Last years, Wavelet Packet Modulation (WPM) or Wavelet Packet Transform based Orthogonal Frequency Division Multiplexing (WPT-OFDM) have been introduced to wired and wireless communication fields as efficient Multicarrier Modulation (MCM) techniques. The wavelets have interesting features such as flexibility, compatibility and localization in both time and frequency domains with no need to use rectangular window function. As a result, the transmitted signal is naturally less sensitive to inter-symbol and inter-carrier interferences (ISI and ICI). Also, it is possible to implement OFDM modulation without adding cyclic prefix (CP) and it is enough only to use time domain or overlap frequency domain equalization (TEQ or overlap FEQ) in order to shorten the effective channel impulse response length with the purpose of avoiding the ISI and decreasing the ICI. In this paper, we compare BER performance for FFT-OFDM and WPTOFDM in the presence of two types of channels defined by ETSI (i. e. Rayleigh P1 and Rician F1 channels). In our simulation Haar, Daubechies6, Symlet5 and Coiflet5 wavelets and overlap frequency domain equalization (overlap FEQ) are used for WPT-OFDM in contrast with FFT-OFDM which uses FEQ equalization. Simulation results show that the performance of OFDM will be improved by using WPT transform and due to no need of CP, the power/bandwidth efficiency of OFDM modulation will be improved as well.

This paper investigates the Multi-band OFDM (MBOFDM) based physical (PHY) layer proposal for IEEE 802.15.3a working group on short-range high data-rate Ultra-wide-Band (UWB) communications. An overview of the MB-OFDM PHY layer architecture with its various parameters is presented and the optimal choice of critical parameters is discussed. Next, we derive the theoretical un-coded Bit Error Rate (BER) of MB-OFDM over the Rayleigh fading channel. Performance results over realistic IEEE UWB channel models are analyzed and compared to a pulsed-OFDM based approach. Although pulsed-OFDM was presented in the literature as an enhancement to the MB-OFDM approach, simulation results showed that with same redundancy-factor, both systems give almost similar BER performance.

Goodness-of-Fit (GoF) based spectrum sensing of orthogonal frequency-division multiplexing (OFDM) signals is investigated in this paper. To this end, some novel local sensing methods based on Shapiro-Wilk (SW), Shapiro-Francia (SF), and Jarque-Bera (JB) tests are first studied. In essence, a new threshold selection technique is proposed for SF and SW tests. Then, three studied methods are applied to spectrum sensing for the first time and their performance are analyzed. Furthermore, the computational complexity of the above methods is computed and compared to each other. Simulation results demonstrate that the SF detector outperforms other existing GoF-based methods over AWGN channels. Furthermore simulation results demonstrate the superiority of the proposed SF method in additive colored Gaussian noise channels and over fading channel in comparison with the conventional energy detector.

This paper develops a new robust cyclostationary detection technique for spectrum sensing of OFDM-based primary users (PUs). To do so, an asymptotically constant false alarm rate (CFAR) multi-cycle detector is proposed and its statistical behavior under null hypothesis is investigated. Furthermore, to achieve higher detection capability, a soft decision fusion rule for performing cooperative spectrum sensing (CSS) in secondary networks is established. The proposed CSS scheme aims to maximize the deflection criterion at the fusion center (FC), while the reporting channels are under Rayleigh fading. In order to be able to evaluate the performance of the cooperative detector, some analytic threshold approximation methods are provided for the cases where the FC has direct sensing capability or not. Through numerical simulations, the proposed local and CSS schemes are shown to significantly enhance CR network performance in terms of detection probability metric.

This paper assumes each user has more than one queue, derives a new packet-dependant proportional fairness power allocation pattern based on the sum of weight capacity and the packet's priority in users' queues, and proposes 4 new cross-layer packet-dependant OFDM scheduling schemes based on proportional fairness for heterogeneous classes of traffic. Scenario 1, scenario 2 and scenario 3 lead respectively artificial fish swarm algorithm, self-adaptive particle swarm optimization algorithm and cloud adaptive particle swarm optimization algorithm into sub-carrier allocation in packet-dependant proportional fairness scheduling, and use respectively new power allocation pattern, self-adaptive particle swarm optimization algorithm and population migration algorithm to allocate power. Scenario 4 uses greedy algorithm concerning fairness to allocate sub-carriers, and uses new power allocation pattern to allocate power. Simulation indicates scenario 1, scenario 2 and scenario 3 raise the system's total rate on the basis of undertaking the fairness among users’ rates and average packet delay, scenario 4 not only meets users’ rates and average packet delay demands, but also improve the fairness among users’ rates.