< draft-ietf-lpwan-schc-compound-ack-02.txt		draft-ietf-lpwan-schc-compound-ack-03.txt >
	lpwan Working Group JC. Zuniga		lpwan Working Group JC. Zuniga
	Internet-Draft SIGFOX		Internet-Draft SIGFOX
	Intended status: Standards Track C. Gomez		Intended status: Standards Track C. Gomez
	Expires: 13 June 2022 S. Aguilar		Expires: 12 August 2022 S. Aguilar
	Universitat Politècnica de Catalunya		Universitat Politècnica de Catalunya
	L. Toutain		L. Toutain
	IMT-Atlantique		IMT-Atlantique
	S. Céspedes		S. Céspedes
	D. Wistuba		D. Wistuba
	NIC Labs, Universidad de Chile		NIC Labs, Universidad de Chile
	10 December 2021		8 February 2022
	SCHC Compound ACK		SCHC Compound ACK
	draft-ietf-lpwan-schc-compound-ack-02		draft-ietf-lpwan-schc-compound-ack-03
	Abstract		Abstract
	The present document describes an extension to the SCHC (Static		The present document describes an extension to the SCHC (Static
	Header Compression and Fragmentation) protocol [RFC8724]. It defines		Context Header Compression and fragmentation) protocol [RFC8724]. It
	a SCHC Compound ACK message format, which is intended to reduce the		defines a SCHC Compound ACK message format, which is intended to
	number of downlink transmissions (i.e., SCHC ACKs) by accumulating		reduce the number of response transmissions (i.e., SCHC ACKs) by
	bitmaps of several windows in a single SCHC message (i.e., the SCHC		accumulating bitmaps of several windows in a single SCHC message
	Compound ACK).		(i.e., the SCHC Compound ACK).
	The message format is generic, and can be used, for instance, by any		The message format is generic, and can be used, for instance, by any
	of the four LWPAN technologies defined in [RFC8376], being Sigfox,		of the four LWPAN technologies defined in [RFC8376], being Sigfox,
	LoRaWAN, NB-IoT and IEEE 802.15.4w.		LoRaWAN, NB-IoT and IEEE 802.15.4w.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on 13 June 2022.		This Internet-Draft will expire on 12 August 2022.
	Copyright Notice		Copyright Notice
	Copyright (c) 2021 IETF Trust and the persons identified as the		Copyright (c) 2022 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents (https://trustee.ietf.org/		Provisions Relating to IETF Documents (https://trustee.ietf.org/
	license-info) in effect on the date of publication of this document.		license-info) in effect on the date of publication of this document.
	Please review these documents carefully, as they describe your rights		Please review these documents carefully, as they describe your rights
	and restrictions with respect to this document. Code Components		and restrictions with respect to this document. Code Components
	extracted from this document must include Revised BSD License text as		extracted from this document must include Revised BSD License text as
	described in Section 4.e of the Trust Legal Provisions and are		described in Section 4.e of the Trust Legal Provisions and are
	provided without warranty as described in the Revised BSD License.		provided without warranty as described in the Revised BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
	3. SCHC Compound ACK . . . . . . . . . . . . . . . . . . . . . . 3		3. SCHC Compound ACK . . . . . . . . . . . . . . . . . . . . . . 3
	3.1. SCHC Compound ACK Message Format . . . . . . . . . . . . 3		3.1. SCHC Compound ACK Message Format . . . . . . . . . . . . 4
	3.2. SCHC Compound ACK Behaviour . . . . . . . . . . . . . . . 4		3.2. SCHC Compound ACK Behaviour . . . . . . . . . . . . . . . 5
	3.2.1. Sender Behaviour . . . . . . . . . . . . . . . . . . 5		3.2.1. Sender Behaviour . . . . . . . . . . . . . . . . . . 5
	3.2.2. Receiver Behaviour . . . . . . . . . . . . . . . . . 5		3.2.2. Receiver Behaviour . . . . . . . . . . . . . . . . . 6
	3.3. SCHC Compound ACK Examples . . . . . . . . . . . . . . . 5		3.3. SCHC Compound ACK Examples . . . . . . . . . . . . . . . 6
	3.4. SCHC Compound ACK YANG Data Model . . . . . . . . . . . . 6		3.4. SCHC Compound ACK YANG Data Model . . . . . . . . . . . . 7
	3.4.1. SCHC YANG Data Model Extension . . . . . . . . . . . 6		3.4.1. SCHC YANG Data Model Extension . . . . . . . . . . . 7
	3.4.2. SCHC YANG Tree Extension . . . . . . . . . . . . . . 9		3.4.2. SCHC YANG Tree Extension . . . . . . . . . . . . . . 10
	4. SCHC Compound ACK Parameters . . . . . . . . . . . . . . . . 9		4. SCHC Compound ACK Parameters . . . . . . . . . . . . . . . . 10
	5. Security considerations . . . . . . . . . . . . . . . . . . . 9		5. Security considerations . . . . . . . . . . . . . . . . . . . 10
	6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9		6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
	7. Normative References . . . . . . . . . . . . . . . . . . . . 10		7. Normative References . . . . . . . . . . . . . . . . . . . . 11
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
	1. Introduction		1. Introduction
	The Generic Framework for Static Context Header Compression and		The Generic Framework for Static Context Header Compression and
	Fragmentation (SCHC) specification [RFC8724] describes two		Fragmentation (SCHC) specification [RFC8724] describes two
	mechanisms: i) a protocol header compression scheme, and ii) a frame		mechanisms: i) a protocol header compression scheme, and ii) a frame
	fragmentation and loss recovery functionality. Either can be used on		fragmentation and loss recovery functionality. Either can be used on
	top of radio technologies such as the four LWPAN defined in		top of radio technologies such as the four LWPAN defined in
	[RFC8376], being Sigfox, LoRaWAN, NB-IoT and IEEE 802.15.4w. These		[RFC8376], being Sigfox, LoRaWAN, NB-IoT and IEEE 802.15.4w. These
	LPWANs have similar characteristics such as star-oriented topologies,		LPWANs have similar characteristics such as star-oriented topologies,
	network architecture, connected devices with built-in applications,		network architecture, connected devices with built-in applications,
	etc.		etc.
	SCHC offers a great level of flexibility to accommodate all these		SCHC offers a great level of flexibility to accommodate all these
	LPWAN technologies. Even though there are a great number of		LPWAN technologies. Even though there are a great number of
	similarities between them, some differences exist with respect to the		similarities between them, some differences exist with respect to the
	transmission characteristics, payload sizes, etc. Hence, there are		transmission characteristics, payload sizes, etc. Hence, there are
	optimal parameters and modes of operation that can be used when SCHC		optimal parameters and modes of operation that can be used when SCHC
	is used on top of a specific LPWAN technology.		is used on top of a specific LPWAN technology.
	The present document describes an extension to the SCHC protocol. It		The present document describes an extension to the SCHC protocol for
	defines a SCHC Compound ACK format, which is intended to reduce the		frame fragmentation and loss recovery. It defines a SCHC Compound
	number of downlink transmissions (i.e., SCHC ACKs) in the ACK-on-		ACK format, which is intended to reduce the number of response
	Error mode of SCHC. The SCHC Compound ACK extends the SCHC ACK		transmissions (i.e., SCHC ACKs) in the ACK-on-Error mode of SCHC.
	message format so that it can contain several bitmaps, each bitmap		The SCHC Compound ACK extends the SCHC ACK message format so that it
	being identified by its corresponding window number.		can contain several bitmaps, each bitmap being identified by its
			corresponding window number.
	The SCHC Compound ACK:		The SCHC Compound ACK:
	* provides feedback only for windows with fragment losses,		* provides feedback only for windows with fragment losses,
	* has a variable size that depends on the number of windows with		* has a variable size that depends on the number of windows with
	fragment losses being reported in the single Compound SCHC ACK,		fragment losses being reported in the single Compound SCHC ACK,
	* includes the window number (i.e., W) of each bitmap,		* includes the window number (i.e., W) of each bitmap,
	skipping to change at page 4, line 12 ¶		skipping to change at page 4, line 17 ¶
	Figure 1 shows the regular SCHC ACK format when all fragments have		Figure 1 shows the regular SCHC ACK format when all fragments have
	been correctly received (C=1), as defined in [RFC8724].		been correctly received (C=1), as defined in [RFC8724].
	|- SCHC ACK Header --|		|- SCHC ACK Header --|
	+ -------+---+------ + ------------ +		+ -------+---+------ + ------------ +
	| RuleID | W | C=b'1 | b'0-pad(opt) |		| RuleID | W | C=b'1 | b'0-pad(opt) |
	+ ------ + - + ----- + ------------ +		+ ------ + - + ----- + ------------ +
	Figure 1: SCHC Success ACK message format, as defined in RFC8724		Figure 1: SCHC Success ACK message format, as defined in RFC8724
	In case SCHC fragment losses are found in any of the windows of the		In case SCHC Fragment losses are found in any of the windows of the
	SCHC Packet, the SCHC Compound ACK MAY be used. The SCHC Compound		SCHC Packet, the SCHC Compound ACK MAY be used. The SCHC Compound
	ACK message format is shown in Figure 2.		ACK message format is shown in Figure 2.
	The window numbered 00, if present in the SCHC Compound ACK, MUST be		The window numbered 00, if present in the SCHC Compound ACK, MUST be
	placed between the Rule ID and the C bit to avoid confusion with		placed between the Rule ID and the C bit to avoid confusion with
	padding bits.		padding bits.
	|--SCHC ACK Header--| W = w1 |...| W = wi |		|--SCHC ACK Header--| W = w1 |...| W = wi |
	+-------------------+ ------ +...+ ------- + ------ +------------+		+-------------------+ ------ +...+ ------- + ------ +------------+
	|RuleID|W=b'w1|C=b'0| Bitmap |...| W=b'wi | Bitmap |b'0-pad(opt)|		|RuleID|W=b'w1|C=b'0| Bitmap |...| W=b'wi | Bitmap |b'0-pad(opt)|
	skipping to change at page 4, line 49 ¶		skipping to change at page 5, line 7 ¶
	whole SCHC Compound ACK message.		whole SCHC Compound ACK message.
	Each different SCHC LPWAN technology profile MUST specify how the		Each different SCHC LPWAN technology profile MUST specify how the
	SCHC Compound ACK is different from the Receiver-Abort message as per		SCHC Compound ACK is different from the Receiver-Abort message as per
	[RFC8724], e.g., the Receiver-Abort message is padded with 1s with an		[RFC8724], e.g., the Receiver-Abort message is padded with 1s with an
	extra byte appended at the end, while the SCHC Compound ACK is		extra byte appended at the end, while the SCHC Compound ACK is
	0-padded.		0-padded.
	3.2. SCHC Compound ACK Behaviour		3.2. SCHC Compound ACK Behaviour
	Besides the ACK-on-Error behaviour described in section 8.4.3 of		The SCHC ACK-on-Error behaviour is described in section 8.4.3 of
	[RFC8724], when implementing the SCHC Compound ACK the following		[RFC8724]. The present document slightly modifies this behaviour,
	applies:		since in the baseline SCHC specification a SCHC ACK reports only one
			bitmap for the reception of exactly one window of tiles. The present
			SCHC Compound ACK specification extends the SCHC ACK message format
			so that it can contain several bitmaps, each bitmap being identified
			by its corresponding window number.
			The following sections describe the differences between the baseline
			SCHC specification and the present SCHC protocol extension
			specification.
	3.2.1. Sender Behaviour		3.2.1. Sender Behaviour
	On receiving a SCHC Compound ACK:		OLD TEXT ([RFC8724], section 8.4.3.1) - On receiving a SCHC ACK:
	* The fragment sender MUST resend SCHC Fragment messages containing		* (...)
			* the fragment sender MUST send SCHC Fragment messages containing
			all the tiles that are reported missing in the SCHC ACK.
			* if the last of these SCHC Fragment messages reported missing is
			not an All-1 SCHC Fragment, then the fragment sender MAY either,
			send in addition a SCHC ACK REQ with the W field corresponding to
			the last window, continue the transmission of the remaining
			fragments to be transmitted, or repeat the All-1 fragment to
			confirm that all fragments have been correctly received.
			NEW TEXT - On receiving a SCHC Compound ACK:
			* (...)
			* the fragment sender MUST resend SCHC Fragment messages containing
	all the tiles of all the windows that are reported missing in the		all the tiles of all the windows that are reported missing in the
	SCHC Compound ACK.		SCHC Compound ACK.
	* If the last of these SCHC Fragment messages reported missing is		* if the last of these SCHC Fragment messages reported missing is
	not an All-1 SCHC Fragment, then the fragment sender MAY either,		not an All-1 SCHC Fragment, then the fragment sender MAY either,
	send in addition a SCHC ACK REQ with the W field corresponding to		send in addition a SCHC ACK REQ with the W field corresponding to
	the last window, continue the transmission of the remaining		the last window, continue the transmission of the remaining
	fragments to be transmitted, or repeat the All-1 fragment to		fragments to be transmitted, or repeat the All-1 fragment to
	confirm that all fragments have been correctly received.		confirm that all fragments have been correctly received.
	3.2.2. Receiver Behaviour		3.2.2. Receiver Behaviour
	On receiving a SCHC ACK REQ:		OLD TEXT ([RFC8724], section 8.4.3.2) - On receiving a SCHC ACK REQ
			or an All-1 SCHC Fragment:
	* If the receiver knows of any windows with missing tiles for the		* if the receiver knows of any windows with missing tiles for the
	packet being reassembled, it MAY return a SCHC Compound ACK for		packet being reassembled, it MUST return a SCHC ACK for the
	the missing fragments, starting from the lowest-numbered window.		lowest-numbered such window.
	On receiving an All-1 SCHC Fragment:		NEW TEXT: On receiving an All-0 SCHC Fragment:
	* If the receiver knows of any windows with missing tiles for the		* if the receiver knows of any windows with missing tiles for the
			packet being reassembled (and if network conditions are known to
			be conducive), it MAY return a SCHC Compound ACK for the missing
			fragments, starting from the lowest-numbered window.
			NEW TEXT: On receiving a SCHC ACK REQ or an All-1 SCHC Fragment:
			* if the receiver knows of any windows with missing tiles for the
	packet being reassembled, it MUST return a SCHC Compound ACK for		packet being reassembled, it MUST return a SCHC Compound ACK for
	the missing fragments, starting from the lowest-numbered window.		the missing fragments, starting from the lowest-numbered window.
	3.3. SCHC Compound ACK Examples		3.3. SCHC Compound ACK Examples
	Figure 3 shows an example transmission of a SCHC Packet in ACK-on-		Figure 3 shows an example transmission of a SCHC Packet in ACK-on-
	Error mode using the SCHC Compound ACK. In the example, the SCHC		Error mode using the SCHC Compound ACK. In the example, the SCHC
	Packet is fragmented in 14 tiles, with N=3, WINDOW_SIZE=7, M=2 and		Packet is fragmented in 14 tiles, with N=3, WINDOW_SIZE=7, M=2 and
	two lost SCHC fragments. Only 1 compound SCHC ACK is generated.		two lost SCHC fragments. Only 1 compound SCHC ACK is generated.
	skipping to change at page 6, line 20 ¶		skipping to change at page 7, line 20 ¶
	|-----W=0, FCN=2 --X-->|		|-----W=0, FCN=2 --X-->|
	|-----W=0, FCN=1 ----->|		|-----W=0, FCN=1 ----->|
	|-----W=0, FCN=0 ----->| Bitmap: 1111011		|-----W=0, FCN=0 ----->| Bitmap: 1111011
	(no ACK)		(no ACK)
	|-----W=1, FCN=6 ----->|		|-----W=1, FCN=6 ----->|
	|-----W=1, FCN=5 ----->|		|-----W=1, FCN=5 ----->|
	|-----W=1, FCN=4 ----->|		|-----W=1, FCN=4 ----->|
	|-----W=1, FCN=3 ----->|		|-----W=1, FCN=3 ----->|
	|-----W=1, FCN=2 ----->|		|-----W=1, FCN=2 ----->|
	|-----W=1, FCN=1 --X-->|		|-----W=1, FCN=1 --X-->|
	|-- W=1, FCN=7 + RSC ->| Integrity check: failure		|-- W=1, FCN=7 + RCS ->| Integrity check: failure
	|<--- Compound ACK ----| [C=0, W=0 - Bitmap:1111011,		|<--- Compound ACK ----| [C=0, W=0 - Bitmap:1111011,
	|-----W=0, FCN=2 ----->| W=1 - Bitmap:1111101]		|-----W=0, FCN=2 ----->| W=1 - Bitmap:1111101]
	|-----W=1, FCN=1 ----->| Integrity check: success		|-----W=1, FCN=1 ----->| Integrity check: success
	|<--- ACK, W=1, C=1 ---| C=1		|<--- ACK, W=1, C=1 ---| C=1
	(End)		(End)
	Figure 3: SCHC Compound ACK message sequence example		Figure 3: SCHC Compound ACK message sequence example
	|-- SCHC ACK Header ---|- W=00 --|----- W=01 -----|		|-- SCHC ACK Header ---|- W=00 --|----- W=01 -----|
	+ -------------------- + ------- + ---- + ------- + ------------- +		+ -------------------- + ------- + ---- + ------- + ------------- +
	| RuleID | W=00 | C=0 | 1111011 | W=01 | 1111011 | b'0-pad (opt) |		| RuleID | W=00 | C=0 | 1111011 | W=01 | 1111101 | b'0-pad (opt) |
	+ ------ + ------ + -- + ------- + ---- + ------- + ------------- +		+ ------ + ------ + -- + ------- + ---- + ------- + ------------- +
	Figure 4: SCHC Compound ACK message format example: Losses are		Figure 4: SCHC Compound ACK message format example: Losses are
	found in windows 00 and 01		found in windows 00 and 01
	3.4. SCHC Compound ACK YANG Data Model		3.4. SCHC Compound ACK YANG Data Model
	The present document also extends the SCHC YANG data model defined in		The present document also extends the SCHC YANG data model defined in
	[I-D.ietf-lpwan-schc-yang-data-model] by including a new leaf in the		[I-D.ietf-lpwan-schc-yang-data-model] by including a new leaf in the
	Ack-on-Error fragmentation mode to describe both the option to use		Ack-on-Error fragmentation mode to describe both the option to use
	skipping to change at page 7, line 50 ¶		skipping to change at page 8, line 50 ¶
	they appear in all capitals, as shown here.		they appear in all capitals, as shown here.
	***************************************************************		***************************************************************
	This module extends the ietf-schc module to include the		This module extends the ietf-schc module to include the
	Compound ACK behavior for ACK-on-Error as defined in RFC YYYY.		Compound ACK behavior for ACK-on-Error as defined in RFC YYYY.
	It introduces a new leaf for ACK-on-Error defining the format		It introduces a new leaf for ACK-on-Error defining the format
	of the SCHC Compound ACK, adding the possibility to send		of the SCHC Compound ACK, adding the possibility to send
	several bitmaps in a single SCHC ACK message.";		several bitmaps in a single SCHC ACK message.";
	revision 2021-12-08 {		revision 2022-02-08 {
	description		description
	"Initial version for RFC YYYY ";		"Initial version for RFC YYYY ";
	reference		reference
	"RFC YYYY: SCHC Compound ACK";		"RFC YYYY: SCHC Compound ACK";
	}		}
	identity bitmap-format-base-type {		identity bitmap-format-base-type {
	description		description
	"Define how the bitmap is formed in ACK messages.";		"Define how the bitmap is formed in ACK messages.";
	}		}
	skipping to change at page 8, line 40 ¶		skipping to change at page 9, line 40 ¶
	description		description
	"type used in rules";		"type used in rules";
	}		}
	augment "/schc:schc/schc:rule/schc:nature/schc:fragmentation/schc:mode/schc:ack-on-error" {		augment "/schc:schc/schc:rule/schc:nature/schc:fragmentation/schc:mode/schc:ack-on-error" {
	leaf bitmap-format {		leaf bitmap-format {
	when "derived-from(../schc:fragmentation-mode, 'schc:fragmentation-mode-ack-on-error')";		when "derived-from(../schc:fragmentation-mode, 'schc:fragmentation-mode-ack-on-error')";
	type schc-compound-ack:bitmap-format-type;		type schc-compound-ack:bitmap-format-type;
	default "schc-compound-ack:bitmap-RFC8724";		default "schc-compound-ack:bitmap-RFC8724";
	description		description
	"How the bitmaps are included in the Ack message.";		"How the bitmaps are included in the SCHC ACK message.";
	}		}
			leaf last-bitmap-compression {
			when "derived-from(../schc:fragmentation-mode, 'schc:fragmentation-mode-ack-on-error')";
			type boolean;
			default true;
			description
			"when true ultimate bitmap in the SCHC ACK message can be compressed";
			}
	description		description
	"added to SCHC rules";		"added to SCHC rules";
	}		}
	}		}
	<CODE ENDS>		<CODE ENDS>
	Figure 5: SCHC YANG Data Model - Compound ACK extension		Figure 5: SCHC YANG Data Model - Compound ACK extension
	3.4.2. SCHC YANG Tree Extension		3.4.2. SCHC YANG Tree Extension
	skipping to change at page 9, line 35 ¶		skipping to change at page 10, line 42 ¶
	byte appended at the end, while the SCHC Compound ACK is 0-padded.		byte appended at the end, while the SCHC Compound ACK is 0-padded.
	5. Security considerations		5. Security considerations
	The current document specifies a message format extension for SCHC.		The current document specifies a message format extension for SCHC.
	Hence, the same Security Considerations defined in [RFC8724] apply.		Hence, the same Security Considerations defined in [RFC8724] apply.
	6. Acknowledgements		6. Acknowledgements
	Carles Gomez has been funded in part by the Spanish Government		Carles Gomez has been funded in part by the Spanish Government
	through the Jose Castillejo CAS15/00336 grant, the TEC2016-79988-P		through the TEC2016-79988-P grant, and the PID2019-106808RA-I00 grant
	grant, and the PID2019-106808RA-I00 grant, and by Secretaria		(funded by MCIN / AEI / 10.13039/501100011033), and by Secretaria
	d'Universitats i Recerca del Departament d'Empresa i Coneixement de		d'Universitats i Recerca del Departament d'Empresa i Coneixement de
	la Generalitat de Catalunya 2017 through grant SGR 376.		la Generalitat de Catalunya 2017 through grant SGR 376.
	Sergio Aguilar has been funded by the ERDF and the Spanish Government		Sergio Aguilar has been funded by the ERDF and the Spanish Government
	through project TEC2016-79988-P and project PID2019-106808RA-I00,		through project TEC2016-79988-P and project PID2019-106808RA-I00,
	AEI/FEDER, EU.		AEI/FEDER, EU (funded by MCIN / AEI / 10.13039/501100011033).
	Sandra Cespedes has been funded in part by the ANID Chile Project		Sandra Cespedes has been funded in part by the ANID Chile Project
	FONDECYT Regular 1201893 and Basal Project FB0008.		FONDECYT Regular 1201893 and Basal Project FB0008.
	Diego Wistuba has been funded by the ANID Chile Project FONDECYT		Diego Wistuba has been funded by the ANID Chile Project FONDECYT
	Regular 1201893.		Regular 1201893.
	The authors would like to thank Rafael Vidal, Julien Boite, Renaud		The authors would like to thank Rafael Vidal, Julien Boite, Renaud
	Marty, Antonis Platis, Dominique Barthel and Pascal Thubert for their		Marty, Antonis Platis, Dominique Barthel and Pascal Thubert for their
	very useful comments, reviews and implementation design		very useful comments, reviews and implementation design
	skipping to change at page 10, line 36 ¶		skipping to change at page 11, line 42 ¶
	DOI 10.17487/RFC8724, April 2020,		DOI 10.17487/RFC8724, April 2020,
	<https://www.rfc-editor.org/info/rfc8724>.		<https://www.rfc-editor.org/info/rfc8724>.
	Authors' Addresses		Authors' Addresses
	Juan Carlos Zúñiga		Juan Carlos Zúñiga
	SIGFOX		SIGFOX
	Montreal QC		Montreal QC
	Canada		Canada
	Email: JuanCarlos.Zuniga@sigfox.com		Email: j.c.zuniga@ieee.org
	URI: http://www.sigfox.com/
	Carles Gomez		Carles Gomez
	Universitat Politècnica de Catalunya		Universitat Politècnica de Catalunya
	C/Esteve Terradas, 7		C/Esteve Terradas, 7
	08860 Castelldefels		08860 Castelldefels
	Spain		Spain
	Email: carlesgo@entel.upc.edu		Email: carlesgo@entel.upc.edu
	Sergio Aguilar		Sergio Aguilar
	Universitat Politècnica de Catalunya		Universitat Politècnica de Catalunya
End of changes. 26 change blocks.
	50 lines changed or deleted		91 lines changed or added
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