Following are some data about radio range of Mica2/Mica2Dot motes. Practical experiment shows much difference with crossbow specification. for Mica2/Mica2Dot we might assume reliable range to be 100-150ft radius.

Specification by Crosbow for Mica2

For MPR400CB kit outdoor range 500 ft.For MPR410CB, MPR420CC-radio range=1000ft.1/4 wave dipole, line of sight

For Mica2Dot Specification by Crosbow for Mica2

For MPR500CB kit outdoor range 500 ft. For MPR510CA, MPR520CA-radio range=1000ft.1/4 wave dipole, line of sight

TinyOS1.0 and MICA motes The application seems very sensitive to the placement of the motes. even within a few inches or feet. If I line them up on my bench, or spread them out ~ 30 feet apart they work quite well. Anything else seems to be very unreliable

I've repeatedly gotten a maximum range in an open field of about 106 feet +/- 2 feet. I've also done the same thing in a small "valley" (the sides of the valley are about 6-7 feet tall), and got a range of about 116 feet. In an indoor hallway, I've gotten communication up to 200 feet.

I've found that in the 900 MHz range with the standard antenna I'm getting a range of up to 35m. The tests were carrried out outside in an open field with the motes set on full power and held at about 1m height off the ground.

According to Crossbow the range we're seeing is poor, they say that they have been able to get a range of about 150m with the standard antenna in similar circumstances.

The objective of this network is to see how reliable these motes were less than 36 feet away from each other. This distance was chosen because I was under space restrictions with LOS within my work area, and a short experiment in an open space at 40 feet showed difficulty getting a consistent signal.

This demonstrates the extreme impact line of sight can have on the reliability of these motes. Otherwise, this graph demonstrates nearly 100% reliability at a range of 8-14 feet.

It also might be interesting to explore just how reliable nodes are at 0-15 feet. If we can consistently get 99%+ reliability, they may make a mean network with little need for many extra messages.

The radio on the MICA2 has an extremely sensitive receiver, which can be interfered with by an adjacent local oscillator from another MICA2. A distance of at least 50 cm should be maintained between MICA2 units to avoid local oscillator interference.

Radio Range: Lower radio frequencies for example, 433 MHz, will have longer ranges in an outdoor deployment. Depending on the foliage and environmental conditions, expect ranges of 200-500 feet at 433 MHz and 100-300 feet with 916 MHz. Remember, the XMesh stack will automatically configure the network and allow for radio range extension via message hopping across multiple deployed sensors.

Placement: Units are usually placed at least 1-3 feet above the ground. Placing units at ground level will decrease communication range. Grass and other foliage will also decrease distance. Crossbow recommends the following average mesh grid density:

• 916 MHz: 1 mote/2500 sq feet (50’ by 50’).
• 433 MHz 1 mote/10000 sq feet (100’ by 100’).

Foliage and other RF obstacles will decrease distance. However, if the units are deployed such that motes can find other motes (parents) then the network will automatically reroute radio traffic.