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The electrophysiological (EP) effects and safety of renal artery denervation (RDN) in chronic kidney disease (CKD) are unclear.The purpose of this study was to investigate the arrhythmogenicity of RDN in a rabbit model of CKD.Eighteen New Zealand white rabbits were randomized to control (n = 6), CKD (n = 6), and CKD-RDN (n = 6) groups. A 5/6 nephrectomy was selected for the CKD model. RDN was applied in the CKD-RDN group. All rabbits underwent cardiac EP studies for evaluation. Immunohistochemistry, myocardial fibrosis, and renal catecholamine levels were evaluated.The CKD group (34.8% ± 9.2%) had a significantly higher ventricular arrhythmia (VA) inducibility than the control (8.6% ± 3.8%; P.01) and CKD-RDN (19.5% ± 6.3%; P = .01) groups. In the CKD-RDN group, ventricular fibrosis was significantly decreased compared to the CKD group (7.4% ± 2.0 % vs 10.4% ± 3.7%; P = .02). Sympathetic innervation in the CKD group was significantly increased compared to the control and CKD-RDN groups [left ventricle: 4.1 ± 1.8 vs 0.8 ± 0.5 (10Neuromodulation by RDN demonstrated protective effects with less structural and electrical remodeling, leading to attenuated VAs. In a rabbit model of CKD, RDN plays a therapeutic role by lowering the risk of VA caused by autonomic dysfunction.

Objective Rumination is a maladaptive emotional-regulation strategy that is strongly associated with depression. Impaired executive function can lead to difficulties in disengaging from rumination, thus exacerbating depression. In this study, we inspect an electroencephalograph neurofeedback protocol that enhance the target peak alpha frequency (PAF) activation in the prefrontal region. We examine the protocol's effects on depression and rumination. Methods We randomly assigned 30 dysphoric participants into either the neurofeedback training group or the control group. We then evaluated their depression, rumination, and executive function at pre- and posttraining so as to examine the effects of the neurofeedback. Results The results show that this neurofeedback protocol can specifically enhance participants' target PAF. The participants' executive function performances significantly improved after undergoing 20 neurofeedback sessions. Compared with those in the control group, those in the neurofeedback group had significantly fewer depressive symptoms and significantly reduced rumination. Moreover, as target PAF and executive function improved, depression and rumination both declined. Conclusion Our data are in line with those of previous studies that indicated a relationship between upper-band alpha activity and executive function. This PAF neurofeedback can effectively enhance participants' executive function, which can reduce rumination and ameliorate depression. This neurofeedback training is based on basic cognitive neuroscience, so it sheds light on depression's pathological factors and etiology.

Reference to the 5G network specifications defined by 3GPP, the online charging system has been greatly added and modified both in terms of interface and architecture. Since traditional online charging systems are mostly closed systems, a small number of open-source projects are no longer maintained, which makes the research in recent years extremely lacking in a suitable simulation environment. It encourages the emergence of free5GC project, which is the world's first 5G core network, developed by Taiwan independently and adopting the Apache 2.0 open-source specification. In this research, we try to implement the network function of the online charging system under the free5GC architecture and integrate it with third-party public cloud services. Adopting cloud computing, we focus on improving Charging Data Record (CDR) in computing and storage to compose a highly available and reliable B5G/6G charging system.

Introduction Phase singularity (PS) mapping provides additional insight into the AF mechanism and is accurate in identifying rotors. The study aimed to evaluate the feasibility of PS mapping in identifying AF rotors using data obtained from an automatic ultra-rapid high-resolution mapping system with a high-density mini-basket catheter. Methods Twenty-three pigs underwent rapid right atrial (RA) pacing (RAP 480 bpm) for 5 weeks before the experiment. During AF, RA endocardial automatic continuous mappings with a mini-basket catheter were generated using an automatic ultra-rapid mapping system. Both fractionation mapping and waveform similarity measurements using a PS mapping algorithm were applied on the same recording signals to localize substrates maintaining AF. Results Seventeen (74%) pigs developed sustained AF after RAP. Three were excluded because of periprocedural ventricular arrhythmia and corrupted digital data. RA fractionation maps were acquired with 6.17 ± 4.29 minutes mean acquisition time, 13768 ± 12698 acquisition points mapped during AF from 581 ± 387 beats. Fractionation mapping identified extensively distributed (66.7%) RA complex fractionated atrial electrogram (CFAE), whereas the nonlinear analysis identified high similarity index (SI > 0.7) parts in limited areas (23.7%). There was an average of 1.67 ± 0.87 SI sites with 0.43 ± 0.76 rotor/focal source/chamber. AF termination occurred in 11/16 (68.75%) AF events in 14 pigs during ablation targeting max CFAE. There was a higher incidence of rotor/focal source at AF termination sites compared with non-AF termination sites (54.5% vs 0%, P = 0.011). Conclusions The data obtained from ultra-rapid high-density automatic mapping is feasible and effective in identifying AF rotors/focal sources using PS technique, and those critical substrates were closely related to AF procedural termination.

Background Epidemiological evidence has shown an association between ambient fine particulate matter (PM2.5) exposure and cardiovascular mortality. Increased ventricular premature complex (VPC) burden can cause left ventricular dilatation and dysfunction. We aimed to investigate the relationship between acute PM2.5 exposure and VPC burden in patients without structural heart disease. Methods We reviewed 26 820 patients who underwent 24-hour Holter electrocardiogram (ECG) recordings between 1 Jan 2013 and 1 Dec 2016. We enrolled patients with significant idiopathic (structurally normal heart) VPC burden defined as ≥30 VPCs/h (Lown grade 2) who had at least two Holter ECG recordings. The VPC burden between the studies on high and low PM2.5 exposure dates was compared in 24 and 12 hours time periods. Result Sixty-seven patients (31 men, 56.49 ± 18.35 years) were enrolled. Patients were exposed to 25.63 ± 11.47 and 14.66 ± 7.51 μg/m 3 of PM2.5 during the high and low study dates, respectively. The overall VPC counts (10,490.69 ± 10,681.63/day) and burden (10.22% ± 10.17%) were significantly higher on the days with higher PM2.5 exposure compared with low PM2.5 exposure dates (8293.31 ± 9009.09; P = 0.014% and 9.14% ± 12.73%, P = 0.012, respectively). Compared with low PM2.5 exposure dates, the VPC burden on high exposure dates was significantly higher from 9 am to 9 pm (5.85% ± 6.41% vs 4.84% ± 6.97%; P = 0.025) but not at nocturnal periods. Conclusion Our study demonstrated a significantly higher VPC burden on high PM2.5 exposure date. The burden was increased in the daytime but not at nighttime. This result suggests that daytime PM2.5 exposure may be associated with ventricular arrhythmia burden in the healthy population.

Sleep and estrogen levels have an impact on neural regulation and are associated with cardiovascular (CV) events. We investigated the effects of estrogen on heart rate variability (HRV) and circadian cycle in spontaneously hypertensive rats (SHRs). Polysomnographic recording was performed in seven male and seven female SHRs during sleep. The electroencephalogram (EEG) and electromyogram (EMG) were evaluated to define active waking (AW), quiet sleep (QS), and paradoxical sleep (PS) stages. Cardiac activities were measured by RR interval of the electrocardiogram (ECG), mean arterial pressure (MAP), and power spectrum of HRV.In ECG, estrogen prolonged the RR interval in total sleep when compared with that at baseline in male SHRs (203.74 ± 6.61 versus 181.30 ± 8.06 ms, P < 0.001) and in female SHRs (169.21 ± 6.43 versus 160.76 ± 10.66 ms, P < 0.05). In HRV, the estrogen increased the high frequency (HF) in total sleep when compared with that at baseline in male SHRs (1.03 ± 0.28 versus 0.60 ± 0.43 ln (ms2), P < 0.001) and in female SHRs (0.71 ± 0.26 versus 0.42 ± 0.19 ln (ms2), P < 0.05).In male SHRs, estrogen increased the frequency of QS (26.50 ± 4.85 versus 20.79 ± 5.07, P < 0.01) and PS (25.64 ± 5.18 versus 20.14 ± 4.75, P < 0.05) stages when compared with baseline. In female SHRs, estrogen increased the percentage of delta waves in total sleep (79.87% ± 3.10% versus 76.71% ± 2.74%, P < 0.05) when compared with that at baseline.In HRV, estrogen leads to neuromodulation by increased parasympathetic tone in all SHRs, suggesting a lower risk to CV events. In sleep analyses, estrogen in male SHRs caused poor sleep quality. In contrast, estrogen in female SHRs demonstrated improved quality of sleep and decreased risk of hypertension.

Background Sympathetic hyperactivity and poor sleep quality are reported in myocardial infarction (MI) patients and angiotensin-converting enzyme inhibitors (ACEI) can improve long-term survival in these patients. We aimed to evaluate ACEI effects on cardiac autonomic activity (CAA) and disordered sleep patterns in ambulatory rats after MI. Methods Polysomnographic recording was performed in sham (n = 8) and MI (n = 9) male rats during normal daytime sleep before and after captopril treatment. Spectral analyses of the electroencephalogram and electromyogram were evaluated to define active waking (AW), quiet sleep (QS), and paradoxical sleep (PS). Central sleep apnea (CSA) events were measured by analyzing the electromyogram of the diaphragm. CAA was measured by power spectrum analyses of heart rate variability (HRV). Results In the MI group, there was a higher low frequency/high frequency ratio during sleep, which reduced significantly after captopril treatment, especially at the QS stage compared to that before captopril treatment. The frequency of sleep interruption was higher in the MI group than the sham group. Increased AW and PS, and decreased QS times were noted in the MI group compared to the sham group. These changes were restored to baseline after captopril treatment in the MI group. CSA events were significantly increased in the MI group, and were restored to the normal level after captopril treatment. Conclusions Our results demonstrate significant sleep fragmentation with sympathetic hyperactivity after MI, and that captopril restores the autonomic dysfunction and sleep disorder. These findings suggest that ACEI improved sleep-related respiration disorder after MI by restoring autonomic homeostasis, and provide a hypothesis generating for future studies in humans.

Aims Both obesity and heart failure (HF) are associated with sudden cardiac death. The current study aimed to investigate the effects of overweight and HF on the substrate for ventricular fibrillation (VF), and whether renal denervation (RDN) can protect the heart from sympathetic activation and cardiac remodelling in HF rabbits fed with high-fat diet (HFD). Methods and results Twenty-four rabbits randomized into control group fed with regular diet (Control), HFD, HFD-HF, and HFD-HF-RDN groups. Rapid ventricular pacing of 400 b.p.m. for 4 weeks was applied in HFD-HF and HFD-HF-RDN. Surgical and chemical RDNs were approached through bilateral retroperitoneal flank incisions in HFD-HF-RDN. All rabbits received electrophysiological study and a VF inducibility test. The ventricular myocardium was harvested for trichrome stain. After 3 months, mean body weight was heavier in HFD, compared with control (3.5 ± 0.1 kg vs. 2.6 ± 0.1 kg, P Conclusion Our results suggest that overweight and HF increase sympathetic activity, structural remodelling, and VF inducibility, but RDN prevents them.

BACKGROUND The relationship between gastroesophageal reflux disease (GERD) and atrial fibrillation (AF) has been previously reported. However, the detailed mechanism remains unknown. In this study, we investigated the effects of acid reflux on the intrinsic cardiac autonomic nervous system, atrial/ventricular electrophysiology, and AF inducibility. METHODS Eighteen rabbits were randomized into three groups: acid reflux (group 1, n = 6), control (group 2, n = 6), and acid reflux with periesophageal vagal blockade (group 3, n = 6). Atrial and ventricular effective refractory periods (ERPs) and AF inducibility were checked at baseline and then hourly until 5 hours after the experiment. RESULTS Three hours after the experiment, atrial ERP prolongation was noted in groups 2 and 3 (P

Background Autonomic imbalance with increased sympathetic and decreased parasympathetic activities is observed in patients after myocardial infarction (MI). We aimed to investigate sleep-related changed in autonomic regulation in left coronary artery (LCA) ligation rats. Methods Wireless transmission of polysomnographic recording was performed in sham and LCA ligation male rats during normal daytime sleep with and without atenolol treatment. Spectral analyses of the electroencephalogram (EEG) and electromyogram (EMG) were evaluated to define active waking (AW), quiet and paradoxical sleeps (QS, PS). Cardiac autonomic activities were measured by analyzing the power spectrum of heart rate variability (HRV). EEG, EMG and HRV were recorded over 6h for consecutive 3days in all groups. Results In LCA ligation group, there were higher LF and LF/HF ratio on QS phase, but not AW and PS phases, compared to atenolol treated sham and LCA ligation groups, respectively. The HF component was not significantly changed on all groups in both sleep and awake phases. Sleep interruption was more frequent in LCA ligation rats compared to sham, and it was not found in LCA ligation with atenolol treatment group. Increased AW, PS and decreased QS time were noted in LCA ligation group, compared to sham and it was restored to baseline in LCA ligation with atenolol treatment group. Conclusions Our results demonstrate significant sleep fragmentations with sympathetic hyperactivity during QS stages after MI, and atenolol could restore the autonomic dysfunction and sleep disturbance. The finding explains the cause of sleep-related fetal arrhythmia and sudden cardiac death after MI.

Background Ambient fine particulate matter (PM2.5) exposure is associated with increased cardiovascular and cardiac arrhythmias events, but the detailed mechanism remains unclear. Objective We aimed to investigate the effect of PM2.5 (particulate matter Method Among 6912 patients who had underwent 24-hour Holter ECG recordings between Oct 1st 2015 and Oct 31st 2016, 46 (25 males, 69.3 ± 12.1 years old) were enrolled with confirmation of living in an environment with a reported PM2.5 level and were classified as elevated (Group 1, >36 μg/m3, 50.73 ± 8.50) or low (Group 2, Result The baseline characteristics including the comorbidities and medications were similar between the 2 groups. The Holter ECG parameters were also similar. There were no significant HRV differences between the two groups for the 24-hour interval analysis. However, the LF/HF ratio was significantly higher in Group 1 than Group 2 in the 9 am to 9 pm (p = 0.028), 8 am to 4 pm (p = 0.024), and 4 pm to 12 pm (p = 0.025) periods, respectively, but not for the nocturnal HRV parameters. Conclusion Our study demonstrated that an elevated PM2.5 exposure had a significant association with an increased daytime LF/HF ratio suggesting a diurnal difference in the response to PM2.5 exposure.

Background Ventricular tachycardia (VT) and ventricular premature complexes (VPCs) originating from the right ventricular outflow tract (RVOT) are generally considered as benign arrhythmias, with ECG morphology showing LBBB pattern and inferior axis. Pathogenic mechanisms in the genesis of RVOT VT/VPC remain largely unknown. We aimed to investigate the neural mechanism in RVOT ventricular arrhythmias in canine model. Methods Twelve mongrel dogs (13.7 ± 1.3 kg, 5 male dogs) were studied through midline thoracotomies. High-frequency stimulation (HFS) was applied to the proximal pulmonary artery (PA) to induce RVOT VT/VPC. An EnSite Array and a mapping catheter were used for electroanatomical mapping. The RVOT and PA were surgically excised for immunohistochemistry studies, including tyrosine hydroxylase (TH) stain for sympathetic nerves and choline acetyltransferase (ChAT) stain for parasympathetic nerves. Results In nine (75%) out of twelve dogs, HFS of the proximal PA induced RVOT VT/VPC. The density of TH-positive nerves was significantly higher than that of ChAT-positive nerves (6803 ± 700 vs. 670 ± 252 μm2/mm2, p Conclusions HFS of the proximal PA could induce RVOT VT/VPC. The sympathetic nerves were densely innervated to the origin of RVOT VT/VPC, indicating the critical role of sympathetic hyperactivity in the initiation and perpetuation of RVOT VT/VPC.

A new distributed space-time coding (DSTC) scheme is proposed based on a modified cooperation protocol. Comparing the conventional DSTC, the proposed DSTC scheme adopts fewer relay nodes, which can be a flexible scheme when relay nodes are limited. As also shown in the error performance, the proposed DSTC outperforms the conventional DSTC owning to less noise enhancement. Additionally, the proposed DSTC scheme is more economic than the conventional DSTC in spending resource to synchronize the relay network.

Background Frequent ventricular premature complexes ( VPC s) can lead to the development of dilated cardiomyopathy and sudden cardiac death. Renal artery sympathetic denervation ( RDN ) may protect the heart from remodeling. This study aimed to investigate the effect of frequent VPC s on structural and electrical properties and whether RDN can protect the heart from remodeling. Methods and Results Eighteen rabbits were randomized to control (n=6), VPC (n=6), and VPC ‐ RDN (n=6) groups. Surgical and chemical RDN s were approached through bilateral retroperitoneal flank incisions in the VPC ‐ RDN group. Pacemakers were implanted to the left ventricular apex to produce 50% VPC burden for 5 weeks in the VPC and VPC ‐ RDN groups. In addition, ventricular myocardium was harvested for western blot and trichrome stain. Echocardiographic results showed left ventricular enlargement after 5‐week pacing in the VPC group, but not in the VPC ‐ RDN group, when compared to baseline. In biventricles, ion channel protein expressions of Nav1.5, Cav1.2, Kir2.1, and SERCA 2 were similar among 3 groups. However, the degree of biventricular fibrosis was extensive in the VPC group, compared to the control and VPC ‐ RDN groups. Importantly, ventricular fibrillation inducibility was higher in the VPC group (41%) when comparing to the control (13%; P VPC ‐ RDN groups (13%; P Conclusions Frequent VPC s are associated with the development of cardiac structural remodeling and high ventricular fibrillation inducibility. RDN prevents cardiac remodeling and the occurrence of ventricular arrhythmia through antifibrosis.

Background: Right ventricular outflow tract ventricular tachycardia (VT) and ventricular premature complexes (VPCs) are characterized as benign in entity with ECG morphology showing LBBB pattern and inferior axis. Pathogenic mechanisms in the genesis of RVOT VT/VPC remain largely unknown. We aimed to investigate the neural mechanism in RVOT VT/VPC in canine model. Methods: Twelve mongrel dogs (13.7 ± 1.3 Kg, 5 male dogs) were studied through midline thoracotomies. High-frequency stimulation (HFS) was applied to the proximal pulmonary artery (PA) to induce RVOT VT/VPC. An EnSite Array and a mapping catheter were used for electroanatomical mapping. The RVOT and PA were surgically excised for immunohistochemistry studies, including tyrosine hydroxylase (TH) stain for sympathetic nerves and choline acetyltransferase (ChAT) stain for parasympathetic nerves. Results: In nine (75%) out of twelve dogs, HFS of the proximal PA induced RVOT-VT/VPC. The density of THpositive nerves was significantly higher than that of ChAT-positive nerves (6803 ± 700 vs. 670 ± 252 μm2/mm2, p

Background Heart failure (HF) causes atrial remodeling and increases the incidence of atrial fibrillation (AF). Renal denervation (RDN) has been shown to decrease the development of AF. This study aimed to identify the effects of RDN on the atrial arrhythmogenic substrates in HF. Methods Rabbits were classified into four groups: control (n=9), RDN (n=10), HF (n=6) and HF-RDN (n=9). Surgical and chemical RDN was approached through bilateral retroperitoneal flank incisions in RDN and HF-RDN. Rapid ventricular pacing of 400bpm for 4weeks was applied in HF and HF-RDN. After 4weeks, the rabbits were sacrificed and atrial myocardium were harvested for Western blot and Trichrome stain. Results The bi-atrial effective refractory period (ERP) of HF was significantly longer compared with that of control and RDN. In right atrium, the ERP of HF was also significantly longer compared with that of HF-RDN, but there was no significant difference in left atrial ERP. In bi-atrium, ion channel protein expressions of CaV1.2, NaV1.5, Kir2.1 SERCA2 and NCX were similar among 4 groups. However, the degree of atrial fibrosis was extensive in bi-atrium of HF, when compared to that of control, RDN and HF-RDN. Conclusion The ERP of HF-RDN is partially shortened by RDN compared with that of HF. There are no differences ionic channel protein expressions in bi-atrium among all groups. The degree of atrial fibrosis is severe in HF, but not in HF-RDN, suggesting that RDN may regulate the atrial arrhythmogenic substrates in HF mostly through reverse structural remodeling.

Background Botulinum toxin ( BTX ), temporarily suppressing cholinergic transmission (AF ) for ≥1 year. We aimed to investigate the mechanism underlying long‐term suppression of AF caused by injecting BTX into major atrial ganglionated plexi (GPs). Methods and Results Bilateral thoracotomies in anesthetized dogs allowed programmed stimulation at 4 pulmonary veins, biatrial appendages, and the superior vena cava to determine the effective refractory period ( ERP ) in the first operation. Group 1 (n=10) received BTX injection into all GP s; group 2 (n=7) received no injection. Groups 1 and 2 received rapid atrial pacing (800 bpm) 6 days a week. Group 3 (n=7) did not undergo thoracotomy or rapid atrial pacing to serve as controls for histological studies. A second operation and the same measurements were made 3 months later. During the first operation in group 1, ERP s of 4 pulmonary veins, but not biatrial appendages or superior vena cava, increased immediately after BTX injection. AF burdens increased significantly from the fifth week after the first operation in group 2 but not in group 1. In the second operation, ERP s remained unchanged compared with ERP s before BTX injection in group 1, whereas ERP s shortened significantly at all sites except the superior vena cava in group 2. There was no difference of autonomic nerve density between group 1 and group 3. The GP choline acetyltransferase (+) and atrial tyrosine hydroxylase (+) nerve densities were higher in group 2 than in group 1 and group 3. Conclusions Temporary suppression of major atrial GPs by BTX prevents autonomic remodeling and provides long‐term suppression of AF , indicating the critical role of GPs in AF progression.

In this letter, the realizable direct-sequence code-division multiple-access (DS-CDMA) system occupying Nyquist bandwidth is developed. Several frequently-adopted spreading codes are examined for realization feasibility in the bandlimited DS-CDMA system. It is shown that Nyquist chip-rate transmission can be practically achieved for the bandlimited DS-CDMA system using frequently-adopted spreading codes at the sacrifice of very little user capacity.

A set of novel multi-polar compounds composed of four fluorene-based derivatives with systematic alteration of the molecular structure was synthesized and their nonlinear optical properties in the femtosecond and nanosecond time domain were examined. Preliminary experimental results show that the two-photon activities of the model compounds are connected to structural parameters, such as the number of peripheral electron-donating groups and/or the size of the π-domain in a dye molecule. It is also found that these model chromophores possess large nonlinear attenuation under the irradiation of laser pulses working at nanosecond regimes, indicating that these compounds may have strong two-photon-assisted excited-state absorption within the studied spectral region. Effective optical-power-limiting behaviors of the dendritic fluorophores were also demonstrated to show that such dye molecules can be potential materials for use as broadband and rapid-responsive optical limiters, especially against laser lights with longer pulses.

Adaptive transmission technique adopting rectangularly-pulsed orthogonally multiplexed modulation (OMM) signals is studied for the flat Rayleigh fading channel. By choosing spectrally efficient OMM signals in accordance with channel status under an error rate constraint, constant-power adaptive OMM systems are shown to significantly outperform the conventional constant-power adaptive orthogonal frequency division multiplexing systems in average spectral efficiency.

Orthogonally multiplexed orthogonal amplitude modulation (OMOAM) is a modulation family unifying numerous modulations date back from 1960s and also many standard-preferable modulations. By converting frequency multiplexing to time multiplexing, orthogonally time multiplexed orthogonal amplitude modulation (OTMOAM) is proposed to explore advantages over the conventional orthogonally multiplexed orthogonal amplitude modulation (OMOAM). Transmitter and receiver system models unifying both OTMOAM and OMOAM are provided, and bit error rate (BER) for both systems are also derived for flat Rayleigh fading channel. Numerical results show that OTMOAM provides lower PAPR and better BER performance in high signal-to-noise power ratio than the conventional OMOAM.

The error performance of minimum-bandwidth direct-sequence code division multiple access (MB-DS-CDMA) is studied for synchronous and asynchronous scenarios in Nakagami multipath fading channels. Comparing to the bandlimited raised cosine pulsed DS-CDMA systems, MB-DS-CDMA in both synchronous and asynchronous scenarios realizes Nyquist rate transmission with zero excess bandwidth, but only synchronous MB-DS-CDMA gives equivalent error performance, whereas asynchronous MB-DS-CDMA suffers degradation in error performance, which can be deemed as a trade-off by providing the ultimate Nyquist transmission rate. This work was supported by Ministry of Science and Technology, Taiwan, under contract NSC 102-2221-E-035-005.

A modified minimum-bandwidth direct-sequence code division multiple access system is proposed to approach Nyquist transmission rate without sacrificing error performance or user capacity. When orthogonal spreading code is employed, it is shown that the proposed system is able to accommodate all kinds of spreading codes by trading off a negligible excess bandwidth.

Summary Bandlimited direct-sequence code division multiple access (DS-CDMA) attracts much attention for its compact spectrum and the ability to suppress inter-symbol interference. Among the various bandlimited DS-CDMA systems available, minimum-bandwidth DS-CDMA (MB-DS-CDMA) is the only realizable Nyquist rate transmission system. But, MB-DS-CDMA only applies to certain kinds of spreading codes. Accordingly, this study proposes a modified DS-CDMA structure which extends the application of MB-DS-CDMA to all common spreading codes at the expense of a negligible reduction in the transmission rate. Additionally, the bit error rate of the proposed schemes adopting either single-user or multi-user detection receiver is analyzed and compared with that of the commonly-used raised-cosine-pulsed DS-CDMA over multipath fading channels. The numerical results show that given a sufficiently large number of users, the bit error rate performance of modified MB-DS-CDMA is comparable to that of the raised-cosine-pulsed DS-CDMA scheme; meanwhile, the realizable modified MB-DS-CDMA approaches the ultimate transmission rate.

Research into service robots is popular nowaday. In 2006, the RoboCup@home league was founded as part of the RoboCup competition[1]. In contrast to other robot competitions, the venue is an everyday human environment, where the robot has to perform a set of service tasks. This paper describes the design of our RoboCup@home robot based on the mobile U-Bot platform manufactured by the Taiwanese Industrial Technology Research Institute. Our design provides an integrated mobile service robot platform.

Acquisition is the first step in the signal processing section of a Global Position System (GPS) receiver. It detects the presence of a GPS signal received by antenna and provides estimates of code phase and Doppler frequency to the tracking loops. Three acquisition methods in frequency-domain processing are compared, i.e., namely radix-2, split-radix-2/4 and split-radix 2/8 FFTs. The expectancy of the split-radix algorithm is increasing the acquisition efficiency. It is shown that the split-radix-2/8 FFT can save 25% of data loads and stores compared with split-radix-2/4 FFT. The modified Tone detector is applied to enhance the probability of detection. Finally, the acquisition functions are developed in software architecture running on PC.

A power allocation strategy is proposed for single-antenna overlay cognitive radio networks, in which the secondary user helps transmit the signal of the primary user while concurrently conveying its own signal by means of a superposition coding technique. The study commences by deriving analytical expressions for the bit error rates (BERs) of the primary and secondary users. A power allocation strategy is then proposed for minimizing the total power consumption of the two users while simultaneously satisfying their respective BER constraints. The analytical BER formulas are not convex, and hence the optimization process presents a significant challenge. Accordingly, two more tractable BER approximations for the primary and secondary users are proposed to transfer the non-convex problem into a convex one. The simulation results confirm the effectiveness of the proposed power allocation strategy under various channel environments.