Felix and TomWS, Thank you for your helpful replies. I'm quite new into the RF modules, so good ideas are welcome.
unfortunately, 915MHz I cannot use. I'm living in Europe and the project is also for an European country... 2.4 was another option with the 100MHz bandwith...
For that, I choose the RFD21735 modules from RF Digital, but they will not respond to any email/question. So I will not take one of those...
Extending the Network ID to get in total 65k of network ID's sounds good to me. so it is easy to arrange more than 4k addresses. What I was thinking is using 2x 8 dipswitches on the gateway to set the network ID. And send the network ID with a "pair" algorithm to the nodes. All nodes get an eeprom or flash device, so I can use the ID of the eeprom or flash for unique node/gateway ID. Or use diswitches again
Then I also can use some channels to avoid any interference. But the interference should be quite low because the only interference you probably will have, is that from grid x+1 and grid x-1.
How you determine each node what frequency(channel) and what network ID and node ID it will have - that's a whole different topic.
to determine the frequency, I can use the lsb or maybe the least nibble of the network ID, 16 channels should be sufficient.
Node/gateway ID can be the ID of the flash device.
And during "learn" use all predefined values and during the learning exchange each other unique ID...
@TomWS
It does not only sounds like fun, it is...
1. No, every AP with 8 nodes is an independent network. And none of the AP's will comunicate together.
2. They will probably will not come online at once. When you power up the first time, you'll have to "learn" one by one and after that, they are going to "work" and report once in a few minutes.
Below, You'll see how the network should look like
* is a Robot
-- is the robot track
AP is accesspoint
* - - - - - - - - | * - - - - - - - -|--
- * - - - - - - - | - * - - - - - - -|--
- - * - - - - - - | - - * - - - - - -|--
- - - * - - - - - | - - - * - - - - -|--
AP1 <200m> AP2 <200m> AP3 ...... and so on ...... AP500
- - - - - - * - - | - - - - - - * - -|--
- - - - - * - - - | - - - - - * - - -|--
- - - - * - - - - | - - - - * - - - -|--
- - - - - - - - * | - - - - - - - - *|--