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Multiple-Bit Differential Detection of Shaped-Offset QPSK
, 2007
"... We consider multiple-bit differential detection (MBDD) of differentially encoded shaped-offset quadrature phase-shift keying (SOQPSK), a highly bandwidth-efficient and popular constant-envelope modulation. We propose two MBDD schemes that are based on a recent continuous phase modulation interpreta ..."
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We consider multiple-bit differential detection (MBDD) of differentially encoded shaped-offset quadrature phase-shift keying (SOQPSK), a highly bandwidth-efficient and popular constant-envelope modulation. We propose two MBDD schemes that are based on a recent continuous phase modulation interpretation of SOQPSK. We show that the performance of these MBDD schemes approaches that of coherent detection (CD) as the multiple-bit observation window N increases. The first scheme uses a detection window that spans the full N-bit observation window (F-MBDD), and is shown to require very large values of N to approach the performance of CD. This presents a practical problem since the complexity of MBDD grows exponentially with N. The second scheme is an improved version (I-MBDD) with a detection window that is shortened to N − 2 bit intervals. Although the complexity of I-MBDD also increases exponentially with N, it represents a significant improvement since only modest values of N are needed for high performance. These performance characteristics are identified via a detailed performance analysis, which provides asymptotic formulas for the bit error probability that are confirmed with computer simulations. The analysis is also used to find the symmetric frequency pulse shapes with the best and worst error performance. Finally, we develop a simplified and practical decision feedback differential detection algorithm that achieves near-optimal performance with complexity that grows only linearly with N.
Simplified Detection Techniques for Serially Concatenated Coded Continuous Phase Modulations
, 2007
"... Serially concatenated coded (SCC) systems with continuous phase modulations (CPMs) as recursive inner codes have been known to give very high coding gains at low operative signal to noise ratios (SNRs). Moreover, concatenated coded systems with iterative decoding approach the bit error rate bounds g ..."
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Cited by 2 (0 self)
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Serially concatenated coded (SCC) systems with continuous phase modulations (CPMs) as recursive inner codes have been known to give very high coding gains at low operative signal to noise ratios (SNRs). Moreover, concatenated coded systems with iterative decoding approach the bit error rate bounds given by the maximum likelihood criterion at a lesser complexity. However, when highly bandwidth efficient CPMs are used, they pose two fundamental problems — extremely high decoding complexity and carrier phase synchronization. Desirable properties of SCC systems and their subsequent applications to deep space communication has renewed research interests to look for possible solutions to the above problems. Several complexity reduction techniques have been surveyed in this thesis to address the problem of efficient detection at low SNR operation of the SCC systems. Perfect synchronization at the receiver is often times a delusive assumption. This makes non-coherent detection an attractive option. A heuristic and practical non-coherent detection algorithm is proposed for moderate phase noise environments, which result in huge savings in complexity compared to the
Parameter Estimation Bounds and Preamble Designs for SOQPSK Waveforms
, 2010
"... In this paper, we derive joint parameter estimation bounds for the symbol timing offset, carrier phase, and carrier frequency offset for any shaped offset quadrature phase shift keying (SOQPSK) waveform. Specifically, we calculate the conditional Cramér-Rao bound (CCRB) for a known given data sequen ..."
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In this paper, we derive joint parameter estimation bounds for the symbol timing offset, carrier phase, and carrier frequency offset for any shaped offset quadrature phase shift keying (SOQPSK) waveform. Specifically, we calculate the conditional Cramér-Rao bound (CCRB) for a known given data sequence and compare this to the modified Cramér-Rao bound (MCRB) for the case in which the data pattern is unknown and random. This allows us to assess the performance of candidate preamble waveforms for parameter acquisition. We show how to simplify the CCRB when the preamble waveform is periodic and compare the CCRB performance of several candidate preambles to the MCRB. For the Telemetry Group (TG) variant of SOQPSK (i.e., SOQPSK-TG), we specifically show that certain candidate preambles can offer substantial improvements over the MCRB in terms of symbol timing offset estimation with negligible adverse impact on the estimation of the carrier phase and carrier frequency offset.
Date Approved
, 2014
"... Dummynet is a link emulator that can be used by itself, as well as integrated within testbeds such as Emulab. Despite its popularity in the research community, Dummynet still lacks the ability to precisely emulate certain real network e↵ects. In particular, it has no support for packet reordering. S ..."
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Dummynet is a link emulator that can be used by itself, as well as integrated within testbeds such as Emulab. Despite its popularity in the research community, Dummynet still lacks the ability to precisely emulate certain real network e↵ects. In particular, it has no support for packet reordering. Since reordering is a common and prevalent network phe-nomenon just like packet loss or delay, it cannot be ignored when implementing emulators if we want to provide realistic emulation. It has been observed that networks su↵er from reordering caused by packet striping, retransmissions, load balancing, multipath forwarding, etc. This has significant nega-tive e↵ects on the performance of both Transmission Control Protocol (TCP) and User Datagram Protocol (UDP). With the increase in prevalence of real-time streaming UDP applications such as video conferencing and Internet Protocol Television (IPTV), it has become important to focus on this problem which a↵ects the performance of all these applications. Research into models and tools to diagnose and understand reordering requires that a sophisticated metric be used to describe it.
Serially Concatenated Coded Continuous Phase Modulation for Aeronautical Telemetry
, 2008
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Synchronization Techniques for Burst-Mode Continuous Phase Modulation
"... ii Synchronization is a critical operation in digital communication systems, which establishes and maintains an operational link between transmitter and the receiver. As the advancement of digital modulation and coding schemes continues, the synchronization task becomes more and more challenging sin ..."
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ii Synchronization is a critical operation in digital communication systems, which establishes and maintains an operational link between transmitter and the receiver. As the advancement of digital modulation and coding schemes continues, the synchronization task becomes more and more challenging since the new standards require high-throughput functionality at low signal-to-noise ratios (SNRs). In this work, we address feedforward synchronization of continuous phase modulations (CPMs) using data-aided (DA) methods, which are best suited for burst-mode communications. In our transmission model, a known training sequence is appended to the beginning of each burst, which is then affected by additive white Gaussian noise (AWGN), and unknown frequency, phase, and timing offsets. Based on our transmission model, we derive the Cramér-Rao bound (CRB) for DA joint estimation of synchronization parameters. Using the CRB expressions, the optimum training sequence for CPM signals is proposed. It is shown that the proposed sequence minimizes the CRB for all three synchronization parameters asymptotically, and can be applied to the entire
iNET PREAMBLE DETECTOR PERFORMANCE IN THE PRESENCE OF MULTIPATH INTERFERENCE
"... The iNET preamble can be used to estimate the frequency offset and multipath channel in an aeronautical telemetry link. To accomplish this, the receiver must be able to identify the start of the preamble within the received data stream in the presence of uncompensated frequency offset and unknown mu ..."
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The iNET preamble can be used to estimate the frequency offset and multipath channel in an aeronautical telemetry link. To accomplish this, the receiver must be able to identify the start of the preamble within the received data stream in the presence of uncompensated frequency offset and unknown multipath channel. In this paper, we explore the performance of seven candidate preamble detectors in the presence of a frequency offset and over multipath channels typically en-countered in aeronautical telemetry. A non-coherent post-detection integration (NCPDI) detector considered in this paper demonstrates the best detection performance for a reduced complexity.
