Abstract: A radio communication system (600) having at least two radio interface devices (602) requires an access protocol for accessing a common information bus (605). The bus (605) is necessary for sending information to a communication system controller (601). A first of the interface devices periodically polls the common information bus (605) to determine whether or not it is available for sending information to the communication system controller (601). When available, the device acquires access to the bus (605), and sends information to the controller (601), via the information bus (605). The device then releases the bus (605) at a subsequent polling period for that device, thereafter allowing a second interface device to gain access to the bus (605). The foregoing sequence ensures that each of the interface devices (602) will, within a predetermined time, poll the bus (605) and acquire it, as necessary, for sending information to the system controller (601).

Abstract: A method for backing up and erasing encryption keys that provides a backup power supply (110) so that keys stored in a memory (104) will not be lost inadvertently, while still permitting keys to be erased, either in response to a low battery condition in the absence of the main supply (101), or in response to an external key erase input (105).