As WIRELESS networks with high data rate get widely deployed, improving the performance of TCP over these networks plays vital role. WIRELESS link losses have dramatic adverse impact on TCP performance due to the difficulty in distinguishing the congestion losses from WIRELESS link losses. We first, studied the various existing Bandwidth Estimation Algorithms over the WIRELESS networks. In this paper, we propose an enhanced bandwidth estimation technique with congestion control algorithms to improve TCP performance over WIRELESS link with random loss. We propose, a new technique called TCP- BWIW to estimate the bandwidth and the congestion window is set accordingly. The performance of TCP-BWIW is analyzed, and it mitigates the Network congestion.

In this paper, a WIRELESS powered COMMUNICATION network (WPCN) is considered, in which the hybrid access point (HAP) and the users are equipped with multiple antennas. In the downlink phase, an energy HAP transfers the energy signal to the users and in the uplink phase, users apply the harvested energy to transfer their information to the HAP using spatial division multiple access (SDMA) technology. By considering the nonlinear behavior of energy harvester in system design and aiming to maximize the sum of the rates, we propose an optimal method for designing energy pre-coding matrices, user information pre-coding matrices, and time devoted to the downlink and uplink phases. For this purpose, we rewrite the problem as a convex optimization problem by appropriate change of variables and propose a method to solve it. The simulation results show that in practical scenarios, employing the nonlinear energy harvesting model in the system design could reduce the transmitted energy, increase and the sum rate of the users.

This paper deals with the design consideration and performance results for low power low noise self-matched as well as an inductive-matched SiGe amplifier developed for the GSM/DCS/WCDMA multi-band cellular systems.The self-matched amplifier is based on the current reuse concept, and accommodates an active balun. On the other hand, the inductive-matched amplifier is a single-stage common emitter circuit with inductive on-chip matching. Both amplifiers have internal bias circuits. These amplifiers consume 5.0mA and 6.0mA at 3V to respectively provide a power gain of higher than 18dB and 13dB, a noise figure lower than 4dB, and an IIP3 higher than –16dBm and -4dBm, over 0.9-2.2GHz. With such a low current consumption, the developed amplifiers can be a candidate for low-power multimode mobile terminal applications.

In this paper, a dual-polarized antenna fed by CPW is presented. The proposed includes a conductor on the ‎radiator and has defected ground, so it has been achieved as an omnidirectional antenna which makes it a low loss, ‎and a simple antenna which is appropriate for a WIRELESS COMMUNICATION system. By imposing the different ‎circumstances of U-shape elements on the ground, the features of antennas have been improved. The scattering ‎characteristic of the antenna are less than -20 dB with high impedance matching at 2.2GHz, 4.8GHz, and 6.6GHz. ‎Also, the antenna covers 400 MHz bandwidth from 2 GHz to 2.4 GHz, 500 MHz bandwidth from 4.6 GHz to 5.1 GHz, ‎and 1.3 GHz bandwidth from 5.7 GHz to 7 GHz, respectively. In addition, the maximum gain of the antenna is almost ‎‎10 dB. The simple and compact antenna with an overall size of 25x20mm2 is designed on an FR-4 substrate with 0.8 ‎mm thickness. On the one hand, the structure is fabricated and tested. The results of the antenna have shown that ‎the measured results agree with the simulated results; The performance of the antenna with CPW-fed, consisting of ‎compact size, circular polarization, and suitable gain at resonance frequencies, make it a suitable choice for the ‎COMMUNICATION system and the portable device.‎

The world is embroiled in a pandemic of a new coronavirus at the end of 2019 and early in 2020, with such a large scale that it has severely involved the political, economic, and social systems in most countries around the world. The scale of the crisis is so widespread that many experts believe that the post-corona world will be substantially different from the pre-corona world. In the face of this massive epidemic, how people perceive risk and how to risk is communicated, plays a central role in deciding and choosing people's behavior. Fighting with this emerging phenomenon requires mobilizing all the possibilities of society and helping all people in the field of empathy and altruism. In this article, we briefly review aspects of the important concept of risk perception and COMMUNICATION in this pervasive crisis.

Performance improvement of uplink of analog WIRELESS COMMUNICATION systems employing spatial diversity Signal attenuation is one of the most important problems in WIRELESS COMMUNICATION systems. The message conveyed by the transmitted waveform will not be recovered correctly if this attenuation is such that the SNR in the receiver is less than a specific threshold. Channel fading which results from receiving many non-coherent reflected versions of transmitted signal in the receiver, is one of the sources of this signal degradation. Fading may result in severe changes in the strength of the received signal in short time intervals. Diversity techniques are the most powerful tools to combat degrading effects of WIRELESS fading, by using two or more independent COMMUNICATION channels. Diversity techniques are mainly designed for digital COMMUNICATIONs, therefore employing them in analog systems such as FM radios is a challenging issue. In this study, spatial diversity in receiver is proposed in order to making the current VHF WIRELESS systems smart against channel fading. Based on this idea, three different applicable methods have been proposed for traditional analog FM repeating systems which can be implemented with little changes in the current hardware system. Simulation results show the improvement in reliability and performance of the systems using these methods.

The exact location of WIRELESS COMMUNICATION systems aimed at both military and civilian applications is an important issue. In WIRELESS COMMUNICATION networks, the user's location is done by using the measured signals time of arrival (TOA) from MS to BS. One of the most accurate methods for determining the TOA -based location systems is the use of neural networks.In this paper, a new algorithm is provided to improve the accuracy of locating based on BP neural network. In the newly proposed algorithm, instead of possible crossing points of TOA circles as neural network input, radius of TOA circle is used that much less than the previous method of complexity and accuracy is increased. Analysis and simulations show reduction positioning errors to a greater extent than half in the new algorithm compared to the previous method and it shows the location carefully.