domingo, 16 de outubro de 2011

Tutorial: How to speed up your wireless network

Tutorial: How to speed up your wireless network: Tutorial: How to speed up your wireless network

How to speed up your wireless network

Wi-Fi is a great technology, but how you set up and use it can have a huge impact on its efficiency.

If you're constantly waiting for web pages in general to load, then before you complain that your ISP isn't supplying that promised 24Mb/s connection, spare a thought for what happens when that signal hits the airwaves in your house.

How it works

To improve Wi-Fi performance, we first need to understand what it actually is. Wi-Fi is also called wireless local area networking or WLAN in the management console of your base station or broadband router, and it uses a group of frequencies clustered around 2.4GHz to transmit and receive data between computers.

To ensure that data gets through, it uses a protocol called 802.11. If every network within range all used the same exact frequency of 2.4GHz, the various devices would swamp each other's signals - a bit like two radio stations transmitting on the same frequency.

To overcome this, the protocol allows devices to use 13 numbered channels, which all use slightly different frequencies to ensure that there's as little interference as possible.

Confusingly, there are a few versions of 802.11. The oldest is 802.11a, which is now obsolete. This has been superseded by 802.11b, which has a maximum data transmission rate of 11Mb/s. 802.11g, which is the dominant version in the UK, can transmit at a healthier 54Mb/s. The newer 802.11n can use two channels for a maximum of 300Mb/s.



Security is very important in Wi-Fi networks, and this has to do with both logging onto the network and how individual packets of data are encrypted. The oldest Wi-Fi security standard is WEP (Wireless Equivalent Protocol). This was part of the original 802.11 protocol and has been cracked, making it insecure.

This insecurity came about because if enough packets can be captured from the airwaves, software can be used to work out what that password is. Several open source packages now exist (AirCrack, for example) that will attempt to solve WEP passwords, thereby allowing people to log onto your network.

An updated security standard called WPA (Wi-Fi Protected Access) was introduced in 2003, with a newer version called WPA2 coming along in 2004. This is still secure and uses a government-strength encryption algorithm to keep your networks safe. In some Wi-Fi equipment, the security used is referred to as RSNA (Robust Security Network Association). This is really just another name for WPA2.


If every computer on your Wi-Fi network transmitted at the same time, they would jam each other's signals. To prevent this, every Wi-Fi network card sold (including the one in the base station) uses a technique called Carrier Sense Multiple Access (CSMA) to share the airwaves.

In CSMA, a situation called contention occurs when a Wi-Fi card wants to transmit a data packet, but hears that a packet is already being transmitted. It waits for a very short but randomly selected time before listening again. If the airwaves are clear at the end of that period, the card transmits its packet before listening again and subsequently transmitting the next packet if the airwaves are still clear.

This 'first come first served' scheme means that over time, all network cards get an equal opportunity to transmit all their packets. CSMA is also used in wired networks, and is a very efficient method of data transmission.

This being the case, it's usually external influences that are to blame for adversely affecting Wi-Fi networks. Before attempting to improve the performance of your Wi-Fi network, it's important to know what its performance is like before you start. Otherwise, how will you know for certain which measures work and which don't?

Set a baseline

speed checker

The easiest way of measuring current performance is to use an online broadband speed testing service. There are plenty available, and they all work in the same way. One service is Broadband Speed Checker.

First, ensure that your entire network is quiet. Turn off all streaming services such as Spotify (including killing the service in the system tray), all social media services, all torrent services, and all email clients that automatically update themselves. Check to make sure that the WLAN light on your base station is not flashing to ensure that everything is turned off.

From a Wi-Fi connected computer, click Start Speed Test and wait until the test completes. Rather than just performing the test once, collect several results over a few days. Try to run the test at different times of the day to see when the local loop from the nearest telephone exchange to the houses it serves is most congested.

Keep the results of these tests on a spreadsheet and you'll be able to see the best time of day to perform large downloads.

It's also a good idea to perform the same tests from a PC wired directly to the base station. This will give you a definitive measure of the difference in performance between wired and Wi-Fi connections.

Whenever you implement a change, re-test the Wi-Fi speed to see if there's any appreciable difference. You may be surprised to find that some simple changes can help you resist an upgrade to a supposedly faster connection.


The 802.11 protocol family uses some very clever low-level encoding techniques to ensure that regardless of circumstances, the signal stands a chance of still being heard over other noise, but anything we can do to help it will improve network performance. In some cases, such techniques can make a dramatic difference.

Everything would be fine if Wi-Fi network cards were the only things transmitting at 2.4GHz in our homes, but they're not. There are plenty of sources of interference that can cause the network cards to have to wait multiple times before being able to transmit their packets.

Incredibly, one of the biggest sources of Wi-Fi interference is your domestic cordless phone. If you have one in the same room as a Wi-Fi device, you can expect network performance to noticeably degrade every time you make or receive a call.

Bluetooth devices also use the golden frequency of 2.4GHz to transmit and receive data, and therefore also tend to cause interference on Wi-Fi networks. Microwave ovens are a domestic boon that we usually take for granted, but they're also a source of 2.4GHz interference.

Despite remaining perfectly safe to humans when cooking food, a microwave oven situated less than about 10 feet away from a Wi-Fi network card will degrade its performance. Don't forget that this 10-foot range can extend through walls into other rooms.

Added to these interference sources there are also less obvious ones. Your neighbour may be transmitting on the same channel, and have placed his base station right near your adjoining wall. Mains wiring running through walls and floors, faulty household appliances containing electric motors, and physical obstacles like brick walls also play a part in degrading performance.

More ways to improve your Wi-Fi

Location matters

router 2

Once you establish a baseline, it's important to think carefully about where you place your base station. The general advice from ISPs is to locate it at a central position in your property, but this overlooks several important factors.

The number of brick walls between the base station and the computer will affect the strength of the signal. Studded walls carrying cables or water pipes will do likewise, and a large aquarium in the way will also absorb some of the signal. Try to site your base station high up to overcome as many obstacles as possible. On top of a bookcase is a good place, and will give the upper floor of your home a little more signal.

Metal surfaces reflect electromagnetic radiation, and mirrors are no exception. A large mirror will shield the room behind it from Wi-Fi signals. Try to find out where your immediate neighbours keep their base station. With a little co-operation to maximise the distance between them, you can both improve performance.

On a desktop or tower PC, the Wi-Fi network card's antenna may be internal. Because the metal parts of the case and internal frame are earthed, they act as a Faraday cage, helping shield the card from the outside world. Try turning the PC so that as little metal as possible stands between the Wi-Fi card and base station.

Other dense materials can also block Wi-Fi signals. Very large wooden wardrobes, full bookcases and so on can all contribute a small amount to the overall degradation of the signal.

At the base station

If your base station and Wi-Fi network cards all use 802.11g, there's no point occupying the airwaves by also transmitting over the older 802.11b. Transmitting both is called 'mixed mode'. To turn off 802.11b, you'll have to go into the web-based management interface on your base station. To do so, you'll need the admin password (which you changed from the factory default when you got it, right?).

The management software used in different manufacturer's base stations differs, but the terminology is usually the same. In the section for interface setup, select the Wireless or WLAN page. One of the general configuration parameters will determine whether you transmit 802.11b, 802.11g or 802.11b+g. For compatibility, the default is almost certainly 802.11b+g, meaning that you're transmitting both versions of the protocol. Change this to 802.11g and then save the configuration.

If another network within range uses the same channel as you, there's a good chance that it'll interfere with your network's ability to transmit and receive packets. See the box 'Monitor The Airwaves' to discover if this is the case.

Rather than hunt for an unused one as the new BT hubs do, most base stations simply default to channel one, which increases the dreaded network contention. To ensure the least interference from other networks, pick a channel as far away from the strongest signals as possible. When you save the configuration, the Wi-Fi network cards in your computers will all automatically begin using the new channel.

Repeat yourself

If you still have problems after doing your best to increase the strength of your Wi-Fi signal and to minimise interference, there's one last method of overcoming problems. A Wi-Fi repeater simply retransmits any traffic it hears on your network, thereby increasing the signal's strength and extending the network's range.

A repeater can act as a relay to parts of the house that simply can't get a decent signal from the base station itself. If you're particularly security conscious, you can use multiple repeaters and run everything at the minimum transmission power so your signals are less visible beyond your property's borders. Each repeater, again set to transmit at low power, can still serve the farthest reaches of the house.

Get a new aerial


The aerials on Wi-Fi base stations are omni-directional antennas. The signal is transmitted with equal strength in a doughnut shape perpendicular to the aerial. This means that if the aerial is vertical, it sends Wi-Fi signals out across the room.

The antenna that came with your base station has a power transmission rating of about 2dBi (sometimes referred to simply as 'two units'). The higher this number, the more efficient the aerial is at transmitting the power passed through it. Every 3dBi effectively doubles the transmitted power, so if you've increased your base station's power output to the maximum in its web management console and want more, you can increase it using an aerial with a higher dBi rating.

The problem with these aerials is that they transmit in all directions. Most of the transmitted energy is lost, but you can reduce this using a directional aerial, which focuses the transmitted signal in one direction. This creates a long hotspot through your property and can be used to extend your Wi-Fi network to out-buildings without losing most of the signal. Prices start at around £20.

Monitor the airways


InSSIDer2 is a free tool by MetaGeek that you can use to analyse Wi-Fi signal strengths and to ensure you pick an unused channel.

Once installed, run the program and it'll show any Wi-Fi networks in range. In the lower pane it also shows signal strength and channel number. Click the 'Time graph' tab and select your network in the upper pane.

If you're monitoring on a laptop, try moving a few centimetres in any direction. The signal strength will change - but why? All electromagnetic waves have a wavelength, which is calculated by dividing the speed of light (about 300 million metres per second) by the frequency (2.4GHz). This gives a wavelength of roughly 12.5cm.

What this means is that across the room, the signal is stronger at some points than others. You can use this technique to map the areas of your home that have the strongest signal.

Sneakily, you can also use dips in the strength of a Wi-Fi signal to tell when someone is between you and a base station. This is because people are mostly water, which absorbs radio waves. As long as the monitoring PC is in the same position, moving around will affect the signal in a predictable way.

Update your firmware


Some ISPs automatically upgrade the firmware on the Wi-Fi base stations they supply as part of their broadband packages, but if you bought your base station separately to use with an existing wired broadband connection, you'll have to upgrade it yourself. This is a simple process that can fix bugs and improve Wi-Fi performance.

First, make sure you have a network cable at the ready in case the process wipes your current configuration and you need to access the web-based management console without Wi-Fi access.

Next, go to your base station manufacturer's website. Make sure you download the firmware for your exact hardware model - this can be found on a sticker on the bottom of the unit. Download the latest firmware and the latest user manual. This will tell you about any new useful features the firmware upgrade gives.

Upgrading may make the base station lose its configuration, so make sure you save the current settings first. The terminology tends to vary here, so consult the user manual.

When you click the 'Upgrade' button in your base station's maintenance page, browse for the firmware file and click 'OK'. The process takes a few minutes, after which the unit will reboot. If necessary, reload the saved configuration and you're done.

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