Long Distance Wireless Communication-Free-Samples for Students

Questions: 1.Different antenna, such as yagi, horn, and celluar antennas, etc. has different merits. Research these technologies in details and pay specific attention to how they are used as well their strengths and weakness. 2.Compare and Contrast the multiplexing techniques CDMA and FDMA in the area of wireless Networking? Answers: 1.Antennas are devices that couple moving electromagnetic waves to and from electronic circuits using conductors that are either apertures or wires(MIT, 2004). Now, these antennas are categorised based on how they propagate waves, which defines the different types of antennas used today i.e. directional, semi-directional and Omni-directional Yagi antenna one of the most popular and successful RF antenna used. Its a directional antenna, thus it propagates RF waves in one direction which is associated with high gains and directivity. Its used in areas that require these characteristics e.g. television reception. Strengths: Low-cost design. High gains and directivity. Simple to install and use. Weaknesses For high gain levels, a long structure is required. Its gain is limited(radio-electronics, 2017). Horn antenna a directional antenna that is popular for transmitting ultra-high frequency (300MHz-3GHz) signals. Its name comes from its design, where a horn like structure, flares out to radiate signals enabling it to have high gains(Rouse, 2017). Strengths: It can operate at a wide range of frequencies and bandwidth. High gains. Simple construction Weaknesses It requires lengthened structure to operate effectively. Complex to install. Cellular antenna An Omni-directional antenna that can propagate signals in all direction and is common in mobile devices such as mobile phones, tablets and vehicles. Its usually small in size which facilitates its functionalities(Carr, 2012). Strengths Can amplify and operate in all directions. Optimal boosting capabilities. Weaknesses Minimal gains. Short coverage distance. Future of medium and long distance wireless communication Cellular antennas seem to have laid a solid foundation for mobile devices which marks them as the future of wireless communication. However, their low gains and coverage limit their functionalities, which necessitates the need for booster towers unlike the directional antennas highlighted above. Therefore, cellular antennas will require modifications in order to operate beyond their current applications. In light of these outcomes, the future may experience smart antennas designed as hybrids of both directional and Omni-directional antennas. 2.CDMA Code division multiple access FDMA Frequency division multiple access. Both are multiplexing techniques that were designed to meet a telecommunication challenge, that of assigning bandwidth to consumers i.e. the signals. CDMA: In this technique, the entire communication bandwidth is shared among many users by assigning them unique identification codes. In essence, the users are represented by multiple signals that are propagated in common channels, thus are uniquely identified by the codes. Now, the signals outlined above are tagged with the said codes during transmission and are used to separate the signals at the reception stage(corps, 2000). Consider the CDMA standard IS-95, which uses the 1.225 bandwidth range. This standard uses 64 Walsh codes to propagate signals. FDMA: In this technique, the entire band of frequencies are shared among many users by dividing it into multiple radio frequency channels. Furthermore, non-overlapping frequencies are used so as to transfer each signal uniquely to its destination. A good example is the GSM model where the 25 MHz frequency band is split into 124 carriers each having an estimated bandwidth of 200 kHz. CDMA FDMA A common frequency is used. Channel is usually idle when not in use. Every user has a unique pseud-code. Suitable for analogue applications. Each receiver must know the code of the transmitter. Filtering is needed to eliminate interferences. Only desired codes are detected, the rest appear as noise. Narrow band is used (Zahra, 2015) References Carr, J. (2012). Directional or Omnidirectional antenna? Joe Carr's Radio Tech-notes, Retrieved 14 August, 2017, from: https://www.dxing.com/tnotes/tnote01.pdf. corps, W. (2000). FDMA vs. TDMA vs. CDMA. Connecting Wireless, Retrieved 14 August, 2017, from: https://wirelessapplications.com/pdf/lf/FD_TD_CDMA.pdf. MIT. (2004). Chapter 3: Antennas. MIT, Retrieved 17 August, 2017, from: https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-661-receivers-antennas-and-signals-spring-2003/readings/ch3new.pdf. radio-electronics. (2017). Yagi Antenna / Yagi-Uda Antenna. Antennas and propagation, Retrieved 14 August, 2017, from: https://www.radio-electronics.com/info/antennas/yagi/yagi.php. Rouse, M. (2017). Horn antenna. Research gate, Retrieved 17 August, 2017, from: https://searchmobilecomputing.techtarget.com/definition/horn-antenna. Zahra. (2015). FDMA-TDMA-CDMA. Multiple access techniques in wireless communication, Retrieved 16 August, 2017, from: https://www.slideshare.net/SammarKhan2/fdmatdmacdma.