Wireless Sensor Networks

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Need help choosing best wireless technology

Hii all.

 

I want to select the best wireless technologies (BLE? ANT? Custom RF Sub-1Ghz?) to implement the following project:

 

  • A wireless sensors network, with a star topology.
  • short range (max distance 1.5m).
  • One “Master” with typically 8/10 sensors, up to 16 is desirable.
  • During the "main" use case, there is no need for duplex communicaiton. The data flow from sensors to master. There will have some bi directionnal (yet not full duplex) communication periodically to manage sleep/wake cycles.
  • The main technical objective is to achieve at the very least a message rate of 20 messages per second / per sensor, with also a latency as short as possible (50ms is a worst case. 5 to 10ms are desirable). The actual data load of each message doesn’t need to be huge. 8bits sufficient, 16 bits would be better. So required bandwidth per sensor is somewhere from 160 bps to 3.2kbps.
  • Battery life, for the sensors, is a key element too. With one coin cell (2032?) several hours of wake (measurements with the message rate specified above) are required (more is better), and “sleep” battery life needs to be good also.
  • The uC doesn’t need to do much more than read the actual sensor outputs (digital) and transmit it with the specified  rate. It may have to do some averaging if the sensor’s readings are fasters than the message rate, and otherwise:
    • Read and transmit battery level once at wake/sleep
    • Manage a sleep/wake cycle depending of what is received from the Master (and of the battery level)
  • Cost for the sensor parts is also a very important objective.
  • Cost and battery life for the Master module is not so important.
  • Ease of implementation matters, as well as not having huge licensing costs!

Any advice would be highly appreciated. I have started looking at ANT but I’m not sure if it is really the best implementation.

 

To illustrate better the use case, imagine wireless game controllers. (up to 16 of them). I'd like up to 16 players to be able to play a sport video game together wirelessly in front of the SAME screen (we are not taking internet gaming). The data flow from the game controller to the game console is quite small. Yet latency is super important, and you don't want a player to be privileged more than another so you want either simultaneous channels, or a very fast cycling/scheduling reading of all the sensors.   

THANKS FOR ANY ADVICE!



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Hello kickass,

 

This sounds like an interesting application. Those who monitor this forum typically support the NI-WSN products ( http://www.ni.com/wsn/ ), which sound like they would not be an appropriate system to implement for your application as they are for applications which require sample rates of around 1 S/s.  They use ZigBee technology and can be battery-powered.

 

What devices are you using? Are you planning on using LabVIEW to enable communication and control with your devices? If so, perhaps posting to the LabVIEW Forums may be your best bet in getting some wide-ranged advice from our community.

 

I hope this helps!

Nadine H.
Applications Engineer
National Instruments
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