Universal powerline bus
From Infogalactic: the planetary knowledge core
Universal powerline bus (UPB) is a proprietary software protocol for power line communication between devices used for home automation. Household electrical wiring is used to send digital data between UPB devices via pulse-position modulation.[1]
Communication can be peer to peer, with no central controller necessary.[2]
UPB addressing allows 250 devices per house and 250 houses per transformer, and switches can co-exist with other powerline carrier systems within the same house.[3]
While UPB may be more efficient than X10, it has far fewer products available on the market.[4]