September 7, 2017
September 7, 2017
This part (and last) of The Beam-Hopping blog explores the fundamental ecosystem and resource management functions needed to operate a beam-hopping satellite network. we also discuss the satellite operator gains and conclude the whole post. Part One and part two of the series was published a few weeks ago.
The market aspects are as important to the success of the beam-hopping system as the technical aspects. The figure below shows a block diagram of a satellite system supporting, in this case, broadband data transmissions. It describes the main entities that cooperate in forming such a system.
The main player is naturally, the satellite operator (SO) who own and controls the satellite. In addition to the satellite, the SO has the functionalities of satellite telemetry and control (TT&C) and operation management. The SO can provide service directly to end customers, as a Service Provider (SP) and thus operate the whole infrastructure including teleports, which contains means of data accessing the satellite, namely gateways.
Alternatively, the gateways can be connected to a different entity – a virtual service provider (SVNO), which serves the end consumers, and provides them with a point of presence to the Internet via the satellite. in this model, the user terminals can be owned by the SO, licensed by the SO to the ISP’s to provide them to their customers, or licensed by the SO to the end-consumers to be purchased according to the buy your own device (BYOD) model.
Alternative operation model would be that of a Satellite SP, which is a service provider who also owns gateways for directly accessing the satellite. The data path between the Internet and the terminals is made via the ISP (Satellite ISP, virtual SP or SO owned ISP), gateways (SO owned or independent), the satellite and the terminals (consumer-owned, SP owned or SO owned).
As described in part two of this blog, a beam-hopping system requires a strong and accurate synchronization. The synchronization source should be a centralized one distributed to all the gateways, the satellite, and the terminals. Further synchronization can be made by the satellite itself synchronizing to the actual hopping rate. An important component of the system is the beam-hopping planner, the entity that determines the beam hopping transmission plan. It is not a trivial task and can be appreciated by some of the suggested algorithms. It needs at its input the demand requirement from each of the SP entities and provides the plan to the satellite and to the gateways, which allocates beams and time slots for the transmissions.
Optimal usage of the satellite resources requires an intimate knowledge of the satellite capabilities and operation conditions, together with accurate information on the traffic volume and its characteristics, geographical distribution, and distribution in time, as required by the users. Such coupling suggests that a single entity would control both the satellite resource allocation and operation as well as the access to those resources by the ground equipment. From the market point of view, this is a vertical market solution.
On the other hand, a multi-vendor environment has well-known advantages for promoting market development and growth. Such an environment would include satellite operators, service providers and virtual service providers for a variety of applications. To enable such an environment, with multiple entities, a common interface between satellite operators and service providers is required, which would enable the exchange of the needed information between the service providers, each with its own particular use case, and the satellite operator.
Recently, work was initiated in ETSI that studies the need, requirements, content, and structure of a protocol between satellite service provider(s) and satellite operator(s), which conveys the service resources demand of the service provider to the satellite operator and the allocated resources from the operator to the service provider. The results of the study are to be published as a technical report (TR-103-522).
The report describes the capabilities of existing and planned satellites and the flexibility they offer in frequency, bandwidth, power and antenna beams resources. Applications of flexible satellites are given with the particular requirements. Broadband, broadcast, M2M for fixed and mobile land, aeronautical and maritime service are typical applications. The technical report will present a number of use cases for the relations between Service providers and Satellite operators. The technical report will also include a generic reference architecture for a flexible satellite system defining the main building blocks and the interfaces among them, general function requirements and ranges of values of the various parameters related to the interfaces described.
A question raised, who benefits from new beam-hopping technology? Satellite operation changes due to beam hopping yields OPEX and CAPEX cost reduction. How does the satellite operator benefit after investing large initial capital? Beam hopping technology offers the most flexible and efficient way of utilizing ground and space segment resources. This, in turn, optimizes the invested OPEX and CAPEX which increases ARPU and total revenue.
A primary CAPEX saving component is the number of High Power Amplifiers (HPA, i.e TWTAs) operating at any time. Beam Hopping technology reduces redundant (unused) transmission. Beam Hopping uses a single or quad HPA to drive all the beams in time-sharing fashion. thus reducing the satellite payload weight, size, and power (consumption). This decreases the satellite cost and increases the satellite lifespan. Another major cost saving factor is the reduced number of ground segment infrastructure (GWs), required to provide the same capacity, compare to the traditional payload (HTS).
From the OPEX saving point of view, we identify several factors that contribute to the maximization of the system efficiency, the space-segment use:
All translate to more and more competitive and affordable service!
SatixFy is developing an emulator (tested) for the beam hopping, in order to mitigate the risk involved in its implementation by putting in place a beam hopping emulator based on existing hub and terminal hardware, which is modified and enhanced in functionality to serve as a beam hopping emulator.
The emulator will have a number of purposes and phases:
Phase 1: The initial purpose of the testbed will be principally Layer 1 validation, to test the functionality of using DVB-S2X superframe structure as a physical layer enabler for the beam hopping and looking at timing and synchronization.
Phase 2: This will test additional critical components of the architecture, such as directing traffic to appropriate beams (S2X Frame Formatter) and managing system quality of service.
Phase 3: Integration with a beam-hopping payload prototype from a satellite manufacturer. Validation of timing synchronization between the hub and the payload.
In all cases, the Testbed will generate traffic from a single teleport going over an emulated satellite link at L-band. Phase 1 will focus on the ability of the terminals to successfully handle traffic when receiving a non-continuous downstream. The hub will suppress transmission to emulate beam hopping, and the traffic generator will alternate traffic between the remotes. Phase 2 will upgrade the hub equipment to validate beam hopping in conjunction with the quality of service. the Phase 3 will only proceed with the cooperation of the selected satellite manufacturer and will require a lab prototype of the beam-hopping payload.
This testbed can be used together with a satellite operator to demonstrate Beam Hopping (internally and externally), compare the performance with and without BH, compare different types of super-frames, analyze the impact of different BH schedules.
Beam-Hopping provides satellite systems with an additional dimension of agility making it possible to adjust the allocation of the scarce satellite spectral and power resources to the demand which varies in space and geography as well as with time. The advantages of beam hopping compared to conventional and other flexible techniques have been studied and presented in various venues. On the other hand, the technique, which requires a paradigm shift in its operation compared to existing satellite systems, had not found its way into the main track of satellites. Demonstrating the fact that it still needs to gain the confidence of satellite operators and users of satellite services.
In this post, we presented a short summary of the advantages of beam hopping, both in terms of unmet capacity, excess capacity and power consumption. We also described some of the technical issues involved in the implementation, in terms of payload, terminals, and waveform. We showed that solutions for the technical issues, such as network synchronization and terminal burst operation are available today.
An important area that must be addressed is the operational and marketing aspects of beam hopping systems. A beam hopping system requires a high level of synchronization among all transmitters as well as intimate knowledge of the demand requirements in order to be able to provide a transmission plan which is well adapted to the demand. This seems to lead to a vertical market where a single entity operates the satellite as well as providing the service. In order to enable a multi-vendor environment that would reduce the risk of the satellite operator, and increase the opportunities for new market niches and applications, there is a need for defined standard protocol between service providers and satellite operators.
The main technology advantages and the main motivation to embrace and implement Beam- Hopping are well reflected the overall reduced OPEX and CAPEX, compare to traditional HTS satellites.
A key obstacle in the implementation is the confidence of satellite operators and service providers. In order to build up that confidence, SatixFy is now developing a testbed to enable operators and service providers to test and evaluate the system performance within various scenarios and applications. SatixFy is also driving the Eco-System standardization process in ETSI.
How quickly do you expect that Beam Hopping technology to dominate in the SATCOM industry? Share your thoughts in the comments!
Thanks for reading! Please reach out and connect with me here on LinkedIn. A version of this article also appeared on www.satixfy.com/blog