Buyers’ Guide: Cellular Bonding Solutions
While many of us are excited by the possibilities of 5G today, those possibilities are mostly unrealized at present. In terms of streaming, the higher data rates promised with 5G are not as important as the new bands/frequencies that enable a given tower to serve more active connections, as opposed to being completely blocked up with hundreds of other cellular users trying to push or pull data at the same time.
In the absence of widespread high-bandwidth 5G availability, one technology that has been with us for several years remains the most reliable solution for getting your streams to the cloud when Wi-Fi and wired connections are unavailable: cellular bonding.
What is Bonding?
For those unfamiliar, cellular bonding is a process whereby multiple connections to the internet—e.g., multiple cellular carriers—are all used, simultaneously, to send and receive data. This is very different than having multiple Wide Area Networks (WANs), or a Multi WAN router that can use multiple internet connections at the same time, and even switch between them and offer some failover. Sending office VoIP traffic over one WAN connection and customer internet browsing over a second WAN connection is not bonding. Having one primary connection and then having everything drop to a second connection if the first one fails is also not bonding.
Bonded video service is a process that involves two distinct halves of a whole. Most often, it is a paid service, and there is a key reason why true bonding has a price—the “de-bonding” service, as I call it.
No matter whether you have a VidiU, LiveU, Kiloview, Peplink, or other bonding router, each of these devices is designed to connect to a server and service at the other end. Let me explain why.
When your video come in to the device, it is compressed into data and that data is sliced into packets (1, 2, 3, 4, 5, 6, 7, 8…). Each of these packets is distributed, or should be distributed, like playing cards at the poker table—a packet to each connected service. Each of those packets is numbered. Each of those packets flies through the air or a wire, or bounces around the city or the country, and gets to the receiving server. Whether it be Teradek Core, LiveU server, Kiloview Server, or Peplink’s SpeedFusion, there’s a very specific destination these packets go to. Because each route they take is different, they will never, ever, arrive in order.
You cannot “bond” your video directly to YouTube, or Facebook, or Vimeo, or to any delivery network.
These de-bonding servers exist to receive the packets, in whatever order—e.g., 3, 1, 4, 2, 6, 5, 7, 8...—as they arrive by postal carrier, UPS, carrier pigeon, tied to a rock, etc. The server “de-bonds” the packets and puts them back in order—1, 2, 3, 4, 5, 6, 7, 8—and then, with a single reliable fast connection to the internet, it then sends this single stream of data to your intended destination. This de-bonding service requires a computer to dedicate itself to processing your video, and renting someone else’s computer for this task has a cost.
Sometimes, these servers also serve to transcode the stream. For instance, if the bonding device sends HEVC/H.265 to be very efficient with data, but not all Content Delivery Networks (CDNs) accept HEVC directly, so then the de-bonding server takes the received HEVC and transcodes it to MPEG-4/H.264 to send along to the destinations. This transcoding process takes server horsepower, and thus often adds cost to the service.
Another common feature of the de-bonding server is multicasting: You send one stream from your bonding device to the server, at which point the server splits it and casts it to multiple destinations. This again saves on data being sent because you’re only sending one stream, but it can end up going to 2, 5, 10, or more different destinations. Again, this process of splitting, managing connections, and sending out all these streams is, in almost all cases, part of a paid service.
So if you have a bonding device, and you’re not paying for any (de)bonding service, it may behoove you to look more closely into whether you are truly getting bonding service, or whether there’s something else going on.
You’ll note a recurring theme: using as little data as possible to send the stream. Whether it be leveraging HEVC or cloud multicasting, there is a key reason why these tools strive for the lowest-bitrate data stream possible. That reason is reliability. Consider sending one 3 Mbps HEVC stream that is multicast to 10 destinations, versus directly sending ten individual outbound 6 Mbps H.264 streams. This would require 60 Mbps up just for the streams, and typically, with data fluctuations, you want double what the stream will be, so you’d really need at least 120 Mbps upload bandwidth to handle that first mile reliably.
For businesses, or broadcast, there’s often the money to make sure that big bandwidth is there, and probably a lot more to spare. For the vast majority of independent producers and freelancers, however, that big bandwidth is often not there. Plus, when using cellular connections—especially when moving—you are at the mercy of what the towers can provide to you (and everyone connected to the same towers) at that second. So, the lower you can keep your demand, the less you will need to push through, and the more likely it is that all your packets will make it through in a timely manner.
There are many bonding solutions on the market today, so let’s discuss a few of the key offerings currently in use.
Teradek VidiU & Core
Teradek has been doing bonding for a long, long time. From a long line of VidiU products, and also their Wave monitor/encoder. These all rely on Teradek’s Core service to receive, de-bond, transcode, and multicast your stream.
Teradek’s VidiU X bonding-capable streaming encoder
Core as a service is also built for large-scale use, handling multiple encoders using multiple connections, multiple administrators working in the same account, and multiple “sets” of destinations for shows or events that repeat. This makes it easy for productions, like a traveling band to set up in a new place each night and repeatedly, reliably stream out to a half-dozen destinations every time with just the push of a button on the streaming device, once it’s all set up on Core.
LiveU has made a name for itself in the broadcast and news reporting industry because their bonding encoders can push to the cloud, or they also push to a specific hardware receiver than you can purchase and set up wherever you need it. It is “the cloud” and it’s also in the rack of gear in the studio so it can receive the remote news reporter, reliably, and it’s available as if it’s just another source in the studio.
The LiveU Solo line of wireless streaming encoders
LiveU also leverages bidirectional status communication and dynamically adjustable compression to help ensure the stream gets through, even when networks are not cooperating. This means that if two of the four cellular connections are not able to accept data at this moment, and bandwidth is cut in half, what might have resulted in dropped frames is avoided when the server tells the encoder to use a smaller frame size and reduce the stream data rate to fit the available bandwidth. The viewer will seldom, if ever, notice anything. The bi-directional communication also enables the LiveU to assess that the bandwidth is available again, and can instruct the encoder to return to the previous frame size and encoding settings.
Similar to LiveU, Dejero offers mobile encoding packs that leverage multiple cellular models to transmit live video across a bonded connection to the internet. They call this Smart Blending. Dejero also has rackmount encoders, as well as rackmount receivers and return servers offering dedicated point-to-point bonded connections—not just for the delivery of video, but also return video/prompter and more.
Dejero’s EnGo 263 LTE Mobile Transmitter
Dejero’s Hybrid Encoding Technology also offers to dynamically adapt the encoding in real time to help adapt for changing connectivity conditions throughout your broadcast. Of course, there are also cloud solutions that offer the receiving and redistribution of the video, as well as cloud management of the devices sending the video, much like LiveU, Teradek, and our next highlighted company, Kiloview.
Kiloview is newer to the bonded encoder market than Teradek and LiveU, but they have put together a nice encoder that can take two internal SIM cards, Wi-FI, and two USB connections for USB cellular modems or USB to Ethernet connections. It is compact and, while it lacks an integrated LCD screen for status and settings like the VidiU or LiveU, you can access the Kiloview's settings locally over the LAN with an app, or a web browser.
Kiloview’s 4G Bonding Encoder
Earlier I mentioned the cloud server that de-bonds your stream. Typically, someone else sets up and maintains the server that you pay to use. However, of the devices I mentioned, Kiloview is the only one that offers the server software to end users. Currently, this software is free. But you have to set it up. You provide the server. You provide the big-bandwidth pipe to the internet. If you are in a position to do this, and have the IT know-how to administer the server, then this can be an interesting option.
Understand, though, that there is still a server computer, plus server costs, as well as internet costs. While those may be amortized into overall business overhead, they still exist. For many, though, the faster, simpler option is paying the fee for something turnkey.
Mushroom has multiple solutions from packet-level load-balancing routers for home offices to software-defined WAN appliances that connect branch offices together. These solutions are geared towards business and corporate solutions and serve to bond multiple connections point to point. This means, if you wanted to connect two offices in different cities as if they were in the same building, you could leverage multiple internet connections at each end, and a Mushroom device on each end, and these devices would connect those two data centers together with multi-WAN and broadband bonding between the two Mushroom devices for reliable video streaming within their own intranet.
Mushroom Networks’ Portabella 4000i Multi-SIM LTE Broadband Bonding Appliance
Mushroom also offers streamer hardware that can bond connections to Mushroom’s cloud service, or to dedicated relay units, on-premise hardware to receive the bonded signal and distribute the video feed, similar to LiveU. Mushroom touts that their software works around network problems and paths are removed and re-added to service without interrupting your stream, which is what bonding is supposed to do.
Peplink offers many devices with multiple connections to the internet. They have several devices designed for mobile integration and deployment, such as for police or other emergency services. These fanless, passively cooled, rugged devices offer 2, 3, or 4 cellular modems; WiFi; WAN; and more for automotive and other rugged needs. They also offer rackmount units with far more LAN ports for more typical needs, while still offering multiple cellular, multiple WAN and other connections as well.
Peplink’s SpeedFusion is the bonding glue that aggregates your data across multiple networks between your Peplink router and their servers. Note, also, that I said “data,” because Peplink dos not have any video ports. You can leverage the bonded connection for any data, multiple uploads, and also download links to check the feed, manage cloud stream connections, view analytics, viewer comments, and more. There is a lot of value to not limiting your bonding to just the video upload, because if you can’t check to see that it's being received, or make a critical change, then you may be just as stuck as if you didn't have bonding.
A Peplink Speedfusion bandwidth bonding schematic
Speedify is a software-only solution that touts the ability to run on the computer you may be using for vMix, Wirecast, Mimo Live, or any number of software-based solutions. The software inserts itself in between the OS on Mac, PC, Linux, and even iOS and Android. Speedify reaches out and leverages any internet connection it can find, ties them all together using whichever mode you set it to use, and then presents one “Speedify” connection to the OS. Some have taken to installing Speedify on a compact, embeddable type of computer that then makes all the connections and provides a single WAN that connects to your router or switch.
Speedify bonding in action
The software lets users pick whether they want to prioritize one connection over the others. For example, you may prefer Ethernet over cellular, like a multi-WAN router. Or you can set multiple connections as primary and force it to spread the data across all of them. While the connection may not be the speediest, the goal is to always make use of all the connections to ensure that they are all leveraged for use. Some have had mixed success with live streaming through Speedify, saying that higher service levels that offer a dedicated server on their end deliver more reliable and faster bonding than the lowest tiers of service.
Buffering at Both Ends
In addition to bonding as detailed here, there are a couple of other nuances that have emerged over time that also help improve the reliability of streamed content. One is to use some buffering to be able to hide a longer-term (several-second) glitch in the matrix. If there is a multi-second break—say 10 or 20 seconds—that is a break where some streaming services may think the stream is finished and close your streaming event. But a buffer could help you avoid this.
To this end, Zixi and other systems utilize buffered content at both ends. YoloLiv has also added this capability to its YoloCast service as Ardent Streaming Protocol (ASP). These buffers exist both in the sending device, and also at the receiving end. You set it for a pre-determined length of time, like 1 minute or more. This 1-minute buffer is filled up on both the sending and receiving ends, so that if the connection between your sending device and the server is lost for 10, 20, or 30 seconds, the server is still sending video from the 1-minute internal buffer to all the content delivery networks. Meanwhile, your sending device is buffering as well, and when it can reconnect to the server, it sends the video—not in real time, but as data, filling that server buffer back up as fast as possible.
Another important technology is the Secure Reliable Transport (SRT) protocol, developed by Haivision and now integrated into all kinds of streaming tech. SRT is similar to buffering, but on a packet by packet basis. By including information about previous and next frames with each frame, it helps overcome visual and audible glitches from lost data. Also, there is a user-definable delay that serves to provide a small buffer of data to, again, overcome glitches in the matrix.
For many, leveraging SRT provides enough reliability that they do not use bonding and de-bonding servers. SRT is device to device. But many commercial content delivery networks like YouTube, Facebook, and Twitch, do not receive SRT natively, so it may still need to go through a server before it is sent to commercial CDNs.
One thing to note is that SRT is not a codec. SRT is a wrapper around whatever codec you choose to send. So you can use SRT to wrap MPEG-4, or you could use SRT with HEVC or other codecs. Because SRT does add a bit of information from frames before and after, depending on how you set your SRT preferences, your data rate will change from your base data stream. Be sure to take that into consideration when setting your data rates and assessing available bandwidth.
With more and more content being streamed every day, everyone from broadcast producers to individual users has a vast assortment of technologies available to them to ensure that their program can reliably reach viewers around the world. They key comes in understanding what bonding truly is, how it is implemented, and what advantages it offers. Then you can compare services more thoroughly and understand what it is you need, and how the services you are comparing satisfy your needs. You can also assess whether new technologies like SRT or buffering can provide the reliability you want, without the need for true bonding services.
Any way you look at it, thanks to bonding and some of the other technologies discussed here, the days of sending glitchy, buffering video to viewers should be behind us. There are many options available, at a wide variety of price points, to ensure that streaming professionals can deliver the best video possible.
To catch up on the past, present, and future of cellular bonding, we spoke with executives from four companies that manufacture and distribute cellular bonding products and services.
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Companies and Suppliers Mentioned