A uniquely decodable code is derived for multiple-access in a two-user interference channel, which is defined as a channel with complex input, output and arbitrary phase difference between the two users. The uniquely ...
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A uniquely decodable code is derived for multiple-access in a two-user interference channel, which is defined as a channel with complex input, output and arbitrary phase difference between the two users. The uniquely decodability is achieved by designing a trellis-coded modulation (TCM) pair, that permits the Viterbi decoder to decompose the composite received signal into the two constituent signals uniquely in any state of the noiseless interference channel. Theoretical proof is given, the result is confirmed by computer simulations.
We present previous results making a connection between generalised Reed-Muller codes and Golay (1949) complementary pairs and sets of sequences. We apply this work to obtain a flexible range of OFDM coding schemes en...
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We present previous results making a connection between generalised Reed-Muller codes and Golay (1949) complementary pairs and sets of sequences. We apply this work to obtain a flexible range of OFDM coding schemes enjoying efficient encoding and decoding and tightly controlled peak-to-mean envelope power ratio. We give an outline of previous work on decoding algorithms for these codes.
A new class of labelings and encoders for which the uniform bit error property holds is introduced, and an application to the design of good serially concatenated TCM schemes is presented.
A new class of labelings and encoders for which the uniform bit error property holds is introduced, and an application to the design of good serially concatenated TCM schemes is presented.
This paper describes the application of spectrally efficient phase shaped 8PSK trellis coded modulation (8PSK-TCM) to the 5 and 25 kHz UHF follow-on (UFO) SATCOM channels. The satellite channel is characterized by a m...
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This paper describes the application of spectrally efficient phase shaped 8PSK trellis coded modulation (8PSK-TCM) to the 5 and 25 kHz UHF follow-on (UFO) SATCOM channels. The satellite channel is characterized by a multi-pole linear filter followed by a hardlimiter, zonal filter and traveling wave tube (TWT) amplifier. For the additive white Gaussian noise (AWGN) channel the trellis coding provides about 2.9 dB of coding gain at P/sub be/=10/sup -5/ without bandwidth expansion, however, a high-rate Reed Solomon outer code is used to obtain an additional 1.1 dB resulting in a bandwidth expansion of less than 7%. The performance is examined for symbol rates as high as the channel bandwidth (B/sub c/T/spl ges/1). For operation at lower symbol rates, B/sub c/T>1, the outer code rate is adjusted downwards to fully utilize the channel bandwidth while achieving additional coding gain for disadvantaged terminals, i.e., those with lower C/N/sub 0/ capability. Demodulator equalization is required to minimize intersymbol interference (ISI). Spectral control is achieved by shaping the symbol phase transitions, and the resulting constant envelope waveform exhibits very little spectral re-growth following the satellite bandlimiting and non-linearity. The use of periodically inserted pilot bits to maintain coherent detection with dedicated channel applications also serve as stuff bits for matching the symbol rate to the user data rate and the internal clock. The pilot bits result in a bandwidth expansion of typically 3-5%. The paper describes the performance results based on detailed Monte-Carlo simulations of both the spectral characteristics and the bit-error performance and compares the results with laboratory measurement data.
A very high time domain resolution channel sounder dedicated to the 60 GHz band indoor channel is presented. Based on Cox technique, it provides a 3 ns delay resolution. The value of the sliding factor k and the analy...
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A very high time domain resolution channel sounder dedicated to the 60 GHz band indoor channel is presented. Based on Cox technique, it provides a 3 ns delay resolution. The value of the sliding factor k and the analysed impulse response length are electronically programmable, which allows a maximum Doppler analysis of more than 25 kHz. In all cases, the sampling frequency is minimised and direct PC hard disk storage is set up to perform very long acquisition sequences. Then, both long term and short term analysis of the impulse response are obtained. The first radio propagation measurement results are shown. Moreover, a BER measurement tool is under development. Simultaneous propagation and BER measurements will then be taken.
We examine two paradigms for computing multicomponent AM-FM image models. In channelized components analysis, estimates for one AM-FM component are extracted from each channel of a multiband filterbank. Tracked multi-...
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We examine two paradigms for computing multicomponent AM-FM image models. In channelized components analysis, estimates for one AM-FM component are extracted from each channel of a multiband filterbank. Tracked multi-component analysis represents an image using fewer components by tracking the estimated modulating functions of each component across the filter bank channels. While both approaches work well for synthetic images, they have difficulty with natural images that contain phase discontinuities. We show that phase discontinuities lead to wideband frequency excursions that make the computation of AM-FM models difficult and can also severely degrade the quality of image reconstructions obtained from the models. We use postfilters to ameliorate the effects of the frequency excursions and compute AM-FM models for two natural images.
A new procedure is presented, applied to single-phase DC-AC power converters with bipolar output, in order to perform a programmed harmonic elimination using a previous calculation of notch angles. The method is based...
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A new procedure is presented, applied to single-phase DC-AC power converters with bipolar output, in order to perform a programmed harmonic elimination using a previous calculation of notch angles. The method is based on the transformation of the trigonometric equations system into its equivalent in algebraic form by means of Chebyshev functions. This gives notable advantages in terms of convergence and processing time. Later, a modulation technique is described for single-phase unipolar output power converters, that obtains an additional elimination on the three multiples order harmonic range. Finally, comparative results to the conventional SPWM (sinusoidal pulse width modulation) wave are presented.
For Rayleigh fading channels, the primary code design criterion for a trellis coded modulation scheme is to maximize its effective code length (ECL). This paper concerns the design of optimal (2,1) Z/sub 2/-convolutio...
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ISBN:
(纸本)0780350006
For Rayleigh fading channels, the primary code design criterion for a trellis coded modulation scheme is to maximize its effective code length (ECL). This paper concerns the design of optimal (2,1) Z/sub 2/-convolutional encoders (CE) which, when combined with the continuous phase encoder (CPE) of CPFSK scheme, reaches the upper bound of ECL of a generic trellis coded modulation scheme. We develop sufficient conditions for the optimality of such a CE and the upper bound of the complexity for the test of these sufficient conditions is also shown.
In this paper, the error performance of multilevel (block) coded asymmetric 8-PSK modulations with multistage decoding and unequal error protection (UEP) is analyzed. Upper bounds on the corresponding bit error rates ...
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In this paper, the error performance of multilevel (block) coded asymmetric 8-PSK modulations with multistage decoding and unequal error protection (UEP) is analyzed. Upper bounds on the corresponding bit error rates (BER) are derived by union bound arguments. Also simpler and tighter approximations are evaluated by considering asymmetries and effective nearest neighbors.
A type of serial "turbo code" is investigated, where a differential encoder (e.g., a DPSK modulator) is concatenated with a convolutional code, separated by interleaving. On fading channels, "turbo-DPSK...
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A type of serial "turbo code" is investigated, where a differential encoder (e.g., a DPSK modulator) is concatenated with a convolutional code, separated by interleaving. On fading channels, "turbo-DPSK" has the (perhaps surprising) potential to slightly outperform the performance of coded coherent PSK without differential encoding and perfect channel estimation.
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