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.

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.‎