I'm trying to help a buddy research implementing some form of wireless communication between a dozen or so self-contained sensors to collect data placed outside around a small area (less than 20ft between nodes) and send that data off to a central point.

Each unit will be self-powered (battery) and encased in some form of metal tamper-proof casing and possibly even embedded into exterior walls so only 1 side would not be covered by building material.

He's been looking at a 802.15.4 PAN implementation using 915mhz.

I'm a software guy and not very familiar with electronics, let alone something specific like RF communications. So I just need some general help in understand how to choose the correct wireless communications package for this scenario.

802.15.4 PAN looks like it will fit the bill as it comes to having nodes communicate with each other and reporting that back to a PAN Coordinator but is 915mhz the best frequency to use?

I know this is a very high level and vague set of questions, I just don't know where to start other than asking on the StackExchange network.

UPDATE: Looks like ZigBee is going to be my best bet. Low power consumption, runs at either 2.4ghz or 915mhz, bandwidth should be sufficient, good range, and most of the network code is done for me.

I searched Mouser for ZigBee and got a ton of results, from what I can decipher the differences are mainly in form and power output/range. Not sure what else I would be looking for.

Is there a preferred company for these modules?

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    \$\begingroup\$ What about IoT security! Zigbee is poor for that but meets your other requirements. Then there is NFC. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Nov 18 '17 at 18:48
  • \$\begingroup\$ @TonyStewart.EEsince'75 Excellent point I didn't think about, security will be important as well as interference since it's outside. I did start reading about Zigbee but being so new to this it's hard for me to decide what would work. I also looked at Microchips Mi-WI which looked promising. Thanks for your reply. \$\endgroup\$ – user3953989 Nov 18 '17 at 18:50
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    \$\begingroup\$ You probably want a plastic casing rather than metal. Many things will work for your range needs as long as your receiving station is mains powered and so able to be receiving all the time. If you're going to be putting your own MCU in each node anyway, it's hard to beat the price of the NRF24/clone type packetized 2.4 GHz solutions. 915 MHz may better penetrate some materials but the antennas will be larger, and the price will likely be several dollars per node radio instead of $1. \$\endgroup\$ – Chris Stratton Nov 18 '17 at 18:59
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    \$\begingroup\$ This would be a good point to start reading: edn.com/design/5G/4428131/1/… Certainly 802.15.4 is going to be a good low power entry. You could also consider Bluetooth which is cheap, but is a star configuration. A good comparison chart here: glowlabs.co/wireless-protocols \$\endgroup\$ – Jack Creasey Nov 18 '17 at 19:01

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