Title White Paper on DVB-S2 For CCSDS Authors Kuang Tsai, Milton Sue, Don Olsen Date October 2008 Justification Frequency spectrum is becoming more and more congested as more and more wireless and other radio based services are created. A few of the more recent ones include HDTV, cellular phones, and various satellite services, such as communications, navigation, and remote sensing, including weather and other modes of Earth observation. Data accuracy is becoming a driver as finer Earth sensor resolution and more spectral observation bands are needed. All of this is driving the data rates and hence the bandwidth needed to support data transfer. Frequency management agencies such as the ITU, NTIA, FCC, etc., are being asked to allocate more commercial use of highly desirable, formerly government-only bands. Such services in many cases are leasing these bands at considerable cost and thus providing significant revenue to governments. These demands are forcing the frequency management agencies to require better bandwidth- efficient use of what in many cases is a nonrenewable use of radio spectrum. In the wake of the above pressure, the European TV broadcasting and equipment- manufacturing community headed by the Joint Technical Committee (JTC) of the European Telecommunications Standards Institute (ETSI), European Committee for Electrotechnical Standardization (CENELEC), and European Broadcasting Union (EBU) has developed a series of more spectrally efficient standards for video transmission called Digital Video Broadcasting for satellite television (DVB-S). The latest of these is the Second Generation DVB-S, or DVB-S2. Programs that Plan to or Could Benefit from the Use of DVB-S2 Spectral Efficiency Several space programs that are significantly increasing their communication link data rates include: NASA Constellation GOES-R US Air Force AFSCN CNES Pleiades Spot Demeter Parasol Others The US Air Force has been directed to upgrade the L band and added S-band AFSCN links to use more Spectrally Efficient Waveforms. DVB-S2 is currently being considered. Existing Hardware Several modem manufactures have developed modems that support DVB-S and DVB-S2. They include Comtech ef, Raydyne, RT Logic/In-Snec, Alcatel-Lucent, etc. Most of these support the full range of DVB signaling modes. Analysis This white paper documents our support to the AFSCN Program Office pertaining to the development of a Spectral Efficient Waveform (SEW). It provides a set of power spectral density (PSD) and bit error rate (BER) graphs for DVB-S2. These include the DVB-S2 standard block sizes as well as WiMax small-block LDPC-coded waveforms. The paper also details the technical intricacies associated with the development of a set of DVB-S2-compliant simulation tools, and provides the set of full-fledged DVB-S2 BER simulation data specifically called for on behalf of a prospective hardware emulation effort. The AFSCN/SEW development, starting in March 2008, has been a fast-track tool development effort with the dual goals of developing Monte Carlo PSD/BER simulation tools for a collection of LDPC-coded waveform candidates (GMSK, RRC/BPSK, RRC/QPSK, RRC/OQPSK, RRC/8PSK, RRC/16APSK, RRC/32APSK), and generating corresponding simulation data in the presence of a high-power amplifier (HPA) with multiple output back-off (OBO) settings. In a broader context, the square root raised-cosine (RRC) waveform shaping is brought in to provide the desired spectral efficiency over the conventional rectangular- shaped PSK waveforms, and the low-density parity check (LDPC) forward error-correction (FEC) code is brought in to provide further power efficiency by way of coding gain. Gaussian minimum-shift keying (GMSK), on the other hand, requires no RRC-shaping and is a intrinsically spectrally efficient waveform by virtue of being constant-envelope; it is included in the SEW waveform candidate list due to its proven technology maturity in commercial and military applications such as GSM and AEHF. To ensure sufficient coverage of coding gain assessment over a 7-waveform 3-OBO-setting trade space in a 13-week turnaround time, a judicious decision was made to initially confine the scope of the task deliverables to PSD/BER simulation data associated with small-block LDPC codes (i.e., those with a block size around 3K or 4K coded bits) in exchange for a broader range of FEC code rates. Three different LDPC codes, all designed using a well- established progressive-edge-growth (PEG) technique, of three archetypical code rates (0.5, 0.67, 0.75) and block sizes (3456, 4600, 4608) were treated along with three HPA OBO settings. Table 1 summarizes these small-block LDPC cases in terms of the power and bandwidth efficiencies of the underlying coded waveforms. Figure A depicts the classic power-versus-bandwidth efficiency tradeoff for the Table 1 entries associated with OBO = 3dB. Table 1. Power/Bandwidth Efficiency of small-block LDPC-coded Waveforms Family Modulation Chip/Symbol Required Eb/No for BER=1e-6 (dB) 30dB-Bandwidth Efficiency (bps/Hz) Linear OBO=3dB OBO=0dB OBO=PAR Linear OBO=3dB OBO=0dB OBO=PAR LDPC Code Rate GSM GMSK(L=3=1/BT) 1 1.5 1.5 1.5 na 0.39 0.39 0.39 na r=2304/4608= 0.50 AEHF GMSK(L=6=1/BT) 1 2.1 2.1 2.1 na 0.48 0.48 0.48 na r=2304/4608= 0.50 TSAT RRC/BPSK 1 1.5 1.6 2.7 na 0.37 0.36 0.15 na r=2304/4608= 0.50 DVB-S2 RRC/QPSK 2 1.5 1.6 2.2 na 0.74 0.74 0.31 na r=2304/4608= 0.50 NASA RRC/OQPSK 2 1.5 1.6 2.0 na 0.74 0.74 0.33 na r=2304/4608= 0.50 DVB-S2 RRC/8PSK 3 4.3 4.5 5.2 na 1.47 1.47 0.62 na r=2304/3456= 0.67 DVB-S2 RRC/16APSK(12+4) 4 5.5 5.7 8.4 6.9 1.93 1.93 0.83 0.87 r=2304/3456= 0.67 DVB-S2 RRC/32APSK(16+12+4) 5 8.0 9.4 ∞ ∞ 2.72 2.64 1.16 1.29 r=3450/4600= 0.75 Power/Bandwidth Efficiency Tradeoff, Small-block LDPC 10 LTWTA (OBO = 3 dB) 1 Bandwidth Efficiency, bps/Hz 0.1 -2-10123456789101112131415 Eb/No for BER = 1e -6, dB Shannon GMSK(L=6=1/BT) RRC/BPSK RRC/(O)QPSK RRC/8PSK RRC/16APSK(12+4) RRC/32APSK(16+12+4) GMSK(L=3=1/BT) Figure A. Power/Bandwidth Efficiency Trade-off of small-block LDPC-coded Waveforms (OBO = 3dB) While the bandwidth efficiency entries in Table 1 are based on the emblematic 99%-power bandwidth, two alternative bandwidth efficiency entries based on the atypical 30dB and 40dB down bandwidth are given in Table 2 for reference purposes. The bandwidth efficiency entries in both Table 1 and Table 2 reflect the code rates of the underlying LDPC codes. Table 2. Alternative Bandwidth Efficiency of small-block LDPC-coded Waveforms Family Modulation Chip/Symbol 30dB-Bandwidth Efficiency (bps/Hz) 40dB-Bandwidth Efficiency (bps/Hz) Linear OBO=3dB OBO=0dB OBO=PAR Linear OBO=3dB OBO=0dB OBO=PAR LDPC Code Rate GSM GMSK(L=3=1/BT) 1 0.39 0.39 0.39 na 0.26 0.26 0.26 na r=2304/4608= 0.50 AEHF GMSK(L=6=1/BT) 1 0.48 0.48 0.48 na 0.39 0.39 0.39 na r=2304/4608= 0.50 TSAT RRC/BPSK 1 0.37 0.36 0.15 na 0.33 0.10 0.07 na r=2304/4608= 0.50 DVB-S2 RRC/QPSK 2 0.74 0.74 0.31 na 0.67 0.38 0.20 na r=2304/4608= 0.50 NASA RRC/OQPSK 2 0.74 0.74 0.33 na 0.67 0.54 0.28 na r=2304/4608= 0.50 DVB-S2 RRC/8PSK 3 1.47 1.47 0.62 na 1.33 0.74 0.53 na r=2304/3456= 0.67 DVB-S2 RRC/16APSK(12+4) 4 1.93 1.93 0.83 0.87 1.61 0.84 0.52 0.56 r=2304/3456= 0.67 DVB-S2 RRC/32APSK(16+12+4) 5 2.72 2.64 1.16 1.29 2.11 0.88 0.70 0.84 r=3450/4600= 0.75 Fueled by the prospect of conducting a hardware emulation effort using a commercial-off-the- shelf (COTS) DVB-S2 modem, an expansion of task scope occurred mid-way through our small-block LDPC development effort, escalating the SEW task deliverables to also include BER simulation data associated with the DVB-S2 standard blocks. The expanded SEW task scope necessitated the development of a separate set of DVB-S2-specific simulation tools within the same 13-week task time frame, in addition to the ongoing small-block LDPC tool development. Developing tools to perform DVB-S2 simulations in the time allotted was a major undertaking, not to mention the inherently lengthy simulation time needed to generate a single set of full-fledged DVB-S2 BER data with three different HPA OBO settings. This is because, for physical layer simulations, a full DVB-S2 capability dictates a BCH outer codec, an LDPC inner codec, a bit interleaver, a bit-to-symbol mapping, physical layer framing, physical layer scrambling, and filtering. Not only are there a multitude of components, but each component has many options interrelated with those of other components. The BCH outer codec is a high-rate code with a correction capability ranging from 8 to 12 bits, with the code rate and block size dependent upon those of the LDPC inner codec.