Securing confidentiality in PON and HFC networks

In Some kind of networks like PON (Passive Optical Networks) and HFC (Hybrid Fiber Coaxial) networks, the information from the central station (headend) to the terminals is broadcast to all of them. So each one of them besides its own data gets also the data destined for the others. Under these conditions privacy and confidentiality do not exist. The usual way to overcome this drawback is conventional encryption of the data between headend and terminals. This method besides making the communication procedure more complex, has also the drawback that traffic data cannot be protected, since the destination field of each cell cannot be encrypted. Here another method is presented which, although not encryption in the conventional meaning of the term, secures a high degree of individuality and confidentiality. The basic idea is to use different multiplexing patterns for each connection so that each terminal can demultiplex only its own data. The method is suited for the high data speed of the PON networks and maybe preferable to conventional encryption.