Concatenative Complete Complementary Code Division Multiple Access and its Fast Transform based Implementation

Over multipath channels, \textit{complete complementary code division multiple access} (CC-CDMA) and \textit{convolutional spreading code division multiple access} (CS-CDMA) provide {\it inter-channel interference} (ICI) free transmission with an enhanced {\it spectral efficiency} (SE). However, the {\it convolutional spreading} (CS) operation of the systems is computationally complex and involves a high \textit{peak-to-average power ratio} (PAPR). Address such issues, we propose the \textit{concatenative complete complementary code division multiple access} (CCC-CDMA). Since the CCCCs can be generated from the rows of the Walsh-Hadamard or \textit{discrete Fourier transform} (DFT) matrices, the CS operation can be implemented using corresponding {\it fast transforms} (FTs) to reduce computational complexity. Simulation results shown that enlargement of {\it spreading factor} (SF) strengthens the robustness against clipping noise and the binary CCCC generated by Walsh-Hadamard matrix has excellent robustness against Doppler frequency shifts.

Concatenative Complete Complementary Code Division Multiple Access and its Fast Transform based Implementation

Over multipath channels, \textit{complete complementary code division multiple access} (CC-CDMA) and \textit{convolutional spreading code division multiple access} (CS-CDMA) provide {\it inter-channel interference} (ICI) free transmission with an enhanced {\it spectral efficiency} (SE). However, the {\it convolutional spreading} (CS) operation of the systems is computationally complex and involves a high \textit{peak-to-average power ratio} (PAPR). Address such issues, we propose the \textit{concatenative complete complementary code division multiple access} (CCC-CDMA). Since the CCCCs can be generated from the rows of the Walsh-Hadamard or \textit{discrete Fourier transform} (DFT) matrices, the CS operation can be implemented using corresponding {\it fast transforms} (FTs) to reduce computational complexity. Simulation results shown that enlargement of {\it spreading factor} (SF) strengthens the robustness against clipping noise and the binary CCCC generated by Walsh-Hadamard matrix has excellent robustness against Doppler frequency shifts.

A Fast Transform for Brain Connectivity Difference Evaluation

Anatomical and dynamical connectivity are essential to healthy brain function. However, quantifying variations in connectivity across conditions or between patient populations and appraising their functional significance are highly non-trivial tasks. Here we show that link ranking differences induce specific geometries in a convenient auxiliary space that are often easily recognisable at mere eye inspection. Link ranking can also provide fast and reliable criteria for network reconstruction parameters for which no theoretical guideline has been proposed.

Analysis of 25 Years of Polar Motion Derived from the DORIS Space Geodetic Technique Using FFT and SSA Methods

Polar motion (PM) has a close relation to the Earth’s structure and composition, seasonal changes of the atmosphere and oceans, storage of waters, etc. As one of the four major space geodetic techniques, doppler orbitography and radiopositioning integrated by satellite (DORIS) is a mature technique that can monitor PM through precise ground station positioning. There are few articles that have analyzed the PM series derived by the DORIS solution in detail. The aim of this research was to assess the PM time-series based on the DORIS solution, to better capture the time-series. In this paper, Fourier fast transform (FFT) and singular spectrum analysis (SSA) were applied to analyze the 25 years of PM time-series solved by DORIS observation from January 1993 to January 2018, then accurately separate the trend terms and periodic signals, and finally precisely reconstruct the main components. To evaluate the PM time-series derived from DORIS, they were compared with those obtained from EOP 14 C04 (IAU2000). The results showed that the RMSs of the differences in PM between them were 1.594 mas and 1.465 mas in the X and Y directions, respectively. Spectrum analysis using FFT showed that the period of annual wobble was 0.998 years and that of the Chandler wobble was 1.181 years. During the SSA process, after singular value decomposition (SVD), the time-series was reconstructed using the eigenvalues and corresponding eigenvectors, and the results indicated that the trend term, annual wobble, and Chandler wobble components were accurately decomposed and reconstructed, and the component reconstruction results had a precision of 3.858 and 2.387 mas in the X and Y directions, respectively. In addition, the tests also gave reasonable explanations of the phenomena of peaks of differences between the PM parameters derived from DORIS and EOP 14 C04, trend terms, the Chandler wobble, and other signals detected by the SSA and FFT. This research will help the assessment and explanation of PM time-series and will offer a good method for the prediction of pole shifts.

PSIII-6 Analysis of vocal sounds for detecting abnormal symptoms in sows

Various technologies for animal health have been introduced and used in the livestock field as a part of an integrated processing methodology to construct a successful smart farm. This study aims to present a health assessment method applied to an individual pig using acoustic vibration. The experiment was based on the hypothesis that there is a strong relationship between acoustic phenotype and health condition. The information from a normal and abnormal sow was simultaneously and continuously recorded using a sound recorder for 24 hours. The abnormal sow was given an injection of 70% dextrose to the knee, which experienced necrosis due to a subsequent osmotic phenomenon. The experiment began at 9 am and continued until 8 am the next day and was repeated twice. During the experiment, the high-resolution recorder was located 50 cm from the top of the farrowing crate and directed at the sow’s head to reduce interferences from other sources of sound and noise. The first step of analysis was denoising the recorded acoustic information. Then, the Fourier fast transform was applied to the preprocessed data. Data were analyzed with PROC GLM (SAS 9.3), where a trial and treatment were included as fixed effects. The magnitude of frequency between normal and abnormal sows was significantly different (P < 0.05), in which the range of magnitude value was higher and lower than 0.015 for the normal and abnormal sow, respectively. The range 0.015 to 0.020 for the normal sow was clearly discriminated from the range 0.010 to 0.015 for the abnormal one. A more accurate interpretation of sows’ vocal data depends on the quality and quantity of data regarding their health condition. A promising algorithm of processing acoustic phenotype related to bio information could be useful in numerous complex health assessments.

Reliability of Trigonometric Transform-based Multi-Carrier Scheme

This work is looking for a new physical layer of a multi-carrier wireless communication system to be implemented in low complexity way, resorting to suitable fast transform. The work presents and assesses a scheme based on Discrete Trigonometric Transform with appending symmetric redundancy either in each or multiple consecutive transformed blocks. A receiver front-end filter is proposed to enforce whole symmetry in the channel impulse response, and bank of one tap filter per sub-carrier is applied as an equalizer in the transform domain. The behaviour of the transceiver is studied in the context of practical impairments like fading channel, carrier frequency offset and narrow band interference. Moreover, the performance is evaluated in contrast with the state of art methods by means of computer simulations, and it has been found that the new scheme improves robustness and reliability of communication signal, and record lower peak to average power ratio. The study demonstrates that front-end matched filter effectively performs frequency synchronization to compensate the carrier frequency offset in the received signal.