Wireless Local Area Networks (WLAN) and Their Advantages: IEEE 802.11a, b, g, and Beyond, Slides of Computer Networks

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Wireless Lan

Hardik Joshi (18mca012) Institute of Technology, Nirma University Ahmedabad, Gujarat, India. E-mail: 18mca012@nirmauni.ac.in

Abstraction

Wireless Local Area Networks (WLAN) is a data transmission system designed to provide location-independent network access between computing devices by using radio waves rather than a cable infrastructure. The protocol standard for WLAN is IEEE 802.11b, 802.11a, 802.11g.

Introduction

Wireless communications is one of the most active areas of technology development of our time. This development is being driven primarily by the transformation of what has been largely a medium for supporting voice telephony into a medium for supporting other services, such as the transmission of video, images, text, and data. Thus, similar to the developments in wireline capacity in the 1990s, the demand for new wireless capacity is growing at a very rapid pace. Although there are, of course, still a great many technical problems to be solved in wireline communications, demands for additional wireline capacity can be fulfilled largely with the addition of new private infrastructure, such as additional optical fiber, routers, switches, and so on. On the other hand, the traditional resources that have been used to add capacity to wireless systems are radio bandwidth and transmitter power. Unfortunately, these two resources are among the most severely limited in the deployment of modern wireless networks: radio bandwidth because of the very tight situation with regard to useful radio spectrum, and transmitter power because mobile and other portable services require the use of battery power, which is limited. These two resources are simply not

Rohan Pandya (18mca020) Institute of Technology, Nirma University Ahmedabad, Gujarat, India. e-mail: 18mca020@nirmauni.ac.in

growing or improving at rates that can support anticipated demands for wireless capacity. On the other hand, one resource that is growing at a very rapid rate is that of processing power. Moore's Law, which asserts a doubling of processor capabilities every 18 months, has been quite accurate over the past 20 years, and its accuracy promises to continue for years to come. Given these circumstances, there has been considerable research effort in recent years aimed at developing new wireless capacity through the deployment of greater intelligence in wireless networks. A key aspect of this movement has been the development of novel signal transmission techniques and advanced receiver signal processing methods that allow for significant increases in wireless capacity without attendant increases in bandwidth or power requirements. The purpose of this book is to present some of the most recent of these receiver signal processing methods in a single place and in a unified framework.

WHAT IS WIRELESS

COMMUNICATION

Wireless communication involves the

transmission of information over a distance

without the help of wires, cables or any

other forms of electrical conductors.

Features of Wireless

Communication

• The transmitted distance can be anywhere between a few meters (for example, a television's remote control) and thousands of kilometers (for example, radio communication).
• Wireless communication can be

used for cellular telephony,

wireless access to the internet,

wireless home networking, and so

on.

Wireless – Advantages

• Cost effectiveness

Wired communication entails the

use of connection wires. In

wireless networks, communication

Basic Service Set (BSS). An Extended Service Set (ESS) is a set of two or more BSSs that form a single sub network.

MAC Sublayer

The medium access control sublayer is the layer that controls the hardware responsible for interaction with the wired, optical or wireless transmission medium. The MAC sublayer and the logical link control sublayer together make up the data link layer.

Types of Wireless lan

• WLAN : 802.11a

When there's need for much higher performance. 802.11a is the ideal technology to support higher end applications involving video, voice, and the transmission of large images and files and when there is requirement for Higher Frequency band to avoid significant RF interference caused by other devices. The use of 802.11a operating in the 5 GHz band will avoid this interference.

• WLAN : 802.11b

For larger facilities, such as a warehouse or department store, 802.11b will provide the least costly solution because of fewer access points.the relatively high costs associated with migrating from a large-scale 802.11b system to 802.11a will be difficult to sell to the company's financial decision makers.

• WLAN : 802.11g

802.11g Wi-Fi supports maximum network bandwidth of 54 Mbps compared to 11 Mbps for 802.11b and 150 Mbps or more for the newer 802.11n Wi-Fi. to maintain backward compatibility with older Wi-Fi network equipment, 802.11g uses the same 2.4 GHz range of communication frequencies as 802.11b.

Application of wireless lan

- Inventory Control

Many businesses profit from using wireless LANs when managing their manufacturing processes. This lowers operating costs. Because the connections between the manufacturing equipment and main control systems are wireless, the company can reconfigure the assembly process at any time from anywhere, saving time and money.

- Health Care

More and more hospitals are deploying wireless networks to improve operational efficiency and convenience. In most cases, hospitals deploy wireless LANs in high patient-traffic areas including emergency rooms, critical care wards, nursing stations, as well as in doctor's offices and patient waiting areas. Hospital staff can use mobile computer devices to increase efficiency and accuracy when caring for patients.

- Education

Many colleges and elementary schools are finding beneficial reasons to install wireless LANs, mostly to provide mobile network applications to their students. In fact, schools have begun using the existence of wireless LAN access as a competitive advantage. These schools are targeting the growing number of students with laptops and expectations of accessing the Internet and school resources from anywhere on campus. such as classrooms, libraries, quads, and dormitories. Students are able to readily check e-mail, surf the Web, access specialized school applications, check grades,

and view transcripts. As a result, students make better use of their time.

- Public Networks

Because of the significant proliferation of laptops, PDAs, and cell phones, a growing need exists for mobile interfaces to the Internet and corporate applications. Users want and expect seamless, constant mobile connectivity to all information sources with high levels of performance and availability. Wireless networks provide the infrastructure to support these needs in public areas that are away from the home or office.

- Location-Based Services

With wireless networks, you can make the location of a particular person or item available to a central location. The ability to track the position of moving objects brings about some interesting applications. The coordinates of users can feed into a server- based application that implements a location-based service.

Future of wireless Lan

One possible avenue of future development in wireless LAN technology is in the area of “cooperative diversity.” Cooperative diversity can be viewed as somewhat of a cross between MIMO techniques and mesh networking. In a cooperative diversity scheme, redundancy in transmission is achieved in a manner analogous with diversity transmission in MIMO. However, the redundant transmission is realized via the cooperation of third party devices rather than solely from the originating device. In a cooperative diversity scheme, third parties which can successfully decode an on-going exchange will effectively regenerate and relay, with appropriate coding, the original transmission in order to improve the effective link quality between the intended parties.

Conclusion

Wireless LAN technology has experienced extraordinary advances in rate, range, and spectral efficiency. These advances, initially constrained by regulatory policy related to the

use of unlicensed spectrum, are now driven entirely by technical innovation and end user application demand which show no sign of abatement. As these new technical innovations continue, the challenges of providing low power operation will continue to mount while new opportunities to lower power consumption will present themselves to innovative designers.