Communication system transmits information from one place to another by means of electrical energy. This article describes the analysis and design of electronic circuits used in radio frequency communication systems covering the frequency range up to several hundred megahertz. The actual frequency switched on depends on whether the circuit is made with decree components or as an integrated circuit. The electromagnetic waves that leave The transmitting antenna arrive at the receiving antenna in one of many waves. These include earth waves, sky waves, space waves and satellites. Ground waves travel along the ground and follow the terrain. Radio wave propagation concerns how the radio signal generated by a transmitter travels to a receiver located a certain distance away. The portion of the electromagnetic frequency spectrum used for broadband wireless communications extends from 300 MHz to 300 GHz. The frequency range covers a wavelength of 1 m to 1 mm. In these frequency bands, radio waves are transmitted as space waves. In other words, neither earth waves nor sky waves are used at these frequencies. The simplest radio propagation environment is free space with no atmosphere or solid objects along the path between transmitter and receiver. Such an environment allows radio signals to travel in line of sight and be received as direct waves. Unfortunately, this model oversimplifies practical propagation environments in which the radiated wave contacts solid objects that produce changes in its amplitude, phase, and direction of propagation. Even in the absence of solid objects, the strength of radio signals decreases as the probation distance increases. The medium over which the radio wave passes...... middle of paper ......ts. This means that the network management system must be such that it will periodically monitor the RSSI for each word. When the RSSI is below a predefined threshold, it should be possible to remotely reconfigure the affected mote so that it can access the network via the second access point it can see. The task of network management is complicated by many factors, including different networking technologies, heterogeneous systems from a myriad of vendors; and a number of distributed applications, some of which have vendor-specific requirements. Added to this is the fact that many new network applications place high demands on quality of service and security on the network. The task of configuring the network to meet the end-to-end quality of service and security requirements of each application is a tedious task that cannot be handled by traditional network management systems..