Get Smart - Smart FEC vs. Carousel: Solving the Mobility Challenge

Over decades, KenCast built a first-class reputation for perfecting file and stream delivery for some of the world’s most demanding customers. Our Application Layer FEC is renowned for its extremely high efficiency correcting errors via supplemental packets generated pre-transmission and sent together with the source data. Now, KenCast raises the bar by solving the mobility challenge -- ensuring reliable content delivery to receivers in-an-out of coverage.

With Smart FEC, all of the transmitted packets are supplemental/error correction packets and no source packets are sent out. This patented innovation achieves exceptional bandwidth efficiency, savings, timeliness and reliability -- not only for vehicles but for fixed sites as well.

The three examples below illustrate why Smart FEC is, well, smarter.

Unpredictable Links, Predictable Inefficiency

Interference causes vehicles on the move to move transmissions.   In this scenario, a file is transmitted once in five segments with each containing roughly 20% of the total data. Unfortunately, a tree canopy prevents the car from receiving the second and third segments. The transmission failed.

The file is sent in a continuous loop. As before, interference causes the car to miss transmissions –tree canopy, tunnel, a rainstorm and parking garage. It is not until the 4th transmission that the car receives the 3rd segment for a complete file. Compared with a single transmission, carousel delivery has a higher probability of success, but it’s inefficient. It will likely take multiple transmissions, increasing delivery costs. We only show a single car but thousands are more realistic. More vehicles require more transmissions to ensure 100% of all car receives 100% of a file.

Here is how we solve this challenge.

The solution

Instead of traditional FEC, KenCast Smart FEC packets are used -- unique FEC packets that were generated from the source material. The same obstacles appear but this car doesn’t need the 1st segment, 2nd segment and so on. As long as it receives five total segments Smart FEC can reconstruct the complete file. It is timely and reliable, saving bandwidth and costs!

If typical FEC, LL-FEC and AL-FEC, works by solving for holes in a file or stream with supplemental data packets generated prior to transmission, KenCast's latest innovation uses all supplemental packets at transmission - there is no original file data.  This smart innovation increases bandwidth efficiency when multicasting content to fixed sites (removing the need for carouseling content) but it is invaluable when sending to receivers in-and-out of coverage, such as groups of moving vehicles (such as airplanes traversing spot beams).

Smart FEC vs. Carousel: A Tale of Two Roads

Here is a side-by-side comparison.

Stuck in the Loop with Redundant Data

The above chart, based on a live demonstration that KenCast provides for customers at trade shows, tells a revealing story. Both systems begin receiving the same 60-second file transmission. At 18 seconds, a coverage loss occurs (e.g., entering a tunnel), lasting until 48 seconds. By the 60-second mark, both vehicles have received about half the file. But then something unexpected happens.

From 61 seconds onward, only one line keeps rising: the green line representing Fazzt Smart FEC. The blue line—the system using traditional carousel transmission—stalls.

Why doesn’t it keep increasing? Why isn’t more of the file being received?

The carousel system is still receiving data—but it’s just a repeat of the first transmission. It’s sending the same original packets again, which the receiver already has. No new file percentage is added because there’s nothing new to fill the missing gaps.

Meanwhile, Fazzt Smart FEC is delivering unique repair packets, enabling the receiver to reconstruct the missing data. By 94 seconds, the file is complete. The carousel system never finishes.

Multiply this outcome across hundreds or thousands of receivers, and the consequences of using traditional carousel FEC become clear: wasted bandwidth, stalled deliveries, and failed results. In contrast, Smart FEC ensures that every second of regained signal counts — delivering fresh, non-redundant packets that bring the receiver closer to full file recovery.

This moment after 60 seconds is the turning point: one system moves forward, the other loops in place. It's not just a technical difference — it's the difference between completion and failure.

The Smart Way to Stream, Scale, and Succeed

With the demands for mobility, digitization, improved terrestrial throughput and real-time streaming applications only set to increase, content distributors need to look closely at their current distribution methods and ensure they have access to the best and most complete broadband multicast/ unicast solutions on the market.  Be Smart.