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I need to create a wireless network with high expactations to redundancy and security, making my choise fall on a mesh type network. Between the nodes I should be able to transfer video or at least still images within 5-10 seconds or so to a central, communication on 868MHz without worrying about battery time since it is going to be powered with transformed mains power.

I haven't worked with mesh networks before, so I have started reading up on existing protocols and architectures, but if someone have any suggestions to what architectures I could try to use I would be very grateful.

EDIT: And how would I go forth to implement an open protocol on a microcontroller? Are there libraries I can use that is available for the general public?

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ZigBee is a mesh network protocol working in the 868MHz band (amongst others), and the only one I know to have reach an acceptable level of maturity. According to the ZigBee Wikipedia article:

868 MHz provides a data rate up to 20 kbit/s

At that datarate, transmission of a still image is possible in less than 10 seconds (assuming heavy JPEG compression), but video is not.

The 868 band is limited in size (863 to 870MHz), the RF power is limited to 14dBm and emitters must limit their duty cycle to less than 1%, so this band is really not suited for high datarates application.

Given your constraints, I suggest you switch to the 2.4GHz band, that is much wider (80MHz of usable band), allow more powerful nodes, and does not limit duty cycle. ZigBee 2.4GHz would be a solution, so would a solution based on mesh-WiFi (standard WiFi routers with community-developed firmware running mesh routing protocols such as BATMAN ).

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  • \$\begingroup\$ The problem is that I am designing a security systems, restricted under EN regulations that don't allow any other band than 868Mhz. Thank you very much for your info, it really helps \$\endgroup\$ – chwi Sep 19 '12 at 12:11

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