33 lines
1.0 KiB
Markdown
33 lines
1.0 KiB
Markdown
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JeeMesh is a mesh protocol in development at HacDC to extend the
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[JeeNode](http://cafe.jeelabs.net/lab/jn5/)
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[RF12](http://cafe.jeelabs.net/sw/library_-_rf12/) low power wireless
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protocol for mesh routing, packet fragmentation, and (more) reliable
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delivery.
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RF12 has the following limitations:
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- up to 30 nodes (typically 26 nodes and 4 servers/gateways)
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- MTU 66 bytes
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- range of about 30' to 50' at 915mhz
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We intend to extend these limits somewhat:
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- MTU 1023 bytes
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- range up to 200' by routing through up to four nodes on a mesh
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A 16 bit header is added using the first two bytes of the RF12 packet
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data as follows:
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- 5 bits for original source node
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- 5 bits for final destination node
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- 2 bits for ttl
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- 4 bits for fragment sequence
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This allows us to reconstruct 1024 byte JeeMesh packet from 16 64-byte
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packet fragments. We further add another 8 bit header to the first
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packet fragment, reducing the MTU to 1023 bytes:
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- 4 bits number of fragments
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- 4 bits packet type
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[Category:Previous_Projects](Category:Previous_Projects "wikilink")
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