Wireless lans Wireless Local Area Networks Tom Franklin TechLearn




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Wireless Local Area Networks

Tom Franklin

TechLearn

Contents


Contents 2

Executive Summary 1

1 Introduction 3

1.1 Wireless Basics 3

1.2 What is a LAN 6

1.3 Benefits of wireless LANs: 7

1.4 Disadvantages of wireless LANs: 7

2 Types of Wireless LAN 10

2.1 Standards 10

2.2 IEEE 802.11 10

2.3 Bluetooth 11

2.4 WECA 11

2.5 IrDA 12

2.6 HiperLAN/2 12

2.7 Wireless telephony 12

3 Regulatory issues 14

3.1 Radio Frequencies 14

3.2 Infrared 15

4 Security 16

5 Mobility 17

5.1 Itinerancy 17

5.2 Roaming 17

6 The US position 18

6.1 Costs of wireless versus wired LANs 18

7 College and university drivers 20

8 Wireless LANs: the future 21

9 Pedagogy 23

9.1 Wireless enabled teaching 23

9.2 In conjunction with universal PDA / laptops 24

10 Some College Experiences 27

10.1 State University of New York, Morrisville 27

10.2 Seton Hall University 28

10.3 Carnegie-Mellon University, Pennsylvania 30

11 Conclusion 32

12 Comparison of Wireless technologies 33

13 Glossary 34

14 Annotated Bibliography 39

General 39

Wireless LAN use in education 40

Standards 41

Security 42

Figures


Figure 1. Wireless uses in differing environments 4

Figure 2. Data rates and mobility for communication types 5

Figure 3. A Wireless LAN set up 6

Figure 4. Licensed bandwidth in the 5 GHz band 15


Tables


Table 1 some wireless LAN standards 8

Table 2 Comparison of different wireless LAN technologies 33





Executive Summary


This report is intended for IT service staff planning enhancements to their network, and for learning technologists who want to understand the ways in which wireless local area networks (LAN) can be used to enhance the learning process for students at their institutions.

The report does not require a technical understanding of LANs, and anyone who is not interested in the various standards can skip section 2 "Types of Wireless LAN".

It is hoped that IT and network managers will not only gain an understanding of some of the technical issues involved in implementing a wireless LAN, but that they will also appreciate the ways in which a wireless LAN can enhance educational processes for students (and staff) and may consider installing wireless LANs in areas which already have adequate wired LAN facilities, as well as considering the use of wireless LANs when extending or enhancing existing LANs.

Educational technologists will want to consider how the use of wireless LANs can enhance education and, in particular, what staff development is required to help teaching staff make effective use of the new opportunities that wireless LANs offer.

A wireless LAN is a method of linking computers together without using cables. Until recently computers could only be effectively networked using wires, however it can also be done using radio signals or infrared light.

This report discusses what a LAN is and the issues which are involved in determining whether a wireless LAN is appropriate for any institution and how to go about implementing a wireless LAN if it is, and continues by looking at the educational opportunities which the use of wireless LANs opens up for colleges and universities, and how this should affect the way in which wireless LANs are implemented.



  • Wireless local area networks (LAN) can be installed where there are economic or educational benefits for so doing.

There are likely to be economic benefits where there is not already a good existing LAN and one is needed. This is especially true in buildings where it is difficult to lay cables, for example because they are listed buildings and require consent or because there is asbestos in the building and drilling through walls or floors may be prohibitively expensive.

Wireless LANs also provide enhanced flexibility. With a wired LAN any tables that have network connections have to be fixed to the floor or walls so that the wires are not pulled out. This means that the room cannot be re-arranged in the way that the teacher might want. Wireless LANs also enable the provision of "computer carts". A computer cart is a trolley with a number of laptops and a wireless access point, which can be wheeled into the room where they are wanted. This means that all teaching spaces become computer rooms when computers are needed. This can include laboratories and even outdoors. This can reduce space requirements as there is less need for specialist computer labs for teaching and also eases timetabling.

Educational benefits are most likely to accrue where there are courses which require all students to have a laptop or personal digital assistant (PDA) such as a Palm or iPaq. While few colleges or universities within the United Kingdom currently have courses which mandate these it is already common in the USA and is likely to start to happen here soon. This ubiquitous computing with wireless connectivity opens up new educational possibilities which are beginning to be explored. Evidence suggests that this technology enhances collaborative work and is bringing new teaching methods into the classroom.


  • In almost all situations wireless LANs will be used in conjunction with wired LANs to maximise the benefits for the college.

A wireless LAN requires a "backbone" to connect the parts together, and in most cases this will be wired (though point-to-point wireless connections can also be used). Also, there will be locations where wiring makes sense. Examples of this include computer laboratories where the need to provide power cables means that laying data cables at the same time is comparatively inexpensive and the density of computers and the bandwidth requirements make wired LANs the most sensible solution.

  • Great care needs to be taken with the management of the wireless network if reasonable security is to be achieved. Reasonable means that the wireless part of the network is no more vulnerable than the wired parts of the network to hackers.

Wireless is inherently more vulnerable for two reasons. Firstly, the hacker does not even need to enter the premises to be able to gain access to the network from inside any institutional firewall as radio signals will pass through walls. Secondly, it is easier to monitor the radio signals compared to those in a wired LAN.

To overcome this a standard called wired equivalent privacy (WEP) has been developed. There have been some serious flaws in this, although a solution to the most significant flaw has now been developed and any new equipment purchased should comply with the enhanced standard.



To get the security in perspective it should be remembered that in most colleges it is not difficult for anyone to walk in and start using a computer in one of the labs, and the major problem is the ability to monitor traffic on the network and so learn user names and passwords if the security is not set up correctly.

  • Wireless LANs do have a role to play in creating a good network in colleges and universities in particular where a college or university may be wishing to extend the network into additional buildings or parts of buildings or where "flood wiring" is being considered.

However, care is needed in designing the network as the available bandwidth is lower (4 - 54 Mb/s depending on the technology) and it is shared between all the users.

  • Wireless LANs can use either radio frequencies or infrared light to transmit signals. While it is considerably cheaper to install infrared networks, as many devices (such as most laptops and PDAs and many printers) already have infrared (IrDA) ports the limitations (low bandwidth and the need for line of sight) mean that it will rarely be the system of choice. Radio frequency (RF) comes with a number of restrictions as most of the available frequencies are licensed for instance for use for television, radio and mobile phones. There are currently two bands which can be freely used, but this means that the available space is also used by other devices such as cordless telephone handsets, garage door openers and Bluetooth enabled devices, and therefore there may be problems of interference from other devices.

  • When choosing a technology for wireless it is important to consider not only the installation costs but also the upgrade possibilities of any technology. Currently there two major families of wireless LAN technologies, and they are incompatible with each other as they work in different parts of the radio frequency spectrum. In most cases colleges and universities will want to use the technologies in the industrial, scientific and medical (ISM) band as these are better established, cheaper, offer more security and require less equipment. Their drawback is that the available bandwidth is less (but rapidly growing) and there is more likely to be interference from other devices (especially Bluetooth).

Currently wireless LANs should be built using Wi-Fi certified equipment which will ensure that it will work with equipment from any supplier and will provide a simple upgrade to equipment meeting the new 802.11g as that becomes available.

  • Determining exactly how to install a wireless LAN is more complex than for a wired LAN as the way the radio signals travel in the buildings needs to be checked as wiring, plumbing and building materials can all affect how the signal travels. It is essential to undertake site survey to determine how the LAN should be installed. If this is not done then there are likely to be areas where no service is offered and additional equipment will be needed to give sufficient coverage. Without a survey planned growth will also be more difficult.

  • Wireless LAN use will continue to grow and become more important over the next five years, by which time it will be as unthinkable for a university or college not to have a wireless LAN as it is for a college not to have a LAN now. They will continue to supplement wired LANs which will always have an important role to play, both providing the backbone within campuses and serving key areas such as computer labs where large numbers of computers needing high bandwidth are found.

The report looks at each of these issues and will help determine the most appropriate for of wireless LAN for your college or university.
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