Spread spectrum techniques in wireless communication Part 2: Transmission issues in free space

The second part of Spread Spectrum Techniques in Wireless Communication focuses on wireless transmission issues and implementation of a water quality assessment wireless system. I present concepts of electromagnetic propagation, some important issues in open space electromagnetic transmission particularly when a transmission link is over a conductive surface, and a simplified analysis of common occurrences that impair the transmission´s quality or can even block the communication between network nodes. I introduce the primary techniques that are used to mitigate open space propagation problems, giving particular attention to solutions that can be used to mitigate fading effects in spread spectrum communication systems. Then, I present experimental results of a wireless transmission system used in water quality assessment.