What is the range of bluetooth and is it strictly 1:1?

Question

Does anyone know what kind of range can you get from the iPhone bluetooth? Also, would the connection be strictly one to one? I know you can choose from a number of peers to connect to but once the connection is established, it seems you can only transfer data between one peer? So basically, is it possible to create some kind of "multiplayer" experience?

Answer 1

The bluetooth in the iPhone is Class-2, with a 10-meter range, approximately.

Unfortunately I can't answer the other parts of your question.

Answer 2

The connection is one-to-one, but you can create an adhoc network with one of the phones acting as the master/coordinator. The other phones would route all their communication through the master/coordinator.

Answer 3

Apple iPhone 3G has a Class 2 bluetooth module. Class 2 Bluetooth devices have a communication range of 10 meters.

At a given instance a device can connect to just one device because it follows a master/slave communication model. But still we can perform a multiplexing. So we can virtually connect to more than 1 device and by rapidly changing the connected device.

I found a good article here. It explains bluetooth very well.

According to the my knowledge, multicasting is not impossible with bluetooth. So gaining a multiplayer experience is NOT impossible.

Answer 4

One device can be connected up to 8 others. It all depends on the iPhone bluetooth API (which I don't know anything about), but with Bluetooth itself you could then send data to multiple devices.

Answer 5

Just answering the range part of your question...

The 10 meter figure for class 2 devices (of which the iPhone is an example) is very much a guideline.

The range of a Bluetooth device is limited by many real world factors. The 2.4 GHz radio frequency used by Bluetooth is strongly absorbed by water. For example, consider an iPhone connected to a Bluetooth mono headset. If the headset is in one ear and the iPhone is in your trouser pocket on the opposite side of your body, then there's a lot of water between the two devices. This will often cause a significant amount of packet loss in practice (you can hear this in the audio being carried). So, in this case, the range is about one meter.

At the opposite extreme, two class 2 devices separated by nothing more than clear air can get ranges of hundreds of meters.

Other factors that influence things are:

1. Interference - Lots of things use 2.4 GHz. WiFi, for example can cause problems.
2. Antenna design - Space and cost constraints often mean that the antenna design is sub-optimal. I don't know how good the iPhone is in this respect.
3. Walls - Generally walls attenuate Bluetooth signals. However, sometimes they are useful reflectors.
4. Quality of hardware - Some chips work better than others. Even different firmware revisions of the same chip may perform differently. Different versions of the iPhone probably have (or will have) different chips in them.
5. Protocol - It is possible to work around poor signal quality with error correction and retransmission. Even if the iPhone SDK forces you to use a particular protocol, careful design of your application can make a difference.

So, in summary, you should probably do some real world tests.

Answer 6

One device can theoretically connect to 7 devices. according to the master-slave role, the device can multiplex between each of them giving the user an impression that you are connected to all of them simultaneously. Bluetooth specification does not stop you from doing that.This is theory.

Now for the iphone, whether it can connect to to more than one device can only be answered by apple or someone who knows the iphone bluetooth API. But I am pretty sure the bluetooth chip inside iphone should be able to connect to more than one device.

Answer 7

Range is essentially going to be good enough for a normal sized room to be covered. It can be longer or shorter depending on environmental circumstances, but remember that bluetooth was created to implement short range connections.

A bluetooth device can be part of a piconet of eight devices, one master and up to seven slaves. The slaves cannot communicate with each other, they must talk through the master, think of a star topology with the master in the center. The iPhone SDK has a GameKit framework that can be used to create the network for multiplayer games. Go to developer.apple.com at look at the GKTank and GKRocket sample code to see how it's used. These games only support two players, but the GameKit framework supports more. Look at the app store and you will see games that have four or more players.

Hope this helps to get started.

Answer 8

I tether my iPhone to my laptop over bluetooth every day, and I seem to remember having done that at the same time as using a bluetooth headset. YMMV.