new ccna 200-301 book pdf

new ccna 200-301 book pdf.3.2.2 Factors Affecting Wireless Transmission Now that you have a clear understanding of wireless transmission and what it entails, it is the perfect time to discuss the factors that affect the wireless signal. Some effects may cause the wireless signal to fail to propagate, while others may simply shorten the transmission distance. In short, you should be aware of these factors and use them as a basis to plan and adjust your deployment accordingly. In this section, you will learn about the free path loss model, absorption, reflection, scattering, multipath, refraction, and line-of-sight.1 - Understanding the Free Path Loss ModelTo understand FreePathLoss, imagine that you jump into a pool with a bang. This will cause many ripples to propagate around you. The closer you are, the bigger the ripples. Likewise, the farther away you are, the smaller the ripples. After a certain distance, the ripples become very wide and slowly fade away.You may recall what you learned before: an object in motion stays in motion until something stops it. But there is nothing to stop the wave; the wave can only disappear. This is where the term free( fi*ee) comes from. As shown in Figure 3. 1, you can see a wave-or, in this case, the wireless letter one being propagated- slowly weakening as it travels outward from the source. The change in the wave is represented by the transformation of the thick black dot to an increasingly faint black dot.3.2 Basic themes 25Figure 3.1 Free path loss model3.2 Basic Themes 26You may also notice that the farther the signal is from the center, the more sparse the points become. Figure 3.1 has a transmitting device (which you can think of as an AP) and multiple receiving devices. Not all of the receiving stations get every signal sent by the transmitter. Devices close to the transmitter usually get a more focused signal in terms of strength, while receivers far from the transmitter might only get a very weak signal.The determination of that range is related to energy loss and distance. If the receiver is placed outside that range, the receiver cannot receive the wireless signal from the AP and, fundamentally, such a network will not work.2. Understanding Absorption