WIFI technology has brought many laptop / netbook travelers the joys of free Internet access. It's great to discover open WIFI networks with the opportunity to check e-mail for free and to surf the web. The same euphoria becomes frustration when the connection is suddenly lost. What usually follows are attempts to reconnect, wondering what might have happened. Here's practical info how to deal with weak or lost WIFI connections based on a 3,5 year and ongoing journey with the Machine through Asia, The Middle-East and Europe.
WIFI waves in a nutshell
WIFI is a 2.4 Ghz radio signal divided into several communication channels. Because the waveform is very short and lacks (penetrating) power, communication is vulnerable to objects standing in the path between 2 WIFI stations. Therefor "Line of Sight" is key to a speedy WIFI connection. Unfortunately full Line of Sight is a rare thing specially when traveling with the Machine. Parking 10.000 Kg of travel machinery in line of sight of a WIFI Access Point isn't always appreciated. So WIFI signals are usually received as reflections and / or weakened by physical obstructions. Knowing what causes WIFI signal degradation and what to do about it is key to staying connected over large distances.
WIFI connected at the Meydan horse race track in Dubai - UAE
NOTE :: mind the legal aspects of connecting to open WIFI networks.
Here's a list of real situations where a WIFI network connection is lost while connected over quite a distance;
1) The washing machine : The perfect WIFI jammer - put it between 2 WIFI stations during spin cycle and it blocks / distorts the WIFI signal. Specially cheap electric motor put up a perfect WIFI barrier when spinning at 1400 RPM. The same effect applies to dryers. With cycle lengths up to 30 minutes it's a frustrating experience to see the connection come and go. The WIFI signal can be seen if it's strong enough however can hardly be connected to.
2) The Microwave oven : Although less lethal to WIFI than a cheap washing machine, the standard 2.45 GHz used in a Microwave oven interferes with 2.4 Ghz WIFI. Again cheaper machines do a better job in jamming a WIFI signal. Luckily microwave ovens are often used for only a short time.
3) Passing traffic, parked cars, trucks, boats and trains : Suddenly a car is parked in the street and the WIFI signal is lost or becomes so weak it's hardly usable. Specially trucks and boats do a particular good job as WIFI signal obstruction.
4) WIFI channel competition : During office hours more and more WIFI Access Points are switched on and start competing with that unprotected open WIFI signal. Usually that's due to sharing the same WIFI channel. Channel 6 and 11 seem to be dominant, most likely the factory setting of many WIFI Access Points. At a distance the forest of AP signals blurs that single popular free WIFI access point.
5) Lengthy WIFI downloads : Although WIFI signal strength is there, the responsiveness and speed of the connection suddenly drops. Usually this happens when a WIFI client closer to the AP (usually the owner) starts a heavy / lengthy download session.
6) Trees / bushes - wet or growing : Nature is good at putting up slow growing WIFI signal barriers. Autumn / winter time is a perfect time for good line of sight. Although snow in trees can block a WIFI signal also.
7) WIFI AP is moved : Moving the Access Point usually has an effect on a WIFI connection over quite a distance. In the best case speed and responsiveness of the active WIFI connection drops, worst case the signal disappears completely.
8) WIFI AP reset : Specially when the Internet connection of the WIFI AP owner is intermittent, slow or non-responsive router / access points are reset and sometimes moved. This might also be the case because of heavy activity / competition on the free WIFI access point by many users.
9) Door closes, blinds shut : Shutting a door, closing a window, shutting blinds can weaken a WIFI signal over quite a distance.
10) Fogy weather : Specially over quite a distance, fog degrades a WIFI signal. Over a large distance even a little bit of fog is enough. Frequent reconnects, lower bandwidth while the fog thickens up-to signal loss in very thick fog.
Experiences with other situations that caused your WIFI signal to be degraded or boosted? Contact the laptop junction to add the case to the list above.
Given the right antenna, the placement of the antenna is of key importance. To discover the best placement and avoid "dead spots" is best done using NetStumbler. Activate MIDI and move the antenna to the spot with the highest audio tone. WIFI cards with an external antenna or USB WIFI cards using an USB extension cord allow the best antenna placement flexibility. On large distances without line of sight moving the antenna for just a few centimeters / inches can mean all the difference.
Better WIFI antenna
Antenna's are everything, specially with weak and reflected WIFI signals. The machine has 2 WIFI antenna's, both omni-directional placed at two sides of the truck. Even with low powered WIFI cards a better antenna has a significant effect on the range. Not all WIFI clients allow external antenna's such as internal laptop WIFI miniPCI cards. Maximum flexibility can be reached with USB connected WIFI adapters. The WIFI adapter can moved around using an USB extension cord for best antenna placement. USB adapters like the Alfa Network AWUS036H has an external antenna jack allowing even greater flexibility.
WIFI antenna's in the machine
High powered WIFI client
When the distance is too far to cover with either antenna placement, a better antenna then more WIFI power might help. See the article about the Alfa Network USB wireless adapter for an impression of the capabilities of high powered WIFI adapters.
WIFI repeater, Range extender
When even a high powered WIFI adapter doesn't help, a WIFI repeater station can help to bridge the distance.See the article how to operate a simple WIFI repeater to bridge an Internet connection over a distance of approximately 490 feet (150 meters) without line of sight.
With line of sight, WIFI can have a dramatic range even up-to 18 miles (30 Km) in length (horizon) under ideal circumstances. Even without special WIFI equipment large distances can be covered. As for example, the height at which is the antenna is placed is an important parameter same as the required speed of the connection. Without line of sight, WIFI range can be reduced to almost nothing. In most urban settings WIFI signal reflections influence WIFI range capability to a large extend.
All wireless signals suffer from an effect called Multi-path effects. The same WIFI wave arrives at the antenna at different times due to the differences in travel distance. Sort of like an echo. The echo's can arrive at the antenna in phase (thus amplified), out of phase (degraded) or in between (weakened) depending upon whether the signals have come direct or by reflection. Out of phase signals can create dead spots even at a short distance. Antenna placement is therefor important same as what objects are moving between the 2 stations.
Struggling with weak cellphone GSM signals? Have a look at cellphone signal boosters in rural area's.
Free WIFI is often associated with free Internet access, which is true in many cases. Depending on country or state laws it's illegal to connect to an open / unsecured private WIFI network. Connecting to public service networks from companies or government usually is legal. In any case when surfing the Internet using an open WIFI access point be aware of the legalities of your actions. Network activity can be logged / monitored or even used for purposes you're not aware of.