Adaptive Channel Estimation Using Pilot-Embedded Data-Bearing Approach for MIMO-OFDM Systems

Multiple-input multiple-output (MIMO) orthogonal-frequency-division-multiplexing (OFDM) systems employing coherent receivers crucially require channel state information (CSI). Since the multipath delay profile of channels is arbitrary in the MIMO-OFDM systems, an effective channel estimator is needed. In this paper, we first develop a pilot-embedded data-bearing (PEDB) approach for joint channel estimation and data detection, in which PEDB least-square (LS) channel estimator and maximum-likelihood (ML) data detection are employed. Then, we propose an LS fast Fourier transform (FFT)-based channel estimator by employing the concept of FFT-based channel estimation to improve the PEDB-LS one via choosing a certain number of significant taps for constructing a channel frequency response. The effects of model mismatch error inherent in the proposed LS FFT-based estimator when considering noninteger multipath delay profiles and its performance analysis are investigated. The relationship between the mean-squared error (MSE) and the number of chosen significant taps is revealed, and hence, the optimal criterion for obtaining the optimum number of significant taps is explored. Under the framework of pilot embedding, we further propose an adaptive LS FFT-based channel estimator employing the optimum number of significant taps to compensate the model mismatch error as well as minimize the corresponding noise effect. Simulation results reveal that the adaptive LS FFT-based estimator is superior to the LS FFT-based and PEDB-LS estimators under quasi-static channels or low Doppler's shift regimes     

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Novel peptides from dried squid head by-products obtained from snack process

The novel peptides were successfully produced with commercial protease hydrolysis (Alcalase® and Flavourzyme®) at the fixed concentration of 3%by weight of protein in substrate. The hydrolysis was performed at various hydrolysis times (0, 300, 450, 600 and 750 min) at the optimal pH and temperature. When the hydrolysis was performed until 750 min, the peptide solutions with high soluble protein content were resulted (47.58 and 42.53 mg protein per mL for Alcalase® and Flavourzyme® hydrolysis, respectively). After freeze drying, the peptide powder from Alcalase® and Flavourzyme® hydrolysis had degree of hydrolysis at 71.87% and 66.39%, respectively. Alcalase® hydrolysis provided the novel peptide fraction with DPPH scavenging, ABTS activity and ACE-inhibitory activity at 64.20%, 102.50 µg mL⁻¹ and 56.98%, respectively. This peptide fraction possessed the lowest molecular weight (m/z 807.418) as detected by MALDI-TOF/MS, and the most potent peptide sequence was Arg-Glu-Gly-Tyr-Phe-Lys which has the potential as functional ingredient in novel food, snacks and beverages.     

Characterisation of physical,chemical and antimicrobial properties of allicin–chitosan complexes

Formation of allicin (freshly used after prepared from fresh garlic cloves) and chitosan (78%DD with 1100 kDa, and 88%DD and 1020 kDa) complexes were conducted under the optimum conditions. After complete complexation (pH 4.5–4.8, 4 °C, and 48 h), the optimum weight ratio was resulted (1:1). The highest yield after freeze drying was 64.98%. The light yellow complexes (L* 81.0–87.3, a* 0.4–2.2 and b* 16.8–21.2) can be dissolved in wide pH range (3–11). Scanning electron micrographs revealed the round shape complexes with diameter between 5 and 15 μm. The FT‐IR analysis showed the main functional groups, including alkyl group, alkyl group‐hydroxy or possibly amino substituent, hydroxyl or amino compound, and aliphatic alcohol with carbonyl substitution. XRD results showed that the complex crystalinity was amorphous. The clear zone results and MIC (mg mL^?1) revealed that allicin–chitosan complexes exhibited the antibacterial activity against spoilage bacteria indicated the possibility to use as antimicrobial agent in foods.