What are the benefits of an optimized process for the detailed design?

I am not very experienced in this area, all I know is from the research I have done on my project, which you can read up on in my project. 

I need a receiver which can receive up to 3 transmissions, I am not trying to send data over it apart from just the system picking it up and flashing either 1, 2 or 3 lights depending on how many signals are received. So far, I have come across multiplexing which may help. My goal is to try and make something that is as simple as possible to reduce possible errors, and as cheap as possible. 

I realise I haven't directly answered your question, but I hope I've given you a better idea of what I'm after. 

Thanks

The need to bend around and the ability to go through cars and lorries go with different frequencies.  High frequencies where the wavelength is smaller than the windows will go through cars and lorries - unless the windows are metallised, and low frequencies with wavelengths longer than the length of the vehicle will go round vehicles.  If the wavelength is much less than the width of an obstacle, there will be a deep shadow behind it, which will go backwards a long way, a longer distance for smaller wavelengths.

Thank you very much.