Internet DRAFT - draft-authors-lpwan-schc-802154
draft-authors-lpwan-schc-802154
Internet Area J. Robert
Internet-Draft FAU Erlangen-Nuernberg
Intended status: Standards Track C. Perkins
Expires: January 17, 2019 Futurewei
July 16, 2018
SCHC for 802.15.4 lpwan applications
draft-authors-lpwan-schc-802154-00
Abstract
This document provides guidelines for creating Rules for Static
Context Header Compression for IEEE 802.15.4. Since 802.15.4
provides layer-2 acknowledgements, some complexities that were
designed for more general systems can be avoided.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. SCHC parameters . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Size of the Rule ID . . . . . . . . . . . . . . . . . . . 4
3.2. Use of Padding . . . . . . . . . . . . . . . . . . . . . 4
3.3. Fragmentation Delivery Reliability Option . . . . . . . . 4
3.4. MAX_ACK_REQUEST . . . . . . . . . . . . . . . . . . . . . 4
3.5. FCN . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.6. DTag . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.7. L2 CRC . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.8. Fragmentation ACK Parameters (not used) . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative References . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Static Context Header Compression (SCHC)
[I-D.ietf-lpwan-ipv6-static-context-hc] is a solution for header
compression, highly specialized for very predictable IPv6 packets to
and from an lpwan node with significant resource constraints
(especially power). This document provides guidelines for creating
Rules for Static Context Header Compression (SCHC) for IEEE 802.15.4
[dot4]. Since 802.15.4 provides layer-2 acknowledgements, some
complexities that were designed for more general systems can be
avoided.
The Low-Power, Wide-Area IEEE 802.15.4w task group (LPWA) has been
chartered to specify modifications to 802.15.4 MAC and PHY parameters
that would be needed to make the technology more suitable for lpwan
applications [lpwa_par], [lpwa_csd]. Although 801.15.4g [dot4g] and
802.15.4k [dot4k] were previously designed for such systems, recent
experiments and further experience with new use cases have indicated
the need for additional specification and wider applicability.
LPWA has listed different use-cases that may be relevant for LPWAN in
a study group document [lpwa_use_cases]. The LPWAN use-cases
discussed in that document are characterized as follows:
o Focusing on uplink data
o Typical Payload data length less than 16 bytes
o No strict latency requirements
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The LPWA also determined that it would be useful to produce a
document for the IETF lp-wan Working Group to suggest parameters for
the use cases. The discussion so far in LPWA has resulted in the
document [lpwa_schc].
|
+-----+
| | Gateway (default) router
| |
+-----+
|
|
+-----+
| | LPWA access point
| |
+-----+
o
o o o o
o o o o o
o o o o
o o o
LLN
Figure 1: Representative Architecture for 802.15.4w Use Cases
A typical 802.15.4w use case is illustrated in Figure 1. The header
compression context is statically configured for the transmission and
reception of packets between the LPWA access point and the individual
low-power devices (indicated as 'o'). Most of the rules follow the
recommended practice in [I-D.ietf-lpwan-ipv6-static-context-hc] for
compressing the IPv6 addresses and UDP ports; the same rulesets can
be used for the possibly thousands of low-power devices, only
changing the IPv6 address for the particular device relevant to the
context.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[RFC2119].
This document uses the following definitions:
LPWA
Low-Power Wide Area
PAN
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Personal Area Network
802.15.4w
Low-Power Wide Area (LPWA) task group within IEEE 802.15
3. SCHC parameters
In this section we provide details about parameter selection for a
static compression context to be used over 802.15.4, according to the
guidelines in [minaburo_email]. The method by which the context is
agreed upon by sender and receiver is left unspecified. For the
purposes of this document, the rule-ID, rule parameters, and other
uncompressed information is to be considered as a normal L2 payload
that will be decompressed before delivery to L3.
3.1. Size of the Rule ID
Size of the Rule ID should be 3, to allow for up to 8 rules.
3.2. Use of Padding
Pad to a multiple of 8 bits in the L2 payload.
3.3. Fragmentation Delivery Reliability Option
802.15.4 link acknowledgement should be used, since the static
context as defined should be decompressed after delivery over a
single link.
3.4. MAX_ACK_REQUEST
MAX_ACK_REQUEST SHOULD be set to 3, following usual practice in
802.15.4.
3.5. FCN
FCN SHOULD be set to 0, since unfragmented traffic is expected for
most use cases under consideration in 802.15.4w.
3.6. DTag
Similarly, DTag SHOULD be set to 0, since unfragmented traffic is
expected for most use cases under consideration in 802.15.4w.
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3.7. L2 CRC
Either CRC-16 or CRC-32 as defined in 802.15.4 could be used.
3.8. Fragmentation ACK Parameters (not used)
Since acknowledgments SHOULD be handled at Layer 2, no specification
is made here for the following:
o The timer duration for Fragmentation ACK Always
o When to abort in ACK Always
o MAX_ATTEMPTS counter size
o The timer size between windows in ACK On Error.
o The inactivity timer.
4. Security Considerations
This document does not introduce any security mechanisms, and does
not have affect existing security mechanisms or vulnerabilities
already present in the base SCHC document.
5. IANA Considerations
This document does not specify any IANA actions.
6. Acknowledgements
This document has benefitted from discussions with the following
people, in alphabetical order: Pat Kinney
7. References
7.1. Normative References
[I-D.ietf-lpwan-ipv6-static-context-hc]
Minaburo, A., Toutain, L., Gomez, C., and D. Barthel,
"LPWAN Static Context Header Compression (SCHC) and
fragmentation for IPv6 and UDP", draft-ietf-lpwan-ipv6-
static-context-hc-16 (work in progress), June 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
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7.2. Informative References
[dot4] P802.15, "Part 15: Wireless LAN Medium Access Control
(MAC) and Physical Layer (PHY) Specifications", March
2012.
[dot4g] P802.15, "Part 15: Wireless LAN Medium Access Control
(MAC) and Physical Layer (PHY) Specifications", March
2012.
[dot4k] P802.15, "Part 15: Wireless LAN Medium Access Control
(MAC) and Physical Layer (PHY) Specifications", March
2012.
[lpwa_csd]
P802.15, "Part 15: Wireless LAN Medium Access Control
(MAC) and Physical Layer (PHY) Specifications", March
2012.
[lpwa_par]
P802.15, "Part 15: Wireless LAN Medium Access Control
(MAC) and Physical Layer (PHY) Specifications", March
2012.
[lpwa_schc]
Joerg Robert, "Discussion on Suitable Parameters for
SCHC", May 2018.
[lpwa_use_cases]
Joerg Robert, "LPWA Use-Cases", Mar 2017.
[minaburo_email]
Ana Minaburo, "SCHC technology specific parameters", Feb
2018.
Authors' Addresses
Joerg Robert
Friedrich-Alexander Universitaet Erlangen-Nuernberg
Am Wolfsmantel 33
Erlangen 91058
Germany
Phone: +49-9131-85-25373
Email: joerg.robert@fau.de
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Charles E. Perkins
Futurewei Inc.
2330 Central Expressway
Santa Clara, CA 95050
USA
Phone: +1-408-330-4586
Email: charliep@computer.org
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