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lpwan Working Group                                           JC. Zuniga
Internet-Draft                                                    SIGFOX
Intended status: Informational                                  C. Gomez
Expires: May 3, 2018                Universitat Politecnica de Catalunya
                                                              L. Toutain
                                                          IMT-Atlantique
                                                        October 30, 2017


                         SCHC over Sigfox LPWAN
                 draft-zuniga-lpwan-schc-over-sigfox-00

Abstract

   The Static Context Header Compression (SCHC) specification describes
   a header compression scheme and fragmentation functionality for LPWAN
   (Low Power Wide Area Network) technologies.  SCHC offers a great
   level of flexibility that can be tailored for different LPWAN
   technologies.

   The present document provides the optimal parameters and modes of
   operation when SCHC is implemented over a Sigfox LPWAN.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 3, 2018.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of



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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Static Context Header Compression . . . . . . . . . . . . . .   3
     3.1.  SCHC Rules  . . . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  Packet processing . . . . . . . . . . . . . . . . . . . .   4
   4.  Fragmentation . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Fragmantation headers . . . . . . . . . . . . . . . . . .   4
     4.2.  Uplink fragment transmission  . . . . . . . . . . . . . .   4
     4.3.  Downlink fragment transmission  . . . . . . . . . . . . .   4
   5.  Security considerations . . . . . . . . . . . . . . . . . . .   5
   6.  Informative References  . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   The Static Context Header Compression (SCHC) specification
   [I-D.ietf-lpwan-ipv6-static-context-hc] defines a header compression
   scheme and fragmentation functionality that can be used on top of all
   the LWPAN systems defined in [I-D.ietf-lpwan-overview].  These LPWAN
   systems have similar characteristics such as star-oriented
   topologies, network architecture, connected devices with built-in
   applications, etc.

   SCHC offers a great level of flexibility to accomodate all these
   LPWAN systems.  Even though there are a great number of similarities
   between LPWAN technologies, some slight differences exist with
   respect to the tranmission characteristics, payload sizes, etc.
   Hence, there are optimal parameters and modes of operation that can
   be used when SCHC is used on top of a specific LPWAN.

   This document describes the optimal parameters and modes of operation
   when SCHC is implemented over a Sigfox LPWAN.

2.  Terminology

   The reader is assumed to be familiar with the terms and mechanisms
   defined in [I-D.ietf-lpwan-overview] and in
   [I-D.ietf-lpwan-ipv6-static-context-hc].




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3.  Static Context Header Compression

   Static Context Header Compression (SCHC) avoids context
   synchronization because data flows are highly predictable in LPWAN
   networks.  Contexts must be stored in both ends, and they can be
   learned by a provisioning protocol, by out of band means, or they can
   be pre-provisioned.  The way the context is learned on both sides is
   out of the scope of this document.

        Dev                                                 App
   +--------------+                                  +--------------+
   |APP1 APP2 APP3|                                  |APP1 APP2 APP3|
   |              |                                  |              |
   |      UDP     |                                  |     UDP      |
   |     IPv6     |                                  |    IPv6      |
   |              |                                  |              |
   |   SCHC C/D   |                                  |              |
   |   (context)  |                                  |              |
   +-------+------+                                  +-------+------+
            |   +--+     +----+     +---------+              .
            +~~ |RG| === |NGW | === |SCHC C/D |... Internet ..
                +--+     +----+     |(context)|
                                    +---------+

                          Figure 1: Architecture

   Figure 1 represents the architecture for compression/decompression
   and fragmentation, which is based on [I-D.ietf-lpwan-overview]
   terminology.

   The Device is sending applications flows that are compressed (and/or
   fragmented) by a Static Context Header Compression Compressor/
   Decompressor (SCHC C/D) to reduce headers size and/or fragment the
   packet.  The resulting information is sent to a layer two (L2) frame
   to a LPWAN Radio Network (RG) which forwards the frame to a Network
   Gateway (NGW).

   The NGW sends the data to an SCHC C/D for decompression (and/or
   reassembly) which shares the same rules with the Dev.  The SCHC C/D
   can be located on the Network Gateway (NGW) or in another place as
   long as a tunnel is established between the NGW and the SCHC C/D.
   The SCHC C/D in both sides must share the same set of Rules.  After
   decompression (and/or reassembly), the packet can be forwarded to one
   or several LPWAN Application Servers (App).

   The SCHC C/D process is bidirectional, so the same principles can be
   applied in both uplink and downlink.




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3.1.  SCHC Rules

   TBD

3.2.  Packet processing

   TBD

4.  Fragmentation

   The SCHC specification [I-D.ietf-lpwan-ipv6-static-context-hc]
   supports several modes of operation to fragment packets.  These modes
   have different advantages and disadvantages depending on the specific
   of the underlying LPWAN technology.  This section describes how the
   SCHC fragmentation functionality SHOULD optimally be used over a
   Sigfox LPWAN.

4.1.  Fragmantation headers

   A list of fragmentation header fields, their sizes and related
   details for SCHC fragmentation over Sigfox are provided below:

   TBD

4.2.  Uplink fragment transmission

   TBD

4.3.  Downlink fragment transmission

   In some LPWAN technologies, as part of energy-saving techniques,
   downlink transmission is only possible immediately after an uplink
   transmission.  This allows the device to go in a very deep sleep mode
   and preserve battery, without the need to listen to any information
   from the network.  This is the case for Sigfox devices, which can
   only listen to downlink communications after performing an uplink
   transmission.

   When there are multiple fragments to be transmitted in the downlink,
   an uplink message is required to trigger the downlink communication.
   In order to avoid potentially high delay for fragmented datagram
   transmission in the downlink, the fragment receiver MAY perform an
   uplink transmission as soon as possible after reception of a fragment
   that is not the last one.  Such uplink transmission may be triggered
   by sending a SCHC message, such as an ACK.






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5.  Security considerations

   TBD

6.  Informative References

   [I-D.ietf-lpwan-ipv6-static-context-hc]
              Minaburo, A., Toutain, L., and C. Gomez, "LPWAN Static
              Context Header Compression (SCHC) and fragmentation for
              IPv6 and UDP", draft-ietf-lpwan-ipv6-static-context-hc-07
              (work in progress), October 2017.

   [I-D.ietf-lpwan-overview]
              Farrell, S., "LPWAN Overview", draft-ietf-lpwan-
              overview-07 (work in progress), October 2017.

Authors' Addresses

   Juan Carlos Zuniga
   SIGFOX
   425 rue Jean Rostand
   Labege  31670
   France

   Email: JuanCarlos.Zuniga@sigfox.com
   URI:   http://www.sigfox.com/


   Carles Gomez
   Universitat Politecnica de Catalunya
   C/Esteve Terradas, 7
   08860 Castelldefels
   Spain

   Email: carlesgo@entel.upc.edu


   Laurent Toutain
   IMT-Atlantique
   2 rue de la Chataigneraie
   CS 17607
   35576 Cesson-Sevigne Cedex
   France

   Email: Laurent.Toutain@imt-atlantique.fr






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