Rev up your router

wireless routers have liberated computers from restrictive ethernet cable connections, but they’re not completely problem-free.like any radio communication technology,WiFi is affected by interference from other devices,which can result in reduced data transfer speeds poor network range and dropped connections.

THE TROUBLE WITH 2.4GHZ

802.11b and 802.11g WiFi operates on the 2.4Ghz frequency,as do most 802.11n devices. The problem is that a host of other wireless devices also use this frequency and it’s pretty congested as a result.Baby monitors, DECT cordless phones ,Bluetooth headsets and other wireless PC peripherals all use the 2.4GHz part of the radio spectrum, with a WiFi signal.

The range of an indoor WiFi network can also be affected by the building materials that surround it. Wood, plaster and glass have little effect on 2.4GHz radio waves, but brick and concrete can impede them to some degree and metal can stop them completely.So, if your WiFi router is mounted on an interior brick wall or sitting on a metal shelf , it might be a good idea to move it.

CHOOSING A CHANNEL

The other major cause of WiFi network interference is other networks.Residential WiFi is now so popular that it’s not uncommon to see several networks within a small area. WiFi is split across different channels to combat interference in such situations, but ensuring that all the networks are configured appropriately is seldom possible.

The first step in establishing whether nearby network are causing problems for your own WiFi network is to conduct a site survey .Looking at the list of available WiFi networks in Windows will give you some idea of the surrounding networks , but this won’t show the channel or signal strength. Foe this you need a free utility, such as NetStumbler for Windows

Although 2.4GHz WiFi has 13 channels in the UK.overlapping frequency ranges mean there are are never more than three overlapping combinations of channels

Luckily,2.4GHz WiFi for 802.11n supports 13 channels in the UK,but check which channels your WiFi adaptors support before using channels 12 and 13

(www.netstumbler.com) , or a handheld app, such as WiFi Analyzer for Android (available in Android Market).So equipped, you can then wander around your home, making a note of the channels used by nearby WiFi networks with the strongest signal (weak networks aren’t worth worrying about).

WiFi in the UK is split across 13 channels in the 2.4GHz band (two more than in the US), but this doesn’t mean you can simply pick a different channel from those of nearby networks to avoid interference Channels 1 to 11 are only 5MHz apart, while 12 and 13 are 12MHz apart, and since each channel is around 22MHz wide , this means there’s a fair amount of overlap: 1,6 and 11;2,7 and 12; and so on .

If you manage more than one WiFi network, setting them up to use complementary channel combinations will avoid cross-network interference.If you can’t persuade nearby network owners to do the same, your only option is to set your WiFi router’s channel so that it has as little overlap with the other networks as possible -just pick any of the same-colour channels in the graph on the left.

FIX INTERFERENCE WITH 5GHZ

if your WiFi network uses only 802.11n devices you may have a better option for avoiding interference.The 802.11n specification can also operate at 5GHz, which is a far less congested frezuency.Better still, its 19 UK channels(not all of which are available on all routers) have no overlap, which makes it much easier for nearby networks to coexist

If your 802.11n WiFi router is dual- hand it can use the 5GHz frequency-just look for the appropriate option under its WiFi settings in its admin panel.Unless your router supports simutaneous dual-band WiFi , though switdching to 5GHz will stop 802.11b/g devices being able to connect. Not all 802.11n WiFi adaptors support the 5GHz frequency .so turning off 2.4GHz will cut them off too(the iphone 4 falls into this category.for example).

The only with 5GHz is that is doesn’t have quite the same range as 2.4GHz WiFi,as its higher -frequency radio waves can’t penetrate solid objects as easily. THis may not matter for most homes but it’s worth thinking about if you make the change and can’t get a strong signal.

DOUBLE UP

If you have an 802.11n router, whether it’s 2.4GHz or 5GHz,ther’s an option for a Wide Channel. This uses an additional wireless channel to double the throughput.In fact, the 300Mbit/S headline speed of 802.11n assumes that two channels are used.

This thechnique,knwon as channel bonding, should be avoided on 2.4GHz 802.11n networks.This radio spectrum is already over -crowded, and using up another radio channel simply doubles the interference. It’s not only for the sake of your neighbours, but your own networks.This radio spectrum is already over-crowed, and using up another radio channel simply doubles the interference. It’s not only for the sake of your neighbours, but your own network’s performance: channel bonding can cause all kinds of interference problems that stop your network working. Our advice is to turn it off.

For 5GHz 802.11n networks, the channels don’t overlap and there are more of them .As such , channel bonding isn’t such a bad thing, so turn it on and see if it boosts your speeds.

ACCESS ALL AREAS

Securing a WiFi network against unathorised access is simple enough-just enable WPA2 encryption and set up your computers and other devices accordingl. Controlling what the computers on your network are allowed to do is another matter.Sorting out server access and setting up user accounts is beyound the scope of this project, but most broadband routers have features that allow you to place limits on internet access, which is something most parents will welcome.

The terminology varies from router to routerm but you’ll usually find these options in the admin panel under something like ‘ Access restrictions’ or ‘Block sites’ . At the very least , a router should allow you to block internet access for computers with specific IP addresses on certain days or during certain times. You’ll obviously need to configure your networked computers to use static IP addresses on certain days or during certain times. You’ll obviously need to configure your networked computers to use static IP addresses for this to be for broadband routers that use wireless chipsets from Atheros and BRoadcom. Trying to cover every compatible rorter in this column wouldn’t be practical . Fortunately, these two chipsets are extremely common and the DD-WRT database lists more than 200 compatible broadband routers. DD-WRT also requires a router with at least 4MB of flash memory, but a ‘micro’ 2MB version is also availabl.

DD-WRT DOES IT ALL

The first step is to check that the DD-WRT upgrade supports your make and model of broadband router by going to http ://tinyurl.com/DD-WRTlist. If your router is on the list, the next step is to peruse the firmware installation

DD-WRT’s strength is its comprehensive suite of network controls, including per-application QoS settings for fine tuning network performance

Most home broadband routers offer some form of internet access control and more sophisticated models provide policy based restrictions

overview at http://tinyurl.com/DD-WRTinstall. Some routers are easier to upgrade than others -we used the Buffalo WZR-HP_G300NG home broadband WiFi router, as it can be upgraded to DD-WRT via its usual firmware upgrade procedure (Buffalo will also be using DD-WRT site to do this. As such , we haven’t covered the upgrade procedure here, as there are too many variables to fit into two pages .

With the upgrade complete and your router restarted, you need to log in to its admin panel at 192.168.1.1, the default DD-WRT admin address. You’ll be prompted to set a mwe administrator username and password before you can go any further, but from here on , the admin options resemble those of any broadband router.

Anyone who’s set up a home broadband WiFi router before will find configuring DD-WRT straightforward . Use the options in the Basic Setup tab to set up your ADSL or cable modem, and those in the Wireless tab to configure your WiFi network. That’s really all you need for a simple network , but the beauty of DD-WRT is that it also provides a comprehensive set of more advanced options for example , you can tweak the WiFi transmission power and antenna gain to increase your network’s range, create multiple virtual WiFi networks with different SSIDs and security settings , and set up DD-WRT even provides options for using a home broadband router as a commercial WiFi hotspot

One particularly useful feature of DD-WRT for networks that handle various types of traffic is the Quality of service (QoS)option .As we project (see Advanced Projects,Shopper 263)this allows you to priorities certain types of network traffic to prevent Bit Torrent transfers affecting VoIP calls , for example , or to avoid lag when playing online games. Many routers simply offer an on /off toggle for QoS, but DD-WRT provides full control per application, complete with bandwidth limits.