I tried to ask this in a different forum but without success, so here goes...
What is the maximum amount of slaves in a wireless system? I found this in white paper pdf...
Network Size
The maximum number of devices belonging to the network’s
building cell is 8 (7 slaves plus one master) for a Bluetooth and
UWB piconet, over 65000 for a ZigBee star network, and 2007
for a structured Wi-Fi BSS.
Can anyone confirm that this is true for the Arduino environment and hardware world?
These are theoretical maximums and usually not relevant for real live applications.
What do you want to achieve? Why does this seem relevant to you?
I submit that the paper you quote is is mostly irrelevant, non-commital nonsense written by three bored chinese who just wanted to get into the booze and the girls at the 33rd annual conference, and needed to write some junk in order to get in for free. The only noteworthy parts are the very last sentence, which says all you need to know, and the date at the top, which tells you it is out of date.
The maximum size of a network is as likely to be determined by the ability of the devices to store the addresses of its partners and, if you really do need to think on that sort of scale, I imagine the Arduino is a poor choice to do it with, as it is probably too slow. If you are serious about Arduino communications, rather than dopey theorising, you will get better information right here on this forum.
All you need to do is work out what you want to do.
Max amount is dependent on how the system is arranged. If your protocol is the master sends out a request, all the slaves see and only the appropriate one responds, then the limit is only based on how many unique addresses your protocol supports.
For example, you use an byte to hold the address - then 0-255 is the max.
If you use an int, then 0- 65535 is the max.
If your protocol is any slave can send when it wants, then there is more potential for interference. If each slave listens breifly before transmitting to see if there is valid traffic occurring, then interference potential is reduced.
I prefer poll & response to keep comm's cleaner:
Master: #1, got data?
#1: Nope.
Master: #2, got data?
#2: Nope.
Master: #215, got data?
#215: (no reply)
Master: #215, got data? (keeps track that #215 did not respond
#215: (no reply)
Master signals an error is occurring with #215.
Master: #302, got data?
#302: yes, 50 bytes
Master: #302, send your data
#302: 5 bytes transmitted
Master: #302, 50 bytes received
#302: Acknowledged (deletes data, resumes task)
(master resumes polling)
Master: #517, got data?
#517: Nope
etc.
From a practical perspective, it depends on what the slaves are required to send and how often.
Since the entire system is sharing a common frequency, you can basically determine the number of slaves by simply dividing the
data requirement of each slave into the total bandwidth available.
Answered perfectly.
For the (comparatively) small amount of slaves needed, under 20 w/ non time sensitive packets, I'll treat this as a software/programming issue and not a hardware limitation issue.
Thx,
Jim