|Internet-Draft||SCHC Convergence||October 2022|
|Aguilar, et al.||Expires 26 April 2023||[Page]|
- lpwan Working Group
- Intended Status:
- Standards Track
SCHC Convergence Profile
The present document defines a profile of Static Context Header Compression and fragmentation (SCHC) [RFC8724] for multi-radio devices or multi-network application. This profile can be used simultaneously over LoRaWAN, Sigfox, NB-IoT and any other technology that may use SCHC Fragmentation/Reassembly functionality.¶
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The Static Context Header Compression and fragmentation (SCHC) specification [RFC8724] provides generic adaptation layer functionality, including Compression/Decompression (C/D) and Fragmentation and Reassembly (F/R) functionality. The latter offers three different modes, providing different features.¶
SCHC over LoRaWAN [RFC9011], SCHC over Sigfox [I-D.lpwan-schc-over-sigfox] and SCHC over NB-IoT [I-D.lpwan-schc-over-nbiot] are technology-specific SCHC profiles, which provide an optimal configuration of SCHC over the corresponding technologies. However, the F/R functionalities of these profiles are not compatible. Therefore, multi-radio devices (e.g., supporting LoRaWAN, Sigfox and NB-IoT interfaces on the same device) require multiple implementations of the SCHC F/R sublayer, one for each technology.¶
Moreover, multi-network solutions, where the same application is deployed over different LPWAN technologies also require multiple implementations of the SCHC F/R sublayer, one for each deployment.¶
To reduce implementation complexity, and enable a single convergent F/R sublayer, this document provides the F/R details for a SCHC profile that can be used over all the LPWAN technologies overviewed in [RFC8376], leveraging the benefits of the Compound ACK. This profile can also be used over other technologies that may use SCHC Fragmentation/Reassembly functionality.¶
IoT applications running over LPWAN devices are tied up to the selected LPWAN technology. The LPWAN constrains influence the design of the IoT application itself. This presents problems when migrating to other LPWANs or networks, as it may imply redesigning the complete IoT application (from device code to backend code). The LPWAN, as a Layer 2 (L2), should be transparent to IoT application (and developers), as it is in the IP domain.¶
Current advances in the adoption of IPv6 over LPWAN achieved interoperability for application thanks to SCHC [RFC8724], and a single SCHC C/D sublayer. However, each LPWAN technology requires a different implementation of the SCHC F/R sublayer, with different (but actually very similar) F/R modes. Therefore, an IoT application using multiple LPWANs (multiple radios o multiple networks) will require multiple SCHC F/R implementation in device and backend code. This is not the case for the C/D sublayer.¶
To reduce code complexity and maintenance, and achieve a single convergent SCHC F/R sublayer, this document provides a SCHC Profile which considers the singularities of LoRaWAN, Sigfox and NB-IoT, while providing general F/R modes that work over all of these technologies simultaneously.¶
The SCHC over All profile has several use cases:¶
- Generic SCHC F/R Profile for implementation of SCHC to test over a new technology. SCHC out-of-the-box F/R modes.¶
- Multi-radio devices: Devices implementing more than one LPWAN radio.¶
- Multi-network applications: Applications deployed over more than one LPWAN.¶
- Network Redundancy:¶
- Increased device duty-cycle as more networks are available, e.g., if SCHC Packet transmission is not possible over LoRaWAN due to duty-cycle restriction, SCHC Packet transmission may be performed over Sigfox or NB-IoT. This applies also for SCHC Fragments.¶
- Devices sending SCHC Fragments over different LPWANs to check available coverage.¶
[RFC8376] overviews the LoRaWAN, Sigfox, and NB-IoT protocols and their network architectures. More specifically, [RFC9011] maps the network architecture entities between LoRaWAN and LPWAN, as described in [RFC8724]. Similarly, [I-D.lpwan-schc-over-sigfox] and [I-D.lpwan-schc-over-nbiot] for Sigfox and NB-IoT performs the same mapping for Sigfox and NB-IoT, respectively.¶
In the SCHC over All Profile, as devices have a single SCHC F/R implementation, F/R RuleIDs are the same, independently of the LPWAN technology used, reducing the device memory and complexity requirements when compared to multiple SCHC F/R implementation.¶
To simplify the access to RuleIDs and to converge the different device IDs provided by the networks involved, a device needs to have a new identifier called the single SCHC ID.¶
A device ID translation table maps the network device ID to single SCHC ID. Then, with the single Device ID, it is possible to look up the Rules set and identify the corresponding Rules for such device. This dissociates the network device ID form the Rules, allowing to use the same Rule set for the same device independently of the access network.¶
The network device IDs used by the LPWAN technologies included in this Profile are:¶
The RuleID MUST be 8 bits. In LoRaWAN it MUST be encoded in the LoRaWAN FPort.¶
This section depicts the different formats of SCHC Fragment, SCHC ACK (including the SCHC Compound ACK defined in [I-D.ietf-lpwan-schc-compound-ack]), SCHC Aborts and ACK Request used in SCHC over All Uplink ACK-on-Error mode.¶
Carles Gomez has been funded in part by the Spanish Government through the TEC2016-79988-P grant, and the PID2019-106808RA-I00 grant (funded by MCIN / AEI / 10.13039/501100011033), and by Secretaria d'Universitats i Recerca del Departament d'Empresa i Coneixement de la Generalitat de Catalunya 2017 through grant SGR 376.¶
Sergio Aguilar has been funded by the ERDF and the Spanish Government through project TEC2016-79988-P and project PID2019-106808RA-I00, AEI/FEDER, EU (funded by MCIN / AEI / 10.13039/501100011033).¶
- Zuniga, JC., Gomez, C., Aguilar, S., Toutain, L., Cespedes, S., and D. Wistuba, "SCHC Compound ACK", Work in Progress, Internet-Draft, draft-ietf-lpwan-schc-compound-ack-07, , <http://www.ietf.org/internet-drafts/draft-ietf-lpwan-schc-compound-ack-07.txt>.
- Ramos, E. and A. Minaburo, "SCHC over NBIoT", Work in Progress, Internet-Draft, draft-ietf-lpwan-schc-over-nbiot-12, , <http://www.ietf.org/internet-drafts/draft-ietf-lpwan-schc-over-nbiot-12.txt>.
- Zuniga, JC., Gomez, C., Aguilar, S., Toutain, L., Cespedes, S., Wistuba, D., and J. Boite, "SCHC over Sigfox LPWAN", Work in Progress, Internet-Draft, draft-ietf-lpwan-schc-over-sigfox-13, , <http://www.ietf.org/internet-drafts/draft-ietf-lpwan-schc-over-sigfox-13.txt>.
- Farrell, S., Ed., "Low-Power Wide Area Network (LPWAN) Overview", RFC 8376, DOI 10.17487/RFC8376, , <https://www.rfc-editor.org/info/rfc8376>.
- Minaburo, A., Toutain, L., Gomez, C., Barthel, D., and JC. Zuniga, "SCHC: Generic Framework for Static Context Header Compression and Fragmentation", RFC 8724, DOI 10.17487/RFC8724, , <https://www.rfc-editor.org/info/rfc8724>.
- Gimenez, O., Ed. and I. Petrov, Ed., "Static Context Header Compression and Fragmentation (SCHC) over LoRaWAN", RFC 9011, DOI 10.17487/RFC9011, , <https://www.rfc-editor.org/info/rfc9011>.