[Satellite News 11-27-12] Recent advancements in high-throughput Ku-band satellites will allow commercial Ku-based aeronautical mobile satellite systems (AMSS) to equal or exceed commercial Ka-band AMSS systems on cost and performance, according to a study conducted by Panasonic Avionics and LinQuest. The research presents a statement that lies at the very core of how FSS operator Intelsat is trying to refresh attitudes toward Ku-band.

   Though Ku-band currently dominates the AMSS broadband market, its hold on the sector has been and will continue to be challenged by forthcoming Ka-band systems, such as Inmarsat’s Global Xpress offering powered by its new Inmarsat-5 satellites.

   Intelsat Regional Vice President of North American Sales Mark Rasmussen told Satellite News that his company’s collaboration with Panasonic on its new EpicNG open architecture platform would demonstrate the true potential of Ku-band. “In some cases, there’s a perception that the term ‘high-throughput’ is synonymous with Ka-band,” said Rasmussen. “Ku-band, however, has been providing high-throughput services for years.  Systems like Panasonic’s eXConnect, Row 44 and Yonder have been providing high-throughput Ku-band services to the commercial markets with great success. The key to Ka-band high-throughput is not the frequency of operation, but rather the use of spot beams. This means that a Ku-band satellite using similarly sized spot beams can equal or exceed the performance of Ka-band.”

   Intelsat begins the launch of its EpicNG offering with the development of the Intelsat-29e satellite, which includes customized coverage to provide Ku-band AMSS service over North America and the North Atlantic. The spacecraft uses a combination of spot beams for data service in dense regions and wide beams for video and data service in low-density areas.

   “These beams employ a combination of C-, Ku- and Ka-band,” Rasmussen noted, adding that the notion of Intelsat being anti-Ka-band is incorrect due to the fact that Ka-band will play a part in its offering where necessary. “The C-, Ku- and Ka-band combination will provide high-throughput communications for media, broadband, mobility and government service in a way that makes the system interoperable with other types of networks. The high-throughput beams that are supported by Intelsat-29e exceed those of the similar Ka-band systems on Inmarsat-5 as a direct result of using spot beams smaller than 2 degrees.”

   The Panasonic/LinQuest study notes that Ka-band’s almost exclusive association with high-throughput, as well as Ku-band’s association with wide-beam, are more reflective of the progression of the satellite industry rather than the suitability of either bandwidth for high-through applications.

   “Existing Ku-band systems were developed for video distribution and widely dispersed VSAT networks, with mobile services evolving more recently,” report authors Chris McLain and Sunil Panthi from Panasonic and James Hetrick from LinQuest wrote in the study. “By the time high-throughput direct-to-home (DTH) Internet services like SpaceWay and ViaSat-1 were envisioned, all of the prime Ku-band slots had been claimed by incumbent FSS operators, limiting new entrants to previously unused spectrum within Ka-band. Since these services were designed for high-throughput from the beginning, Ka-band is often associated with high-throughput.”

   The report also points out that when it comes to uplink regulatory limits, Ku-band holds a major advantage over Ka-band. “Small mobile terminals are often regulatory limited. The FCC, ITU and other regulatory bodies have established limitations on the off-axis EIRP spectral density (ESD) that may be radiated from a terminal towards adjacent satellites to prevent interference between systems. For historical reasons, these limits vary substantially – the limits for Ku-band exceed the equivalent Ka-band limits by 14 dB.”

   The relative advantage of the Ku-band off-axis limits, however, is somewhat offset by the lower directivity of Ku-band antennas. The report notes that the lower directivity of the Ku-band antenna reduces its advantage in on-axis ESD from 14 dB to 6 dB, but states that the net advantage is still substantial.

   “In the best case for Ka-band, a power limited Ka-band terminal will perform no better than a power limited Ku-band terminal when equivalent size spot beams are used, but may perform considerable worse if the terminals are regulatory limited,” the report authors wrote.

   Rasmussen believes that in addition to EpicNG’s performance potential, the platform will offer smart redundancy, availability and most importantly – scalability. “Almost all of the world’s flight routes are currently covered by at least one Ku-band wide beam and often are covered by several beams,” he said. “This provides an inherent back up to a spot beam satellite. This would not be the case in a system that uses three dedicated satellites to provide global coverage, as the failure of one of those satellites would cause a lengthy outage. High-throughput Ku-band AMSS is scalable into the foreseeable future, as newer satellites will likely be able to support even larger antennas, meaning that our EpicNG spacecraft can continue to scale to higher capacities as traffic grows. A mixed architecture of spot and wide beams will match capacity to demand.”