Wavelet Shift-Keying: A New Digital Modulation

Wireless Communications and Mobile Computing, 2005

As proven by the success of OFDM, multicarrier modulation has been recognized as an efficient solution for wireless communications. Waveform bases other than sine functions could similarly be used for multicarrier systems in order to provide an alternative to OFDM.In this paper, we study the performance of wavelet packet transform modulation (WPM) for transmission over wireless channels. This scheme is shown to be overall quite similar to OFDM but with some interesting additional features and improved characteristics. A detailed analysis of the system's implementation complexity as well as an evaluation of the influence of implementation-related impairments are also reported. Copyright © 2004 John Wiley & Sons, Ltd.

Canadian Conference on Electrical and Computer Engineering 2004 (IEEE Cat. No.04CH37513), 2004

This paper introduces a Multi-Wavelet Packet Modulation (MWPM) which is a multi-band multi-dimensional modulation scheme with a flexible dyadic time-frequency tiling. The proposed MWPM can be considered as a generalization of orthogonal frequency division multiplexing (OFDM) or wavelet packet multiplexing (WPM). Gompared to OFDM, the bandwidth eficiency of MWPM is increased T times for the multi-wavelet packets with multiplicity of r . In addition, the effects offrequency-selective wireless channels and high peak to average power ratio (PAPR) in OFDM can be mitigated in the new scheme by properly designing the MWPM dyadic structure. The implementation based on T x r matv+xfilters for MWPM is also presented in which the fast Mallat algorithm is eztended into the vector form. To demonstrate MWPM effectiveness in wireless communication systems, this paper investigates the performance of M-ary &AM signaling combined with MWPM in different sub-bandg for the additive white Gaussian noise (AWGN) channel, the slow flat Rayleigh fading channel and the Nakagamim fading channel. With its advantages, the MWPM is a potential candidate for adaptive implementations in time varying and time dispersive fading channels.

2016

Recently, issues surrounding wireless communications have risen to prominence because of the increase in the popularity of wireless applications. Bandwidth problems, and the difficulty of modulating signals across carriers, represent significant challenges. 2 Abdullah Almuttiri, Centre for Electronics and Communications Engineering, 1.05 Queens Building, De Montfort University, Leicester, LE1 9BH, United Kingdom. Appendix B: Journal Articles 266 | P a g e Every modulation scheme used to date has had limitations, and the use of the Discrete Fourier Transform in OFDM (Orthogonal Frequency Division Multiplex) is no exception. This paper investigates a new modulation scheme called OWDM “Orthogonal Wavelet Division Multiplex”, which utilizes the wavelet transform as a substitute to Fourier transforms in OFDM. This paper comprehensively investigates the new modulation scheme, and proposes multi-level dynamic sub-banding as a tool to adapt variable signal bandwidths. Furthermore, all compa...

The Third Advanced International Conference on Telecommunications (AICT'07), 2007

Based on the good time-frequency localization of the pulse shaping, it is possible to build a multicarrier modulation that reduces both narrowband interferences and multipath channel interferences. In this paper, the given solution is based on wavelet theory: wavelet packet based multicarrier modulation is introduced and compared to the useful Orthogonal Frequency Domain Multiplexing (OFDM) modulation in a wireless environment with narrowband interferences and multipath channel interferences. Simulations show that the use of wavelet is more robust to narrowband interferences than the OFDM modulation. For multipath transmission, simulations show that the use of complex wavelet outperforms the use of real one and outperforms the OFDM modulation when the cyclic prefix technique is not used.

International journal of computer applications, 2013

An investigation into the wavelet packet transform (WPT) modulation scheme for Multiple Input Multiple Output (MIMO) band-limited systems is presented. The implementation involves using the WPT as the base multiplexing technology at baseband, instead of the traditional Fast Fourier Transform (FFT) common in Orthogonal Frequency Division Multiplexing (OFDM) systems. An investigation for a WPT-MIMO multicarrier system, using the Alamouti diversity technique, is presented. Results are consistent with those in the original Alamouti work. The scheme is then implemented for WPT-MIMO and FFT-MIMO cases with extended receiver diversity, namely 2 ×Nr MIMO systems, where Nr is the number of receiver elements. It is found that the diversity gain decreases with increasing receiver diversity and that WPT-MIMO systems can be more advantageous than FFT-based MIMO-OFDM systems.

Orthogonal Frequency Division Multiplexing (OFDM) is very efficient technique used for high data rate digital communication system. It is a special type of multicarrier modulation. Conventionally Fourier Transform (FFT) is used in OFDM to generate orthogonal subcarriers. The orthogonality is destroyed if the transmitted signal is exposed to multipath environment. To maintain orthogonality cyclic prefix is added to each symbol before transmission. But this addition reduces the spectral efficiency of the system. In this paper a comparison is done between conventional OFDM and recently proposed wavelet based OFDM. Wavelet has been emerged as replacement of Fourier Transform. The wavelet Transform has several advantages over Fourier Transform because it can provide time and frequency resolution simultaneously. Many modulation schemes are implemented to compare both the systems. After comparisons and discussion based on their performance in simulation it is concluded that wavelet transform is better choice for OFDM systems. Keywords- DWT-OFDM, FFT-OFDM, Fourier Transform, Wavelet Transform.

International Journal of Engineering Sciences & Research Technology, 2013

Success of Orthogonal Frequency Division Multiplexing (OFDM) has proved that Multi carrier modulation is an efficient solution for mobile communication. Wavelet Packet based Multi-Carrier Modulation (WPMCM) offers an alternative to the well-established OFDM as an efficient multicarrier modulation technique. Wavelet Packet Modulation (WPM) is a new type of modulation for transmission of multicarrier signal on mobile channel that uses orthogonal wavelet bases other than sine functions. It has strong advantage of being generic transmission scheme whose actual characteristics can be widely customized to fulfill several requirements and constraints of advanced mobile communication systems.

2013

In this paper, a different scheme of encoding digital data using wavelet functions instead of sinusoidal waves is explained. Data communications use various modes of encoding the data bits into a frequency signal. Phase shift keying of various forms such as Binary Phase Shift Keying, Quaternary Phase Shift Keying, etc., are in vogue in several current communication schemes, such as Global system for mobile communication. Errors in bits at the received end through a wireless channel are common in such data communication. These errors are mainly caused by improper phase changes in the detected audio signal. Since the method presented here with the use of wavelet functions provides several clues for identification of the data symbol instead of just by one criterion viz., the phase of the carrier as in the Phase shift keying schemes, this method is found to be better in performance. Simulation of the scheme was made with Matlab and the results provide an improved bit error ratio. Also, ...

… , IEEE Transactions on, 2007

Over the past three decades, the scientific and industrial communities have injected considerable resources into perfecting Orthogonal Frequency Division Multiplex (OFDM) -the driving technology behind many applications used today (such as IEEE 802.11g, Asymmetric Digital Subscriber Line (ADSL), and Digital Terrestrial Television). In 1997, OFDM was officially sanctioned for use in the European Telecommunications Standards Institute (ETSI) EN 300 744 standard known as Digital Video Broadcasting -Terrestrial (DVB-T).

Lecture Notes in Computer Science, 2010

With the rapid expand of wireless digital communications, demand for wireless systems that are reliable and have a high spectral efficiency have increased too. Orthogonal Frequency Division Multiplexing (OFDM) has been recognized for its good performance to achieve high data rates. Fast Fourier Transforms (FFT) has been used to produce the orthogonal sub-carriers. Due to the drawbacks of OFDM-FFT based system which are the high peak-to-average ratio (PAR) and the synchronization, many works have replaced the Fourier transform part by wavelet transform. In this paper, an efficient technique for the OFDM system using wavelet transform is proposed. This system shows a superior performance when compared with traditional OFDM-FFT systems through an Additive White Gaussian Noise (AWGN) channel. The system performance is described in Bit Error Rate (BER) as a function of Signal to Noise Ratio (SNR) and the peak-to-average ratio (PAR). Furthermore, the proposed system gives nearly a perfect reconstruction for the input signal in the presence of Gaussian noise.