Due tomorrow night Computer science

1. Radio Frequency Characteristics

Radio frequency (RF) refers to the modification of the alternating current (AC), manipulated, and input onto an antenna, which could generate an electromagnetic field appropriate for wireless communication. Additionally, frequency describes the number of times a signal cycles per second, known as Hertz (Hz). Along with frequency, there is the wavelength, which refers to the distance between repeating wave pattern. In a sine wave, the wavelength is the space between any point on a wave and the matching point on the following wave in what it is called the wave train. Furthermore, there is an opposite association between frequency and the wavelength because as the frequency increases, the wavelength decreases. Goleniewski, L. (2007). Moreover, frequencies have classes or types with different purposes or key application ranging from low extremely low to extremely high and performance distance. For example, low frequencies (<3Hz – 300Hz) travel quicker without dropping power but carry much less information due to the bandwidth. High frequencies (3Hz – 30 GHz) have a greater bandwidth but significantly affected by interference from a variety of source. Extremely and very high frequencies (30GHz – 300GHz and 3GHz – 30 GHz) are greatly affected by bad weather conditions. Moreover, Wireless transmission has impairments from path loss, fading, interference noise, and environmental obstacles.

2. Radio Frequency Bands

Radio frequency is a signal created by using alternating current to create an electromagnetic field. This field is sent and received through antennae. This field is referred to as a radiowave or RF field. This field is used by a variety of communications including cell phones, radio, two- way radios, microwaves, and satellite systems. The following is a list of band designation into which the RF spectrum is divided into (TechTarget, 2015):

3. Wireless Communication Protocols

Wireless communication is the transfer of information from one point to another. These points are not connected physically by wiring. The distance can be a vast distant such as radio to space communication by or a short distance such as a television remote control device. There are several types of stationary, portable or mobile devices such as cell phones, PDA, walkie-talkies, baby monitors and wireless devices. Examples of wireless devices are a wireless printer, computer, mouse, keyboard, cordless phone, a GPS, and a garage door opener. Wireless protocols are essentially a set of rules that need to be followed in networking devices which allows them to exchange information by means of airwaves without any wires.

Wireless protocols come in three main classes. These include long range, medium range, and short range (Goleniewski, 2007). The difference between each is the range limit, where long range is in miles, medium range is in tens or hundreds of feet, and short is in ten feet or less. These three contain different protocols with their own capabilities but make each dependent. Long-range Wireless protocols with a long range often will give up speed to send communications over longer distances. An example of this would be supplying services to an individual device like a laptop or smart phone. WiMAX, (Worldwide Interoperability for Microwave Access), or WiMAX, was first designed to allow mobile devices access to the Internet. GSM, (Global System for Mobile Communications), is the most widely used long distance wireless protocol used in the world. Its main focus is supplying data communication to a vast majority of the world's cellular phones. Medium-range WLAN, (Wireless Local Area Network) known as mid- range wireless protocols mostly used for Communications between computers to restore or improve a traditional wired LANs.

The four main protocols, listed below, are part of the Institute of Electrical & Electronics Engineers, or IEEE, 802.11 standard. 802.11a, and can achieve a speed of 54 megabits per second most often over a shorter range than its competition. 802.11b has a longer range than 802.11a, but sacrifices speed with a lower maximum of 11 Mbps (Goleniewski, 2007). 802.11g combines the best of 802.11a and 802.11b by offering 54 Mbps at longer ranges. Short-range WPAN (Wireless Personal Area Networks), is a short distance protocol with lower frequencies on devices that are only a few feet apart. Bluetooth is a short-range protocol Bluetooth is another wireless standard. Bluetooth networks also operate on the 2.4 Ghz frequency range and are limited to a maximum of eight connected devices. The device transmits at a very low power the range is only approximately 30 feet. The maximum transmission speed is 1 Mbps. A wireless headset connected to a portable phone is one example. Although there are a number of protocols currently being used for wireless networking, the most widely used appears to be 802.11b. The equipment that is used by 802.11b tends to be less expensive and the maximum speed for communications is 11 mbps. The communication standard for the 802.11b wireless performs on a 2.4 Ghz frequency range. This is unfortunate because several other devices such as cordless telephones and baby monitors often interfere with your wireless network traffic. The newer 802.11g standard is a marked improvement to the 802.11b. Although it shares the 2.4 Ghz with other home wireless devices, the 802.11g is capable of transmission speeds up to 54 mbps. Equipment intended for 802.11g will still share communication with 802.11b equipment while mixing the two is not suggested. The 802.11a standard operates on a different frequency range. The 802.11a operates at a 5 Ghz range and does not have many issues with interference from the other devices in the home. 802.11a has the ability of transmission speeds up to 54 mbps the same as the 802.11g standard but the cost is considerably higher.

4. End-To-End Communication

There are many challenges when trying to use satellites in end-to-end communication. One challenge is that there is a lot of interference and noise when using electromagnetic waves. According to Goleniewski (2007), interference and noise is caused by environmental factors such as metals, the weather, and other anomalies. There is constant change in precipitation in the air around the world and will always affect the waves produced by satellites and antennas. There are other impairments such as foliage, path loss, and range and electrical power (Goleniewski, 2007). Another challenge of using satellites for end-to-end communication is Antennas. Goleniewski (2007) stated, “An antenna is a device through which radio frequency (RF) energy is coupled from the transmitter to the outside world and, in reverse, to the receiver from the outside world” (p.11). There are many different types of antennas used for different reasons. The reasons can be to pick up different frequencies or to be able to transmit and different concentration levels. Wireless transmissions are used for the bandwidth available through them. The problem with bandwidth is that it is dependent on the size of the waves that are transmitted. There can only be a certain amount of users in the spectrum and it needs to be controlled. Among the ways to control the spectrum is frequency division multiple access (FDMA) and time division multiple access (TDMA).

Goleniewski, L. (2007). Telecommunications essentials. (2nd ed.) Boston, MA: Pearson

TechTarget. (2015). What is radio frequency? Retrieved May 17, 2015, from http://searchnetworking.techtarget.com/definition/radio-frequency