Beam Hopping — The Next-Generation Satellite Technology
The information in this page is an introduction to the full Next-Generation Satellite Technology paper. Download the full document with the form below
How beam hopping enables the flexibility that is missing in the current generation of satellites and how this technology provides additional revenue opportunities for the next-generation of Ultra High Throughput Satellites (UHTS), that’s the focus of this article.
High Throughput Satellites (HTS) have been a revolutionary satellite technology breakthrough that has occurred over recent years. HTS provided an excellent solution for data unicast/multicast oriented satellite networks. HTS increases the total capacity of the satellite by generating multiple small beams and re-using the available satellite spectrum multiple times. To overcome the interference between adjacent beams, the spectrum is divided to “colors,” which are separated by frequency allocation and polarization.
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A New Satellite Generation
Thirteen years have passed since the first introduction of HTS, and with that debut, the satellite industry has changed as well as usage models and use cases. HTS has enabled the industry to bring a significant reduction in the price of capacity as well as to provide larger amounts of capacity. HTS initiatives have had their fair share of challenges, technical and business. Among these challenges one can count:
- The growth of mobility applications — mostly inflight connectivity and maritime applications, where these applications require large capacity and beam changing, according to the trajectory of the user. HTS architectures struggle to provide high capacity to loaded beams while maintaining coverage to large areas in a cost-efficient manner.
- Low fill factors — an industry that was used to satellites with 70 percent fill factors, or higher, often sees much lower utilization in HTS architectures. Capacity is often not in the right place at the right time. Typically, HTS beams are created equal, while demand on the ground varies according to customer distribution. As a result, many of the beams experience over-capacity, while in others there are unmet capacity requirements and there is no way to institute load balancing. In other cases, demand changes throughout the day and the capacity is fixed. Revenues are lost in saturated beams.
- Increasing competition from terrestrial broadband — as terrestrial broadband — and especially cellular — continues to expand, the satellite industry faces intense competition. This drives satellite operators to lower capacity pricing as well as incorporating lower cost user terminals. To reduce the cost of the capacity, beam size must be reduced. This results in increasing spectrum reuse as well as increasing the effective power of the signal, which has the additional benefit of also reducing satellite terminal cost due to a decrease in the size of the antenna and RF, which are the cost bottlenecks.
- Increased satellite cost while CAPEX investments are stagnant or even declining — while HTS architectures provide more capacity than legacy wide-beam satellites, this comes at an increase of cost. This means that there will be fewer satellites launched and each satellite will be more expensive. At the same time, satellite operators are facing challenging times from their existing business, such as video end enterprise data. All of these conditions drive many satellite operators to reduce their CAPEX investments. A direct outcome is that satellite operators face more uncertainty and risk with decisions regarding HTS — payload design, number of beams, beam planning, coverage areas, and so forth.
Satellite Operators and Service Providers Benefits
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New Exciting Times Ahead
These are exciting times, as the satellite industry is on the verge of introducing a newer generation of UHTS or Terabit satellites. In this new generation of satellites, designed to increase capacity, the coverage will be divided into many more smaller beams. In this manner, each beam will have a higher gain and will enable more capacity at even lower prices.
An additional outcome will be that smaller antennas and RF at the terminals or higher bits/Hz ratio will be enabled through the use of higher MODCODs. However, dividing the coverage to smaller beams increases the probability of having under-utilized beams.
To make Terabit satellites a reality, operators are adding flexibility to overcome the increased uncertainties they face, the most significant being flexibility as to where to allocate the capacity in time and location. This is where beam hopping plays a critical technology role.
What Is Beam Hopping?
The ability to allocate capacity momentarily according to demand and therefore have a flexible capacity mapping is achieved by changing the traditional forward link transmission from continuous to time-based burst. The traditional color separation (frequency/polarization) is replaced by time division multiplexing over a single frequency carrier.
Customer data needs can now be measured constantly and capacity can be allocated to different beams, according to demand. The flexibility is achieved by changing the distribution of capacity in different beams on a time basis using a beam illumination plan that is communicated from the gateway to the satellite and can constantly change (See Figure 2).
The technology foundation for beam hopping has been incorporated into the new DVB-S2X standard, Annex E, which introduces the concept of Super Frames. The ability to receive a forward link carrier in a burst manner is assured by a higher layer of synchronization, which is based on a fixed length Super Frame. There are multiple types of Super Frames defined in the standard, with Super Frame type 4 being the most flexible (See Figure 3).
The Super Frame can hold multiple DVB S2/S2X Baseband frames and allows a guard for the satellite switching between beams.
The use of SF goes handin-hand with an increase in the symbol rate per beam, up-to 500 Msps so that minimal delay is introduced by using a TDM scheme (each Super Frame is ~1 msec long).
For more information and a demonstration, please contact SatixFy