Question

As a network planner designs a wireless LAN (WLAN), what challenges must the planner consider with regards to radio frequency propagation?

Answer 1

Planning of the wireless communication systems, for example, LAN and PAN . The design errors can significantly reduce its performance. Each project is influenced by many factors, which makes the implementation of ready-made scenarios not useful and, as a result, affecting the final result. Due to the complexity of the implementation of projects, short-range wireless networks can be divided into three stages: preparation of the data to the project, the design and implementation of the project and the measurements. Each phase requires the use of an appropriate approach, since errors made in any one of them can undermine efforts in working on the project.

It shows the design algorithm of wireless communication network-:

The various forms of RF-based wireless communication systems,

which is classified into six groups: microwave RF systems, fixed and mobile satellite systems, wireless networks and protocols, personal communication systems, remote sensing systems, and emerging wireless technologies. No distinction is made between the communication layers and protocols in this classification. These systems transmit and receive radio waves tuned to specific bands of frequencies. Microwave is loosely used to describe all radio frequencies between 1 and 40 GHz. This includes the UHF, SHF, and EHF systems. The lower microwave frequencies (i.e., UHF) are most often used for terrestrial-based RF systems, whereas the higher microwavefrequencies (i.e., SHF and EHF) are used for satellite communications. A terrestrial microwave system transmits carefully focused beams of radio waves from a transmitting antenna to a receiving antenna. A terrestrial microwave system uses LOS propagation to communicate between the Tx and the Rx with a typical distance of 30 miles between relay towers.

Satellite communication is one of the traditional RF wireless communication systems. Signals can be transmitted directly from a ground station (GS) or gateway on earth to a satellite, and back to another GS.

Bluetooth is a wireless technology that makes possible connectivity to the Internet from mobile computers, mobile phones, and portable handheld devices without the need for cable connection.

Propagation is the process of wave motion, which is important in the design and operation of RF systems. Because the received signal is always different from the transmitted signal, due to various propagation impairments, and because of the nature of the propagation itself, it is necessary to understand the properties of radio wave propagation. This is most important in telecommunication applications in predicting the transmission characteristics of the channel.

There are the following methods of propagation:-

1. Free Space Propagation:

This is the ideal propagation mechanism when the Tx and the Rx have direct LOS and are separated by a distance d between the Tx and the Rx.

2. Reflection and Refraction:

When a radio wave strikes an object with dimensions very large compared with its wavelength, reflection occurs. All radio waves will undergo reflection if the propagation medium undergoes abrupt changes in its physical properties.

3. Diffraction:

Diffraction of radio waves occurs when the waves encounter some obstruction along their path and tend to propagate around the edges and corners and behind the obstruction.

4. Doppler Effect:

Doppler shift is the change in frequency due to the difference in speed between two points in space. It is observed whenever there is relative motion between the Tx and the Rx.