SCHC for 802.15.4
lpwan applications
Friedrich-Alexander Universitaet Erlangen-NuernbergAm Wolfsmantel 33Erlangen91058 Germany+49-9131-85-25373joerg.robert@fau.deFuturewei Inc.2330 Central ExpresswaySanta Clara95050CAUSA+1-408-330-4586charliep@computer.org
Internet
Internet AreaSCHClpwanIEEE 802.15.4
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.
Static Context Header Compression (SCHC)
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
.
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
,
.
Although 801.15.4g and
802.15.4k 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 .
The LPWAN use-cases discussed in that document
are characterized as follows:
Focusing on uplink data Typical Payload data length less than 16 bytes No strict latency requirements
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
.
A typical 802.15.4w use case is illustrated in .
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
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.
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 .This document uses the following definitions:
Low-Power Wide AreaPersonal Area NetworkLow-Power Wide Area (LPWA)
task group within IEEE 802.15 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 .
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. Size of the Rule ID should be 3, to allow for up to 8 rules.
Pad to a multiple of 8 bits in the L2 payload.
802.15.4 link acknowledgement should be used, since the
static context as defined should be decompressed after
delivery over a single link.
MAX_ACK_REQUEST SHOULD be set to 3, following usual practice
in 802.15.4.
FCN SHOULD be set to 0, since unfragmented traffic is expected
for most use cases under consideration in 802.15.4w.
Similarly, DTag SHOULD be set to 0, since unfragmented traffic is
expected for most use cases under consideration in 802.15.4w.
Either CRC-16 or CRC-32 as defined in 802.15.4 could be used.
Since acknowledgments SHOULD be handled at Layer 2, no
specification is made here for the following:
The timer duration for Fragmentation ACK Always When to abort in ACK Always MAX_ATTEMPTS counter size The timer size between windows in ACK On Error. The inactivity timer. 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. This document does not specify any IANA actions.
This document has benefitted from discussions with the following
people, in alphabetical order:
Pat Kinney
LPWA Use-Cases"IEEE 802 Wireless"https://mentor.ieee.org/802.15/dcn/15/15-16-0770-05-lpwa-lpwa-use-cases.xlsxDiscussion on Suitable Parameters for SCHC"IEEE 802 Wireless"https://mentor.ieee.org/802.15/dcn/15/15-18-0238-02-004w-discussion-on-suitable-parameters-for-schc.pptxSCHC technology specific parameters"IETF [lp-wan] Working Group"https://mailarchive.ietf.org/arch/msg/lp-wan/SexnleQwBTL7XZ9-hC2h7tp79KUPart 15: Wireless LAN Medium Access Control (MAC) and
Physical Layer (PHY) Specifications"IEEE 802 Wireless"http://standards.ieee.org/getieee802/download/802.15-2015.pdf
Part 15: Wireless LAN Medium Access Control (MAC) and
Physical Layer (PHY) Specifications"IEEE 802 Wireless"http://standards.ieee.org/getieee802/download/802.15-2015.pdf
Part 15: Wireless LAN Medium Access Control (MAC) and
Physical Layer (PHY) Specifications"IEEE 802 Wireless"http://standards.ieee.org/getieee802/download/802.15-2015.pdf
Part 15: Wireless LAN Medium Access Control (MAC) and
Physical Layer (PHY) Specifications"IEEE 802 Wireless"http://standards.ieee.org/getieee802/download/802.15-2015.pdf
Part 15: Wireless LAN Medium Access Control (MAC) and
Physical Layer (PHY) Specifications"IEEE 802 Wireless"http://standards.ieee.org/getieee802/download/802.15-2015.pdf