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multirate coding for mobile communications link adaptation

IEE PROCEEDINGS-COMMUNICATIONS 1997年第3期144卷 211-216页

作者： Atungsiri, SA Tateesh, S Kondoz, A UNIV SURREY CTR COMMUN SYST RESGUILDFORD GU2 5XHSURREYENGLAND

A mobile communication system that uses multirate source and channel coding is capable of trading off the source coder bit rate against the channel coder rate to optimise performance over a wide range of channel conditions. This link adaptation enables a mobile station to maintain reasonable speech quality even during marginal carrier to interference ratio conditions. The paper details the design and evaluation of a quad-rate speech and channel coder optimised to provide wireless Link adaptation by seamless rate switching.

关键词： link adaptation multirate coding speech coding universal mobile telecom

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multirate DISTRIBUTED SOURCE coding IN WIRELESS SENSOR NETWORK USIND LDPC CODES

MULTIRATE DISTRIBUTED SOURCE CODING IN WIRELESS SENSOR NETWO...

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22nd IEEE Canadian Conference on Electrical and Computer Engineering

作者： Rezayi, Elham Abolhassani, Bahman Iran Univ Sci & Technol Tehran Iran

ISBN: (纸本)9781424435098

Energy conservation in wireless sensor networks (WSNs) is the primary performance parameter, because of their limited energy resources. Thus, some energy saving technologies should be applied. One of these technologies for WSNs is distributed source coding (DSC), related to correlation between sensor outputs. In this paper, we propose to apply multirate distributed source coding to reduce energy consumption for a target BER value. Low Density Parity Check (LDPC) code is one of the practical codes that can be used for DSC to compress close to Slepian-Wolf limit. The simulation results for codes of length 1000 and three different compression ratios show that the proposed multirate approach achieves better energy efficiency rather than a single rate code with similar maximum BER value.

关键词： wireless sensor networks distributed source coding multirate coding Low-Density Parity-Check

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multirate DIGITAL-FILTERS, FILTER BANKS, POLYPHASE NETWORKS, AND APPLICATIONS - A TUTORIAL

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PROCEEDINGS OF THE IEEE 1990年第1期78卷 56-93页

作者： VAIDYANATHAN, PP Dept. of Electr. Eng. California Inst. of Technol. Pasadena CA

The basic concepts and building blocks in multirate digital signal processing (DSP), including the digital polyphase representation, are reviewed. Recent progress, as reported by several authors in this area, is discussed. Several applications are described, including subband coding of waveforms, voice privacy systems, integral and fractional sampling rate conversion (such as in digital audio), digital crossover networks, and multirate coding of narrowband filter coefficients. The M-band quadrature mirror filter (QMF) bank is discussed in considerable detail, including an analysis of various errors and imperfections. Recent techniques for perfect signal reconstruction in such systems are reviewed. The connection between QMF banks and other related topics, such as block digital filtering and periodically time-varying systems, is examined in a pseudo-circulant-matrix framework. Unconventional applications of the polyphase concept are discussed

关键词： M-band quadrature mirror filter QMF banks block digital filtering building blocks digital audio digital crossover networks digital filters encoding errors filter banks filtering and prediction theory fractional sampling rate conversion multirate coding multirate digital signal processing narrowband filter coefficients periodically time-varying systems polyphase networks signal processing signal reconstruction subband coding voice privacy systems

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Approaching near-capacity on a multi-antenna channel using successive decoding and interference cancellation receivers

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JOURNAL OF COMMUNICATIONS AND NETWORKS 2003年第2期5卷 116-123页

作者： Sellathurai, M Guinand, P Lodge, J Commun Res Ctr Ottawa ON K2H 8S2 Canada

In this paper, we address the problem of designing multirate codes for a multiple-input and multiple-output (MIMO) system by restricting the receiver to be a successive decoding and interference cancellation type, when each of the antennas is encoded independently. Furthermore, it is assumed that the receiver knows the instantaneous fading channel states but the transmitter does not have access to them. It is well known that, in theory, minimum-mean-square error (MMSE) based successive decoding of multiple access (in multi-user communications) and MIMO channels achieves the total channel capacity. However, for this scheme to perform optimally, the optimal rates of each antenna (per-antenna rates) must be known at the transmitter. We show that the optimal per-antenna rates at the transmitter can be estimated using only the statistical characteristics of the MIMO channel in time-varying Rayleigh MIMO channel environments. Based on the results, multirate codes are designed using punctured turbo codes for a horizontal coded MIMO system. Simulation results show performances within about one to two dBs of MIMO channel capacity.

关键词： multiple-input multiple-output (MIMO) turbo codes successive decoding interference cancellation per-antenna rates multirate coding minimum-mean-square error (MMSE)

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New speech processing issues in IP telephony

New speech processing issues in IP telephony

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16th World Computer Congress (WCC 2000)

作者： Beritelli, F Casale, S Ruggeri, G Dipartimento Ingn Informat & Telecomunicaz I-95125 Catania Italy

ISBN: (纸本)0780363949

In the field of IP Telephony there are various problems to be dealt with before the QoS currently guaranteed by PSTN networks can be achieved. Tn this paper we discuss the main causes of degradation in the quality of conversation in an IP communication scenario. We then point out some new QoS problems involved in speech processing. More specifically, two important aspects of discontinuous transmission are dealt with: the impact of the VAD on source throughput and the need for an efficient system of comfort noise. In addition, in a Differentiated services (DiffServ) scenario we demonstrate the importance of using a multirate intrastandard codec, together with valid criteria for the reconstruction of lost frames.

关键词： IP Telephony speech coding voice activity detection comfort noise generation multirate coding

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A scalable bandwidth extension algorithm

A scalable bandwidth extension algorithm

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32nd IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Berisha, Visar Spanias, Andreas Arizona State Univ Dept Elect Engn SenSIP Ctr Tempe AZ 85287 USA

ISBN: (纸本)1424407281

Most modern bandwidth extension techniques predict the high- frequency band based on features extracted from the lower band. While this works for some frames, problems arise when the correlation between the low and the high band is insufficient. In these situations, additional high-band information must be sent to the decoder. In this paper, we propose a scalable speech coding method based on the principles of bandwidth extension. The rate selection is based on explicit psychoacoustic criteria, while the bandwidth extension is performed using a constrained MMSE estimation technique. Objective and subjective evaluations indicate that the proposed system performs at a lower average bit rate when compared to other similar algorithms while improving speech quality.

关键词： bandwidth extension multirate coding scalable speech coding speech enhancement psychoacoustics

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New Speech Processing Issues in IP Telephony

New Speech Processing Issues in IP Telephony

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2000 International Conference on Communication Technology(WCC2000·ICCT2000)

作者： F.Beritelli S.Casale G.Ruggeri Dipartimento di Ingegneria Informatica e delle Telecomunicazioni Viale A.Doria 6 95125 Catania-Italy

In the field of IP Telephony there are various problems to be dealt with before the QoS currently guaranteed by PSTN networks can be *** this paper we discuss the main causes of degradation in the quality of conversation in an IP communication *** then point out some new QoS problems involved in speech processing. More specifically,two important aspects of discontinuous transmission are dealt with:the impact of the VAD on source throughput and the need for an efficient system of comfort *** addition,in a Differentiated services(DiffServ) scenario we demonstrate the importance of using a multirate intrastandard codec,together with valid criteria for the reconstruction of lost frames.

关键词： IP Telephony speech coding voice activity detection comfort noise generation multirate coding

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