The SatSite Basestation and Shipboard IoT

This article tells how the Legba SatSite is an exceptional choice for a low-cost, single-box DCSA IoT data gateway on a vessel (as described in Section 3.1 of “IoT Container Standards: IoT Standard for Gateway Connectivity Interfaces“).

What is a “data gateway on vessel”?

The DCSA IoT architecture defines a gateway as an entity that connects the “internal interfaces” of the cargo containers (radio interfaces) to the “external interfaces” of the IoT management system (IP or other data interfaces). These gateways are intended to support specific “use cases”: on land, at specific transition points (“events”, like customs clearance), used with handheld scanners, or on a vessel. Different radio or wireless technologies are suited to different use cases. Our specific focus is on the use of cellular technology, which is potentially suited for the land and vessel cases.

From DSCA “IoT Container Standards: IoT Standard for Gateway Connectivity Interfaces”

Why 2G GSM/GPRS is the Best Choice for Vessel Gateways

The DCSA standard lists 2G, 4G, and 5G as candidate cellular technologies for land and vessel use cases. They specifically exclude 3G because ” (i) it does not offer specific characteristics that can be applied to IoT applications that are not already covered by 2G and 4G and (ii) it is being phased out”.

While all of these standards (2G GSM/GPRS, 4G LTE/LTE-M/NB-IoT, 5G NR) have options for supporting low-power and low-complexity container devices, 2G is unique in that it does not require mutual authentication between the device and the network. This allows a 2G vessel gateway to support container devices at sea, using any installed SIM, without the need for a roaming agreement and without the need for a real-time backhaul connection from the vessel to a mobile operator. Any other cellular technology, including the recommended 4G, would require the vessel operator to

  1. install its own SIMs in all of the container devices, which is completely impractical, or
  2. have a roaming agreement with one or more mobile operators, which adds a lot of administrative complexity, technical complexity, and cost.

Using a 2G GSM/GPRS network avoids both of these problems. Granted, 2G systems may deliver only a few kbit/sec for each connection, but for IoT container devices that generate only a few kilobits of traffic per hour, this level of service is still more than adequate, even for networks supporting thousands of containers. And 2G radio modems are very power efficient, in the same range as 4G options like LTE-M and NB-IoT for preserving battery life. This combination of factors makes 2G GSM/GPRS an ideal choice for vessel gateways:

  • sufficient data rate for the container IoT applications (19 kbit/sec per connection, 7-28 available connections per basestation)
  • good battery life, similar to LTE-M or NB-IoT
  • no need for roaming agreements
  • support for local-only connections, without needing constant satellite backhaul support
  • the same 2G modem hardware and SIM will work for land gateways over the public cellular networks

Using the SatSite’s NiPC mode

The Legba SatSite basestation supports a mode called “NiPC”, “network in a PC”. In this mode, the basestation is a completely self-contained GSM/GPRS network, supporting all of the functions required to provide GPRS data, SMS, and call routing services for a 2G GSM/GPRS handset or modem device. The functions include:

  • registration and location updating, without the need for a roaming agreement (detailed technical article here)
  • SGSN/GGSN data session management and IP address assignment, without the need for a centralized core network (detailed technical article here)
  • SIP-based routing for telephone calls and SMS

The figure below shows the on-vessel use case for the SatSite in terms of the DCSA model. From the point of view of the local servers and applications on the vessel, the IoT container devices are IP endpoints with addresses assigned from a configured pool. The SIMs in the IoT container devices can be issued by any operator, and do not even require valid accounts to work in this mode. There are no charges against their roaming accounts, and data can still be backhauled over satellite to land.

Use case for on-vessel gateway, showing the role of the SatSite basestation. From “DCSA IoT data standard for remote Reefer container monitoring on board a vessel”, with added notes in red.

Conclusion

The SatSite basestation, operating in NiPC mode provides a way for GSM/GPRS container devices to connect to an on-vessel IP network, using the same SIMs that they would use on land, and without roaming agreements or roaming charges. For more information on this product, including quotations, please contact sales@leg.ba, or complete the form below.

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