Wireless systems for the fourth generation

Today, third generation networks are consolidated realities, and user expectations on new applications and services are becoming higher and higher. Therefore, new systems and technologies are necessary to move towards the market needs and the user requirements. This has driven the development of fourth generation networks. ”Wireless network for the fourth generation” is the expression used to describe the next step in wireless communications. There is no formal definition for what these fourth generation networks are; however, we can say that the next generation networks will be based on the coexistence of heterogeneous networks, on the integration with the existing radio access network (e.g. GPRS, UMTS, WIFI, ...) and, in particular, on new emerging architectures that are obtaining more and more relevance, as Wireless Ad Hoc and Sensor Networks (WASN). Thanks to their characteristics, fourth generation wireless systems will be able to offer custom-made solutions and applications personalized according to the user requirements; they will offer all types of services at an affordable cost, and solutions characterized by flexibility, scalability and reconfigurability. This PhD’s work has been focused on WASNs, autoconfiguring networks which are not based on a fixed infrastructure, but are characterized by being infrastructure less, where devices have to automatically generate the network in the initial phase, and maintain it through reconfiguration procedures (if nodes’ mobility, or energy drain, etc..., cause disconnections). The main part of the PhD activity has been focused on an analytical study on connectivity models for wireless ad hoc and sensor networks, nevertheless a small part of my work was experimental. Anyway, both the theoretical and experimental activities have had a common aim, related to the performance evaluation of WASNs. Concerning the theoretical analysis, the objective of the connectivity studies has been the evaluation of models for the interference estimation. This is due to the fact that interference is the most important performance degradation cause in WASNs. As a consequence, is very important to find an accurate model that allows its investigation, and I’ve tried to obtain a model the most realistic and general as possible, in particular for the evaluation of the interference coming from bounded interfering areas (i.e. a WiFi hot spot, a wireless covered research laboratory, ...). On the other hand, the experimental activity has led to Throughput and Packet Error Rare measurements on a real IEEE802.15.4 Wireless Sensor Network.

Non invasive assessment of right ventricle in patients with operated tetralogy of Fallot

The objective of this study was to evaluate right ventricular function in patients with right ventricular volume overload in patients with (tetralogy of Fallot, and pulmonary atresia + VSD ) underwent corrective surgery; with echocardiography measure that can be easily applied; and to study the relationship between ProBNP and the contractile function of the right ventricle, dilated right atrium, and the consequences of pulmonary insufficiency . Methods: The study included 50 patients (50% males, mean age 30.64 ± 13.30 years) with prior cardiac surgical intervention of TDF (90%) or pulmonary atresia + VSD (10%). (49 pz) have performed a cardiac MRI and clinical evaluation, (47 pz) echocardiogram, (48 pz) ECG, (34 pz) a cardiopulmonary exercise testing, (29 pz) a dosage of ProBNP. Results: The S-wave velocity (p <0.0001), the TAPSE (p <0.0001) correlated significantly with RVEF estimated by cardiac MRI. The VO2 max was 27.93 ± 12.91 ml / kg / min, 15% of patients had VE/VCO2 The peak> 35. ProBNP correlated positively and significantly with the area of the right atrium (p = 0.0001), and negative and significant with VO2 max (p = 0.04). Those who have increased pulmonary insufficiency (PVR fraction> 30%) have a significantly increased RVED volume (p = 0.01), reduced VO2 max (p = 0.04), and lower ejection fraction of LV (p = 0.02) than the group of patients with PVR ≤ 30. Conclusion: The TAPSE and S-wave velocity are fundamental and may become the technique of choice for routine assessment of RV systolic function in adult patients with TOF. The monitoring of the Pro BNP is probably a choice, given the simplicity and their information that correlate with the test cardiopulmonary. In view of the ventricular-ventricular interaction, so measures to maintain or restore the functioning of the pulmonary valve could preserve biventricular function.