So you want to get connected!

WiFi – Common problems and some solutions for 802.11b/g

Antonia J. Jones, Computer Science, Cardiff University

(Fall 2005)

 

Introduction.

"Get broadband and a LapTop", they say, "and it will change your life!" Well, in my experience that’s actually true. However, there are some ‘buts’.

Despite the slick ads on TV pushing Intel Centrino technology, existing WiFi is an emerging technology that is not yet stabilized (if you want the awful truth, the fact is none of this technology will EVER stabilize, it's going to keep rapidly changing for the foreseeable future) and the average user can run into some fairly irritating and puzzling problems. This article describes some common problems for Windows Laptops running XP and a few solutions. (It seems to be that case that Apple WiFi LapTops have fewer connectivity problems, but I have no first hand experience in this area – so I’ll leave it to an Apple aficionado to write about that.)

One aspect of wireless networks I don’t even attempt to get into here is security. This is a big subject, fraught with pitfalls – the simplest forms of security are childishly easy to break. Once you have your network set up and running you will certainly want to secure it. However, in my experience, there are enough problems getting the whole system working properly even without any security. If you add in security whilst you are setting the system up you may never complete the project! So my advice is: get it all working first and add in the security afterwards.

Maybe there is another way.

Most of us are inveigled into wireless technology by the vision of being out-and-about, but able to pick up our email etc. at the nearest cybercafe or hotspot. Having bought into this vision it is a short step to having a wireless home. Before launching into the trials and tribulations of going wireless I ought to point out that if ALL you want is to use a computer at home online in some room a long way away from your router or cable connection, then there is a much simpler way than spending a large amount of money on a new wireless LapTop - especially if you are quite happy with your existing computers. Of course, you could wire your house with ethernet cables but, if you think that is too much of a hassle, then why not use an Powerline Ethernet Adapter kit.  Essentially this is a way of using the AC power wiring in your house as an ethernet link. In the UK you can get a Devolo High Speed ethernet startup kit (http://www.dsl-warehouse.co.uk/product.asp?pr=1154),  which will connect a router to a computer at 85Mb/s - that is a constant connect speed far faster than current WiFi. For less money, there are a variety of other similar units giving a connect speed of 14Mb/s. In the States I couldn't find a Powerline Ethernet Adaptor faster than 14Mb/s.  Still,  a solid 14Mb/s is plenty fast enough, so it's a great solution if you want to save money by not going wireless, OR you want to use VoIP applications like Skype that are very sensitive to the kind of variations in the connect speed which are inevitable with wireless connections (see Installing a Powerline Ethernet Adaptor).

Getting wirelessly online.

At present there are essentially two available ways to get wirelessly online:

[1] Using one of the two IEEE standards 802.11b (11 Mb/s) or 802.11g (54Mb/s) - there are other standards, e.g. 802.11a, but I have not run into them - these all require a wireless access point (AP), provided by a Router, which is usually hooked into a broadband connection via a Modem of some description – these days the Router and Modem are often combined into a single unit. Nobody buys 802.11b any more – although it uses less power so your battery lasts longer - virtually all new equipment is 802.11g. If your LapTop is not WiFi enabled you can get a card which plugs into the PCMCIA slot at the side. All this is ‘off the shelf’ technology from your local big Computer store.

First warning: all manufacturers are not equal, some equipment works better than others. My personal choice for this kit is Belkin, which is admittedly a tad more expensive than some of the alternatives, their stuff works really well and has never given me any problems - but see remarks on Pre-N router below.

The future of WiFi seems to be headed towards something called WiMax – this, we are told, will give us wide area high bandwidth connectivity. The rumour in the Biz is that Google are going to provide it as a free service for every major city in the US! They’ll know where every LapTop in the US is, probably who owns it, and be able to provide precision targeted advertising! Oh, joy! But you can’t yet buy WiMax-enabled LapTops in your local store. In the meantime….

[2] There is something called EDGE technology, which will, in principle, get you online at a modest bandwidth wherever there is a GSM cell phone signal. In the States only some cell phone networks are GSM (e.g. T-mobile and Cingular), others like Verizon use a different technology. You can buy an EDGE PCMCIA card, take out a subscription for about $80 per-month with a company like Cingular, they give you a SIM card to put in the PCMCIA card, and you can be LapTop connected more or less wherever you go. In the States Cingular have teamed up with Sony and produced the VGN-T350P, a tiny LapTop with built-in EDGE technology, running Windows XP Professional, that fits into a biggish purse (handbag) – more of a communications device than a LapTop – expensive but I love it to bits (see right)!

Once you have set up the Router and Modem at home and got yourself a WiFi LapTop (you don’t actually need a DeskTop anymore) then you can have a lot of fun configuring it. You may not want to ‘have a lot of fun configuring it’, but you had better resign yourself to at least the possibility of becoming a wireless nerd if you want to get connected.

On line at with Mercury at Jasmine's Cyber Cafe, St. Augustine FL.

Second warning: Your WiFi-LapTop is a radio transceiver normally operating at a microwave frequency around 2.4Ghz, transmitting at a variable but very low power of around 100mW. It will NOT work at all well in a high radio-noise environment. In practice this means that if you put your cell phone down on the desk next to the LapTop you may lose your network connection completely (it depends how far away the AP is), or the connection speed will drop radically (a factor of 10 is not unusual) as more and more error correction is required. The same thing applies to cordless phones AND their base stations, radio receivers (which generate their own levels of radio frequencies - RF), florescent lights, and of course other computers. Many cordless phones operate in the same 2.4GHz band, which is hopeless for a close-by LapTop. For about $40 you can go out and buy a 5.8GHz cordless phone, which is better. Still, don’t put any such devices next to the LapTop. With many applications, such as email, you may not notice your LapTop connection speed drop, but with other applications, e.g. VoIP (Voice Over Internet Protocol) programs such as Skype, the lower connection speed will be instantly noticeable (and extremely irritating).

What you need to know about configuring.

Routers

Configuring Routers/Modems is usually no problem – just follow all the instructions that came with it. I do recommend that you give your network a name different from the default name assigned by the Router software. You need some information, such as the local IP address of the Router (this is supplied by the manufacturer of the Router/Modem and is usually something like 192.168.1.1) and the DNS (Domain Name Server) IP address together with an alternate DNS address (these will be supplied by your broadband provider - ISP). Wi-Fi base station Routers have an operating range of 50 feet to 300 feet - often less. If you have a large area that you want your WiFi connection to work over, you may have to install repeaters, or a spur, to provide multiple APs for the same network. This can produce a whole set of new problems that do not arise with single APs - one is mentioned below. In practice multiple APs for a network are not at all uncommon. For example, most universities are running multiple AP wireless networks. So the fact that many LapTops do not work properly when connected to a multiple AP network is a real problem.

Windows LapTops

When it comes to the XP-LapTop everything is supposed to be automatic, but for various reasons sometimes automatic configuration does not work very well. It may get you connected, but then 10mins later you can lose connectivity.

Owing to the absolutely useless nature of battery technology (believe it or not some people have actually suggested alcohol powered LapTops - imagine pulling up at the local Gas station, offering them your LapTop and saying "Fill her up"!), the software implementation of the driver (that’s the software that manages it) for the WiFi (WLAN) card is critical to conserving LapTop power. Since the network is idle a lot of the time it is not necessary, or desirable, to keep the WLAN card fully powered all the time. When the WLAN card is sleeping incoming packets will be buffered at the AP (this is exceedingly tiresome for VoIP applications). The penalty for saving power is greater latency on the delivery of new incoming packets (see http://www.atheros.com/pt/whitepapers/atheros_power_whitepaper.pdf ). So drivers need to balance power saving against bandwidth. Some drivers are better at this than others – the resulting power consumption per data transferred in unit time can differ by up to a factor of 15 between different manufacturers.

Because of the need to conserve power when running on battery, even in the best of RF conditions, reported connection speeds may constantly vary between 1Mb/s (totally useless) up to 54Mb/s (sounds good if you can keep it there). Unfortunately even with the LapTop plugged into the mains this may still be the case, even though the variable connection speed is then unnecessary. It depends on how your LapTop’s power management system is configured, what hardware chip set is providing the WiFi, and the WLAN card driver.

Two things to worry about.

Assuming your AP is up and running there are two main things you need to get right in order to get the LapTop fully WiFi connected.

[1] First you need to get the LapTop talking to the Router. Usually this is fairly straightforward. It may even happen all by itself! If you are running a LapTop with built-in WiFi, find out where the wireless switch is and make sure it is turned on (sounds obvious, but you would be amazed how often it happens). If you get connected you can see a little computer screen icon in task bar with tiny little waves coming from it. (Make a nice cup of tea and reward yourself with a piece of cake - that should take about 10mins. If you can still connect to Google then maybe you are not going to have to become a nerd after all.) If you right click on that icon you can see various options, one of which is ‘Status’ – click on that and see what happens. You should see a panel which says "Wireless network connection status", it gives you various facts and options regarding your connection and configuring it.

If you are using a PCMCIA card to wireless-enable your LapTop you will need to first install the drivers and associated software. Many cards come with ‘Smart Connection’ software which overrides the usual Windows wireless network management software. If this all works fine then don’t bother with what follows. If it doesn’t then disable the ‘Smart Connection’ software and try some of the steps outlined below which use the standard Windows software.

If you don’t get connected automatically, then you are going to have to connect manually. Get the "Wireless network connection status" pane up, as described above or, alternatively, go to the Windows ‘Start’ menu (bottom left of the screen) and select ‘Settings/Control Panel/NetworkConnections. In the "Network Connections" pane that come up, the one you are interested in is the one that says "Wireless Network Connection". If the status is ‘Connected’ then the LapTop is talking to the Router, otherwise we have to configure a few things.

Right click on the Wireless Network Connection link and click on ‘Status’. Now click ‘Properties’. Where it says "Connect Using" click on "Configure". In this box, in the ‘General’ Tab make sure under ‘Device usage’ that "Use this device (enable)" is selected. Under the ‘Advanced’ Tab make sure "Wireless On" is selected. Leave the other settings alone for now – they are probably OK. Click on OK and get out.

Now go back to the "Wireless network Connection Status" pane and click on "View Wireless Networks". With any luck you should see the name of the network you are trying to connect to under "Choose a wireless network". If you don’t see anything at all, and you know the Router is up and running, the most likely explanation is that the wireless switch on the LapTop is turned off (I did warn you!). If things still don’t work properly the router or LapTop/card may be faulty – look on the box the Router came in and see if there is a sticker on it saying "Returned Merchandise"!

Assuming you can see the network, and that it is not secured (in which case you will need passwords and stuff), then you should be able to get connected by clicking on ‘Connect’. If that all works, congratulations you just took your first step towards becoming a wireless network computer nerd.

[2] Now you have got the LapTop talking to the Router you may think that your problems are over (foolish child) and, if you are lucky, they may well be. But there is a second part to getting fully connected. This is to assure that your LapTop has been assigned a local IP address on the WiFi network and can connect to the net. This is very easy to check. Get your favourite Internet Browser up and running and try to visit Google (http://www.google.com/), if you get there then all is well.

If you go back to the "Wireless Network Connection Status" pane and click on ‘Properties’ under the ‘General’ tab and cursor down you should see "Internet Protocol (TCP/IP)". Highlight this and click on ‘Properties’. See if the "Obtain an IP address automatically" box is checked. If you have connected faultlessly then leave well enough alone. If you have not Internet connected, or if you have connected but keep loosing your connection, then see if the following helps.

Third Warning: The Problem. The problem is failure of the Windows XP Professional Microsoft Software Wireless Management system if when in

Wireless_Connection_Properties/General/Internet_Protocol(TCP/IP)/Properties

the box "Obtain IP address automatically" is checked. The symptom is failure to assign an IP address automatically, or if an address is allocated the IP address is subsequently erratically lost, resulting in failure of Internet Explorer to connect to the net, or Outlook Express to Send/Receive email.

Circumstances of problem. The problem occurs when attempting to connect to any wireless network at the 54Mb/s 802.11g rate. It is noticeably worse if the network has multiple Access Points. It does not appear to occur at the 802.11b 11Mb/s rate. So one partial fix in most situations is to wind down the connection speed to11Mb/s.

*How to do this* In the "Wireless Networks Connection Status" pane click on ‘Properties’. Next to "Connect using" click on "Configure". Under ‘Advanced’ cursor down to "Wireless Mode", highlight it and uncheck the box which says "Use default value". Now select "802.11b only", click on OK and then try connecting again.

However, all this is not much help if the wireless network uses the Belkin Pre-N router (the one with three antennas), because if you set the LapTop to only operate at the 11 Mb/s rate then it can’t even see the Pre-N network. If you buy a Pre-N PCMCIA card for the LapTop then, with a Pre-N router you will get faultless connectivity at 108 Mb/s, and with other routers at 54Mb/s. You have to use the Belkin drivers and turn off the LapTop built-in wireless at the switch and software-disable levels. This gives wonderful connectivity, but is not an acceptable solution if one needs the card slot for other purposes (which I often do). The problem is evidenced even when ‘Wireless network Connection Properties’ reports an 'excellent' or 'good' connection.

A temporary fix is to uncheck the "Obtain IP address automatically" box, then check the "Use the following IP address" box and enter an appropriate IP address. This assumes that you can figure out a spare IP address on the current wireless network - one way to do this is to crib the required details from another machine on the network (which is working correctly) and systematically change the last digit until you get the system working  (so, using the example IP address for the Router as 192.168.1.1, you might end up with a local IP address for the machine you are trying to connect as 192.168.1.5 for example - this assumes there is no other machine with that IP address currently on the network). I say "the system", rather than the current machine, because a downside of this approach is that if you configure an IP address that is in use by another machine on the wireless network it will cause a network wide problem. The 'Subnet mask' will probably automatically set itself as 255.255.255.0, and the 'Default gateway' is the local address of the Router, which in our example is 192.168.1.1. You may need to also manually insert the DNS address using the ‘Advanced’ tab, etc. (A collateral consequence of this fix is that you have to go back and undo it when trying to connect to a different network at a later time.)

¨ By itself this fix may not work if there are multiple AP’s for the same network (you may have to drop the connection speed to 11Mb/s - see above).

Note. Because I have multiple computers running around the house I have given up entirely on the "Obtain an IP address automatically" and have configured all the local IP addresses manually. This has the advantage that I can set the firewall to "Trust" that exact range of IP addresses.

Comment. This problem has been reported on some Toshiba and Sony computers. Most people who buy a LapTop, myself included, do so precisely because of the built-in wireless capability, and want to painlessly connect at the highest rate possible. If this is a general problem across a wide range of models it is extremely serious. I have personally experienced these symptoms on a Toshiba Tecra M3, but not on other LapTops I have tested. These include the HP Pavillion, the Sony VAIO VGN T350P Notebook, and an Apple iBook, under identical conditions on the same network as the Tecra M3. I had no problems with any of these machines, whilst the Tecra was continually failing (a few feet from the router).

** This, plus the well known battery/overheating problems under high processor loading, means I do not at present recommend Toshiba laptops. **

Footnotes

[1] For those involved in trouble shooting WiFi networks the following is is a useful piece of kit

http://www.metageek.net/

It is a RF receiver which plugs into a USB port (cost about $100) and is essentially a baby spectrum analyser for the 2.4Ghz band. It very easy to use and will tell you instantly if the cause of the problem is RF interference.

[2] Finally if all else fails you might consider

http://www.j-walk.com/other/wifispray/

It seems we are not alone!