Hi AlexDM0,
Thanks for your questions!
The solution demonstrated in this video was created to be a demonstration that would work in a tradeshow environment approx 1 year ago. The purpose was to show that ANT can be in used in home automation, and to help people visualize the end result. Changes would be needed to take this from a trade floor demo (designed to illustrate the technology's capabilities and potential uses) to a final solution.
Having said that, the demo application has been further developed to show how to handle some of the missing pieces in the original application.
So, to specifics:
In ANT, a shared channel is different to a normal star topology in that it uses just one synchronous channel on the master device to connect to many other devices. You are correct that these devices do all need to be within range of the master device. Being on one channel allows all the connected devices to be commanded using the same message - making it much simpler to get the lights to all turn on at once (for example). The shared channel also uses addressing so that the master can poll each shared address, allowing each slave to reply to the master in turn (and avoiding data collisions). A shared channel can use a 1 or 2 byte address field - hence up to 250 or 65k devices can connect to one shared channel. The demo uses 1 byte addressing as it seemed unlikely that we'd need to control more than 250 lights within the range of the hub (the master device in this system).
In this demo, an auto-shared channel (where the lights handshake with the hub to obtain their address automatically) is used to connect a hub to the lights.
In addition the hub opens another independent (non-shared) channel broadcasting its capabilities and information about the lights. This channel is found and connected to by one or more remote control device(s) (in this demo I think a PC app and mobile phone app were used as remote controls). These remote controls can send commands to the hub to control the lights, individually, in groups, or all at once. The number of remote controls that can synchronize with the hub to control the lights at once is theoretically unlimited. However as a normal non-shared channel is used, the reverse channel commands sent from the remotes may collide if both were to send commands at once. Given how infrequently people change the settings of their lights, this was considered to be a minor issue.
So looking at the whole system many possible remotes may be used to control many possible lights, in groups or specifically. This is a common goal of mesh networks, but achieved using a simpler system -> hence the term 'practical mesh'.
To move this to being a true mesh solution, we would also need to provide at least one redundant path for the information. This is not included in the demo shown on the video, but has since been created and demonstrated as part of the Nordic Tech Tour. This is done by adding additional hubs that are able to handshake with the lights, and create hub to hub connections.
The demo shown in the video is largely based on the new ANT+ Hub Controls Device Profile (currently only available to ANT+ members), which is implemented by the Garmin Virb (many cameras are able to be controlled by many remotes).
Hope that helps clear things up,
Kind regards,
Kat
. I will double check with their engineers to be sure.
