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An Evolution of Wireless Technology: A Summary of "smart Wi-Fi" by Alex Hills

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In "Smart Wi-Fi," Alex Hills argues that as more people start to use wireless fidelity (Wi-Fi) networks, improvements to the wireless technology are needed to ensure reliable and secure services. An increase in popularity of Wi-Fi has come at the cost of creating difficult problems for designers of the technology. However, Hills notes that there has been "substantial progress" towards solving many of these problems.

Hills covers some of the developments in wireless local area network (LAN) technology since he and his team built the first large-scaled wireless LAN at Carnegie Mellon University. One development is the adoption of the IEEE 802.11 standard by wireless LAN. This standard is largely known as Wi-Fi. Hills then covers the workings of Wi-Fi networks.

Hills states that the "four major concerns" facing designers of Wi-Fi networks are reliability, performance, coverage, and security. The reason for these concerns is the use of radio transmission in Wi-Fi networks. A signal in a Wi-Fi network can degrade due to several reasons. The first reason is "attenuation," which means that radio signals weaken over long distances. The second reason is due to a phenomenon called "multipath distortion," which means that signals can bounce off objects to cause duplicate signals to arrive at the receiver. The third reason for signal degradation is caused by interference. Interference can come from many sources, including microwave ovens and natural sources.

"Overcoming" these problems come at a high cost. Methods to deal with these problems lead to slower transmission speeds and extra overhead costs for error reduction. Fortunately, work has been done by Hills and his colleagues towards improving the Wi-Fi technology in "the areas of reliability, performance, design and security." The improvements gave rise to a second generation of Wi-Fi technology, called "Smart Wi-Fi" by the author. The author then addresses four ways that Smart Wi-Fi improves on its predecessor.

The first improvement is the way that Smart Wi-Fi deals with network congestion. Since multiple clients and access points (APs) must share a single channel, only one station can transmit at a time. The way that Wi-Fi networks deal with this limitation is by implementing the carrier sense multiple access with collision avoidance (CSMA/CA) protocol. However, there are two difficulties caused by the use of the CSMA/CA protocol. Firstly, when a collision occurs between transmissions from different stations, both stations must retransmit. As more stations connect to the same AP the rate of collision increases, requiring many retransmissions. The second difficulty is a phenomenon known as "co-channel overlap," in which a station picks up transmission from a distant station using the same channel. The distant transmission is treated as if it was coming from the station's own cell, causing unnecessary delays in the network. These problems can be reduced by carefully assigning the channels to not cause overlaps, and using a new feature called "load balancing." Load balancing is a method in which the network tries to distribute the load evenly among different APs.

The second improvement deals with the problems of attenuation, multipath distortion, and interference. These problems as traditionally dealt with by a "good" network design. A good network design should maximize coverage and performance, but minimize co-channel overlap. On top of a good



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