Wavelet Packet Division Multiplexing Research Articles

Joint SCMA and waveform optimisation for WPDM‐based logging cable telemetry systems under sampling clock offset

This study introduces sparse code multiple access (SCMA) and wavelet packet division multiplexing (WPDM) to logging cable telemetry systems (LCTSs). The authors study the feasibility of SCMA for LCTSs and provide a WPDM-based system model, as well as the associated optimal waveform design under sampling clock offset (SCO) via a genetic algorithm. The performance advantages of the designed scheme over the conventional WPDM and orthogonal frequency division multiplexing (OFDM) are demonstrated by both analytical and simulation methods. Numerical results show the performance of the SCMA-based mapping method over quadrature amplitude modulation in terms of improved spectral efficiency. Furthermore, the new scheme outperforms conventional WPDM and OFDM in bit error rate performance and transmission rate under SCO. Such advantages with the flexible design of basis functions make SCMA and WPDM a significant candidate for LCTSs.

Design of Dynamic Wavelet Packet Division Multiplexing

At the reception of wireless communications the wavelet packet-division multiplexing (WPDM) has shown susceptibility to multipath fading. Inspired by WPDM, this paper proposes a new scheme of multiplexing, which has been called “Dynamic Wavelet Packet-Division Multiplexing (DWPDM)”, that allow adapt to the channel conditions and improve their performance both in time-variant as time-invariant channels. The proposed scheme also allow increase the quality of service and improve the security of transmission of binary message thanks to the random variation in the time of the carries or wavelet packet functions. The scheme were evaluated by simulation in three communication scenarios: AWGN channel, selective fading channel and slowly-varying notch channel, showing improvement compared with WPDM, Branch-Hopped WPDM and WOFDM.

System and Waveform Design for Wavelet Packet Division Multiplexing-based Visible Light Communications

This study introduces the wavelet packet division multiplexing (WPDM) to visible-light communication (VLC) system. We provide the transceiver system model for the WPDM-based VLC, as well as the associated optimal waveform design under the lighting emitting diodes (LEDs) dispersion. The dispersion specific to each LED shows that such waveform design is done in an offline manner. Numerical results show the performance gain of the WPDM over the OFDM, in terms of improved out-of-band power leakage, smaller PAPR, more robust to LED nonlinearity and the channel dispersion. Moreover, the optimized waveform for the LED distortion shows performance gain over the conventional wavelet function, e.g., Daubechies wavelet functions. Such advantages make WPDM a good candidate for future VLC systems.

On the Efficient Broadcasting of Heterogeneous Services over Band-Limited Channels: Unequal Power Allocation for Wavelet Packet Division Multiplexing

Multiple transmission of heterogeneous services is a central aspect of broadcasting technology. Often, in this framework, the design of efficient communication systems is complicated by stringent bandwidth constraint. In wavelet packet division multiplexing (WPDM), the message signals are waveform coded onto wavelet packet basis functions. The overlapping nature of such waveforms in both time and frequency allows improving the performance over the commonly used FDM and TDM schemes, while their orthogonality properties permit to extract the message signals by a simple correlator receiver. Furthermore, the scalable structure of WPDM makes it suitable for broadcasting heterogeneous services. This work investigates unequal error protection (UEP) of data which exhibit different sensitivities to channel errors to improve the performance of WPDM for transmission over band-limited channels. To cope with bandwidth constraint, an appropriate distribution of power among waveforms is proposed which is driven by the channel error sensitivities of the carried message signals in case of Gaussian noise. We address this problem by means of the genetic algorithms (GAs), which allow flexible suboptimal solution with reduced complexity. The mean square error (MSE) between the original and the decoded message, which has a strong correlation with subjective perception, is used as an optimization criterion.

A power-based unequal error protection system for digital cinema broadcasting over wireless channels

This paper deals with the efficient and robust wireless broadcasting of JPEG2000 digital cinema (DC) streams from studios to theatres. Several unequal error protection (UEP) techniques have been proposed in literature for the transmission of JPEG2000 images. Some are based on variable forward error correction (FEC) coding applied to different parts of the stream according to their importance. Alternatively, UEP can be achieved by means of unequal power allocation (UPA) schemes based on differentiated transmission power over the stream. On the other hand, in DC applications UPA achieves weak performance if considered as the only protection strategy, unless high-power budget is assigned to transmission. This work proposes a novel hybrid FEC–UPA system adopting the resilience tools of the JPEG2000 wireless (JPWL) standard. The JPWL stream is partitioned into a certain number of packet groups to which “light” FEC coding is applied. Groups are then transmitted through separate wavelet packet division multiplexing (WPDM) sub-channels at different power. Both stream partitioning and UPA are driven by the sensibilities of the JPWL packets to the channel errors. The novelty of the proposed technique relies on the use of JPWL error resilience tools for the codestream partitioning, on optimized UPA among JPWL packets based on genetic algorithms (GA) and supported by “light” FEC channel coding. The proposed system is compared to the state of the art UEP techniques on JPEG2000 transmission. The performance is evaluated in case of transmission over wireless channels with both sparse and packet error statistics. Experiments show that the proposed approach allows achieving an average peak signal-to-noise ratio (PSNR) on the reconstructed frames compliant to the standard quality required by DC applications (40 dB) for bit error rate (BER) up to 10 −4.

Optical Wavelet Signals Processing and Multiplexing

We present compact integrable architectures to perform the discrete wavelet transform (DWT) and the wavelet packet (WP) decomposition of an optical digital signal, and we show that the combined use of planar lightwave circuits (PLC) technology and multiresolution analysis (MRA) can add flexibility to current multiple access optical networks. We furnish the design guidelines to synthesize wavelet filters as two-port lattice-form planar devices, and we give some examples of optical signal denoising and compression/decompression techniques in the wavelet domain. Finally, we present a fully optical wavelet packet division multiplexing (WPDM) scheme where data signals are waveform-coded onto wavelet atom functions for transmission, and numerically evaluate its performances.

A Novel Wavelet Packet Division Multiplexing Based on Maximum Likelihood Algorithm and Optimum Pilot Symbol Assisted Modulation for Rayleigh Fading Channels

Wavelet packet division multiplexing (WPDM) is a high-capacity, flexible, and robust multiple-signal transmission technique. In this paper, a novel WPDM system based on optimum pilot symbol assisted modulation (OPSAM) and a maximum likelihood (ML) algorithm is studied for Rayleigh fading channels. The ML detecting algorithm and the new discrete wavelet packet transform structure, which is based on pilot symbol assisted modulation (PSAM) using a least mean squares algorithm, are two novel aspects of the presented system. An expression for the bit error rate of the WPDM scheme on quadrature phase-shift keying (QPSK) is derived in the presence of flat fading and Gaussian noise. It is demonstrated by simulation results that the OPSAM WPDM scheme can provide greater immunity to flat fading channels and Gaussian noise than the OPSAM orthogonal frequency division multiplexing scheme, the differential QPSK WPDM scheme, and the normal PSAM WPDM scheme.

Performance of wavelet packet-division multiplexing in impulsive and Gaussian noise

Wavelet packet-division multiplexing (WPDM) is a high-capacity, flexible, and robust multiple-signal transmission technique in which the message signals are waveform coded onto wavelet packet basis functions for transmission. We derive an expression for the probability of error for a WPDM scheme in the presence of both impulsive and Gaussian noise sources and demonstrate that WPDM can provide greater immunity to impulsive noise than both a time-division multiplexing scheme and an orthogonal frequency-division multiplexing scheme.

Wavelet packet division multiplexing and wavelet packet design under timing error effects

Wavelet packet division multiplexing (WPDM) is a multiple signal transmission technique in which the message signals are waveform coded onto wavelet packet basis functions for transmission. The overlapping nature of such waveforms in time and frequency provides a capacity improvement over the commonly used frequency division multiplexing (FDM) and time division multiplexing (TDM) schemes while their orthogonality properties ensure that the overlapping message signals can be separated by a simple correlator receiver. The interference caused by timing offset in transmission is examined. A design procedure that exploits the inherent degrees of freedom in the WPDM structure to mitigate the effects of timing error is introduced, and a waveform that minimizes the energy of the timing error interference is designed. An expression for the probability of error due to the presence of Gaussian noise and timing error for the transmission of binary data is derived. The performance advantages of the designed waveform over standard wavelet packet basis functions are demonstrated by both analytical and simulation methods. The capacity improvement of WPDM, its simple implementation, and the possibility of having optimum waveform designs indicate that WPDM holds considerable promise as a multiple signal transmission technique.