You may wonder how the Blunami app is able to accommodate many simultaneous users operating in close proximity. The bluetooth low energy (BLE) protocol supports 40 channels and channel sharing (3 are reserved for special use). That means there are 37 available channels to transmit control signals. The DCC packet command signals sent by the app contain only a few bytes of data per command, which occupy miniscule portions of bandwidth. The Blunami app is carefully designed to prevent flooding the signal with command packets. The first 37 users operating in a small space will each have their own channel to send command signals to their train, and because the packet data is so small, each channel is available 95% of the time to handle command controls from other users (channel sharing).

The first 37 smart devices in a small space will be able to operate with negligible latency. The next 37 users in the room will involve channel sharing, so once you reach 74 users in close proximity, 37 of them might experience a latency of 20-50 milliseconds (in the event that any commands they send were sent simultaneous to another user). This 1/20th of a second should not really be perceptible. If you add 37 more users into this small space, 37 users will experience negligible latency, 37 might experience a 20-50 millisecond delay, and 37 might experience a 40-100 millisecond delay. Remember this latency will only occur if commands are sent simultaneously, so there is a good chance that might not happen at all.

Channel sharing (technically referred to as Adaptive Frequency Hopping) is more sophisticated than the simplified process described above, but that’s the idea. Its worth saying that there are other BLE devices (like Apple Watch and FitBit) which may also transmit packets in these channels if operated in the same space.

The take home message is that between the 37 channels available in BLE (bluetooth low energy), channels sharing, the brevity of the packets, and the Blunami app’s careful design on packets sent, users should not expect a tremendous amount of latency when operating at close quarters with other users.