Demystifying WI-FI And Other Transmission Methods

By Scott Penno.

The use of technology within schools continues to increase at a rapid pace. Today, electronic whiteboards, netbooks, tablets and other mobile devices are prolific within education – and who knows what the future will hold. Will students no longer carry books to read and write with but use a tablet to store all information? Will electronic whiteboard and display technology evolve to the point where it will be technically possible and cost effective enough to build a wall that is a whiteboard and display surface? Regardless of what future technology will be seen in classrooms and around schools, it is of little use if it operates in isolation: technology must be connected to students, teachers, the school community and the rest of the world.

There are many different connectivity mediums or transmission methods available – each of which has its strengths and weaknesses. For example, a cabled solution is not going to be ideal if you want portability or mobility. Similarly, wireless technology is not going to be that great if you are looking for an extremely secure solution. So, it’s not as simple as saying one technology is better than all others – but more a case of considering the specific requirements and choosing the most appropriate technology to meet those needs.

So, what are the options that are available when considering communication technologies? The various different options can be broken down into two basic types – wired and wireless – and within each type there are a number of different options. For example, wired communication technologies would include Unshielded Twisted Pair (UTP) more commonly known as ‘ethernet’ cable, point-to-point or active fibre and passive or PON fibre such as that currently being rolled out by the National Broadband Network (NBN). When it comes to wireless technology there is 802.11 Wireless LAN (WLAN) technology and a variety of different mobile wireless technologies including 3G, WiMax, LTE and HSPA+ which are all loosely considered fourth generation or 4G mobile technologies.

With the proliferation of mobile devices within education, wireless is seen as the preferred communication medium within many schools, however, this is a recent development. In the past, there were often computer rooms or ‘labs’ with a number of computers that were all directly connected or cabled to one or more ‘switches’ around the school. That cabling – often blue and referred to as ethernet cable – continues to be used for a few different reasons. Cable-based technologies can deliver bandwidth or performance that is unrivalled by wireless technology. Depending on the quality of the cable and the practices used during installation, ethernet cable can support at least 1 gigabit per second (Cat 5e) or up to 10 gigabits per second (Cat 6a). And unlike wireless technology, where the air is shared, cable delivers dedicated bandwidth. This makes it ideal for bandwidth intensive applications like traffic between servers and storage infrastructure or between graphics or CAD workstations and servers. Another benefit of cable is that pretty much every device has an ethernet port where many don’t feature a wireless interface – or it’s an optional extra for a price. This means that regardless of what device you are looking at, you can pretty much guarantee that it can be connected to a network using ethernet cable.

In the same way that we can use ethernet cable, we can use optic fibre for transmission. Ethernet cable has a limitation where the length of the cable between the two connected devices cannot exceed 100m. Fibre can be run for tens of kilometres or more between two devices, thus making it ideal for interconnecting buildings within a school or for connecting campuses where more more than one exists. There are two main fibre types – multi-mode and single-mode – and two different ways of deploying them – active or point-to-point and passive or PON. While this may sound complicated, when you consider how they are used, it’s relatively easy.

Point-to-point or active technology uses a fibre pair between two devices to create a service. For relatively short distances (less than 300m) then multi-mode fibre will deliver the bandwidth required (either 1Gbps or 10Gbps) and is a less expensive option than single-mode fibre when you consider the price of the optics that are required. Single mode fibre would be used where the distance exceeds 500m (or 300m if considering 10GbE). For most schools, multi-mode fibre would be used between buildings within the same campus and single-mode fibre would be used for interconnecting different campuses.

Passive Optical Network or PON technology is a point to multi-point technology which ‘splits’ a fibre service among a number of subscribers or users – typically 16, 32 or 64 ways. PON technology generally only uses single-mode fibre and is deployed by carriers or telco’s for delivering communications services to a user such as a residence, a commercial building or a school. The National Broadband Network (NBN) is a fibre to the home (or school or business) network that is being built using PON technology. With a PON network such as the NBN, the bandwidth available (2.5Gbps or 10Gbps) is shared among the given number of subscribers (16, 32 or 64). While this may sound less than ideal, the sporadic nature of traffic and the fact that not everyone will be using the network at the same time generally means there is more than sufficient bandwidth for all users. If a user needs more bandwidth then the split ratio can be decreased or point-to-point technology can be used. Moving forward, all schools will be interconnected through the NBN which will allow improved access to government-based services and also improve collaboration among schools – both here and overseas. It is also possible that a school could use the NBN for interconnecting campuses. However, this would be dependant on distance, bandwidth and price.

Wireless technology delivers a service or connection without needing to be cabled or connected to the network. This makes it ideal for devices and applications where portability is important such as netbooks and tablets for students or wireless VoIP handsets that may be used by staff in outdoor areas. Wireless technology uses the air around us to deliver a service and it is important to understand that it is a shared medium, that is, it is shared by all users of that network in the area.

Wireless LAN technology has evolved rapidly over the last few years from 802.11b (max 11Mbps) to 802.11g (54Mbps) to the latest standard, which is 802.11n (max 450Mbps today). The air around us can be divided up into different sections or frequency ranges and it is the ranges around 2.4GHz and 5GHz that are used for WLAN’s. Due to the way waves move through the air, they travel further at 2.4GHz than at 5GHz which means that when operating at 5GHz, more access points will be required to deliver the same amount of coverage as at 2.4GHz.

Many schools have had WLAN technology deployed for some time and, due to the increased number of devices connected to the network and increased use of the network, are looking to move from a wireless LAN that delivers coverage to a wireless LAN that delivers performance. Many of today’s wireless LAN solutions use a cell-based topology where access points are arranged in cells to deliver coverage over a specific area. Global research organisation Gartner considers these cell-based solutions as the third generation or evolution of wireless LAN technology. Gartner has also identified a number of vendors that deliver wireless LAN solutions using a blanket-based topology. These solutions deliver better performance and overcome a number of challenges associated with cell-based topologies.

Where Wireless LAN technology would be used within a school or possibly for a point-to-point link between schools, mobile wireless technology would be used beyond the confines of the school where the school doesn’t have wireless LAN coverage. Mobile wireless technologies such as 3G, WiMax, LTE and HSPA+ use a mobile carrier’s network to deliver a data service. These services provide coverage almost anywhere across the country but do so at a cost that is charged by the telco or carrier delivering the service. Today’s 3G services have the potential to deliver bandwidth from a couple of hundred kilobits per second to several megabits per second but this does fluctuate and does not ‘feel’ like the performance of a wireless LAN. 4G technologies such as WiMax, LTE and HSPA+ are either being deployed or about to be deployed by telcos within Australia and have the potential to deliver high tens to hundreds of megabits per second of bandwidth. These 4G services have the potential to provide ‘wire-like’ performance beyond the confines of the school

With so many technologies to choose from, it is unlikely a school will use a single technology for all of its communication requirements and instead will use a blend of different technologies to meet the range of different needs found within today’s educational institutions.

 

Scott Penno has a Bachelor of Communication Engineering and an MBA in IT Management and has been working in the communications industry in Australia for nearly 20 years. Today Scott is the Country Manager for Allied Telesis – a leading vendor of wired and wireless technology for businesses and schools across Australia and the globe.  Scott can be contacted on 1800 000 880

 

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Education Technology Solutions has been created to inspire and encourage the use of technology in education. Through its content, Education Technology Solutions seeks to showcase cutting edge products and practices with a view to expanding the boundaries and raising the standards of education curricula. It introduces teachers and IT staff to the latest products, services and developments in education technology with a view to providing practical how-to guidance designed to facilitate the integration of those products and services into the school environment in the most productive and beneficial manner possible.
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