Can i have a WSN network with moving nodes?

[Vitor_Miranda]

Hy,

I'm attempting to create a WSN network with the nodes mouted in moving devices that would change its positions from time to time and remain still for some days. With this configuration I can't really tell wich of the nodes would have to work as end nodes and router nodes and i won't. This devices would be placed within a 30m distance from each other and the most distant device could be in a distance up to two kilometers. This scenario brings up some questions:

1 - Can i have a network in wich all the nodes are configured as routers?

2 - Even though NI recomends no more than two intermediate nodes to be placed between the furthest node of the network and the gateway will it work if i use more? (the network has a low thruput)

3 - How long does the batery last in a node configured as a router?

4 - If i have two gateways can i run two parallel networks at the same time, defining wich nodes are to be connected to each network?  

Thanks!

[Peñata]

Hi V_Miranda,

First, I will answer your questions:

1 - Can i have a network in wich all the nodes are configured as routers?

Yes, you can definitely have a network in which all of the nodes are configured as routers.

2 - Even though NI recomends no more than two intermediate nodes to be placed between the furthest node of the network and the gateway will it work if i use more? (the network has a low thruput)

We test our specifications up to 3 hops. Unfortunately, we can not guarantee functionality and/or performance beyond that.

3 - How long does the batery last in a node configured as a router?

It is difficult to give a concrete answer to this question. I can tell you that the battery life will be significantly less when configured as a router than as an end node. This is because a router is constantly on in order to relay radio messages from other nodes, while a node configured as an end node preserves battery life by sleeping between samples. Radio transmissions are what eat up the battery life on these nodes, so the more a router node is used to relay radio transmissions, the faster its battery will die. This is why we recommend using a power supply on all router nodes.

4 - If i have two gateways can i run two parallel networks at the same time, defining wich nodes are to be connected to each network? 

If you have two gateways running in the same vicinity, we recommend running them on different Zigbee channels. The channel that a gateway operates on can be set from within MAX. In addition to this, you will need to add the nodes (router and end nodes) that you want associated with a specific gateway to that gateway in MAX as well.

Second, I have a few questions regarding your application:

1.) How many nodes and gateways total would you be using in your application?

2.) How fast would these moving devices be moving?

3.) When you say that the most distant device could be two kilometers away, is that the distance between a node and the next node or the distance between a node and the gateway?

Thanks!

Aaron P

National Instruments

Applications Engineer

http://www.ni.com/support

[Vitor_Miranda]

Thanks for your awnser.

About the adicional questions you made me:

1.) How many nodes and gateways total would you be using in your application?

At first, my intention was to use only one gateway but then i found out that i could only have 36 nodes per gateway. I can't precise at this point how many nodes are gonna be used, but if we stick to the inicil idea its gonna be something around 100. So i will need at last 3 gateways.

2.) How fast would these moving devices be moving?

This devices are gonna move slowly.

3.) When you say that the most distant device could be two kilometers away, is that the distance between a node and the next node or the distance between a node and the gateway?

This is the distance between the last node and the gateway. The nodes would be within a 40m distance from each other.

if you could send me your email address i would like to share some more details.

Thanks!

[Kevin_H]

Hey V_Miranda,

Feel free to email me with more application details:

kevin.harwood@ni.com

Look forward to hearing from you.

Kevin

[Garrett Cook]

3 - How long does the batery last in a node configured as a router?

We (another company, not NI) did a test where a router would relay data from a couple other nodes and the battery life (using alkalines) lasted about 4.5 days.

[Kevin_H]

Hey Garrett,

That is about what we have seen here at NI as well.

Kevin