Hi authors,

I am the assigned Opsdir reviewer. 

Summary: This is a standard track publication. This document defines a profile of SCHC (RFC 8724) for use in Sigfox networks and provides parameter values and modes of operation.

Major issues:None

Minor issues:Yes

1. Section 1：
Sigfox is an LPWAN technology  that offers energy-efficient
   connectivity for devices at a very low cost.  Sigfox brings a
   worldwide network composed of Base Stations that receive short (12
   bytes)  uplink messages sent by devices over the long-range Sigfox
   radio protocol.

This paragraph gives an overview of Sigfox and also gives some details, such as 12 bytes uplink messages.
It would be clearer that a reference of Sigfox specification can be provided. Regarding 12 bytes uplink messages, why is it emphasized here? This is not mentioned in the sections 3.2 uplink and Section 3.8. Padding says 12 bytes payload. The same applies to 8 bytes downlink messages.

2. Section 2：
It is suggested that Terminology can be added, such as RSSI, Dtag needs some definition.

3. Section 3：
About "Provisioning protocol", can you give an example? Is this suggesting Netconf protocol?
 
4. Section 3.1
The terms used in the architecture figure 1 and the document are little confusing.

In the figure 1, only sigfox device and Sigfox BS is marked, are the other network entities not part of sigfox network? Maybe the scope of the sigfox network can be provided.
It is suggested to be consistent that Network Gateway (NGW) is called the Sigfox cloud-based Network or cloud-based Sigfox Core Network? 

5. Section 3.4 SCHC-ACK on Downlink 
Section 3.3 Downlink and Section 3.4 are parallel sections. Should section 3.4 be subsection of Section 3.3?

6. Section 3.6.1.5 All-1 and RCS behaviour
It is better to add a complete title name, e.g. All-1 SCHC Fragments?

Minor Nits:

7.Abstract
s/The present document/The document

8. Consistency in section title 
s/3.6.1.1 SCHC-Sender Abort/ 3.6.1.1 SCHC Sender-Abort
3.7 SCHC-over-Sigfox F/R Message Formats –> SCHC over Sigfox F/R Message Formats
3.7.3.4.  SCHC Sender-Abort Messages-> SCHC Sender-Abort Message format
3.7.3.5  SCHC Receiver-Abort Message -> SCHC Receiver-Abort Message format
The same applies to::
3.7.4.4.  SCHC Sender-Abort Messages
3.7.4.4.  SCHC Sender-Abort Messages
3.7.5.4.  SCHC Sender-Abort Messages
3.7.5.5.  SCHC Receiver-Abort Message