Cellular for near-shore internet connection

Burmarc has been testing various scenarios using its own Starlink, installing systems on a variety of client vessels and would summarise the experience as a very useful addition but not a standalone solution.

How can I fulfil my connectivity need most effectively?

Cellular for near-shore ship’s communications

Background:

Data connectivity demand continues to grow exponentially with existing and new applications all requiring to be connected and looking to secure bandwidth. Telecoms operators are working to keep pace with this trend; 5G is rolled out more widely and 6G+ in development. From a maritime perspective the good news is that most of the range and performance improvements that we are likely to be able to make use of already exist with the later iterations of 4G (LTE).

Not all 4G is equal!

Different categories of 4G modem are on the market which vary significantly in performance:

Some common examples and approximate limits in ideal conditions are shown in the example table below.

**Please note these speeds are the maximum theoretic values not real-world values and many internal and external factors will influence the real-world throughput, however it is still as useful relative measure of the modem performance; these modems will often form part of a router package and so the throughput of this element, the downstream network as well as the modem to cellular network link characteristics will all play a part…

Do I need 5G?

There is an argument for ensuring you have the hardware to take advantage of future infrastructure rollout and many port areas already support high performance 4G and 5G networks.

Both high category 4G and 5G modems are backwards compatible to lower technologies to continue communications where the best technology reachable is only a single band transmission due to range etc.

5G does attract a higher cost but this is also true of the higher Category 4G modems.

Best performance…

A single modem will be constrained by factors such as the category discussed above, the signal (via antenna & cable - we’ll touch on this shortly), the chosen network operator and the coverage in that location, as well as standard RF reception issues like line-of-sight / blockage / reflection and user density on the cell tower you are communicating with.

A secondary SIM can be used in many routers to provide an alternative provider when communication with your preferred network is lost, however, there is a delay (with no IP traffic possible) while the modem switches SIM and logs onto the new network. This is a cost-effective way of increasing coverage and mitigating some of the issues associated with single carrier dependency.

Next on the options list is to add a second modem (or third / fourth) which not only provides the opportunity to add carrier diversity but these devices can be concurrent meaning if one modem has lost signal there may well still be an available connection on the other; add dual SIMs per modem and that first modem can have switched to an available operator without the vessel losing connection. This arrangement is nearly ideal; but for some applications like voice/video calling the session using the first modem will of course disconnect when that link is lost but can be re-established over the second modem but the interruption is unwelcome… combining the 2 or more links into a bonded VPN tunnel means that there is a constant connection provided at least one modem is connected with sufficient bandwidth, the loss of a link will not drop the call but will reduce the bandwidth available for lower priority traffic.

Now imagine coupling this with satellite communications; with failover to the more costly (£/MB) link will cut in when no terrestrial links are available to give a truly seamless experience. Newer LEO technologies can even be added to the VPN as the latency is similar enough - you can also, for further failover, bond multiple GEO links to provide the same benefits but not combine with terrestrial or LEO in the same VPN).

Antennae & Cables

Antennae are a key factor in the ability to make reliable links. A high gain antenna can work well on land as the target tower position is fixed, however, the higher the gain the narrower the aperture and with vessels subject to rolling a high-gain antenna could create an unstable link to the shore tower; so a moderate gain with wide enough aperture is likely to perform better in many marine cases.

Directional or omni directional?

Well as the vessel moves past towers and changes heading the starting point would definitely by omni-directional. There are however a new breed of antenna where an array of directional antenna are used to increase gain and reduce noise while maintaining suitable roll capacity; these tend to be suitable for higher category multi-modem installations. 

Cables; the frequency ranges that cellular communications operate do not transmit losslessly within cables so there is a balance between antenna & modem separation (and optimal location for each) and the cable length to achieve this. In cases where the optimal antenna position requires more than 15m of cable to reach the modem then there are combined modems within antenna housings to provide a solution and connect below decks via Ethernet cable (upto 90m). The directional array antenna solutions also tend to have space within the housing to install modems too. The downside of above decks modems assuming we have them in suitable weather tight enclosures is access to the SIM cards; this can be assisted with the use of remote SIM injectors or eSIM use in supporting modems.

Once we have the link via our modem(s) we then configure the router element to provide the desired network and traffic management to suit the client’s needs and deliver the network(s) to the required locations via wired & wireless (Wi-Fi) means as required. Clients love our ability to remotely support them as onboard needs change, new connection opportunities present themselves; taking advantage in the current & future LEO, MEO & GEO satcomms to expand the geographic coverage that cellular can afford them all the time keeping one eye on the cost vs need to ensure that non-essential traffic isn’t being sent over more expensive links than desired.