Greetings,
I'd like to develop a wireless sensor network based on your products, but have a few concerns based on my lack of knowledge of how Bluetooth LE works.
I've checked out several Developer Zone questions, and know that it's possible to have a master nRF51 connected to 6 other nRF51 (acting as slaves that transmit sensor information) through the S120 SoftDevice.
I'd like to know what ranges to expect in terms of bandwidth and latency, because I've read that BLE isn't really suited for data streaming.
- Bandwidth:
Each one of my sensors outputs 26 bytes @ 100Hz, roughly 21 kbit/s. Can I expect 21 kbit/s in each of the simultaneous connections? Table 32 (BLE data throughput), in page 50 of the S120 manual doesn't make it look promising, but maybe I don't understand the table fully. Can I maybe achieve my needed data rates by limiting the number of nodes to 3 slaves, 1 master?
- Latency:
Latency is also crucial in my application. The S120 SoftDevice recommends a t_EEO of 2.25 ms, for a minimum connection interval of ( t_EEO x Links ) (roughly 18 ms for 8 links). Disregarding the connection/pairing delays, if configured to 4 nodes, 1 master and 3 slaves, can I expect a total latency of around 10 ms?
- Etc:
I'd like to expand the size of the sensor network, up to 12-15 sensors. Can a piconet run alongside another piconet, or will it cause a lot of interference/lost packets?
And finally... if BLE throughput is not enough, does NS have any classic BT solutions that supports connections of multiple nodes (in a star topology)?
I understand that those are several questions, but any help would be greatly appreciated!
(Info taken from the S120 guide. Recommended T_EEO, page 18. Recommended intervals and windows page 43.)
