http://helpwithmywireless.superhappyfuntime.com An open ebook to help with your wireless Sun, 25 Mar 2007 16:20:46 +0000 http://backend.userland.com/rss092 en Bandwidth is measured as a bit rate over a time interval. This means that over time, bandwidth available on any link approaches infinity. Unfortunately, for any given period of time, the bandwidth provided by any given network connection is not infinite. You can always download (orupload) as much traffic as ... http://helpwithmywireless.superhappyfuntime.com/2007/03/25/traffic-optimization/ The most critical component to building long distance network links is line of sight (often abbreviated as LOS). Terrestrial microwave systems simply cannot tolerate large hills, trees, or other obstacles in the path of a long distance link. You must have a clear idea of the lay of the land ... http://helpwithmywireless.superhappyfuntime.com/2007/03/24/chapter-3-repeaters/ The unlicensed ISM and U-NII bands represent a very tiny piece of the known electromagnetic spectrum. Since this region can be utilized without paying license fees, many consumer devices use it for a wide range of applications. Cordless phones, analog video senders, Bluetooth, baby monitors, and even microwave ovens compete ... http://helpwithmywireless.superhappyfuntime.com/2007/03/23/chapter-3-avoiding-noise/ While calculating a link budget by hand is straightforward, there are a number of tools available that will help automate the process. In addition to calculating free space loss, these tools will take many other relevant factors into account as well (such as tree absorption, terrain effects, climate, and even ... http://helpwithmywireless.superhappyfuntime.com/2007/03/22/chapter-3-link-planning-software/ To calculate the link budget, simply approximate your link distance, then fill in the following tables:   Free Space Path Loss at 2.4GHz Distance (m) 100 500 1,000 3,000 5,000 10,000 Loss (dB) 80 94 100 110 113 120   Antenna Gain: Radio 1 Antenna (dBi) + Radio 2 Antenna (dBi) = Total Antenna Gain _ _ _   Losses: Radio 1 + Cable Loss (dB) Radio 2 + Cable Loss (dB) Free Space Path Loss ... http://helpwithmywireless.superhappyfuntime.com/2007/03/21/chapter-3-tables-for-calculating-link-budget/ As an example, we want to estimate the feasibility of a 5km link, with one access point and one client radio. The access point is connected to an omnidirectional antenna with 10dBi gain, while the client is connected to a sectorial antenna with 14dBi gain. The transmitting power of the ... http://helpwithmywireless.superhappyfuntime.com/2007/03/20/chapter-3-example-link-budget-calculation/ The power available in an 802.11 system can be characterized by the following factors: Transmit Power. It is expressed in milliwatts or in dBm. Transmit Power ranges from 30mW to 200mW or more. TX power is often dependent on the transmission rate. The TX power of a given device should ... http://helpwithmywireless.superhappyfuntime.com/2007/03/19/chapter-3-calculating-the-link-budget/ Wireless links can provide significantly greater throughput to users than traditional Internet connections, such as VSAT, dialup, or DSL. Throughput is also referred to as channel capacity, or simply bandwidth (although this term is unrelated to radio bandwidth). It is important to understand that a wireless device's listed speed (the ... http://helpwithmywireless.superhappyfuntime.com/2007/03/17/chapter-3-estimating-capacity/ As long as the WiFi-cards can 'see' each other directly with their radios, doing a ping will work whether olsrd is running or not. This works because the large netmasks effectively make every node link-local, so routing issues are sidestepped at the first hop. This should be checked first if ... http://helpwithmywireless.superhappyfuntime.com/2007/03/16/chapter-3-troubleshooting/ Compile the olsr plugins separately and install them. To load the plugin add the following lines to /etc/olsrd.conf LoadPlugin "olsrd_dot_draw.so.0.3" { PlParam "accept" "192.168.0.5" PlParam "port" "2004" } The parameter "accept" specifies which host is accepted to view ... http://helpwithmywireless.superhappyfuntime.com/2007/03/15/chapter-3-installing-the-dot_draw-plugin/