mode derived from [IEEE.802.15.4] using the AppSKey.
Gateways are not expected to be provided with the AppSKey or NwkSKey,
all of the infrastructure-side cryptography happens in (or "behind")
the network server. When session keys are derived from the AppKey as
a result of the join procedure, the Join-Accept message payload is
specially handled.
The long-term AppKey is directly used to protect the Join-Accept
message content, but the function used is not an AES-encrypt
operation, but rather an AES-decrypt operation. The justification is
that this means that the end device only needs to implement the AES-
encrypt operation. (The counter-mode variant used for payload
decryption means the end device doesn't need an AES-decrypt
primitive.)
The Join-Accept plaintext is always less than 16 bytes long, so
Electronic Code Book (ECB) mode is used for protecting Join-Accept
messages. The Join-Accept message contains an AppNonce (a 24-bit
value) that is recovered on the end device along with the other Join-
Accept content (e.g., DevAddr) using the AES-encrypt operation. Once
the Join-Accept payload is available to the end device, the session
keys are derived from the AppKey, AppNonce, and other values, again
using an ECB mode AES-encrypt operation, with the plaintext input
being a maximum of 16 octets.
2.2. Narrowband IoT (NB-IoT)
2.2.1. Provenance and Documents
Narrowband Internet of Things (NB-IoT) has been developed and
standardized by 3GPP. The standardization of NB-IoT was finalized
with 3GPP Release 13 in June 2016, and further enhancements for NB-
IoT are specified in 3GPP Release 14 in 2017 (for example, in the
form of multicast support). Further features and improvements will
be developed in the following releases, but NB-IoT has been ready to
be deployed since 2016; it is rather simple to deploy, especially in
the existing LTE networks with a software upgrade in the operator's
base stations. For more information of what has been specified for
NB-IoT, 3GPP specification 36.300 [TGPP36300] provides an overview
and overall description of the Evolved Universal Terrestrial Radio
Access Network (E-UTRAN) radio interface protocol architecture, while
specifications 36.321 [TGPP36321], 36.322 [TGPP36322], 36.323
[TGPP36323], and 36.331 [TGPP36331] give more detailed descriptions
of MAC, Radio Link Control (RLC), Packet Data Convergence Protocol
(PDCP), and Radio Resource Control (RRC) protocol layers,
respectively. Note that the description below assumes familiarity
with numerous 3GPP terms.
For a general overview of NB-IoT, see [nbiot-ov].
2.2.2. Characteristics
Specific targets for NB-IoT include: module cost that is Less than US
$5, extended coverage of 164 dB maximum coupling loss, battery life
of over 10 years, ~55000 devices per cell, and uplink reporting
latency of less than 10 seconds.
NB-IoT supports Half Duplex Frequency Division Duplex (FDD) operation
mode with 60 kbit/s peak rate in uplink and 30 kbit/s peak rate in
downlink, and a Maximum Transmission Unit (MTU) size of 1600 bytes,
limited by PDCP layer (see Figure 4 for the protocol structure),
which is the highest layer in the user plane, as explained later.
Any packet size up to the said MTU size can be passed to the NB-IoT
stack from higher layers, segmentation of the packet is performed in
the RLC layer, which can segment the data to transmission blocks with
a size as small as 16 bits. As the name suggests, NB-IoT uses
narrowbands with bandwidth of 180 kHz in both downlink and uplink.
The multiple access scheme used in the downlink is Orthogonal
Frequency-Division Multiplex (OFDMA) with 15 kHz sub-carrier spacing.
In uplink, Sub-Carrier Frequency-Division Multiplex (SC-FDMA) single
tone with either 15kHz or 3.75 kHz tone spacing is used, or
optionally multi-tone SC-FDMA can be used with 15 kHz tone spacing.
NB-IoT can be deployed in three ways. In-band deployment means that
the narrowband is deployed inside the LTE band and radio resources
are flexibly shared between NB-IoT and normal LTE carrier. In Guard-
band deployment, the narrowband uses the unused resource blocks
between two adjacent LTE carriers. Standalone deployment is also
supported, where the narrowband can be located alone in dedicated
spectrum, which makes it possible, for example, to reframe a GSM
carrier at 850/900 MHz for NB-IoT. All three deployment modes are
used in licensed frequency bands. The maximum transmission power is
either 20 or 23 dBm for uplink transmissions, while for downlink
transmission the eNodeB may use higher transmission power, up to 46
dBm depending on the deployment.
A Maximum Coupling Loss (MCL) target for NB-IoT coverage enhancements
defined by 3GPP is 164 dB. With this MCL, the performance of NB-IoT
in downlink varies between 200 bps and 2-3 kbit/s, depending on the
deployment mode. Stand-alone operation may achieve the highest data
rates, up to a few kbit/s, while in-band and guard-band operations
may reach several hundreds of bps. NB-IoT may even operate with an
MCL higher than 170 dB with very low bit rates.
For signaling optimization, two options are introduced in addition to
the legacy LTE RRC connection setup; mandatory Data-over-NAS (Control
Plane optimization, solution 2 in [TGPP23720]) and optional RRC
Suspend/Resume (User Plane optimization, solution 18 in [TGPP23720]).
In the control-plane optimization, the data is sent over Non-Access
Stratum (NAS), directly to/from the Mobile Management Entity (MME)
(see Figure 3 for the network architecture) in the core network to
the User Equipment (UE) without interaction from the base station.
This means there is no Access Stratum security or header compression
provided by the PDCP layer in the eNodeB, as the Access Stratum is
bypassed, and only limited RRC procedures. Header compression based
on Robust Header Compression (RoHC) may still optionally be provided
and terminated in the MME.
The RRC Suspend/Resume procedures reduce the signaling overhead
required for UE state transition from RRC Idle to RRC Connected mode
compared to a legacy LTE operation in order to have quicker user-
plane transaction with the network and return to RRC Idle mode
faster.
In order to prolong device battery life, both Power-Saving Mode (PSM)
and extended DRX (eDRX) are available to NB-IoT. With eDRX, the RRC
Connected mode DRX cycle is up to 10.24 seconds; in RRC Idle, the
eDRX cycle can be up to 3 hours. In PSM, the device is in a deep
sleep state and only wakes up for uplink reporting. After the
reporting, there is a window (configured by the network) during which
the device receiver is open for downlink connectivity or for
periodical "keep-alive" signaling (PSM uses periodic TAU signaling
with additional reception windows for downlink reachability).
Since NB-IoT operates in a licensed spectrum, it has no channel
access restrictions allowing up to a 100% duty cycle.
3GPP access security is specified in [TGPP33203].
+--+
|UE| \ +------+ +------+
+--+ \ | MME |------| HSS |
\ / +------+ +------+
+--+ \+--------+ / |
|UE| ----| eNodeB |- |
+--+ /+--------+ \ |
/ \ +--------+
/ \| | +------+ Service Packet
+--+ / | S-GW |----| P-GW |---- Data Network (PDN)
|UE| | | +------+ e.g., Internet
+--+ +--------+
Figure 3: 3GPP Network Architecture
Figure 3 shows the 3GPP network architecture, which applies to NB-
IoT. The MME is responsible for handling the mobility of the UE.
The MME tasks include tracking and paging UEs, session management,
choosing the Serving Gateway for the UE during initial attachment and
authenticating the user. At the MME, the NAS signaling from the UE
is terminated.
The Serving Gateway (S-GW) routes and forwards the user data packets
through the access network and acts as a mobility anchor for UEs
during handover between base stations known as eNodeBs and also
during handovers between NB-IoT and other 3GPP technologies.
The Packet Data Network Gateway (P-GW) works as an interface between
the 3GPP network and external networks.
The Home Subscriber Server (HSS) contains user-related and
subscription-related information. It is a database that performs
mobility management, session-establishment support, user
authentication, and access authorization.
E-UTRAN consists of components of a single type, eNodeB. eNodeB is a
base station that controls the UEs in one or several cells.
The 3GPP radio protocol architecture is illustrated in Figure 4.
+---------+ +---------+
| NAS |----|-----------------------------|----| NAS |
+---------+ | +---------+---------+ | +---------+
| RRC |----|----| RRC | S1-AP |----|----| S1-AP |
+---------+ | +---------+---------+ | +---------+
| PDCP |----|----| PDCP | SCTP |----|----| SCTP |
+---------+ | +---------+---------+ | +---------+
| RLC |----|----| RLC | IP |----|----| IP |
+---------+ | +---------+---------+ | +---------+
| MAC |----|----| MAC | L2 |----|----| L2 |
+---------+ | +---------+---------+ | +---------+
| PHY |----|----| PHY | PHY |----|----| PHY |
+---------+ +---------+---------+ +---------+
LTE-Uu S1-MME
UE eNodeB MME
Figure 4: 3GPP Radio Protocol Architecture for the Control Plane
The radio protocol architecture of NB-IoT (and LTE) is separated into
the control plane and the user plane. The control plane consists of
protocols that control the radio-access bearers and the connection
between the UE and the network. The highest layer of control plane
is called the Non-Access Stratum (NAS), which conveys the radio
signaling between the UE and the Evolved Packet Core (EPC), passing
transparently through the radio network. The NAS is responsible for
authentication, security control, mobility management, and bearer
management.
The Access Stratum (AS) is the functional layer below the NAS; in the
control plane, it consists of the Radio Resource Control (RRC)
protocol [TGPP36331], which handles connection establishment and
release functions, broadcast of system information, radio-bearer
establishment, reconfiguration, and release. The RRC configures the
user and control planes according to the network status. There exist
two RRC states, RRC_Idle or RRC_Connected, and the RRC entity
controls the switching between these states. In RRC_Idle, the
network knows that the UE is present in the network, and the UE can
be reached in case of an incoming call/downlink data. In this state,
the UE monitors paging, performs cell measurements and cell
selection, and acquires system information. Also, the UE can receive
broadcast and multicast data, but it is not expected to transmit or
receive unicast data. In RRC_Connected state, the UE has a
connection to the eNodeB, the network knows the UE location on the
cell level, and the UE may receive and transmit unicast data. An RRC
connection is established when the UE is expected to be active in the
network, to transmit or receive data. The RRC connection is
released, switching back to RRC_Idle, when there is no more traffic;
this is in order to preserve UE battery life and radio resources.
However, as mentioned earlier, a new feature was introduced for NB-
IoT that allows data to be transmitted from the MME directly to the
UE and then transparently to the eNodeB, thus bypassing AS functions.
The PDCP's [TGPP36323] main services in the control plane are
transfer of control-plane data, ciphering, and integrity protection.
The RLC protocol [TGPP36322] performs transfer of upper-layer PDUs
and, optionally, error correction with Automatic Repeat reQuest
(ARQ), concatenation, segmentation, and reassembly of RLC Service
Data Units (SDUs), in-sequence delivery of upper-layer PDUs,
duplicate detection, RLC SDU discarding, RLC-re-establishment, and
protocol error detection and recovery.
The MAC protocol [TGPP36321] provides mapping between logical
channels and transport channels, multiplexing of MAC SDUs, scheduling
information reporting, error correction with Hybrid ARQ (HARQ),
priority handling, and transport format selection.
The PHY [TGPP36201] provides data-transport services to higher
layers. These include error detection and indication to higher
layers, Forward Error Correction (FEC) encoding, HARQ soft-combining,
rate-matching, mapping of the transport channels onto physical
channels, power-weighting and modulation of physical channels,
frequency and time synchronization, and radio characteristics
measurements.
The user plane is responsible for transferring the user data through
the Access Stratum. It interfaces with IP and the highest layer of
the user plane is the PDCP, which, in the user plane, performs header
compression using RoHC, transfer of user-plane data between eNodeB
and the UE, ciphering, and integrity protection. Similar to the
control plane, lower layers in the user plane include RLC, MAC, and
the PHY performing the same tasks as they do in the control plane.
2.3. Sigfox
2.3.1. Provenance and Documents
The Sigfox LPWAN is in line with the terminology and specifications
being defined by ETSI [etsi_unb]. As of today, Sigfox's network has
been fully deployed in 12 countries, with ongoing deployments in 26
other countries, giving in total a geography of 2 million square
kilometers, containing 512 million people.
2.3.2. Characteristics
Sigfox LPWAN autonomous battery-operated devices send only a few
bytes per day, week, or month, in principle, allowing them to remain
on a single battery for up to 10-15 years. Hence, the system is
designed as to allow devices to last several years, sometimes even
buried underground.
Since the radio protocol is connectionless and optimized for uplink
communications, the capacity of a Sigfox base station depends on the
number of messages generated by devices, and not on the actual number
of devices. Likewise, the battery life of devices depends on the
number of messages generated by the device. Depending on the use
case, devices can vary from sending less than one message per device
per day to dozens of messages per device per day.
The coverage of the cell depends on the link budget and on the type
of deployment (urban, rural, etc.). The radio interface is compliant
with the following regulations:
Spectrum allocation in the USA [fcc_ref]
Spectrum allocation in Europe [etsi_ref1] [etsi_ref2]
Spectrum allocation in Japan [arib_ref]
The Sigfox radio interface is also compliant with the local
regulations of the following countries: Australia, Brazil, Canada,
Kenya, Lebanon, Mauritius, Mexico, New Zealand, Oman, Peru,
Singapore, South Africa, South Korea, and Thailand.
The radio interface is based on Ultra Narrow Band (UNB)
communications, which allow an increased transmission range by
spending a limited amount of energy at the device. Moreover, UNB
allows a large number of devices to coexist in a given cell without
significantly increasing the spectrum interference.
Both uplink and downlink are supported, although the system is
optimized for uplink communications. Due to spectrum optimizations,
different uplink and downlink frames and time synchronization methods
are needed.
The main radio characteristics of the UNB uplink transmission are:
o Channelization mask: 100 Hz / 600 Hz (depending on the region)
o Uplink baud rate: 100 baud / 600 baud (depending on the region)
o Modulation scheme: DBPSK
o Uplink transmission power: compliant with local regulation
o Link budget: 155 dB (or better)
o Central frequency accuracy: not relevant, provided there is no
significant frequency drift within an uplink packet transmission
For example, in Europe, the UNB uplink frequency band is limited to
868.00 to 868.60 MHz, with a maximum output power of 25 mW and a duty
cycle of 1%.
The format of the uplink frame is the following:
+--------+--------+--------+------------------+-------------+-----+
|Preamble| Frame | Dev ID | Payload |Msg Auth Code| FCS |
| | Sync | | | | |
+--------+--------+--------+------------------+-------------+-----+
Figure 5: Uplink Frame Format
The uplink frame is composed of the following fields:
o Preamble: 19 bits
o Frame sync and header: 29 bits
o Device ID: 32 bits
o Payload: 0-96 bits
o Authentication: 16-40 bits
o Frame check sequence: 16 bits (Cyclic Redundancy Check (CRC))
The main radio characteristics of the UNB downlink transmission are:
o Channelization mask: 1.5 kHz
o Downlink baud rate: 600 baud
o Modulation scheme: GFSK
o Downlink transmission power: 500 mW / 4W (depending on the region)
o Link budget: 153 dB (or better)
o Central frequency accuracy: the center frequency of downlink
transmission is set by the network according to the corresponding
uplink transmission.
For example, in Europe, the UNB downlink frequency band is limited to
869.40 to 869.65 MHz, with a maximum output power of 500 mW with 10%
duty cycle.
The format of the downlink frame is the following:
+------------+-----+---------+------------------+-------------+-----+
| Preamble |Frame| ECC | Payload |Msg Auth Code| FCS |
| |Sync | | | | |
+------------+-----+---------+------------------+-------------+-----+
Figure 6: Downlink Frame Format
The downlink frame is composed of the following fields:
o Preamble: 91 bits
o Frame sync and header: 13 bits
o Error Correcting Code (ECC): 32 bits
o Payload: 0-64 bits
o Authentication: 16 bits
o Frame check sequence: 8 bits (CRC)
The radio interface is optimized for uplink transmissions, which are
asynchronous. Downlink communications are achieved by devices
querying the network for available data.
A device willing to receive downlink messages opens a fixed window
for reception after sending an uplink transmission. The delay and
duration of this window have fixed values. The network transmits the
downlink message for a given device during the reception window, and
the network also selects the BS for transmitting the corresponding
downlink message.
Uplink and downlink transmissions are unbalanced due to the
regulatory constraints on ISM bands. Under the strictest
regulations, the system can allow a maximum of 140 uplink messages
and 4 downlink messages per device per day. These restrictions can
be slightly relaxed depending on system conditions and the specific
regulatory domain of operation.
+---+
|DEV| * +------+
+---+ * | RA |
* +------+
+---+ * |
|DEV| * * * * |
+---+ * +----+ |
* | BS | \ +--------+
+---+ * +----+ \ | |
DA -----|DEV| * * * | SC |----- NA
+---+ * / | |
* +----+ / +--------+
+---+ * | BS |/
|DEV| * * * * +----+
+---+ *
*
+---+ *
|DEV| * *
+---+
Figure 7: Sigfox Network Architecture
Figure 7 depicts the different elements of the Sigfox network
architecture.
Sigfox has a "one-contract one-network" model allowing devices to
connect in any country, without any need or notion of either roaming
or handover.
The architecture consists of a single cloud-based core network, which
allows global connectivity with minimal impact on the end device and
radio access network. The core network elements are the Service
Center (SC) and the Registration Authority (RA). The SC is in charge
of the data connectivity between the BS and the Internet, as well as
the control and management of the BSs and End Points (EPs). The RA
is in charge of the EP network access authorization.
The radio access network is comprised of several BSs connected
directly to the SC. Each BS performs complex L1/L2 functions,
leaving some L2 and L3 functionalities to the SC.
The Devices (DEVs) or EPs are the objects that communicate
application data between local Device Applications (DAs) and Network
Applications (NAs).
Devices (or EPs) can be static or nomadic, as they associate with the
SC and they do not attach to any specific BS. Hence, they can
communicate with the SC through one or multiple BSs.
Due to constraints in the complexity of the Device, it is assumed
that Devices host only one or very few device applications, which
most of the time communicate each to a single network application at
a time.
The radio protocol authenticates and ensures the integrity of each
message. This is achieved by using a unique device ID and an AES-
128-based message authentication code, ensuring that the message has
been generated and sent by the device with the ID claimed in the
message. Application data can be encrypted at the application level
or not, depending on the criticality of the use case, to provide a
balance between cost and effort versus risk. AES-128 in counter mode
is used for encryption. Cryptographic keys are independent for each
device. These keys are associated with the device ID and separate
integrity and confidentiality keys are pre-provisioned. A
confidentiality key is only provisioned if confidentiality is to be
used. At the time of writing, the algorithms and keying details for
this are not published.
2.4. Wi-SUN Alliance Field Area Network (FAN)
Text here is via personal communication from Bob Heile
(bheile@ieee.org) and was authored by Bob and Sum Chin Sean. Paul
Duffy (paduffy@cisco.com) also provided additional comments/input on
this section.
2.4.1. Provenance and Documents
The Wi-SUN Alliance <https://www.wi-sun.org/> is an industry alliance
for smart city, smart grid, smart utility, and a broad set of general
IoT applications. The Wi-SUN Alliance Field Area Network (FAN)
profile is open-standards based (primarily on IETF and IEEE 802
standards) and was developed to address applications like smart
municipality/city infrastructure monitoring and management, Electric
Vehicle (EV) infrastructure, Advanced Metering Infrastructure (AMI),
Distribution Automation (DA), Supervisory Control and Data
Acquisition (SCADA) protection/management, distributed generation
monitoring and management, and many more IoT applications.
Additionally, the Alliance has created a certification program to
promote global multi-vendor interoperability.
The FAN profile is specified within ANSI/TIA as an extension of work
previously done on Smart Utility Networks [ANSI-4957-000]. Updates
to those specifications intended to be published in 2017 will contain
details of the FAN profile. A current snapshot of the work to
produce that profile is presented in [wisun-pressie1] and
[wisun-pressie2].
2.4.2. Characteristics
The FAN profile is an IPv6 wireless mesh network with support for
enterprise-level security. The frequency-hopping wireless mesh
topology aims to offer superior network robustness, reliability due
to high redundancy, good scalability due to the flexible mesh
configuration, and good resilience to interference. Very low power
modes are in development permitting long-term battery operation of
network nodes.
The following list contains some overall characteristics of Wi-SUN
that are relevant to LPWAN applications.
o Coverage: The range of Wi-SUN FAN is typically 2 - 3 km in line of
sight, matching the needs of neighborhood area networks, campus
area networks, or corporate area networks. The range can also be
extended via multi-hop networking.
o High-bandwidth, low-link latency: Wi-SUN supports relatively high
bandwidth, i.e., up to 300 kbit/s [FANOV], enables remote update
and upgrade of devices so that they can handle new applications,
extending their working life. Wi-SUN supports LPWAN IoT
applications that require on-demand control by providing low link
latency (0.02 s) and bidirectional communication.
o Low-power consumption: FAN devices draw less than 2 uA when
resting and only 8 mA when listening. Such devices can maintain a
long lifetime, even if they are frequently listening. For
instance, suppose the device transmits data for 10 ms once every
10 s; theoretically, a battery of 1000 mAh can last more than 10
years.
o Scalability: Tens of millions of Wi-SUN FAN devices have been
deployed in urban, suburban, and rural environments, including
deployments with more than 1 million devices.
A FAN contains one or more networks. Within a network, nodes assume
one of three operational roles. First, each network contains a
Border Router providing WAN connectivity to the network. The Border
Router maintains source-routing tables for all nodes within its
network, provides node authentication and key management services,
and disseminates network-wide information such as broadcast
schedules. Second, Router nodes, which provide upward and downward
packet forwarding (within a network). A Router also provides
services for relaying security and address management protocols.
Finally, Leaf nodes provide minimum capabilities: discovering and
joining a network, sending/receiving IPv6 packets, etc. A low-power
network may contain a mesh topology with Routers at the edges that
construct a star topology with Leaf nodes.
The FAN profile is based on various open standards developed by the
IETF (including [RFC0768], [RFC2460], [RFC4443], and [RFC6282]).
Related IEEE 802 standards include [IEEE.802.15.4] and
[IEEE.802.15.9]. For Low-Power and Lossy Networks (LLNs), see ANSI/
TIA [ANSI-4957-210].
The FAN profile specification provides an application-independent
IPv6-based transport service. There are two possible methods for
establishing IPv6 packet routing: the Routing Protocol for Low-Power
and Lossy Networks (RPL) at the Network layer is mandatory, and
Multi-Hop Delivery Service (MHDS) is optional at the Data Link layer.
Figure 8 provides an overview of the FAN network stack.
The Transport service is based on UDP (defined in [RFC0768]) or TCP
(defined in [RFC0793].
The Network service is provided by IPv6 as defined in [RFC2460] with
an IPv6 over Low-Power Wireless Personal Area Networks (6LoWPAN)
adaptation as defined in [RFC4944] and [RFC6282]. ICMPv6, as defined
in [RFC4443], is used for the control plane during information
exchange.
The Data Link service provides both control/management of the PHY and
data transfer/management services to the Network layer. These
services are divided into MAC and Logical Link Control (LLC) sub-
layers. The LLC sub-layer provides a protocol dispatch service that
supports 6LoWPAN and an optional MAC sub-layer mesh service. The MAC
sub-layer is constructed using data structures defined in
[IEEE.802.15.4]. Multiple modes of frequency hopping are defined.
The entire MAC payload is encapsulated in an [IEEE.802.15.9]
Information Element to enable LLC protocol dispatch between upper-
layer 6LoWPAN processing and MAC sub-layer mesh processing, etc.
These areas will be expanded once [IEEE.802.15.12] is completed.
The PHY service is derived from a subset of the SUN FSK specification
in [IEEE.802.15.4]. The 2-FSK modulation schemes, with a channel-
spacing range from 200 to 600 kHz, are defined to provide data rates
from 50 to 300 kbit/s, with FEC as an optional feature. Towards
enabling ultra-low-power applications, the PHY layer design is also
extendable to low-energy and critical infrastructure-monitoring
networks.
+----------------------+--------------------------------------------+
| Layer | Description |
+----------------------+--------------------------------------------+
| IPv6 protocol suite | TCP/UDP |
| | |
| | 6LoWPAN Adaptation + Header Compression |
| | |
| | DHCPv6 for IP address management |
| | |
| | Routing using RPL |
| | |
| | ICMPv6 |
| | |
| | Unicast and Multicast forwarding |
+----------------------+--------------------------------------------+
| MAC based on | Frequency hopping |
| [IEEE.802.15.4e] + | |
| IE extensions | Discovery and Join |
| | |
| | Protocol Dispatch ([IEEE.802.15.9]) |
| | |
| | Several Frame Exchange patterns |
| | |
| | Optional Mesh Under routing |
| | ([ANSI-4957-210]) |
+----------------------+--------------------------------------------+
| PHY based on | Various data rates and regions |
| [IEEE.802.15.4g] | |
+----------------------+--------------------------------------------+
| Security | [IEEE.802.1x]/EAP-TLS/PKI Authentication |
| | TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8 |
| | required for EAP-TLS |
| | |
| | 802.11i Group Key Management |
| | |
| | Frame security is implemented as AES-CCM* |
| | as specified in [IEEE.802.15.4] |
| | |
| | Optional [ETSI-TS-102-887-2] Node 2 Node |
| | Key Management |
+----------------------+--------------------------------------------+
Figure 8: Wi-SUN Stack Overview
The FAN security supports Data Link layer network access control,
mutual authentication, and establishment of a secure pairwise link
between a FAN node and its Border Router, which is implemented with
an adaptation of [IEEE.802.1x] and EAP-TLS as described in [RFC5216]
using secure device identity as described in [IEEE.802.1AR].
Certificate formats are based upon [RFC5280]. A secure group link
between a Border Router and a set of FAN nodes is established using
an adaptation of the [IEEE.802.11] Four-Way Handshake. A set of four
group keys are maintained within the network, one of which is the
current transmit key. Secure node-to-node links are supported
between one-hop FAN neighbors using an adaptation of
[ETSI-TS-102-887-2]. FAN nodes implement Frame Security as specified
in [IEEE.802.15.4].
3. Generic Terminology
LPWAN technologies, such as those discussed above, have similar
architectures but different terminology. We can identify different
types of entities in a typical LPWAN network:
o End devices are the devices or the "things" (e.g., sensors,
actuators, etc.); they are named differently in each technology
(End Device, User Equipment, or EP). There can be a high density
of end devices per Radio Gateway.
o The Radio Gateway, which is the EP of the constrained link. It is
known as: Gateway, Evolved Node B or base station.
o The Network Gateway or Router is the interconnection node between
the Radio Gateway and the Internet. It is known as the Network
Server, Serving GW, or Service Center.
o LPWAN-AAA server, which controls user authentication. It is known
as the Join-Server, Home Subscriber Server, or Registration
Authority. (We use the term LPWAN-AAA server because we're not
assuming that this entity speaks RADIUS or Diameter as many/most
AAA servers do; but, equally, we don't want to rule that out, as
the functionality will be similar.)
o At last we have the Application Server, known also as Packet Data
Node Gateway or Network Application.
+---------------------------------------------------------------------+
| Function/ | | | | | |
|Technology | LoRaWAN | NB-IoT | Sigfox | Wi-SUN | IETF |
+-----------+-----------+-----------+------------+--------+-----------+
|Sensor, | | | | | |
|Actuator, | End | User | End | Leaf | Device |
|device, | Device | Equipment | Point | Node | (DEV) |
|object | | | | | |
+-----------+-----------+-----------+------------+--------+-----------+
|Transceiver| | Evolved | Base | Router | Radio |
|Antenna | Gateway | Node B | Station | Node | Gateway |
+-----------+-----------+-----------+------------+--------+-----------+
|Server | Network | PDN GW/ | Service | Border | Network |
| | Server | SCEF* | Center | Router | Gateway |
| | | | | | (NGW) |
+-----------+-----------+-----------+------------+--------+-----------+
|Security | Join | Home |Registration|Authent.| LPWAN- |
|Server | Server | Subscriber| Authority | Server | AAA |
| | | Server | | | Server |
+-----------+-----------+-----------+------------+--------+-----------+
|Application|Application|Application| Network |Appli- |Application|
| | Server | Server | Application| cation | (App) |
+---------------------------------------------------------------------+
* SCEF = Service Capability Exposure Function
Figure 9: LPWAN Architecture Terminology
+------+
() () () | |LPWAN-|
() () () () / \ +---------+ | AAA |
() () () () () () / \========| /\ |====|Server| +-----------+
() () () | | <--|--> | +------+ |APPLICATION|
() () () () / \============| v |==============| (App) |
() () () / \ +---------+ +-----------+
DEV Radio Gateways NGW
Figure 10: LPWAN Architecture
In addition to the names of entities, LPWANs are also subject to
possibly regional frequency-band regulations. Those may include
restrictions on the duty cycle, for example, requiring that hosts
only transmit for a certain percentage of each hour.
4. Gap Analysis
This section considers some of the gaps between current LPWAN
technologies and the goals of the LPWAN WG. Many of the generic
considerations described in [RFC7452] will also apply in LPWANs, as
end devices can also be considered to be a subclass of (so-called)
"smart objects". In addition, LPWAN device implementers will also
need to consider the issues relating to firmware updates described in
[RFC8240].
4.1. Naive Application of IPv6
IPv6 [RFC8200] has been designed to allocate addresses to all the
nodes connected to the Internet. Nevertheless, the header overhead
of at least 40 bytes introduced by the protocol is incompatible with
LPWAN constraints. If IPv6 with no further optimization were used,
several LPWAN frames could be needed just to carry the IP header.
Another problem arises from IPv6 MTU requirements, which require the
layer below to support at least 1280 byte packets [RFC2460].
IPv6 has a configuration protocol: Neighbor Discovery Protocol (NDP)
[RFC4861]). For a node to learn network parameters, NDP generates
regular traffic with a relatively large message size that does not
fit LPWAN constraints.
In some LPWAN technologies, L2 multicast is not supported. In that
case, if the network topology is a star, the solution and
considerations from Section 3.2.5 of [RFC7668] may be applied.
Other key protocols (such as DHCPv6 [RFC3315], IPsec [RFC4301] and
TLS [RFC5246]) have similarly problematic properties in this context.
Each protocol requires relatively frequent round-trips between the
host and some other host on the network. In the case of
cryptographic protocols (such as IPsec and TLS), in addition to the
round-trips required for secure session establishment, cryptographic
operations can require padding and addition of authenticators that
are problematic when considering LPWAN lower layers. Note that mains
powered Wi-SUN mesh router nodes will typically be more resource
capable than the other LPWAN technologies discussed. This can enable
use of more "chatty" protocols for some aspects of Wi-SUN.
4.2. 6LoWPAN
Several technologies that exhibit significant constraints in various
dimensions have exploited the 6LoWPAN suite of specifications
([RFC4944], [RFC6282], and [RFC6775]) to support IPv6 [USES-6LO].
However, the constraints of LPWANs, often more extreme than those
typical of technologies that have (re-)used 6LoWPAN, constitute a
challenge for the 6LoWPAN suite in order to enable IPv6 over LPWAN.
LPWANs are characterized by device constraints (in terms of
processing capacity, memory, and energy availability), and
especially, link constraints, such as:
o tiny L2 payload size (from ~10 to ~100 bytes),
o very low bit rate (from ~10 bit/s to ~100 kbit/s), and
o in some specific technologies, further message rate constraints
(e.g., between ~0.1 message/minute and ~1 message/minute) due to
regional regulations that limit the duty cycle.
4.2.1. Header Compression
6LoWPAN header compression reduces IPv6 (and UDP) header overhead by
eliding header fields when they can be derived from the link layer
and by assuming that some of the header fields will frequently carry
expected values. 6LoWPAN provides both stateless and stateful header
compression. In the latter, all nodes of a 6LoWPAN are assumed to
share compression context. In the best case, the IPv6 header for
link-local communication can be reduced to only 2 bytes. For global
communication, the IPv6 header may be compressed down to 3 bytes in
the most extreme case. However, in more practical situations, the
smallest IPv6 header size may be 11 bytes (one address prefix
compressed) or 19 bytes (both source and destination prefixes
compressed). These headers are large considering the link-layer
payload size of LPWAN technologies, and in some cases, are even
bigger than the LPWAN PDUs. 6LoWPAN was initially designed for
[IEEE.802.15.4] networks with a frame size up to 127 bytes and a
throughput of up to 250 kbit/s, which may or may not be duty cycled.
4.2.2. Address Autoconfiguration
Traditionally, Interface Identifiers (IIDs) have been derived from
link-layer identifiers [RFC4944]. This allows optimizations such as
header compression. Nevertheless, recent guidance has given advice
on the fact that, due to privacy concerns, 6LoWPAN devices should not
be configured to embed their link-layer addresses in the IID by
default. [RFC8065] provides guidance on better methods for
generating IIDs.
4.2.3. Fragmentation
As stated above, IPv6 requires the layer below to support an MTU of
1280 bytes [RFC8200]. Therefore, given the low maximum payload size
of LPWAN technologies, fragmentation is needed.
If a layer of an LPWAN technology supports fragmentation, proper
analysis has to be carried out to decide whether the fragmentation
functionality provided by the lower layer or fragmentation at the
adaptation layer should be used. Otherwise, fragmentation
functionality shall be used at the adaptation layer.
6LoWPAN defined a fragmentation mechanism and a fragmentation header
to support the transmission of IPv6 packets over IEEE.802.15.4
networks [RFC4944]. While the 6LoWPAN fragmentation header is
appropriate for the 2003 version of [IEEE.802.15.4] (which has a
frame payload size of 81-102 bytes), it is not suitable for several
LPWAN technologies, many of which have a maximum payload size that is
one order of magnitude below that of the 2003 version of
[IEEE.802.15.4]. The overhead of the 6LoWPAN fragmentation header is
high, considering the reduced payload size of LPWAN technologies, and
the limited energy availability of the devices using such
technologies. Furthermore, its datagram offset field is expressed in
increments of eight octets. In some LPWAN technologies, the 6LoWPAN
fragmentation header plus eight octets from the original datagram
exceeds the available space in the layer two payload. In addition,
the MTU in the LPWAN networks could be variable, which implies a
variable fragmentation solution.
4.2.4. Neighbor Discovery
6LoWPAN Neighbor Discovery [RFC6775] defines optimizations to IPv6 ND
[RFC4861], in order to adapt functionality of the latter for networks
of devices using [IEEE.802.15.4] or similar technologies. The
optimizations comprise host-initiated interactions to allow for
sleeping hosts, replacement of multicast-based address resolution for
hosts by an address registration mechanism, multihop extensions for
prefix distribution and duplicate address detection (note that these
are not needed in a star topology network), and support for 6LoWPAN
header compression.
6LoWPAN ND may be used in not so severely constrained LPWAN networks.
The relative overhead incurred will depend on the LPWAN technology
used (and on its configuration, if appropriate). In certain LPWAN
setups (with a maximum payload size above ~60 bytes and duty-cycle-
free or equivalent operation), an RS/RA/NS/NA exchange may be
completed in a few seconds, without incurring packet fragmentation.
In other LPWANs (with a maximum payload size of ~10 bytes and a
message rate of ~0.1 message/minute), the same exchange may take
hours or even days, leading to severe fragmentation and consuming a
significant amount of the available network resources. 6LoWPAN ND
behavior may be tuned through the use of appropriate values for the
default Router Lifetime, the Valid Lifetime in the PIOs, and the
Valid Lifetime in the 6LoWPAN Context Option (6CO), as well as the
address Registration Lifetime. However, for the latter LPWANs
mentioned above, 6LoWPAN ND is not suitable.
4.3. 6lo
The 6lo WG has been reusing and adapting 6LoWPAN to enable IPv6
support over link-layer technologies such as Bluetooth Low Energy
(BTLE), ITU-T G.9959 [G9959], Digital Enhanced Cordless
Telecommunications (DECT) Ultra Low Energy (ULE), MS/TP-RS485, Near
Field Communication (NFC) IEEE 802.11ah. (See
<https://tools.ietf.org/wg/6lo/>
<https://datatracker.ietf.org/wg/6lo/documents/> for details on the
6lo WG.) These technologies are similar in several aspects to
[IEEE.802.15.4], which was the original 6LoWPAN target technology.
6lo has mostly used the subset of 6LoWPAN techniques best suited for
each lower-layer technology and has provided additional optimizations
for technologies where the star topology is used, such as BTLE or
DECT-ULE.
The main constraint in these networks comes from the nature of the
devices (constrained devices); whereas, in LPWANs, it is the network
itself that imposes the most stringent constraints.
4.4. 6tisch
The IPv6 over the TSCH mode of IEEE 802.15.4e (6tisch) solution is
dedicated to mesh networks that operate using [IEEE.802.15.4e] MAC
with a deterministic slotted channel. Time-Slotted Channel Hopping
(TSCH) can help to reduce collisions and to enable a better balance
over the channels. It improves the battery life by avoiding the idle
listening time for the return channel.
A key element of 6tisch is the use of synchronization to enable
determinism. TSCH and 6tisch may provide a standard scheduling
function. The LPWAN networks probably will not support
synchronization like the one used in 6tisch.
4.5. RoHC
RoHC is a header compression mechanism [RFC3095] developed for
multimedia flows in a point-to-point channel. RoHC uses three levels
of compression, each level having its own header format. In the
first level, RoHC sends 52 bytes of header; in the second level, the
header could be from 34 to 15 bytes; and in the third level, header
size could be from 7 to 2 bytes. The level of compression is managed
by a Sequence Number (SN), which varies in size from 2 bytes to 4
bits in the minimal compression. SN compression is done with an
algorithm called Window-Least Significant Bits (W-LSB). This window
has a 4-bit size representing 15 packets, so every 15 packets, RoHC
needs to slide the window in order to receive the correct SN, and
sliding the window implies a reduction of the level of compression.
When packets are lost or errored, the decompressor loses context and
drops packets until a bigger header is sent with more complete
information. To estimate the performance of RoHC, an average header
size is used. This average depends on the transmission conditions,
but most of the time is between 3 and 4 bytes.
RoHC has not been adapted specifically to the constrained hosts and
networks of LPWANs: it does not take into account energy limitations
nor the transmission rate. Additionally, RoHC context is
synchronized during transmission, which does not allow better
compression.
4.6. ROLL
Most technologies considered by the LPWAN WG are based on a star
topology, which eliminates the need for routing at that layer.
Future work may address additional use cases that may require
adaptation of existing routing protocols or the definition of new
ones. As of the time of writing, work similar to that done in the
Routing Over Low-Power and Lossy Network (ROLL) WG and other routing
protocols are out of scope of the LPWAN WG.
4.7. CoAP
The Constrained Application Protocol (CoAP) [RFC7252] provides a
RESTful framework for applications intended to run on constrained IP
networks. It may be necessary to adapt CoAP or related protocols to
take into account the extreme duty cycles and the potentially
extremely limited throughput of LPWANs.
For example, some of the timers in CoAP may need to be redefined.
Taking into account CoAP acknowledgments may allow the reduction of
L2 acknowledgments. On the other hand, the current work in progress
in the CoRE WG where the Constrained Management Interface (COMI) /
Constrained Objects Language ( CoOL) network management interface
which, uses Structured Identifiers (SIDs) to reduce payload size over
CoAP may prove to be a good solution for the LPWAN technologies. The
overhead is reduced by adding a dictionary that matches a URI to a
small identifier and a compact mapping of the YANG data model into
the Concise Binary Object Representation (CBOR).
4.8. Mobility
LPWAN nodes can be mobile. However, LPWAN mobility is different from
the one specified for Mobile IP. LPWAN implies sporadic traffic and
will rarely be used for high-frequency, real-time communications.
The applications do not generate a flow; they need to save energy
and, most of the time, the node will be down.
In addition, LPWAN mobility may mostly apply to groups of devices
that represent a network; in which case, mobility is more a concern
for the Gateway than the devices. Network Mobility (NEMO) [RFC3963]
or other mobile Gateway solutions (such as a Gateway with an LTE
uplink) may be used in the case where some end devices belonging to
the same network Gateway move from one point to another such that
they are not aware of being mobile.
4.9. DNS and LPWAN
The Domain Name System (DNS) [RFC1035], enables applications to name
things with a globally resolvable name. Many protocols use the DNS
to identify hosts, for example, applications using CoAP.
The DNS query/answer protocol as a precursor to other communication
within the Time-To-Live (TTL) of a DNS answer is clearly problematic
in an LPWAN, say where only one round-trip per hour can be used, and
with a TTL that is less than 3600 seconds. It is currently unclear
whether and how DNS-like functionality might be provided in LPWANs.
5. Security Considerations
Most LPWAN technologies integrate some authentication or encryption
mechanisms that were defined outside the IETF. The LPWAN WG may need
to do work to integrate these mechanisms to unify management. A
standardized Authentication, Authorization, and Accounting (AAA)
infrastructure [RFC2904] may offer a scalable solution for some of
the security and management issues for LPWANs. AAA offers
centralized management that may be of use in LPWANs, for example
[LoRaWAN-AUTH] and [LoRaWAN-RADIUS] suggest possible security
processes for a LoRaWAN network. Similar mechanisms may be useful to
explore for other LPWAN technologies.
Some applications using LPWANs may raise few or no privacy
considerations. For example, temperature sensors in a large office
building may not raise privacy issues. However, the same sensors, if
deployed in a home environment, and especially if triggered due to
human presence, can raise significant privacy issues: if an end
device emits a (encrypted) packet every time someone enters a room in
a home, then that traffic is privacy sensitive. And the more that
the existence of that traffic is visible to network entities, the
more privacy sensitivities arise. At this point, it is not clear
whether there are workable mitigations for problems like this. In a
more typical network, one would consider defining padding mechanisms
and allowing for cover traffic. In some LPWANs, those mechanisms may
not be feasible. Nonetheless, the privacy challenges do exist and
can be real; therefore, some solutions will be needed. Note that
many aspects of solutions in this space may not be visible in IETF
specifications but can be, e.g., implementation or deployment
specific.
Another challenge for LPWANs will be how to handle key management and
associated protocols. In a more traditional network (e.g., the Web),
servers can "staple" Online Certificate Status Protocol (OCSP)
responses in order to allow browsers to check revocation status for
presented certificates [RFC6961]. While the stapling approach is
likely something that would help in an LPWAN, as it avoids an RTT,
certificates and OCSP responses are bulky items and will prove
challenging to handle in LPWANs with bounded bandwidth.
6. IANA Considerations
This document has no IANA actions.
7. Informative References
[ANSI-4957-000]
ANSI/TIA, "Architecture Overview for the Smart Utility
Network", ANSI/TIA-4957.0000 , May 2013.
[ANSI-4957-210]
ANSI/TIA, "Multi-Hop Delivery Specification of a Data Link
Sub-Layer", ANSI/TIA-4957.210 , May 2013.
[arib_ref]
ARIB, "920MHz-Band Telemeter, Telecontrol and Data
Transmission Radio Equipment", ARIB STD-T108 Version 1.0,
February 2012.
[ETSI-TS-102-887-2]
ETSI, "Electromagnetic compatibility and Radio spectrum
Matters (ERM); Short Range Devices; Smart Metering
Wireless Access Protocol; Part 2: Data Link Layer (MAC
Sub-layer)", ETSI TS 102 887-2, Version V1.1.1, September
2013.
[etsi_ref1]
ETSI, "Short Range Devices (SRD) operating in the
frequency range 25 MHz to 1 000 MHz; Part 1: Technical
characteristics and methods of measurement", Draft ETSI
EN 300-220-1, Version V3.1.0, May 2016.
[etsi_ref2]
ETSI, "Short Range Devices (SRD) operating in the
frequency range 25 MHz to 1 000 MHz; Part 2: Harmonised
Standard covering the essential requirements of article
3.2 of Directive 2014/53/EU for non specific radio
equipment", Final draft ETSI EN 300-220-2 P300-220-2,
Version V3.1.1, November 2016.
[etsi_unb]
ETSI ERM, "System Reference document (SRdoc); Short Range
Devices (SRD); Technical characteristics for Ultra Narrow
Band (UNB) SRDs operating in the UHF spectrum below 1
GHz", ETSI TR 103 435, Version V1.1.1, February 2017.
[EUI64] IEEE, "Guidelines for 64-bit Global Identifier
(EUI),Organizationally Unique Identifier (OUI), and
Company ID (CID)", August 2017,
<http://standards.ieee.org/develop/regauth/tut/eui.pdf>.
[FANOV] IETF, "Wi-SUN Alliance Field Area Network (FAN) Overview",
IETF 97, November 2016,
<https://www.ietf.org/proceedings/97/slides/
slides-97-lpwan-35-wi-sun-presentation-00.pdf>.
[fcc_ref] "Telecommunication Radio Frequency Devices - Operation
within the bands 902-928 MHz, 2400-2483.5 MHz, and
5725-5850 MHz.", FCC CFR 47 15.247, June 2016.
[G9959] ITU-T, "Short range narrow-band digital radiocommunication
transceivers - PHY, MAC, SAR and LLC layer
specifications", ITU-T Recommendation G.9959, January
2015, <http://www.itu.int/rec/T-REC-G.9959>.
[IEEE.802.11]
IEEE, "IEEE Standard for Information technology--
Telecommunications and information exchange between
systems Local and metropolitan area networks--Specific
requirements Part 11: Wireless LAN Medium Access Control
(MAC) and Physical Layer (PHY) Specifications",
IEEE 802.11.
[IEEE.802.15.12]
IEEE, "Upper Layer Interface (ULI) for IEEE 802.15.4 Low-
Rate Wireless Networks", IEEE 802.15.12.
[IEEE.802.15.4]
IEEE, "IEEE Standard for Low-Rate Wireless Networks",
IEEE 802.15.4, <https://standards.ieee.org/findstds/
standard/802.15.4-2015.html>.
[IEEE.802.15.4e]
IEEE, "IEEE Standard for Local and metropolitan area
networks--Part 15.4: Low-Rate Wireless Personal Area
Networks (LR-WPANs) Amendment 1: MAC sublayer",
IEEE 802.15.4e.
[IEEE.802.15.4g]
IEEE, "IEEE Standard for Local and metropolitan area
networks--Part 15.4: Low-Rate Wireless Personal Area
Networks (LR-WPANs) Amendment 3: Physical Layer (PHY)
Specifications for Low-Data-Rate, Wireless, Smart Metering
Utility Networks", IEEE 802.15.4g.
[IEEE.802.15.9]
IEEE, "IEEE Recommended Practice for Transport of Key
Management Protocol (KMP) Datagrams", IEEE Standard
802.15.9, 2016, <https://standards.ieee.org/findstds/
standard/802.15.9-2016.html>.
[IEEE.802.1AR]
ANSI/IEEE, "IEEE Standard for Local and metropolitan area
networks - Secure Device Identity", IEEE 802.1AR.
[IEEE.802.1x]
IEEE, "Port Based Network Access Control", IEEE 802.1x.
[LoRaSpec]
LoRa Alliance, "LoRaWAN Specification Version V1.0.2",
July 2016, <http://portal.lora-
alliance.org/DesktopModules/Inventures_Document/
FileDownload.aspx?ContentID=1398>. <https://lora-alliance.org/sites/default/
files/2018-05/lorawan1_0_2-20161012_1398_1.pdf>.
[LoRaWAN] Farrell, S. and A. Yegin, "LoRaWAN Overview", Work in
Progress, draft-farrell-lpwan-lora-overview-01, October
2016.
[LoRaWAN-AUTH]
Garcia, D., Marin, R., Kandasamy, A., and A. Pelov,
"LoRaWAN Authentication in Diameter", Work in Progress,
draft-garcia-dime-diameter-lorawan-00, May 2016.
[LoRaWAN-RADIUS]
Garcia, D., Lopez, R., Kandasamy, A., and A. Pelov,
"LoRaWAN Authentication in RADIUS", Work in Progress,
draft-garcia-radext-radius-lorawan-03, May 2017.
[LPWAN-GAP]
Minaburo, A., Ed., Gomez, C., Ed., Toutain, L., Paradells,
J., and J. Crowcroft, "LPWAN Survey and GAP Analysis",
Work in Progress, draft-minaburo-lpwan-gap-analysis-02,
October 2016.
[NB-IoT] Ratilainen, A., "NB-IoT characteristics", Work in
Progress, draft-ratilainen-lpwan-nb-iot-00, July 2016.
[nbiot-ov]
IEEE, "NB-IoT Technology Overview and Experience from
Cloud-RAN Implementation", Volume 24, Issue 3 Pages 26-32,
DOI 10.1109/MWC.2017.1600418, June 2017.
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
DOI 10.17487/RFC0768, August 1980,
<https://www.rfc-editor.org/info/rfc768>.
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
RFC 793, DOI 10.17487/RFC0793, September 1981,
<https://www.rfc-editor.org/info/rfc793>.
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
November 1987, <https://www.rfc-editor.org/info/rfc1035>.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
December 1998, <https://www.rfc-editor.org/info/rfc2460>.
[RFC2904] Vollbrecht, J., Calhoun, P., Farrell, S., Gommans, L.,
Gross, G., de Bruijn, B., de Laat, C., Holdrege, M., and
D. Spence, "AAA Authorization Framework", RFC 2904,
DOI 10.17487/RFC2904, August 2000,
<https://www.rfc-editor.org/info/rfc2904>.
[RFC3095] Bormann, C., Burmeister, C., Degermark, M., Fukushima, H.,
Hannu, H., Jonsson, L-E., Hakenberg, R., Koren, T., Le,
K., Liu, Z., Martensson, A., Miyazaki, A., Svanbro, K.,
Wiebke, T., Yoshimura, T., and H. Zheng, "RObust Header
Compression (ROHC): Framework and four profiles: RTP, UDP,
ESP, and uncompressed", RFC 3095, DOI 10.17487/RFC3095,
July 2001, <https://www.rfc-editor.org/info/rfc3095>.
[RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
C., and M. Carney, "Dynamic Host Configuration Protocol
for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
2003, <https://www.rfc-editor.org/info/rfc3315>.
[RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P.
Thubert, "Network Mobility (NEMO) Basic Support Protocol",
RFC 3963, DOI 10.17487/RFC3963, January 2005,
<https://www.rfc-editor.org/info/rfc3963>.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
December 2005, <https://www.rfc-editor.org/info/rfc4301>.
[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
Control Message Protocol (ICMPv6) for the Internet
Protocol Version 6 (IPv6) Specification", STD 89,
RFC 4443, DOI 10.17487/RFC4443, March 2006,
<https://www.rfc-editor.org/info/rfc4443>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc4861>.
[RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
"Transmission of IPv6 Packets over IEEE 802.15.4
Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,
<https://www.rfc-editor.org/info/rfc4944>.
[RFC5216] Simon, D., Aboba, B., and R. Hurst, "The EAP-TLS
Authentication Protocol", RFC 5216, DOI 10.17487/RFC5216,
March 2008, <https://www.rfc-editor.org/info/rfc5216>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
<https://www.rfc-editor.org/info/rfc5246>.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<https://www.rfc-editor.org/info/rfc5280>.
[RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
DOI 10.17487/RFC6282, September 2011,
<https://www.rfc-editor.org/info/rfc6282>.
[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
Bormann, "Neighbor Discovery Optimization for IPv6 over
Low-Power Wireless Personal Area Networks (6LoWPANs)",
RFC 6775, DOI 10.17487/RFC6775, November 2012,
<https://www.rfc-editor.org/info/rfc6775>.
[RFC6961] Pettersen, Y., "The Transport Layer Security (TLS)
Multiple Certificate Status Request Extension", RFC 6961,
DOI 10.17487/RFC6961, June 2013,
<https://www.rfc-editor.org/info/rfc6961>.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252,
DOI 10.17487/RFC7252, June 2014,
<https://www.rfc-editor.org/info/rfc7252>.
[RFC7452] Tschofenig, H., Arkko, J., Thaler, D., and D. McPherson,
"Architectural Considerations in Smart Object Networking",
RFC 7452, DOI 10.17487/RFC7452, March 2015,
<https://www.rfc-editor.org/info/rfc7452>.
[RFC7668] Nieminen, J., Savolainen, T., Isomaki, M., Patil, B.,
Shelby, Z., and C. Gomez, "IPv6 over BLUETOOTH(R) Low
Energy", RFC 7668, DOI 10.17487/RFC7668, October 2015,
<https://www.rfc-editor.org/info/rfc7668>.
[RFC8065] Thaler, D., "Privacy Considerations for IPv6 Adaptation-
Layer Mechanisms", RFC 8065, DOI 10.17487/RFC8065,
February 2017, <https://www.rfc-editor.org/info/rfc8065>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
[RFC8240] Tschofenig, H. and S. Farrell, "Report from the Internet
of Things Software Update (IoTSU) Workshop 2016",
RFC 8240, DOI 10.17487/RFC8240, September 2017,
<https://www.rfc-editor.org/info/rfc8240>.
[Sigfox] Zuniga, J. and B. PONSARD, "Sigfox System Description",
Work in Progress, draft-zuniga-lpwan-sigfox-system-
description-04,
draft-zuniga-lpwan-sigfox-system-description-04, December
2017.
[TGPP23720]
3GPP, "Study on architecture enhancements for Cellular
Internet of Things", 3GPP TS 23.720 13.0.0, 2016.
[TGPP33203]
3GPP, "3G security; Access security for IP-based
services", 3GPP TS 23.203 13.1.0, 2016.
[TGPP36201]
3GPP, "Evolved Universal Terrestrial Radio Access
(E-UTRA); LTE physical layer; General description", 3GPP
TS 36.201 13.2.0, 2016.
[TGPP36300]
3GPP, "Evolved Universal Terrestrial Radio Access (E-UTRA)
and Evolved Universal Terrestrial Radio Access Network
(E-UTRAN); Overall description; Stage 2", 3GPP TS 36.300
13.4.0, 2016,
<http://www.3gpp.org/ftp/Specs/2016-09/Rel-14/36_series/>.
[TGPP36321]
3GPP, "Evolved Universal Terrestrial Radio Access
(E-UTRA); Medium Access Control (MAC) protocol
specification", 3GPP TS 36.321 13.2.0, 2016.
[TGPP36322]
3GPP, "Evolved Universal Terrestrial Radio Access
(E-UTRA); Radio Link Control (RLC) protocol
specification", 3GPP TS 36.322 13.2.0, 2016.
[TGPP36323]
3GPP, "Evolved Universal Terrestrial Radio Access
(E-UTRA); Packet Data Convergence Protocol (PDCP)
specification (Not yet available)", 3GPP TS 36.323 13.2.0,
2016.
[TGPP36331]
3GPP, "Evolved Universal Terrestrial Radio Access
(E-UTRA); Radio Resource Control (RRC); Protocol
specification", 3GPP TS 36.331 13.2.0, 2016.
[USES-6LO]
Hong, Y., Gomez, C., Choi, Y-H., and D-Y. Ko, "IPv6 over
Constrained Node Networks(6lo) Applicability & Use cases",
Work in Progress, draft-hong-6lo-use-cases-03, October
2016.
[wisun-pressie1]
Beecher, P., "Wi-SUN Alliance", March 2017,
<http://indiasmartgrid.org/event2017/10-03-2017/4.%20Round
table%20on%20Communication%20and%20Cyber%20Security/1.%20P
hil%20Beecher.pdf>.
[wisun-pressie2]
Heile, B., "Wi-SUN Alliance Field Area Network
(FAN)Overview", As presented at IETF 97, November 2016,
<https://www.ietf.org/proceedings/97/slides/
slides-97-lpwan-35-wi-sun-presentation-00.pdf>.
Acknowledgments
Thanks to all those listed in the Contributors section for the
excellent text. Errors in the handling of that are solely the
editor's fault.
In addition to those in the Contributors section, thanks are due to
(in alphabetical order) the following for comments:
Abdussalam Baryun
Andy Malis
Arun (arun@acklio.com)
Behcet SariKaya
Dan Garcia Carrillo
Jiazi Yi
Mirja Kuhlewind
Paul Duffy
Russ Housley
Samita Chakrabarti
Thad Guidry
Warren Kumari
Alexander Pelov and Pascal Thubert were the LPWAN WG Chairs while
this document was developed.
Stephen Farrell's work on this memo was supported by Pervasive
Nation, the Science Foundation Ireland's CONNECT centre national IoT
network <https://connectcentre.ie/pervasive-nation/>.
Contributors
As stated above, this document is mainly a collection of content
developed by the full set of contributors listed below. The main
input documents and their authors were:
o Text for Section 2.1 was provided by Alper Yegin and Stephen
Farrell in [LoRaWAN].
o Text for Section 2.2 was provided by Antti Ratilainen in [NB-IoT].
o Text for Section 2.3 was provided by Juan Carlos Zuniga and Benoit
Ponsard in [Sigfox].
o Text for Section 2.4 was provided via personal communication from
Bob Heile and was authored by Bob and Sum Chin Sean. There is no
Internet-Draft for that at the time of writing.
o Text for Section 4 was provided by Ana Minabiru, Carles Gomez,
Laurent Toutain, Josep Paradells, and Jon Crowcroft in
[LPWAN-GAP]. Additional text from that document is also used
elsewhere above.
The full list of contributors is as follows:
Jon Crowcroft
University of Cambridge
JJ Thomson Avenue
Cambridge, CB3 0FD
United Kingdom
Email: jon.crowcroft@cl.cam.ac.uk
Carles Gomez
UPC/i2CAT
C/Esteve Terradas, 7
Castelldefels 08860
Spain
Email: carlesgo@entel.upc.edu
Bob Heile
Wi-Sun Alliance
11 Robert Toner Blvd, Suite 5-301
North Attleboro, MA 02763
United States of America
Phone: +1-781-929-4832
Email: bheile@ieee.org
Ana Minaburo
Acklio
2bis rue de la Chataigneraie
35510 Cesson-Sevigne Cedex
France
Email: ana@ackl.io
Josep PAradells
UPC/i2CAT
C/Jordi Girona, 1-3
Barcelona 08034
Spain
Email: josep.paradells@entel.upc.edu
Charles E. Perkins
Futurewei
2330 Central Expressway
Santa Clara, CA 95050
United States of America
Email: charliep@computer.org
Benoit Ponsard
Sigfox
425 rue Jean Rostand
Labege 31670
France
Email: Benoit.Ponsard@sigfox.com
URI: http://www.sigfox.com/
Antti Ratilainen
Ericsson
Hirsalantie 11
Jorvas 02420
Finland
Email: antti.ratilainen@ericsson.com
Chin-Sean SUM
Wi-Sun Alliance
20, Science Park Rd 117674
Singapore
Phone: +65 6771 1011
Email: sum@wi-sun.org
Laurent Toutain
Institut MINES TELECOM ; TELECOM Bretagne
2 rue de la Chataigneraie
CS 17607
35576 Cesson-Sevigne Cedex
France
Email: Laurent.Toutain@telecom-bretagne.eu
Alper Yegin
Actility
Paris
France
Email: alper.yegin@actility.com
Juan Carlos Zuniga
Sigfox
425 rue Jean Rostand
Labege 31670
France
Email: JuanCarlos.Zuniga@sigfox.com
URI: http://www.sigfox.com/
Author's Address
Stephen Farrell (editor)
Trinity College Dublin
Dublin 2
Ireland
Phone: +353-1-896-2354
Email: stephen.farrell@cs.tcd.ie