High-throughput Satellite Communication

DVB-S2X Demodulator IP for Professional Equipment

DVB-S2 is widely adopted in satellite broadband (»satellite internet«) for the user downlink and in many interactive or professional peer-to-peer networks. Compared to DVB-S2 developed and specified in the early 2000s, DVB-S2X is a state-of-the-art, backwards-compatible extension and superset, providing higher spectral efficiencies and new features to enable or promote new applications in the professional receiver and modulator/demodulator (MODEM) market.

Satellite communication is a multi-billion market, with dozens of satellites being launched each year, providing terabytes of capacity worldwide. The lion’s share of this capacity is used in direct-to-home (DTH) broadcast, followed by the emerging satellite broadband market using high-throughput satellites (HTS). Professional equipment is used in these mainstream markets in some cases like in-flight entertainment and connectivity and in the military domain (MILCOM). The remainder of the professional market is typically on bandwidth-lease transponders and used for a plurality of applications, including remote site connectivity, backhauling, news and data gathering.

With DVB-S2X replacing DVB-S2 and becoming a »must have«, the subsequent section provides further insight into

  • why to upgrade an existing professional MODEM platform to support DVB-S2X;
  • where DVB-S2X is demanding in terms of resources and implementation effort; and
  • how DVB-S2X technology and IP available at Fraunhofer IIS may be advantageously used in a product design.

Special attention is on the needs of equipment manufactures active in satellite and non-satellite communication markets, currently evaluating why, where and how to add DVB-S2X support into their products.

Why DVB-S2X for professional MODEMs?

Satellite communication can be anything from a tiny communication link into the middle of nowhere to the backbone technology for direct-to-home (DTH) TV broadcast or internet access. Compared to competing terrestrial or wireless technologies, satellite communication has its unique advantage whenever alternative infrastructure is technically not feasible, not yet deployed or incurs prohibitive investment cost per site.

For these markets, the advantages from using DVB-S2X are twofold:

  • Improved performance and spectral efficiency, squeezing more sellable capacity out of the same amount of spectrum, or, vice versa, lowering cost per bit.
  • Additional features, allowing more robust communication and enabling new applications and use cases.

Furthermore, especially the industrial and MILCOM markets demand for standardization and mix and match of equipment from different vendors. Midterm, »DVB-S2« equipment will require the new »DVB-S2X« label or runs the risk of being disqualified in a tender.

For a professional equipment vendor, DVB-S2X is both an opportunity for selling additional and replacement MODEMs, but also a challenge and burden of getting one more technology implemented and products validated and supported. Sooner or later this leads to the decision to make or buy following the assessment of risk, investment cost, time-to-market and market opportunity.

Where’s the difference in a DVB-S2X MODEM?

Figure 1 shows a block diagram of a generic DVB-S2X receiver. The complexity and bandwidth of the receiver is primarily defined by the maximum carrier size supported in the front end. Support for higher order modulations (e.g. 16APSK to 256APSK) requires careful control of the data path bit-widths to minimize quantization noise, including complex algorithms in the de-mapper for producing »soft« log-likelihood ratios (LLR) information for use in the subsequent LDPC decoder. LDPC decoding is an iterative process, where the decoder converges after a number of iterations, providing quasi-error free data. There are various implementation options for the LDPC decoder, including use of »early termination« strategies and internal parallelism to speed up the decoding process and to meet the required throughput.

Compared to a demodulator the resources required in a modulator scale more gracefully with supported carrier size and MODEM throughput. Moreover, DVB-S2X reuses the physical layer frame structure and signaling fields from DVB-S2 and carries DVB-S2X super-frame data in DVB-S2 data frames. Thus, the DVB-S2X specific signaling and spanning of a super-frame structure mainly affects higher (software) layers of the MODEM.

Generic DVB-S2X Receiver
© Fraunhofer IIS

Fig. 1: Generic DVB-S2X receiver

Deciding on the right implementation solution

Besides resource and performance, a DVB-S2X implementer is usually concerned about selecting the right features for a product and the target market. Although of only medium complexity and size, implementing the DVB-S2X standard may be complicated by the variety of different target applications and services and the richness in features – normative, optional or not applicable depending on target application and service.

Therefore, a professional receiver maker not only has to decide on the supported feature set to be implemented and tested, but also on the trade-off between throughput, complexity and price of the platform, while keeping the implementation loss at a minimum. There is no one size fits all solution, and a professional receiver supporting 100 Mbps on a bandwidth-lease transponder using a high-gain ground antenna should be different from a mobile receiver using a low aperture dish. Both receivers will be very different from a receiver designed for processing a 500 MHz carrier and handling in excess of 2 000 Mbps under high SNR conditions.

DVB-S2X chips available on the market today are designed for use in DTH receivers. As such, they are limited in output, throughput and the number of service streams made available. As for DVB-S2, the offer in pure MODEM chips is declining, as the satellite MODEM has become part of a larger system on chip (SoC). Optimization for high volume technically and commercially complicates the integration of such a SoC into a professional product.

Besides readymade silicon, DVB-S2X IP for integration into FPGA is the alternative way to go. Many professional MODEMs are already »software defined«, using configurable FPGA hardware for physical layer processing. There is some limited offer in DVB-S2X IP on the market today; however, the true challenge is to fit such IP to the requirements of the product and the available resources on the MODEM without sacrificing throughput and performance.

DVB-S2X: Be smart, get it right and get it done

Thorough understanding of DVB-S2X technology, the market needs and the constraints of the target application is vital for the right selection of the features and for building a unique and successful product. Thus, as a professional equipment manufacturer, benefit from Fraunhofer IIS’ background and know-how when evaluating DVB-S2X as an extension to your product portfolio and when drafting the product’s DVB-S2X features and capabilities in detail.

Implementing DVB-S2X easily consumes person-years of effort, not even counting functional validation and tuning the decoder performance. Adoption of a validated and field tested implementation minimizes technical and schedule risks. Contact us for an evaluation of a field tested FPGA receiver implementation. Discuss customizations, throughput scaling and evaluate with us how DVB-S2X fits and performs on an existing hardware platform.

Time-to-market is essential staying ahead of competition and for timely return of investment. Fraunhofer IIS offers a readily available DVB-S2X receiver implementation using Annex E, format 4 (super-framing) that can be quickly tailored for different products and throughput ranges, up to the maximum spectral efficiency supported by DVB-S2X on wideband carriers. Different licensing options are available on request.