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Cellular Bonding for Live Event Streaming: The State of The Art

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.

How Can You Improve Your Chances for Success?

There are two ways to get better bonding results: deploy multiple modemsor use signal extenders to make your signal more powerful than the typical cellular phone you’re competing with. On the first point, our executive panel agreed that two modems constituted the bare minimum, but that four was the sweet spot, particularly for those transmitting at 1080p. According to Streambox’s Hildeman, “Bigger providers never go live with two modems. They typically deploy four modems from four different providers to produce a reliable 5–12Mbps.”

Expanding upon the reliability aspect, Mushroom Networks’ Akin points out that the value of multiple cards is more about signal resiliency than top-line throughput. Although a single modem can spike to 10Mbps or higher, you can’t achieve the sustained throughput to “convert an unpredictable link to a predictable one.” For that, you need multiple modems.

Teradek’s Landman disagrees slightly with Hildeman’s provider strategy, particularly for those broadcasting primarily from a single city or similar geographical area. He recommends getting two modems from the strongest service in the area and two from the next strongest. A useful site for identifying the front-runners is, which publishes reports showing coverage in many major geographical regions.

Beyond using multiple modems, you can also deploy signal extenders, either as separate devices or integrated into the cellular bonding modems. Signal extenders can have two components, a larger antenna to receive and broadcast the signals, and a booster to amplify them. Some extenders only have antennas, some have antennas and boosters. For example, the Streambox Signal Extender 2.A shown in Figure 1 (below) has both components, while the company’s Signal Extender 2.0 lacks the amplifier.

Figure 1. The Streambox Signal Extender 2.A

Teradek’s new Node product (Figure 2, below) also combines larger antennas than are available on most cellular modem cards with a signal amplifier for an extra boost. Significantly, this is the first Teradek product that accepts SIM cards directly into the unit, which simplifies transport and usage, and presents a more ruggedized and weather-proof exterior. While the first versions of Node will be region-specific for North and South America and other areas, Teradek plans to introduce a worldwide unit at some point in the future.

Figure 2. Teradek Node, a signal amplifier and modem

Similarly, the LiveU Xtender integrated antenna-only solution can increase network reception for additional resiliency for live video transmission in heavily crowded areas. The bottom line is that whichever cellular bonding system you choose, you can increase your chances of successful transmissions by using two to four modems and signal extenders.

What’s New in 2017?

Potential buyers sorting through new models from these vendors will find plenty of new features, including HEVC encoding from LiveU and Teradek, which should deliver quality comparable to existing H.264-based products at 40–50% bandwidth savings. This is obviously significant when you’re vying for bandwidth, or if you’d like to cut costs by using fewer modems or lower bandwidth.

LiveU’s product is a new HEVC Pro Card, which is available as a user-installable upgrade to LiveU’s LU600 unit, as shown in Figure 3 (below). The card supports both HEVC and H.264, which is important for backward compatibility with most CDNs or live-streaming services.

Figure 3. Upgrading LiveU’s LU600 unit for HEVC transmission

Teradek’s product is the Cube 755, a standalone HEVC/H.264 encoder that can transmit directly via Wi-Fi and GigE support. Alternatively, you can transmit via Teradek ShareLink, a service that bonds signals from multiple iPhones (but not Android phones), along with the Wi-Fi or GigE from the Cube unit itself. Or, you can pair the Cube with a Teradek Bond cellular bonding unit.

Despite the obvious benefits of HEVC, note that you’ll find few direct use cases. That is, few, if any, live-streaming services or CDNs accept HEVC input—yet another result of the devastatingly poor royalty strategy pursued by HEVC IP owners. If your ultimate target is a CDN or live-streaming service, you’ll have to transmit through each company’s cloud service, transcode to H.264 in the cloud, and route the transcoded signal to the desired service or services.

Some services, like Teradek’s Core (Figure 4, below), will charge extra for this, while others, like LiveU, don’t plan to, at least for sub-4K streams. If you’re buying into HEVC to save money, be sure to factor the costs of these transcoding services into the equation. Alternatively, for point-to-point transmissions, you can transmit directly to an HEVC decoder, which both companies offer.

Figure 4. Viewing the connection statistics and changing the settings of a Teradek Cube encoder remotely via Teradek’s cloud service, Core

New from Mushroom Networks are the Streamer 2000i, 4000i, and 8000i devices (Figure 5, below), which have been ruggedized and run through certifications for deployment on trains, or with first responders or law enforcement. These units feature embedded modems, passive cooling, external antenna connectors, embedded Wi-Fi, and optional lockable M12 Ethernet connectors. In addition to streaming video, these units can also provide high-speed internet access, doubling their potential utility. All three units, which feature two, four, and eight embedded modems, respectively, are transmission units only, and can work with most standalone encoders.

Figure 5. Mushroom Networks’ ruggedized Streaming 8000i

Streambox’s most recent innovation focused on modularizing the company’s tiny Avenir Micro so it can be deployed in multiple form factors. The base encoder itself weighs half a pound and uses 10 watts of power, and comes with an AC adapter. The Avenir Micro has HD-SDI and HDMI inputs, along with GigE and Wi-Fi so it can encode and transmit video without any accessories. Modular options include three battery modules (Streambox, Anton Bauer, IDX), embedded and USB-connected modem modules that can accept up to four modems, and more.

Interestingly, like all Streambox encoders, the Avenir encodes using the Streambox proprietary ACT-L3 Advanced Profile Codec, which on this product can encode up to 1080i/59.94 video at data rates ranging from 64Kbps to 18Mbps. Streambox also offers rackmounted hardware that can support up to 4K resolution using the same ACT-L3 codec. As with HEVC as utilized by Teradek and LiveU, this means that the streams are not directly compatible with any CDNs or social media services. To support these sites, you must route the video through Streambox Cloud, or you can send the video to Streambox decoders that can output single-link 6G-SDI 4K, 3G-SDI x 2, or HDMI video with eight-channel embedded SDI audio or analog XLR.

A recent priority for all companies has been building enhanced cloud facilities that have the ability to control and configure their own encoders remotely, and route video to multiple outputs, including social media sites. Beyond this, each company is investing heavily in cloud facilities to provide the broadest and most robust feature set possible. As an example, Streambox has 11 ingestion points around the globe, with fiber connections in between, and its own Low Delay Multi-Path protocol to manage transport from encoder to the last mile. This should pay dividends for producers who are shooting in one part of the world and delivering in another.