Delay-Tolerant Networks Might Be The Killer App Ham Radio Needs

Amateur radio stands to gain more by leveraging the Internet as opposed to fighting it. Projects such as AREDN re-purpose commercial WiFi hardware to provide Internet connectivity over ham radio bands. Sending Internet traffic over amateur radio prevents the use of encryption and any commercial data. The result is a limited use case of AREDN to emergency communications when the Internet is not available and when non-sensitive data must be sent. This doesn’t play on any of the strengths of ham radio. We believe that Delay-Tolerant Networks are a key component to the future of ham radio that utilizes our strengths instead of applying limits.

What Are Delay-Tolerant Networks?

You might be asking yourself what exactly is a delay-tolerant network and why should you care? This type of network technology works when continuous end-to-end connections cannot be guaranteed between two or more devices. Utilizing a mixture of store and forward, ad hoc networking, and high-level routing algorithms data between devices can be exchanged even when they have no continuous path to do so. Delay-tolerant networks differ from mesh networks because mesh networks provide live connectivity through changing routing paths whereas delay-tolerant networks remove the need for a continuous end-to-end connection at all.

Amateur Radio Applications

Our hobby provides plentiful methods of transferring data. By utilizing our assets consisting of HF, VHF/UHF, and microwave links along with AMSAT satellites we can provide the last mile of communications where the Internet does not reach. By connecting a delay-tolerant network to the Internet we can bridge the gap from one mile to three-thousand miles depending on the band used while utilizing the reliability and bandwidth the Internet provides. This ideology uses the Internet to strengthen our hobby.

Use Case: Remote Communications

Imagine you are camping in Joshua Tree National Park here in Southern California. There’s a great 4×4 off-road section named the Geology Tour Road and your campsite is in Pleasant Valley which is absolutely beautiful. There is a catch, however. You are surrounded by mountains and there is no cellular network connectivity whatsoever. This is off the grid.

Geology Tour Road basin in Joshua Tree National Park

Pleasant Valley off of Geology Tour Road in Joshua Tree National Park. Geology Tour Road can be seen towards the right of the image.

You’re camping and want to send a picture to a friend back in Los Angeles, CA but you have no communications from the campsite. Instead of hiking to the nearest mountain top which can be dangerous and exhausting you simply wait. The Faraday radio you brought along only has a 5km radio range since the mountains block you in all directions. That’s the red circle below. A truck comes out to Geology Tour Road and is carrying a Faraday radio as well. As it passes inside your radio horizon communications are established and the image is stored inside the truck as it drives along the green line back towards Twentynine Palms, CA.

Once in Twentynine Palms, the trucks radio sends the image to a Faraday base station which then forwards the data over the Internet to your friend. This is one hour after you sent the image. Your friend responds immediately. The network knows you were in the vicinity of Joshua Tree National Park so the response is therefore routed to the area via the Internet. Along comes a second truck also carrying a Faraday radio which enters the park from Joshua Tree, CA. Our delay-tolerant network sends the response to this second truck for the ride into the park. As this second truck follows the blue line on the map above it then enters within range of your campsite radio and you receive the response. This took an hour from the time your friend responded. Two hours have passed but communications were made!

The Power of Delay-Tolerant Networks

Delay-tolerant networks cannot be compared to the Internet. They serve a completely different use case where communications are intermittent. The power of these networks is in the application of them. Ham radio’s killer app might be the use of a delay-tolerant network! In Joshua Tree there are two options to provide connectivity into the valley with one being to establish an infrastructure there and another to use delay-tolerant networks. Building infrastructure is hard, costly, and slow with traditional solutions. Ham radio can use a delay-tolerant network to expand a digital infrastructure far beyond what is feasible in the hobby today.

The Internet is extremely reliable. Cellular networks are fairing better through disasters such as Hurricane Harvey. It’s not infeasible to imagine the cellular network being less vulnerable to natural disasters as time progresses and technology marches forward. Ham radio has a place in emergency situations but that place appears to be dwindling in terms of technological capabilities. For amateur radio to establish a foothold on the forefront of technology it needs to play its strengths, not weaknesses. Delay-tolerant networking appears to be a technology that can propel the hobby to the front of the pack.

What do you think about this topic? Let us know!

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Author: Brent Salmi

Co-founder of FaradayRF and an electrical engineer working in the aerospace industry in Los Angeles. I’m a General class amateur radio operator (KB1LQD)

17 thoughts on “Delay-Tolerant Networks Might Be The Killer App Ham Radio Needs

  • I hope you’ll allow me to play the devil’s advocate here.

    The concept of delay-tolerant networks is a very good one, but I’m not convinced that you’ll be able to mobilize enough hams to make this system truly useful. There may not even be enough hams currently licensed to make this a reality, except for some small pockets. Consider your scenario. You’re in the middle of nowhere, with no connectivity (via Faraday RF) and miraculously a vehicle with a Faraday RF radio just happens to pass within your radio horizon? What are the real chances of that happening? Then, an hour or two later, another one comes along and passes a reply to you? That’s even more unlikely.

    It seems to me that the real challenge of setting up a ham network–be it a mesh network or a delay-tolerant network or some combination of both–is not a technical challenge. The technology exists. The challenge is setting up the infrastructure, and that includes mobilizing enough hams to get on board, invest in the equipment, and then actually use the system. The ARRL or TAPR, or perhaps some newly-formed organization, is going to have to get on board and really push this.

  • Great article and description. It provides a scenario that even someone is not licensed can understand. I believe that Dan (KB6NU) is correct in that getting buy in to build the infrastructure will be the hardest part.

    As I was reading it occurred to me that the Pigate ( or Tarpn ( could easily use the Faraday radio. The benefit is the low power cost.

  • Great points Dan. Yes you are correct that even with this the tricky part is figuring out critical mass of the network to make it useful. This is why combining assets is key. Yes a 900MHz radio may be very unlikely to come within range as described in this post unless most 4×4 trucks started carrying them. However, if we were to combine this with and AMSAT satellite that periodically came into view then that simply becomes another “layer” as shown below to get our information to where it needs to go.

    Delay tolerant network

    Mesh networking requires this but also a direct connection at all times. This is why a DTN is enticing because we can string together intermittent communications assets. For example, right now we’d need a geosynchronous AMSAT satellite to provide constant connectivity but with a DTN we can actually use LEO satellites much more effectively than we do even now. No need to run outside or wait for a pass. You simply allow the network to figure out the best path for the data to make it out and if waiting for a satellite is that then it does that. Thanks for commenting!

  • Yes Tom it’s been around for a while with the PACSATs. However, once the Internet really took off and became accessible to most people it appears ham radio let that technology expire (for the most part). A lot has changed since the PACSATs. We have massive amounts of open source code that implement TCP/IP standards we can leverage where applicable, Lots of computing power even in microcontrollers, and lots of memory. Rethinking what a modern Delay-Tolerant Network could be nowadays is exciting and could be the niche we as a hobby excel in beyond what the Internet tends to deliver. Thanks for bringing up the PACSATs!

  • This method was not only used with the PACSAT satellites, it was the mechanism behind the store-and-forward BBS system as well. And in fact, originally e-mail (certainly in the UUCP days but well into the SMTP days as well) worked the same way. Messages were sent to a nearby server, which sent it on and on through servers on the path, to be finally delivered to the server where the receiving user would read them. In the meantime they could sometimes wait for quite some time on intermediate systems, until the next link would become available.
    The only practical difference is that those systems normally used static configuration and the hops were mainly used to overcome connectivity time windows, i.e. every hop already knew to which next hop it was going to forward the message, this not being determined by a random next-hop system coming in view but by a forwarding map generated from connectivity data at a certain interval. E.g. UUCP systems called eachother at certain hours in the day and forwarded the messages they had queued. PACSATs were an exception to that, they were of course statically configured as a forward hop but the connecting stations had to wait for passes over the linking stations.
    It could be an interesting project to setup a system as described above, however…

  • Nice @Liotier! Just Googled it and subsequent pulled into a wormhole of Internet history 😉

    We’re advocating for a modern day version that fits amateur radio’s specific niche. Not that it hasn’t been done before but that there’s a lot of interesting problems to solve and applications to apply it to with a modern version. As the post points out, there’s no reason for ham radio to pitch itself against the Internet as it will lose every time!

  • I’m interested in the Phase 4b Geosync ham satellite project. It seems like one of the best ways to leverage all the new tech surrounding radio in a very “ham radio” sort of way, without also needing the “hivemind” to all setup and buy radios that sadly won’t be useful until everyone else *also* buys and setups said radios (the downfall of all new ham modes it seems).

  • I love this concept, and (knowing nothing about the technical details) have a key follow up question:

    If, in theory, one had a wide-band antenna that could transmit and receive a large swath of the spectrum (say, from 100 mhz to 10ghz) with a small footprint (pocket-friendly) and approximately the same energy requirements per packet as a modern LTE smartphone, could one create a hybrid network that could switch between the dense nodes + live connections of mesh and the sparse nodes + delay tolerant concept you’ve outlined here?

  • If I understand your question An Exponent then you are describing a radio that can switch between frequency (AKA frequency division multiplexing) as well as live streams and remote sparse nodes when available. That is really close to what we actually want to do. Combine assets both frequency (HF, VHF/UHF, microwave) as well as location/type (mobile, personal, tower, satellite). When you combine these then it becomes a question of understanding how to effectively combine the assets together. Does this answer your question?

  • I think so!

    If you’re saying that you want to design a network architecture using hardware and software that can switch seamlessly between dense mesh and sparse remote configurations and can leverage mobile, fixed, and satellite infrastructure depending on what is available and the type of data going over the air (voice/video/images/text/etc), then we are on the same page.

    I am trying to make this happen too, have some of the pieces moving already, and should probably talk with an expert like you in more depth in short order.

    Next question: how far along are you? Have you seen Althea Mesh protocol?

    If not, take a look. I think the team (whose founder I know) has figured out a pretty brilliant solution to solving the network density problem.

  • For Ham Radio to thrive I think we need both fundamental change in rules / philosophy as well as technology. DTN is a fine idea but the use case is really limited. I can send a picture of my campsite, great…as long as I’m using some mechanism that doesn’t require a secure password. But I can’t check my email (might be a work message in there! can’t use encryption! someone might send me an email with profanity!), or my bank balance, can’t upload a document or web design I’ve been working on that I might be getting paid for, etc. All of these things are prohibited by rules / philosophy that made a great amount of sense when ham radio was established. Work and personal life were very separated then, and there was little good reason for any kind of secrecy. Times have changed a lot, the way people live and work has changed a lot. Ham radio has changed only a little, and as such ham’s appeal is much less than it used to be. Where once the problem was too many users for the available spectrum, now the vast majority of ham bands sit grossly under-utilized which risks losing them forever to more powerful corporate interests. The rules against encryption and conducting business by individuals need to drastically change. Not everything about ham radio needs to change. For example, the rules against broadcasting do not need to change, prohibiting 3rd party communications for hire does not need to change, etc. What we need is a hobby that individuals can pursue that will directly benefit them personally given the way that people conduct their lives *today*, while they learn and advance technology in the process.

  • Hey Bryce,

    Just looked at your website. We should talk ASAP.

    It looks like you’re working on a key component of the system I’ve been searching for.

    I want to share some more info with you, but not on this channel.

    Can you see my email address from your back end?

  • Interesting view Jason,

    Work/life balance certainly has changed since the beginning of ham radio. Personal lives and work very much blend together for many these days. I would caution that I don’t see a huge benefit for ham radio filling in the gap of Internet services such as work email availability. That’s sensitive information and is technically commercial operations which is illegal over ham radio. Ham radio is meant for experimentation among other thing like emergency communications. I see the private sector providing commercial solutions for the problems you bring up in a much more meaningful way than our hobby could without allowing commercial use.

    That said, there’s likely a ton of uses for information that we don’t want to encrypt but absolutely much authenticate. Whether it’s simply messages or even data that controls physical/virtual items in the real-world we can benefit from authenticating our communications. Delay tolerant networks with solid authentication opens up another avenue. No need to make it just person to person communications. Remote sensing and control is an extremely interesting technology too.

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