Ground Segment 2.0: Making the Most of Space

It’s a technological breakthrough: High Throughput Satellites (HTS) can provide 20 times more total throughput than a classic FSS bird for the same amount of allocated orbital spectrum. This feat significantly reduces the cost per bit, effectively obliterating the end-user notion that satellite is “too expensive,” an old belief that has had an unattractive darkness hang over the industry for far too long. Indeed, it is an exciting time for the satellite industry.

Of course, this achievement has come with its share of challenges. To start, the design of HTS demands more complex infrastructure. But the real challenge is that HTS payloads are steadily adding flexibility into the payload design, capacity reuse, and dynamic allocation of resources. This directly translates to complications for the ground segment, namely in ground station architecture, Radio Frequency (RF) signal monitoring, network management, service quality management, and even satellite command and control. The HTS-induced implications are not just a matter of scale, but evoke a new paradigm that requires tools that are more intelligent, automated and robust.

“We need tools that can support more customers, more capacity, more flexibility and more dynamic usage. The industry’s continuous HTS progress will challenge the ground segment to stay in sync to deliver and support these capabilities,” says Stuart Daughtridge, vice president of advanced technology at Kratos.

The call for next-generation-level tools has brought about devices to tackle challenges in RF Quality of Service (QoS) monitoring and interference, in addition to other vital instruments. How HTS will affect interference is seen through varied perspectives. One is that the small HTS beams are more difficult to jam, resulting in a reduction of intentional interference. While this is laudable by military and broadcast users, the fact is that the majority of interference is inadvertent. Placing so many high-powered beams and satellites closely together, targeting more VSATs with smaller dishes and the growth of mobile applications requiring dynamic pointing, increases the likelihood of interference from misconfigurations and miss-aligned antennas.

“Addressing this, as well as the challenges associated with signal monitoring, led to the development of lower cost sensors for use with HTS. At Kratos, we leveraged our Monics carrier monitoring system technology to develop Monics 200. Designed for spot beam monitoring, Monics 200 provides operators with economical, yet highly versatile digital signal processing-based RF sensors, which automatically determine modulation type, symbol rate, measured Eb/No, and detection and analysis of interfering signals. This is important in that it gives the operator all of the capability of a full Monics sensor, but at a much lower price point because the sensor is specifically designed for the more targeted needs of HTS spot beam monitoring,” explains Daughtridge.

New Tools Call for More Tools

The challenge in HTS signal monitoring is that you can’t simply scale up the signal monitoring done for a regular satellite that has a handful of beams. Monitoring HTS, with 70 or more separate beams, requires the deployment of much lower cost sensors designed to monitor multiple smaller beams from a signal site. Additionally, the monitoring systems need to provide the operator a way to effectively manage all of the data from the different sensors and the sensors themselves. Advanced visualization and management tools are required to provide the operator with the information needed to quickly identify, characterize and rectify problems when they occur.

For this, Kratos developed the Monics Enterprise Manager (MEM), which addresses the critical and complex management and situational analysis of hundreds, if not thousands of spot and traditional beams as well as the growth in services that is expected with HTS. In addition, MEM automates the configuration and management of the Monics 200 sensors to reduce operator workload and improve system performance.

Another challenge is in signal processing. Satellite ground systems have always required their signal processing — that usually being modems — to be physically located close to the antenna/RF system. This is due to the Intermediate Frequency (IF) signal degrading the further it travels. HTS, with all of the spot beams, require numerous gateways and associated signal processing centers, but sometimes the optimum locations for the antenna/RF systems and the signal processing systems are not the same. Antenna/RF systems are best located in places where there is little around to cause interference. Signal processing centers need to be connected to a robust terrestrial infrastructure. Fortunately, new technologies such as digital IF break the collocation requirement, allowing the antenna/RF systems and the signal processing centers to be optimally located for their requirements, while only requiring a standard IP network connection between the sites.

In addition to tools, collaborative planning between equipment providers and satellite providers needs to be stepped up, explains Keith Buckley, president of ASC Signal Division of Communications & Power Industries (CPI ASC Signal), adding that without adequate preparation, adjacent satellite interference cannot be mitigated and the advantage of HTS cannot be gained.

“To enable more powerful HTS capabilities and to ensure success, satellite providers must give appropriate consideration to proper planning and spatial separation between satellites. If they do not do so, ground equipment providers will need complex filtering and narrower beam widths, and overloading of downlink systems might occur. Ground equipment providers need to be a part of the discussion with satellite providers to avoid these issues and help achieve the promise of HTS,” says Buckley.

While identifying the capacity users’ need to have more efficient links is a challenge posed by HTS, Buckley says that ground segment providers must continually strive to achieve lower costs per bit. The industry, he adds, will need higher-gain, multi-band antennas and better tracking capabilities.

“From a more technical angle, gain stable and accurately tracking ground equipment are necessary for reliable operation on HTS. There is a trend toward larger gateways, seeking maximum Effective Isotropic Radiated Power (EIRP) and gain-to-noise-temperature (G/T), in HTS applications. This results in the challenge of gain stability and tracking, which can also force an adjustment in maintenance procedures. Also, with higher-power spacecraft and the larger antennas, there is a tendency of oversaturation of low-noise block downconverters and low-noise amplifiers, which limits the performance and uplink capability of the gateway,” adds Buckley.

CPI ASC Signal has made significant gains through new tracking systems that are integrated into its line of high-performance, multi-band antennas. For Ka-band and above, its Sub-Reflector Tracking (SRT) system coupled with monopulse tracking feed systems are controlled with its Next Generation Controller (NGC) using a highly-accurate, built-in tracking receiver. By combining these technologies, antenna users can track to within 1/1000th of a degree accuracy while compensating for thermal degradation of the main reflector. This keeps the link as solid as possible, while reducing the need for excess bandwidth for margin.

Teleport Tie-Ups

From cooperation to partnerships, HTS can greatly benefit the teleport sector, explains Sergey Raber, COO at CETel. As HTS delivers much more bandwidth than conventional satellites, terrestrial infrastructure needs to be adjusted accordingly. Terrestrial connections to major network backbones at the teleport need to be upgraded to higher bandwidths. At the same time, some HTS require multiple, geographically distributed terrestrial gateways for optimal service availability and highest efficiency. This means additional teleport locations might be required to fully use the potential of HTS. And this is where partnerships come into play.

“With our partner teleports in Europe and around the world we can make use of a network of terrestrial gateways to provide a global footprint to our customers. HTS is a great example of how these partnerships can be of mutual benefit for both service providers and is a key driver for end-customers,” says Raber.

CETel has also entered into partnerships with hardware manufacturers and software developers. Applications and access methods need to be adjusted for optimal utilization of new technological opportunities, which are becoming possible with new generation satellites. Hardware manufacturers and software developers can tailor connectivity solutions to desired applications to offer customers the most out of services in terms of availability and performance.

Likening the trials of HTS to cellular operators tackling frequency reuse at terrestrial base stations, Dave Rehbehn, vice-president of international marketing at Hughes, says that the biggest challenge is to achieve the lowest possible cost per bit, all while designing in the flexibility to deliver capacity where it is needed through deployment of spot beams. There are always trade-offs, he says, with the ultimate goal being to dynamically allocate capacity as needed and maximize profitability. Bandwidth efficiency, lights out gateways and high performance terminals are the key drivers that translate into increased revenue through delivery of a wider range of service offerings and lower operational cost.

To achieve these advantages, Hughes created its Jupiter platform, which was designed in concert with the Echostar 17 satellite that took off in 2012. Being as flexible as possible, the ground system can be implemented by all operators, whether on conventional satellites or HTS. For operators with HTS plans on the horizon, it can be positioned for a seamless migration to future HTS operations. With the Jupiter system, Hughes is able to operate a single carrier over a 250 MHz channel at a rate as high as 1 Gbps. This enables extremely high efficiencies on Hughes’ own satellites as well as on its partners’ Telefonica Media Networks Latin America and the Russian Satellite Communications Corporation (RSCC).

“More HTS systems will go into service in the next three years. This is a big deal in the satellite industry because, previously, capacity was typically optimized for data communications instead of video, and video or images is what everyone wants to send and receive over the Internet. Achieving lower cost per bit and delivering the bits where needed is the ‘Holy Grail’ for VSAT operators. Not surprisingly, satellite operators around the world are either planning to put in HTS capacity or are seriously thinking about it. As a consequence, we are going to see more high quality, cost-effective capacity being deployed over the next several years and an expanded addressable market opportunity for satellite broadband globally. These are exciting times; a great time to be in the satellite industry,” concludes Rehbehn.

Ground Segment Wish List

The top item on CPI ASC Signal’s wish list is, of course, for users and teleports to continue embracing its network of next-generation controllers industry-wide. Users moving to this control platform for their antennas would improve overall accuracy in a networked configuration by measurable factors, says Keith Buckley, president of CPI ASC Signal’s division of communications. The goal of achieving better control of antennas and generating more efficient links through antennas that “talk” to each more efficiently is not just what Buckley wants, but is also desired at teleport and operational levels, he adds.

“We also would like to see links become less limited. We believe that a higher order [Third-Order Intercept Point] 3OIP performance from low-noise block downconverter and low-noise amplifiers is needed with HTS applications. Current solutions are not in sync with HTS performance requirements. This places a handicap on the overall ground segment link budget,” says Buckley.

Sergey Raber, COO at CETel, touches on the significant developments in the area of satellite multiple access technologies seen in recent years.

“I personally wish that in the end we could get a technology that can effectively distribute satellite bandwidth among users with various requirements from the shared bandwidth pool with advanced Quality of Services (QoS) and security levels. This is something the manufacturers are still working on and I really expect some promising enhancements in the near future,” says Raber.

Stuart Daughtridge, vice president of advanced technology at Kratos, has his eye on improving Service Level Agreements (SLA) and QoS performance. “We are investing in IP over everything, virtualization of the ground system including signal processing and antenna assets, and more Big Data analytics tools to better mine network and RF data to improve SLA and QoS performance,” says Daughtridge.

Dave Rehbehn, vice president of international marketing at Hughes, wants electronically steered antennas, highlighting such an item’s benefits.

“High on our list is the development of low-cost electronically steered antennas. Today, our parabolic antennas are low cost but they need to be manually pointed and the pointing accuracy may be impacted over time by wind or other factors. Electronically steered antennas can lower the initial cost of installation and we can always be ensured the antenna is optimally pointed no matter what happens over the life of the installation. This new class of antennas could also open up many new opportunities for communications on the move that today are not economically viable,” says Rehbehn.

_{Adrienne Harebottle is a media specialist and freelance writer for the space, satellite and telecommunications sectors.}