Bluetooth 4.0 Query

hondacrazy

Hi,

I'm currently doing my Masters thesis and I need to find some specific answers that can be backed up from documents somewhere - either on or offline. What I need preferably is someone who is a Bluetooth specialist or a software developer who specialises in embedded wireless technology as the answers need to be accurate - I literally have just three questions that I need answered:

1) Can a Bluetooth system become overloaded, for example, numerous, possibly hundreds of devices paired in a very small area - but paired to one another not to just one master device.

2) What is the peer to peer range of Bluetooth 4.0

3) If, in the small (say 1km square) area, a radio frequency mast was installed, could the devices all work off the mast to gain a longer range - and again, if so, is there potential for the mast signal to become overloaded?

I would really appreciate some input from anyone with Bluetooth experience!
Thanks.

ED E

No bluetooth specialist but with any wireless technology you're using a shared medium and thus always have a point at which you'll overload.

Wiki says it all

Bluetooth operates at frequencies between 2400 and 2483.5 MHz (including guard bands of 2 MHz at the bottom end and 3.5 MHz at the top).[14] This is in the globally unlicensed (but not unregulated) Industrial, Scientific and Medical (ISM) 2.4 GHz short-range radio frequency band. Bluetooth uses a radio technology called frequency-hopping spread spectrum. Bluetooth divides transmitted data into packets, and transmits each packet on one of 79 designated Bluetooth channels. Each channel has a bandwidth of 1 MHz. Bluetooth 4.0 uses 2 MHz spacing, which accommodates 40 channels. The first channel starts at 2402 MHz and continues up to 2480 MHz in 1 MHz steps. It usually performs 1600 hops per second, with Adaptive Frequency-Hopping (AFH) enabled.

That means in a perfect scenario you get 40 individual links before degradation. In reality this is a lot less as all links will be channel hopping all over the place, and 1 WIFI transmitter overlaps almost 25% of the allocated spectrum.



Really, as with wifi, this is no one answer, it really depends. 2.4Ghz is horrendously polluted/congested.

hondacrazy

Thanks ED E!