802. 11 Synthesis Essay

Spectrum sharing: Since there may be multiple CR users trying to access the spectrum, their transmissions should be coordinated to prevent collisions in overlapping

1.     In your opinion, what is the purpose of our dropping the transmit power to such a

spatial variations in the radio environment and avoid interference to other users. Through Cognitive capability, spectrum holes can be identified at specific time or location. Thus the best spectrum and appropriate operating parameters can be selected.

Since CC combat the signal fading, it can be used to extend the transmission range of nodes and the network connectivity \cite{Yu2010,Zhu2012}. Figure \ref{fig:AumentoRaio} exemplify how CC can be used by node $v_i$ to send data to node $v_j$ that is outside of its maximum transmission range $R_{MAX}$. The source node $v_i$ selected the node in green as its helper. The dotted line represents the direct communication of the first phase, between the source and the helper. The solid arrows represents the second phase, where the source and its helper send data cooperatively to the destination. The nodes in black, that are inside $R_{MAX}$ could be selected to be included in the helper

It was designed to replace 802.11a, 802.11b and 802.11g. It has the fastest transfer rate of (600Mbps) and the longest signal range compared to its predecessors. It operates in both 2.4GHz and 5GHz range.

It provides the hardware means of sending and receiving data on a carrier, including defining cables, cards and physical aspects.

0 Use the Internet to research one to two applications of the illustrated wireless technology. List each application found. Be sure to reference the Web site(s) where you found this information.

In this type of communications two frequencies are used therefore the up and down links job is to separate such frequencies and eliminate interference in order to make full duplex communications possible. Usually the frequency carried by the downlink is lower compared to the uplink and the

This helps with transmitting only when there is no traffic in the air. This helps with slow transmission and get better performance overall. The RTS is request to send it sends out to a node and then the CTS is clear to send the requested information when the air is clear and is able to send data with interruption. The throughput is also reduced with the extra frames. (Ciampa, 2013)

and difficult to intercept also this transmission can share a frequency band with many types

It's the only weather station in it's class that uses frequency hopping spread spectrum radio technology translating weather data wirelessly

Although to answer their many questions and concerns, IEEE expanded even further and created 802.11g. Having 802.11g was like having the best of both worlds with and achievable speed of 12 to 25Mbps, top speed of 54Mbps, 2.4 GHz frequency band and the production cost was low what could top that one would have to ask. The disadvantage is that it cost more than the 802.11b, to include the change in modulation created the same congested problems as that of 802.11b. The advantage is that it was compatible with both 802.11a and 802.11b, which made previous compatibility issues null and void. Similar to 802.11a, 802.11g transmit faster because it uses OFDM instead of CCK

Wireless networking hardware requires the use of underlying technology that deals with radio frequencies as well as data transmission. The most widely used standard is 802.11 produced by the Institute of Electrical and Electronic Engineers (IEEE). This is a standard defining all aspects of Radio Frequency Wireless networking

In underlay transmission method the secondary users use the licensed band along with the active primary users but to keep the interference to the PU’s under a predefined threshold level the SU’s will control their power accordingly, where as in interweave transmission the SU’s use the licensed band when no active primary user is present [3].

These techniques allow a large number of users to access information through the same channel in wireless communication systems, also regarded as air-interface as mentioned previously. Thus, also making effective use of allocated bandwidth. The following three techniques come under this category: