What are the four wireless security industry organizations, and what are the duties and responsibilities of the IEEE, IETF, and Wi-Fi Alliance as regulatory domain authorities?
The Institute of Electrical and Electronics Engineers, the Internet Engineering Task Force, the Wi-Fi Alliance, and the International Organization for Standardization are the four industry groups in wireless security (Westcott & Coleman, 2014).
IEEE is a regulatory domain authority tasked with developing standards to ensure networking equipment compatibility and capability. The IETF is responsible for developing internet standards, the majority of which are used in wireless networking and security protocols and standards. The Wi-Fi Alliance is a standards organization whose purpose is to conduct certification testing to ascertain wireless networking apparatus are in conformity with 802.11 WLAN communication procedures.
What are the differences between each Radio Frequency (RF) behavior and the various mediums associated with each behavior?
Absorption occurs when a signal bounces off an object, passes through or moves around it. Medium causing absorption includes brick, drywall and concrete walls, water, paper, cardboard, and fish tanks (Westcott & Coleman, 2014).
Reflection is the bouncing off of waves upon striking a smooth object larger than itself. Particles of the ionosphere cause sky wave reflection. Buildings, roads, water bodies, doors, walls, glass are causes of microwave reflection (Westcott & Coleman, 2014).
Scattering is multiple reflections that occur when a wavelength of an electromagnetic signal is larger than the pieces of the medium the signal is passing through. Smog, sandstorms, uneven surfaces cause scattering.
Refraction is the bending of an RF signal as it propagates through a medium of different density causing the wave to change direction. Mediums of refraction include water vapor, air temperature changes, and changes in air pressure.
Diffraction is the bending of RF signal around an object that is between the transmitter and receiver. Small hills and buildings act as obstructions causing diffraction.
Attenuation is the decrease in signal strength or amplitude as it propagates. Electrical impedance in cables and connectors, attenuators, water, air, walls, and non-tinted glass cause attenuation (Westcott & Coleman, 2014).
Free space path loss is the loss of signal strength due to beam divergence. Space is the medium through which free space path loss is experienced.
Multipath occurs when an RF signal in propagation either reflects, scatters, diffracts, or refracts resulting in two or more paths of the same signal arriving at the receiver. Walls, desks, floors, flat road large water body, buildings, and atmospheric conditions cause multipath.
Gain (amplification) is the increase of signal strength or amplitude. Amplifiers are used to cause active gain while antennas are used to cause the passive gain.
There are practical uses of RF mathematics so knowing that, will the RF communication work? Why?
RF mathematics helps engineers while deploying radio communication links. While deploying radio communications, it is important to perform link budget calculations. The link budget determines what signal amplitude is understandable by a receiver. Combining the link budget with the fade margin can help determine whether communication between certain receivers become successful (Westcott & Coleman, 2014).
Knowing the receiver sensitivity and calculating the link budget, an engineer is able to determine the optimal fade margin to add in link budget calculations. This ensures successful communication while setting up WLAN bridge links to avoid downfades that could be caused by multipath (Radio Frequency Mathematics, n.d.).
What are the issues and variables involved with installing point-to-point communications for the Fresnel Zone?
Obstruction of the first Fresnel zone negatively influences the integrity of RF communication. It causes reflection, scatter, diffraction, and or signal bends hence reduced RF energy at receiving antenna. Typical obstacles include trees and buildings.
Degradation or cancellation of the primary signal affects the second Fresnel zone and is usually due to the presence of flat, arid terrains such as deserts, metal surfaces or calm water along the Fresnel zone. Railroad trestle or freeway, buildings in urban city environments can cause impediments affecting the side radiuses of Fresnel zones. The size of the Fresnel zone is a function of the frequency in use and distance between links (Westcott & Coleman, 2014).
Define what FHSS, DSSS, HR-DSSS, OFDM, ERP, HT, and VHT are?
FHSS is a spread spectrum technology conforming to the 802.11 standard. They are also referred to as Clause 14 devices.
DSSS is a spread spectrum technology that uses fixed channels and conforms to the 802.11 standard. They are referred to as Clause 16 devices.
HR-DSSS is a Physical layer medium defined by the 802.11b WLAN standard.
OFDM is a 5GHz spectrum that uses RF technology and is defined in the 802.11a standard.
ERP is an 802.11g WLAN standard that transmits in the 2.4GHz ISM frequency.
HT is a new operation of the 802.11n WLAN standard that provides PHY and MAC enhancements to support 600 Mbps.
VHT are enhancements defined in the 802.11ad amendments and that use the much higher unlicensed frequency band of 60 GHz to support data rates of up to 7 Gbps (Westcott & Coleman, 2014).
What are the similarities and differences between the transmission methods?
The two RF transmission methods are narrowband and spread spectrum. Narrowband transmission uses very little bandwidth to transmit data while spread spectrum transmission uses more bandwidth than needed to carry data. Narrowband signals are transmitted using much higher power than spread spectrum signals (Westcott & Coleman, 2014).
Spread spectrum systems do not suffer from intersymbol interference (ISI) while Narrowband signals. Spread spectrum is less susceptible to intentional jamming or unintentional interference from outside sources unless the interfering signal was spread across the range of spread spectrum frequencies. On the other hand, narrowband signals face disruption due to intentional jamming or unintentional interference.
References
Cooklev, T. (2004). Wireless communication standards: A study of IEEE 802.
Radio Frequency Mathematics. (n.d.). Retrieved from http://setup-wireless.blogspot.co.ke/2008/11/radio-frequency-mathematics.html
Westcott, D. A., & Coleman, D. D. (2014). CWNA: Certified Wireless Network Administrator Official Study Guide: Exam CWNA-106. Sybex.
