National Taiwan University
In a wiretap channel, a source node wishes to transmit confidential messages securely to a legitimate receiver and to keep the eavesdropper as ignorant of the message as possible. As a special case of the broadcast channels with confidential messages, Wyner characterized the secrecy capacity of the discrete memoryless wiretap channel. The secrecy capacity is the largest rate communicated between the source and destination nodes with the eavesdropper knowing no information of the messages. Motivated by the demand of high data rate transmission and improving the connectivity of the network, multiple antenna systems with security concern are considered by several authors.