SCHC over LoRaWAN Efficiency: Evaluation and Experimental Performance of Packet Fragmentation.

Rodrigo Muñoz,Juan Saez Hidalgo,Felipe Canales,Diego Dujovne,Sandra Céspedes

doi:10.3390/s22041531

Abstract

Low Power Wide Area Networks (LPWAN) are expected to enable the massive connectivity of small and constrained devices to the Internet of Things. Due to the restricted nature of both end devices and network links, LPWAN technologies employ network stacks where there is no interoperable network layer as a general case; instead, application data are usually placed directly into technology-specific two-layer frames. Besides not being able to run standard IP-based protocols at the end device, the lack of an IP layer also causes LPWAN segments to operate in an isolated manner, requiring middleboxes to interface non-IP LPWAN technologies with the IP world. The IETF has standardized a compression and fragmentation scheme, called Static Context Header Compression and Fragmentation (SCHC), which can compress and fragment IPv6 and UDP headers for LPWAN in a way that enables IP-based communications on the constrained end device. This article presents a model to determine the channel occupation efficiency based on the transmission times of SCHC messages in the upstream channel of a LoRaWAN™ link using the ACK-on-Error mode of standard SCHC. The model is compared against experimental data obtained from the transmission of packets that are fragmented using a SCHC over LoRaWAN implementation. This modeling provides a relationship between the channel occupancy efficiency, the spreading factor of LoRa™, and the probability of an error of a SCHC message. The results show that the model correctly predicts the efficiency in channel occupation for all spreading factors. Furthermore, the SCHC ACK-on-Error mode implementation for the upstream channel has been made fully available for further use by the research community.

Highlights

Introduction published maps and institutional affilNowadays, several channel access technologies serve the Internet of Things (IoT).Among them, LoRaWAN, SigFox, and NB-IoT have emerged as technologies designed to deliver high coverage while maintaining a low power consumption
The Static Context Header Compression and Fragmentation (SCHC) Fragment processing time and SCHC ACKReq processing time represent the additional time t proc used to send a LoRa message to the network, which is defined as a vector
For case 1, the time involved in sending 13 SCHC Fragment messages plus receiving a SCHC ACK is given by Table 5

Summary

Introduction

Several channel access technologies serve the Internet of Things (IoT). LoRaWAN, SigFox, and NB-IoT have emerged as technologies designed to deliver high coverage while maintaining a low power consumption. These characteristics are highly valued in IoT because they can support a high density of end devices where periodic battery changes are not feasible or where the available power is limited. Low Power Wide Area Network (LPWAN) technologies do not support native IP addressing because the reduced storage space cannot store a full protocol stack or fragment messages at the link layer. The lack of IP support prevents the use of standard management protocols and direct access to end devices. LoRaWAN has a Maximum Transmission Unit (MTU) in the iations

Results

Discussion

Conclusion