BLE Relay System

[hkartadi]

Hi all,

Basically I am doing an exercise on the BLE system use case. Let's say I want to setup a BLE system where there are the long range BLE capabilities in Relays and the End Devices is shorter range with power saving mode. Below is the rough diagram:

Central Base -------------------- Relay 1 ----------------- Relay 2 ----- End Device 2

                                  \                        \
                                   \                        \
                                    \                        \
                                End Device 1             End Device 3

End Devices can move around and closest relay will serve as their central once the end devices advertise

Question is:

1. Central Base is also equipped with NFC reader, we would like to introduce new End Device (lets say End Device 4) into the system. Pair using OOB to Central Base and bonding information is stored. Can this bond information be shared onto the entire system (e.g. Relay 1 and Relay 2)? how to do this?

2. On this use case, what is the best method to introduce a new End Device into the system? or point #1 above is the best?

3. Should we set the End Device to be able to connect to just one server relay (not multiple relay simultaneously) even when both relays are consider close to the end device.

4. What would be the best mechanism to relay the message from Relay 2 to Relay 1 to Central Base? or Relay 1 to Central Base?

Thank you

Handi

[Hung Bui]

Hi Handi,

Bluetooth Low Energy originally doesn't support what you described. The network topology of a BLE network is star only.

There is no mechanism to have a relay device and switch between relay device as in BLE.

However you can think of using MESH. We have open mesh and Bluetooth smart mesh which is coming.

Another option is to use the S132 v4 where we support up to 20 different connections at the same time. But be aware that when one device connect to 2 central at the same time, they are 2 different network here where each network is a star network with the central at the center. You then will need to do the forwarding on your own.

You can forward bond information, in this case the LTK. However, it's not something we have done before or have example to follow. You will have to make your own code to do that.