IT LOVER

25/03/2009

WIFI GUIDE

Filed under: computer zone — pankaj kuamr @ 1:28 अपराह्न

There’s something akin to a political mantra in technology circles – wireless, wireless, wireless. Specifically in computing, the rage right now is wireless networking.

That means enabling one or more PCs to communicate with devices such as printers and connect to the internet without cables. It means that several users may share files and folders and an internet connection, say. It is a lot less messy than routing wires all over the place.

However, although a wireless network might be physically neat, the world of wireless networking is far from tidy. It is littered with enough acronyms, abbreviations and jargon to overwhelm even experienced PC users. It’s no wonder that so many people find wireless networking a worrisome prospect.

Well, worry no more – we’re here to help. In the first few pages of this feature, we’ll explain what wireless standards mean, and then we will move on to show exactly what’s needed to get a wireless network up and running, at home or in an office. And be assured, we’ll keep the jargon to a minimum.

Which wireless?
There are several varieties of wireless network. For instance, a mobile phone relies on a wireless network of sorts, with coverage provided by radio masts dotted around the country in a cellular arrangement. Similarly, some mobile phone accessories, such as cordless earpieces, rely on another type of wireless network – a short-range system called Bluetooth.However, we will be looking at wireless networking for PCs.

These days this technology is often referred to as Wifi, which is short for wireless fidelity. This term also lends its name to the industry organisation responsible for negotiating and agreeing standards for all things Wifi: called the Wifi Alliance (www.wifi.org). The group is made up of over 250 members, which includes just about every technology company we could name. To all intents and purposes, then, these days the terms wireless networking and Wifi are interchangeable.

Organisation frustration
But while the Wifi Alliance is in charge of certifying compatibility between products, the Alliance is not responsible for ratifying wireless standards as ‘official’. That job belongs to the Institute of Electrical and Electronics Engineers, or IEEE.

Now, being a technically-minded bunch, the folks at the IEEE have little favour for consumer-friendly branding, such as Wifi. Instead, it prefers to label the computer-based wireless-networking standards (or ‘protocols’) that it ratifies with a filing number – which in this case is 802.11.

To further ache confused consumer heads, the IEEE has to date ratified several different varieties of 802.11 wireless networking, appending a letter onto the end of the 802.11 label to distinguish one from another. So, right now it’s possible to buy wireless networking gear that conforms to 802.11a, 802.11b and 802.11g. It’s also possible to buy kit that promises compatibility with 802.11n – a standard that’s yet to be officially ratified.

Of course, none of these labels actually tells consumers anything useful about the equipment they describe. More to the point, nor do they guarantee seamless compatibility between any two products supposedly adhering to the same standard, which might seem to defeat the whole purpose of having formalised standards in the first place – but we’ll explore compatibility issues later.

Recite your ABGs
So, what do all these different suffixes signify? It’s a good question, and one that’s deserving of a detailed answer. The very first 802.11 standard was drawn up and ratified way back in 1997. In simple terms, it specified how existing computer-networking technology (known as Ethernet) could be made to work without wires.

Essentially, computer data could be sent as radio waves at speeds of up to 2Mbits/sec. Compared with the 100Mbits/sec or even the 10Mbits/sec wired Ethernet networks of the time, this was a pretty slow speed.

Within a couple of years, though, the original 802.11 was usurped by 802.11a and 802.11b. The 802.11b standard quickly became the most popular wireless-networking standard with consumers, offering data-transfer speeds of up to 11Mbits/sec and with a maximum working range of up to 120m (around 400ft) from the PC or device providing the wireless connection.

However, in workplace environments, where many people may rely on and use the office computer network, 802.11b’s data-transfer speed of 11Mbits/sec wasn’t fast enough, hence the creation of 802.11a.

Equipment conforming to the 802.11a standard is capable of transmitting data at up to 54Mbits/sec – a speed much more attractive to business customers. However, the unobstructed range is just 30m (100ft). Moreover, thanks to the fact that ‘a’ uses a different part of the radio spectrum than ‘b’ the two standards are not directly compatible.

This brings us nicely on to ‘g’ – that’s 802.11g. It is the standard most recently ratified by the IEEE, and it provides connection speeds of up to 54Mbits/sec over a distance of up to 50m (160ft) from the transmitting device, assuming there are no obstructions to degrade the signal (we’ll explain more about interference later).

As well, 802.11g-based equipment operates on the same frequency as 802.11b devices, so a notebook computer user fitted with an 802.11g network adapter should be able to communicate with an 802.11b network, or vice versa. However, in such circumstances the transmission speed would be restricted to the 802.11b limit of 11Mbits/sec.

Non-standard standards
As if three Wifi standards weren’t enough for consumers to cope with, there’s more on the way. At the same time, in an attempt to steal a march on competitors, some manufacturers of wireless-networking equipment have taken it upon themselves to ‘improve’ existing standards with their own (proprietary) enhancements.

Buffalo, for example, promotes the Turbo G-system, which builds on 802.11g to provide wireless transmission speeds of up to 125Mbits/sec.

Similarly, Netgear markets Super G, which promises to double the 802.11g top speed to 108Mbits/sec. But naturally, Super G and Turbo G aren’t compatible with one another – that would be far too simple.

Finding MIMO
For added confusion – because it isn’t nearly confusing enough already – the clever chaps at the IEEE have yet another Wifi standard waiting in the wings. Called 802.11n, it will feature a variety of enhancements, including something called multi-input, multi-output, or MIMO transmission technology.

This essentially means wireless-networking gear fitted with more aerials – either internal or external ones – which should bolster the reliability of wireless connections and transmission speeds.

But even though 802.11n has yet to be ratified, numerous manufacturers are already marketing ‘pre-n’ Wifi equipment. Although 802.11n should, in theory, be reliably compatible with 802.11b and 802.11g equipment – as it uses the 2.4GHz part of the radio spectrum – remember that it isn’t yet a formalised standard. It could change, rendering

pre-n equipment problematic. However, most manufacturers of pre-n are promising to issue simple hardware-updating software that will ensure pre-n gear conforms to the ratified 802.11n standard.

By the way, if you’re wondering where all letter suffixes between ‘b’, ‘g’ and ‘n’ disappeared to, forget them – they’re not at all relevant to understanding the basic practicalities of wireless networking. And that’s what we’ll cover next.

Logo a-go-go
So, where does all this leave consumers who just want to build a wireless computer network without complication, confusion or fear of compatibility prob lems? Well, potentially a tad overwhelmed but, thanks to the aforementioned Wifi Alliance, there is a simple way to buy wireless equipment with confidence – certification.

Among much else, the Wifi Alliance involves itself with testing the compatibility of wireless-networking products. Those that pass the tests are issued with a certificate and allowed to display one of several Wifi Certified badges. Each of these clearly details which of the 802.11 standards the labelle d product is compatible with – be it a, b, g, or a combination of the three. For reasons which we’ll discuss a little later, such labelling does not constitute a 100 per cent guarantee of compatibility between competing brands, but these days it’s a pretty safe bet.

To further simplify matters, almost all new Wifi equipment on sale today is compatible with both 802.11b and 802.11g. On the packaging this may be summarised as 802.11b/g, or simply with the Wifi Certified b/g logo. This means that any two products bearing such a badge should be compatible with one another – regardless of manufacturer.

So, to recap, wireless networking is often called Wifi, and Wifi is also known as 802.11 – and there are several variants of 802.11. But all you really need to remember is this: shop for wireless equipment bearing the same Wifi Certified b/g badges and it’s hard to go far wrong.

Buying and setting up
The other thing to settle before setting out on a shopping trip is what kind of equipment you need. Obviously, this will depend on the number of computers involved, and how they need to be connected. However, for a practical example we’ll explore the wireless networking of a household that has, say, a couple of desktop PCs, a notebook computer and a single broadband internet connection.

We’ll assume that the PCs aren’t currently networked and that the broadband internet connection is accessible to only one of the desktop PCs. Note that all the products we mention are merely examples of typical products on sale today – do not take them as specific recommendations.

For our example, the most sensible first buy would be a device called a wireless router – the device that directs traffic between all the items attached to the network, and shares out the internet link between users. If the broadband connection is ADSL (ie, it is supplied via a BT phone socket), then shop for an ADSL Wifi router; cable broadband subscribers (that’s essentially Telewest and NTL customers) should buy a cable router.

Two typical examples include Belkin’s £60 Wireless-G ADSL router (www.belkin.co.uk) and the similarly priced AirStation G54 Cable/DSL router from Buffalo (www.buffalotech.com). Note that many ISPs sell their own routers, which you can get support for.

The Wifi router will sit between the main desktop PC and the broadband internet connection, plugging into the existing broadband modem . Combined Wifi router-cum-modems can be bought, if you really want to dispense with the existing modem – or are starting from scratch.

The second desktop PC and notebook computer in our example setup will require a wireless adapter, or Wifi adapter. The desktop PC can have such an adapter fitted internally, slotted into an expansion slot , if you’re confident enough to venture inside.

This is the neatest and cheapest option – expect to pay about £25 for a PCI Wifi adapter card. If you want to avoid internal faffing, then a thumb-sized USB Wifi adapter will do the job just as well, and really won’t be much more expensive. Netgear’s WG111 USB 2.0 adapter, for example, costs £36 (www.netgear.co.uk).

A USB adapter will similarly enable the notebook to communicate with the Wifi router to get network and internet access. However, having a USB device sticking out the side of a notebook computer isn’t ideal, not least because it could easily be dislodged, thus losing the wireless connection. Most notebooks include PC Card slots, which provide a tighter hold on inserted devices: Netgear’s £41 WG511T is a typical example.

To sum up, the equipment requirements come down to a Wifi router connected to the main desktop PC and a Wifi adapter for each computer that needs to be wireless connected. It’s that simple.

Wireless wizardry
When it comes to setting up the Wifi equipment we strongly advise you to read the instructions supplied. Even though Windows XP has a very good wireless-network setup wizard – called the Wireless Network Setup Wizard – Wifi equipment manufacturers supply their own setup software and equipment drivers. They will do much the same job as the Wireless Network Setup Wizard, but with specific attention to the needs of the manufacturer’s equipment.

However, if you’ve bought second-hand equipment you may find you have no supplied software to (see the box headed ‘Save money with second-hand kit?’ on page 18 for more thoughts on buying used equipment).

In such circumstances, open the Control Panel (from the Start button), click on the Network and Internet Connections link and then click on the Wireless Network Setup Wizard link (if you don’t see this option, click the link marked Category View on the left-hand side. On the first dialogue box, click to select the ‘Set up a new wireless network’ radio button and click on Next. Give the network a name – something like the name of your street – and, assuming your equipment supports it, click on the box for WPA encryption (more on this shortly),then click on Next.

What happens from here on will depend on the exact arrangement of your computer equipment and networking requirements, but just follow the wizard’s instructions and prompts to complete the job.

Security
With all your personal files and folders and internet activities flying around the Wifi network over radio waves, it’s reasonable to be concerned about security and privacy. After all, no-one wants a Wifi-equipped neighbour to accidentally or otherwise gain unauthorised access to their wireless network.

Fortunately, Wifi equipment can be protected using data encryption and passwo rds; the best combination of which renders unauthorised network access all but impossible. This is achieved using complicated mathematical algorithms, but don’t go pale at the thought these: as the ‘administrator’ (or boss) of your Wifi network, the only thing you’ll need to remember and keep secret is a passphrase or ‘key’.

The two commonplace Wifi encryption systems are Wired Equivalent Privacy (WEP) and Wifi Protected Access (WPA). WEP is an older, less-secure system (although it’s still pretty safe), while all new equipment should support the virtually-impregnable WPA – as mentioned earlier in regard to the Wireless Network Setup Wizard. Whether using that wizard, or the manufacturer-supplied setup software, encrypting your Wifi network will be no more difficult than ticking the relevant box (WPA if available) and choosing a suitable passphrase.

And that should be that. The Wifi network should be working, and users of computers with Wifi adapters should be able to get internet access via the Wifi router attached to the main PC. Sharing files and folders across computers connected wirelessly is also possible, though whether or not this is activated will depend on the choices made when following the Wireless Network Setup Wizard or the manufacturer-supplied setup software. For more help, see our short guide on the topic in this issue’s Workshops section.

Before we go it’s worth pointing out that once up and running, your wireless network may not always function flawlessly. Wifi devices use the radio spectrum and can be affected by interference. Symptoms may include reduced performance (ie, stuff may be transferred across the network more slowly), or a complete loss of the connection. If this happens often, try placing the Wifi router in a less-obstructed position.

Alternatively, use the supplied software to switch frequencies: Wifi ‘b’ and ‘g’ devices can function across several different ‘channels’ around the 2.4 GHz band and if a neighbour’s Wifi setup is operating on the same one, it could cause problems. Also, see the box below for other ways to deal with patchy wireless connections.

Cut the cords
Really, making Wifi work is not hard. A Wifi router for the main computer and a Wifi adapter for each additional computer is all most home and even small-office users should need. As well, we’d advise sticking to equipment from a single manufacturer, to minimise hiccups during setup.

Should you get stuck, don’t panic. Start afresh and check all stages carefully. We’d also recommend logging on to Computeractive’s online forums, at http://forums.computeractive.co.uk – here you’ll find loads of helpful advice and guidance, both from ourselves and our readers. We also recommend Microsoft’s own networking tips at www.microsoft.com/windows/using.networking/setup/default.mspx. You’ll be cutting the cords and working wirelessly before you know it.

Wifi blackspots
Like all forms of radio, Wifi can be the victim of interference. The relatively low-power signal also struggles when faced with thick interior walls and other sources of radio waves, such as microwave ovens. It’s possible to use ordinary household power sockets to help the network reach parts of your home that the radio signal cannot reach (see box on opposite page), but there are some simpler means to try before buying any new kit.

The Wifi router comes with an aerial. Some are built in, others attached by a thin lead. Try to position the aerial as high in a room as possible, as radio waves spread out in a spherical pattern. It’s also possible to buy signal boosters – devices that receive the signal from the router, and give it a jolt on it’s way to further parts of the house. These boosters often include an extra antenna attached to a thin lead, which means the booster can be situated on one side of a troublesome wall, and the antenna – with a little drilling – on the other. Check your router manufacturer’s website for signal boosting equipment and note that many range expanders need to be connected to the mains to boost the radio signal.

Save money with second-hand kit?
We understand that buying everything required for wireless networking can be a costly endeavour, especially in office environments where there may be many PCs needing wireless adapters. So, it would be understandable if you thought about picking up kit on the cheap – second-hand from the likes of Ebay, say.

In addition to the usual caveats about buying used technical stuff – check it works, mainly – with wireless gear it’s important to ensure that everything bought conforms to, or is otherwise compatible with, the same Wifi standard – the ‘a’, ‘b’, ‘g’ and ‘n’ suffixes discussed in the main article.

As well, bear in mind that even though Wifi devices from different manufacturers may be compatible, differences may exist in their software interfaces and operational behaviours. In other words, as far as is possible, try to stick to equipment from one manufacturer.

Getting the signal through
Sometimes, a wireless network’s coverage may fail to reach a particular part of the home or office, or otherwise be unreliable in its availability in particular spots. There are many possible causes for this, including hard-to-determine interference from other electronic equipment and obvious obstructions, like brick walls.

Such wireless blackspots can be dealt with in numerous ways. Obviously, cables can be strung to provide network access but that rather defeats the point. If there’s a nearby three-pin plug socket, a neater option is to consider a network connection over the mains-power supply.

We covered use of this technology in more detail in issue 222 but in essence, know that it’s possible to extend Ethernet network access by simply plugging a HomePlug adapter into a mains-power socket. Various companies now make such products, including Netgear (www.netgear.co.uk), Solwise, (0845 458 4558; http://www.solwise.co.uk) and Zyxel (01344 303044; http://www.zyxel.co.uk). For more information about HomePlug technology, visit http://www.computeractive.co.uk/2151772.

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