Intro ------ Relay is a function to extend the coverage of WSN network. It adds the functionality re-broadcast a report to other nodes which in turn can re-broadcast report further and so on. How relays works ----------------- An incoming packets are checked for RIME address and SEQNO. 1) If cache does not have an entry for the ADDR/SEQNO. the exact data report is sent/relayed, stats updated and if the RELAY debug option is set. The yellow LED is flashed. 2) If cache already have an entry for the ADDR/SEQNO. No relay packet is sent and packet is silently absorbed. Stats are updated. Firmware -------- The beta-4.4.hex firmware for model S2 adds experimental support for this. What's needed ------------- As the report nodes are fully asynchronous the following criteria must set: 1) radio must be on in the relays nodes. ( Approx 20 mA). USB-TTL cable or firmware command "log on" and power node via DC-input. 2) Node must be configured in firmware to relay. firmware command "relay on" Monitor ------- There is also a new firmware command "relay stats" to monitor the relay function. relay stats sent=4 suppressed=0 Also a new debug option RELAY that flashes Yellow LED when pkt is relayed. Other ----- Note! That relayed reports are also stored in data file and also propagated to remote listeners of TCP port. Example report -------------- Example seen via serial output: # Original Report &: ID=288feadc03000040 PS=1 T=13.00 V_MCU=3.08 UP=2D2F1 [ADDR=143.64 SEQ=53 RSSI=20 LQI=255 DRP=1.00] # Flooded report &: ID=288feadc03000040 PS=1 T=13.00 V_MCU=3.08 UP=2D2F1 [ADDR=143.64 SEQ=53 RSSI=30 LQI=255 DRP=0.75] Content of flooded report is identical but as we see in the relayed report different RSSI and possible LQI. Example topology ---------------- To be added. Example ------- The RSSI is plotted below. We see the white "band" it's two actully two different RSSI values. In this case one is from the originating node and the other from the relaying node. http://www.radio-sensors.com/pictures/apple-tree-relay-RSSI.jpg Issues routing loops -------------------- Probability for routing loops, Time-To-Live (TTL), Protocol version.. Experiences and feedback ------------------------- Please use mailing list for experiences and issues. wsndev@herjulf.se