Which spread spectrum technologies exhibit resistance to narrowband RF interference by design?
Answer(s): A
Frequency hopping spread spectrum is a spread spectrum technique that uses frequency agility to spread the data over more than 83 MHz. Frequency agility refers to the radio's ability to change transmission frequency abruptly within the usable RF frequency band. In the case of frequency hopping wireless LANs, the usable portion of the 2.4 GHz ISM band is 83.5 MHz, per FCC regulation and the IEEE 802.11 standard. Both FHSS and DSSS technologies have their advantages and disadvantages, and it is incumbenton the wireless LAN administrator to give each its due weight when deciding howto implement a wireless LAN. This section will cover some of the factors that shouldbe discussed when determining which technology is appropriate for your organization, including:? Narrowband interference? Co-location? Cost? Equipment compatibility & availabilityThe advantages of FHSS include a greater resistance to narrow band interference. DSSS systemsmay be affected by narrow band interference more than FHSS because of the use of22 MHz wide contiguous bands instead of the 79 MHz used by FHSS. This fact may be a serious consideration if the proposed wireless LAN site is in an environment that has such interference present.
A 2.4 GHz Spread Spectrum phone located near an 802.11b compliant Access Point will not cause interference.
Answer(s): C
communications tower or other legitimate system, the wireless LAN administrator might have to consider using a wireless LAN system that utilizes a different set of frequencies. For example, if an administrator were responsible for the design and installation of an RF network at a large apartment complex, special considerations might be in order. If an RF interference source were a large number of 2.4 GHz spread spectrum phones, baby monitors, and microwave ovens in this apartment complex, then the administrator might choose to implement 802.11a equipment that uses the 5 GHz UNII bands instead of 802.11b equipment that shares the 2.4 GHz ISM band with these other devices. Unintentional jamming occurs regularly due to many different devices across many different industries sharing the 2.4 GHz ISM band with wireless LANs. Malicious jamming is not a common threat. The reason RF jamming is not very popular among hackers is that it is fairly expensive to mount an attack, considering the cost of the required equipment,
Bluetooth uses which type of data modulation?
option. Bluetooth and HomeRF are both FHSS technologies that use GFSK modulation technology in the 2.4 GHz ISM band.
When doing wireless LAN mathematical calculations, it is necessary to be able to convert which of the following?
MilliwattWhen implementing wireless LANs, power levels as low as 1 milliwatt (1/1000 watt, abbreviated as "mW") can be used for a small area, and power levels on a single wireless LAN segment are rarely above 100 mW - enough to communicate up to a half mile in optimum conditions. Access points generally have the ability to radiate 30-100 mW of power, depending on the manufacturer. It is only in the case of point-to-point outdoor connections between buildings that power levels above 100 mW would be used. Most of thepower levels referred to by administrators will be in mW or dBm. These two units of measurement both represent an absolute amount of power and are both industry standard measurements.
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