The DVB-S2 coding standard has seen widespread use in many radio frequency (RF) communications applications. The availability of commercial-off-the-shelf (COTS) intellectual property (IP) that can be used to rapidly prototype and field communications systems makes this well-performing, standards-based approach to forward error correction (FEC) coding extremely attractive. In this paper, we evaluate the application of the DVB-S2 coding standard to an asymmetric satellite communications channel. The uplink comprises a fading optical link employing binary differential phase-shift keyed (DPSK) modulation, while the downlink comprises an RF link employing 16-ary amplitude and phase shift keyed (16-APSK) modulation. To simplify the payload implementation, hard-decision uplink demodulation is considered with uplink channel state information transmitted on the downlink for soft-decision decoding in the ground-based receiver. Additionally, we outline many of the trade offs in the overall system design, and some performance results of a baseline design are presented.
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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.
Communication systems must maintain tight timing synchronization between the transmitter and receiver. Systems typically pull-in timing from a large timing offset and then track timing once it has been sufficiently pulled in. When timing errors are large, additional reference symbols are needed to pull-in time. In some frequency hopping systems, the time pull-in step must be repeated for every hop and could occur many times a second. It then becomes important to develop rapid time pull-in algorithms that can operate on a limited number of data and reference symbols. This paper presents two algorithms for rapid time pull-in. The performance as a function of the number of data and reference symbols is shown.
Space-division multiple access communication system architectures employing frame-switching, where ingress frames from one of N ingress ports are switched to one of N egress ports, can support the simultaneous transmission of data from multiple users. If the switched inputs have undergone channel fading, the frame switch may (incorrectly) switch ingress frames to (incorrect) egress ports. When frame switch errors occur, the egress port data streams may contain an incorrect number of data frames and/or erroneous frame sequence numbers resulting in frame synchronization problems at the end receiver associated with that particular egress port. A maximum-likelihood algorithm is employed to run at the end receiver to correctly recover frames and corresponding frames sequence numbers for proper frame synchronization.
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