Strong secrecy on a class of degraded broadcast channels using polar codes

Two polar coding schemes are proposed for the degraded broadcast channel under different reliability and secrecy requirements. In these settings, the transmitter wishes to send multiple messages to a set of legitimate receivers keeping them masked from a set of eavesdroppers, and individual channels are assumed to gradually degrade in such a way that each legitimate receiver has a better channel than any eavesdropper. The layered decoding structure requires receivers with better channel quality to reliably decode more messages, while the layered secrecy structure requires eavesdroppers with worse channel quality to be kept ignorant of more messages.Postprint (author's final draft