Patent ID: 8295301

Claim:
A method for coexistence of multiple devices on a shared communication medium, the method comprising: in accordance with a schedule for multiple subsets of the devices that includes at least one respective time slot for each subset, transmitting from a first of the multiple devices, which is in a first subset, a presence signal associated with the first subset within the respective time slot for the first subset, wherein the presence signal is unique with respect to other presence signals each of which are associated with different ones of the subsets of the devices and wherein each of the presence signals is configured to indicate the presence of at least one device in the given subset; scanning for the other presence signals during the time slots when the first device is not transmitting the presence signal; synchronizing to a detected zero crossing in response to the first device receiving a resynchronization signal from a second device in a second subset different from the first subset, wherein the second device in the second subset transmits the resynchronization signal in response to an indication from at least one of the multiple devices that one or more presence signals are out of synchronization; and communicating, by the first device, with devices in the first subset based on presence signals detected during said scanning for the other presence signals from one or more devices in at least one different subset.