Showing papers on "Bandwidth expansion published in 2017"

Effective Spectral and Excitation Modeling Techniques for LSTM-RNN-Based Speech Synthesis Systems

Abstract: In this paper, we report research results on modeling the parameters of an improved time-frequency trajectory excitation (ITFTE) and spectral envelopes of an LPC vocoder with a long short-term memory (LSTM)-based recurrent neural network (RNN) for high-quality text-to-speech (TTS) systems. The ITFTE vocoder has been shown to significantly improve the perceptual quality of statistical parameter-based TTS systems in our prior works. However, a simple feed-forward deep neural network (DNN) with a finite window length is inadequate to capture the time evolution of the ITFTE parameters. We propose to use the LSTM to exploit the time-varying nature of both trajectories of the excitation and filter parameters, where the LSTM is implemented to use the linguistic text input and to predict both ITFTE and LPC parameters holistically. In the case of LPC parameters, we further enhance the generated spectrum by applying LP bandwidth expansion and line spectral frequency-sharpening filters. These filters are not only beneficial for reducing unstable synthesis filter conditions but also advantageous toward minimizing the muffling problem in the generated spectrum. Experimental results have shown that the proposed LSTM-RNN system with the ITFTE vocoder significantly outperforms both similarly configured band aperiodicity-based systems and our best prior DNN-trainecounterpart, both objectively and subjectively.

Bandwidth expansion in channel coexistence

Abstract: Aspects of the present disclosure relate to methods and apparatus for bandwidth expansion in channel co-existence situations. An example method generally includes determining information regarding loading of at least one of downlink (DL) or uplink (UL traffic at a first base station that can share at least some bandwidth with at least one neighbor base station, and modifying bandwidth of one or more channels used by the first base station based, at least in part, on the loading information.

Joint Source–Channel Coding for Broadcasting Correlated Sources

Abstract: This paper studies lossy transmission of a memoryless bivariate Gaussian source over a bandwidth-mismatched memoryless Gaussian broadcast channel with two receivers, where each receiver is interested in reconstructing only one source component. For both bandwidth expansion and compression regimes, novel hybrid digital/analog (HDA) coding schemes are proposed. With appropriate choice of parameters, our schemes are shown to specialize to separate source–channel coding studied by Gao and Tuncel, and is, therefore, superior to it in both bandwidth regimes. Our scheme for bandwidth expansion also outperforms the HDA coding scheme of Behroozi et al. On the other hand, if a proposed conjecture (supported by numerical observations) is indeed true, the same superiority follows for the bandwidth compression regime as well. Finally, when the bandwidth expansion/compression ratio approaches 1, both of our schemes become optimal as their performance approaches that of the bandwidth-matched scheme of Tian et al.

Channel negotiation method, stations and channel negotiation system

Abstract: The invention discloses a channel negotiation method, stations and a channel negotiation system. The channel negotiation method comprises the steps of transmitting channel reserving request information which comprises bandwidth expansion instructing information, wherein the bandwidth expansion indicating information is used for instructing a receiving station to perform bandwidth expansion feedback; and transmitting data to the receiving station according to the response bandwidth of the receiving station, wherein the response bandwidth of the receiving station is fed back by the receiving station in the channel reserving request information.

Practical implementation of duobinary pulse position modulation using FPGA and visible light communication

Abstract: Low bandwidth expansion modulation schemes are preferred for free space and optical fibre data transmission, where limited bandwidth is available. One such scheme is duobinary pulse position modulation (DuoPPM), which is the subject of this paper. DuoPPM scheme is not as sensitive to bandwidth expansion issues as digital PPM, with a line rate of twice the data rate. This paper discusses first time practical implementation of DuoPPM coding scheme and its application in free space using visible light LED (30 W) for transmission purposes. Experimental results achieved at the data rate of 14 Mbit/s indicate an error rate that is better than 1 error in 109. The main aim is to analyse the practicality, robustness and limitations of DuoPPM.

Distortion bounds for source broadcasting and asymmetric data transmission with bandwidth expansion

Abstract: We consider the broadcasting of a single Gaussian source over a two-user Gaussian broadcast channel with bandwidth expansion. In addition to the source broadcasting the encoder sends a message reliably to the “higher quality” user. Conditioned on the message rate, we derive an outer bound on the set of attainable mean-squared error distortion pairs at the two users which extends the Reznic-Feder-Zamir bound. Based on the outer bound and an inner bound that we derive we characterize the set of achievable energy-distortion exponents for this problem.

Pilot design for channel estimation in a long-tap faster-than-Nyquist signaling transmission

Abstract: Faster-than-Nyquist (FTN) techniques offer a transmission rate beyond that of Nyquist criterion without imposing bandwidth expansion. On the other hand, orthogonality among modulated pulse shapes can be destroyed because of the FTN signaling, whereupon inter-symbol interference (ISI) appears, and hence an irreducible error floor occurs. This paper presents the optimal pilot design for channel estimation in FTN signaling transmissions. By taking advantage of an additional cyclic prefix, the resultant ISI imposed by FTN signaling can be approximated by a finite-tap circulant matrix structure, which allows us to employ an efficient fast Fourier transform operation and a low pilot-ratio based frequency-domain channel estimation algorithm. Both analytical and simulation results show that the proposed design is especially beneficial for practical long-dispersion channel scenarios.

Bandwidth expansion method of stereo audio and apparatus thereof

Abstract: The invention discloses a bandwidth expansion method of a stereo audio and an apparatus thereof. The method comprises the following steps of decomposing a stereo signal into a direct sound and a diffusion sound; according to a preset frequency band expansion method, carrying out bandwidth expansion on the diffusion sound; separating the direct sound into a plurality of point sound sources of different orientations, and carrying out bandwidth expansion on the plurality of point sound sources so as to acquire the plurality of point sound sources after the bandwidth expansion; remixing the plurality of point sound sources after the bandwidth expansion according to pre-estimated orientation information so as to the direct sound after the bandwidth expansion; according to the direct sound after the bandwidth expansion, combining the diffusion sound after the bandwidth expansion to reconstruct a broadband stereo audio signal. In the prior art, according to subjective quality of a single sound channel reconstruction signal, signal bandwidth expansion is realized, and correlation of signal energy and a phase in two sound channels is not considered so that a reconstructed stereo signal seriously influences determination of a listener to a sound source position and a distance. In the technical scheme of the invention, the above problem is solved.

The Dispersion of Universal Joint Source-Channel Coding for Arbitrary Sources and Additive Channels

Abstract: We consider a joint source channel coding (JSCC) problem in which we desire to transmit an arbitrary memoryless source over an arbitrary additive channel. We propose a mismatched coding architecture that consists of Gaussian codebooks for both the source reproduction sequences and channel codewords. The natural nearest neighbor encoder and decoder, however, need to be judiciously modified to obtain the highest communication rates at finite blocklength. In particular, we consider a unequal error protection (UEP) scheme in which all sources are partitioned into disjoint power type classes. We also regularize the nearest neighbor decoder so that an appropriate measure of the size of each power type class is taken into account in the decoding strategy. For such an architecture, we derive ensemble-tight second-order and moderate deviations results. Our first-order (optimal bandwidth expansion ratio) result generalizes the seminal results by Lapidoth (1996, 1997). The dispersion of our JSCC scheme is a linear combination of the mismatched dispersions for the channel coding saddle-point problem by Scarlett, Tan and Durisi (2017) and the rate-distortion saddle-point problem by the present authors, thus also generalizing these results.

Audio bandwidth expansion method and expansion apparatus thereof

Abstract: The invention discloses an audio bandwidth expansion method and an expansion apparatus thereof. The method comprises the following steps of detecting a coding mode of a current frame signal in a mixing ACELP/TVC core encoder so as to distinguish a signal type; based on the signal type, selecting adaptive high frequency reconstruction strategies for voice and music signals respectively; if the signal is the voice signal, adopting a bandwidth expansion method based on LPC; and if the signal is the music signal, adopting a frequency band copy bandwidth expansion method based on a high and low frequency signal correlation. The expansion apparatus comprises a signal type detection module, a voice signal bandwidth expansion module and a music signal bandwidth expansion module. In the invention, characteristics of different signal types are fully considered; and from an aspect of the signal type, audio recovery quality is increased and high frequency reconstruction can be accurately performed.

Hybrid digital-analog coding with bandwidth expansion for correlated Gaussian sources under Rayleigh fading

Abstract: Consider communicating a correlated Gaussian source over a Rayleigh fading channel with no knowledge of the channel signal-to-noise ratio (CSNR) at the transmitter In this case, a digital system cannot be optimal for a range of CSNRs Analog transmission however is optimal at all CSNRs, if the source and channel are memoryless and bandwidth matched This paper presents new hybrid digital-analog (HDA) systems for sources with memory and channels with bandwidth expansion, which outperform both digital-only and analog-only systems over a wide range of CSNRs The digital part is either a predictive quantizer or a transform code, used to achieve a coding gain Analog part uses linear encoding to transmit the quantization error which improves the performance under CSNR variations The hybrid encoder is optimized to achieve the minimum AMMSE (average minimum mean square error) over the CSNR distribution To this end, analytical expressions are derived for the AMMSE of asymptotically optimal systems It is shown that the outage CSNR of the channel code and the analog-digital power allocation must be jointly optimized to achieve the minimum AMMSE In the case of HDA predictive quantization, a simple algorithm is presented to solve the optimization problem Experimental results are presented for both Gauss-Markov sources and speech signals

Idea of all-digital I/Q modulator

Abstract: The polar RFDAC of the preceding chapters was commercially proven for narrowband wireless cellular modulation standards. However, due to the unavoidable bandwidth expansion, it is less attractive in wideband modulation standards. This chapter proposes a method to convert the previously described all-digital RFDAC into the in-phase/quadrature (I/Q) configuration that avoids the bandwidth expansion. The key idea is a 25% duty-cycle clocking.

Implementation and Performance Analysis of Trellis Coded Modulation in Additive White Gaussian Noise

Abstract: Band-limited channels face a serious challenge in modern communication due to the need to increase transmission rate while bandwidth remains the same. Mobile communications including mobile satellite, wireless mobile and indoor wireless communication all need to transmit at a higher rate. Trellis-coded Modulation (TCM) is a modulation and error control scheme that allow band-limited and/or power limited channels to attain an efficient data rate without an increase in bandwidth. It is an advanced mode of convolutional coding that combines digital modulation and error correction coding in a single stage. This project sought to investigate the performance of TCM in Additive White Gaussian Noise, modelling a mobile wireless channel. To do this, trellis codes are digitally modulated with M-ary PSK and M-ary QAM using computer simulation (MATLAB) and the performance is evaluated when the modulated signals propagates through additive white Gaussian Noise. Experiments were also carried out on hardware equipment using Telecommunication Instructional Modeling System (TIMS). The plot of bit error rate against \( E_{b} /N_{0} \) showed that there is a significant coding gain at no extra cost of bandwidth expansion.

On Robust and Energy-Limited Joint Source-Channel Coding

Abstract: Author(s): Koken, Erman | Advisor(s): Tuncel, Ertem | Abstract: In this thesis we investigate the lossy transmission of single and bivariate Gaussian sources over bandwidth-mismatched additive Gaussian white noise and broadcast channels. For these scenarios we proposed novel hybrid digital/analog based joint source-channel coding schemes which generalize or outperform existing schemes. In the first scenario we assume that side information is available at the receiver, channel state information of additive interference is available at the transmitter, and power is limited. For this scenario we proposed hybrid digital/analog schemes, for both bandwidth expansion and bandwidth compression cases, which can attain the optimum reconstruction levels. For bandwidth expansion we showed that the scheme can attain optimum distortion levels for a set of receivers with different side information and channel qualities simultaneously with a single set of scheme parameters. In the second scenario, where no side information or interference are present, we consider the robustness of scheme where it must attain the optimal distortion at a target signal-to-noise-ratio and we would like to attain the best distortion pair for two possible receivers one with better and the other with worse channel quality. We extended Tian et al.’s result to a set of non-integer bandwidth expansion ratios. Then we investigate the transmission of bivariate sources over broadcast channels. For this scenario we proposed a scheme which outperforms the known schemes which are either purely digital or hybrid schemes. Finally we analyzed energy-distortion tradeoff for lossy transmission of a Gaussian source over bandwidth-unlimited channel. We performed asymptotical analyses as signal- to-noise-ratio goes to infinity. We also considered zero-delay transmission of the source.

Code-aided antenna selection for spectrally shaped DFT-precoded OFDM spatial modulation

Abstract: In this paper, we investigate coded antenna selection for spectrally shaped Spatial Modulation (SM). Spectrally shaped SM aims at reducing the complex envelope fluctuations. This is done at the expense of a bandwidth expansion given by a roll-off factor β when root raised cosine (RRC) spectral filtering is considered. Nevertheless, this extra redundancy can be exploited by enabling the use of redundancy on the bit antenna selection stream. Indeed, we can associate a high performance error correcting code with a corresponding rate R = γ+β used to encode antenna selection bits and thus, we can achieve better performance at the receiver. Simulation results show that the proposed scheme exhibit a lower peak-to-average power ratio (PAPR) compared with the conventional SM scheme while achieving enhanced performance and diversity when an efficient coding scheme is used to improve antenna selection.

Optimal Design Methodology for Frequency Compensation Circuits in Logging Cable Transmission Channel

Abstract: Bandwidth limitation is a vital problem for high-speed data transmission in logging cable telemetry systems (LCTSs). This paper proposes a frequency compensation method with an analog circuit design, possessing high flexibility and robustness. Analytical expressions are derived for the relationship between pole-zero and gain, deviations caused by high temperature; and are then verified via simulation. To address the efficacy of the circuit design, a real case with low computation complexity and high accuracy is proposed and employed. The case of a 7km LCTS shows frequency compensation with a 200% bandwidth expansion — from 160kHz at −55dB of the original cable to 300kHz at −3dB — and a 60dB improvement in high frequency gain. After comparing the signals with and without compensation, the improvements in transmission performance by the proposed pre-emphasis circuit and equalizer are confirmed.

Digital baseband of the polar transmitter

Abstract: This chapter focuses on the baseband part of the digital polar transmitter. It takes binary data stream and provides mapping to appropriate offset 8-PSK symbols. Pulse shaping filter is used to shape the spectrum of output I/Q waveforms to comply with EDGE frequency spectrum specifications. CORDIC is used to convert this data from Cartesian domain to polar (amplitude/phase) domain. This conversion results in bandwidth expansion for phase path, which is explained in Section 3.5 . INL nonlinearity of the DPA is corrected by a predistortion scheme, covered in Section 3.2 . Self-calibration of the predistortion is covered in Section 3.3 . Predistorted amplitude/phase data is upcoverted to >100 MHz sampling rate. Amplitude information is passed to DPA and phase information is processed by DCO. Quantization and sampling rates for each block are derived based on the overall spec requirements—thus this chapter serves as an example for polar transmitter datapath design.

Hybrid Source-Channel Coding with Bandwidth Expansion for Speech Data

Abstract: Hybrid digital-analog (HDA) architectures have been widely developed for efficient digital transmission of analog speech, audio or video data. By considering the advantage of both digital and analog components, HDA systems gain better performances than purely analog and digital schemes in a wide range of channel conditions. However, HDA systems described in previous works are mostly designed for continuous-valued sources. In this paper, we address the problem of transmission of discrete sources over noisy channels. In particular, our work focuses on digital speech data in PCM format. We proposed two analog schemes, linear mapping, and non-linear mappings. The linear analog mapping employs an equal error protection scheme while the non-linear mapping takes into account the heterogeneous nature of error values to provide better protection to important values. The experiment results show that our HDA systems provide a better performance on a wide range of channel qualities in comparison with traditional purely digital systems.

Design of Adaptive Active Constellation Extension (ACE) algorithm for PAPR reduction in MIMO Systems

Abstract: One of the effective methods used for reducing Peak to Average Power Ratio (PAPR) in MIMO - OFDM systems is Adaptive Active Constellation Extension Algorithm. The proposed scheme is employed with Quadrature Phase shift keying (QPSK). One of the big advantages is that the side information does not need to be sent to the receiver. The Adaptive ACE method is the most attractive scheme due to its good system performance and simplicity, also effectively reduces Peak-to-Average Power Ratio (PAPR) for different modulation formats and subcarrier sizes without any complexity increase and bandwidth expansion