Research And Design Of STBC Codes For MIMO Wiretap Channel

The wireless communication is characterized by a lack of physical boundaries,which is open to the eavesdroppers,thus the security of physical-layer has become a key issue in the wireless communication.Traditional security mechanism is a system which is based on the computation complexity,its principal method is that the operational capability of breaking the designed encryption algorithm is larger than eavesdroppers' computation complexity.However,the possibility of breaking the traditional security mechanism turns out to be enlarged along with the performance of modern computer's computation and the high uncertainty over eavesdroppers' computation complexity.Physical-layer security technology can be used as an important support for traditional security mechanisms,additionally,it can also be an independently formed set of information systems which is based on the security system.In order to strengthen the physical layer transmission security,we study the precoding technology before the signal transmission and analyze MIMO technology and information theory.Space-time coding is a set of practical signal design techniques aimed at approaching the information theoretic capacity limit of MIMO channels.The fundamentals of space-time coding and related MIMO signal processing soon evolved into a most vibrant area in wireless communications.This dissertation regards the performance of space-time coding and the security of extended orthogonal space-time block(STBC)codes over MIMO wiretap channel as the research object.We next research the logical model of Wyner wire-tap channel.Wyner has introduced the wire-tap channel in which the transmit side sends a confidential message to a legitimate receiver via the main channel in the presence of an eavesdropper,who listens to the message through the wire-tap channel.Wyner proved that the transmitter could send information to the legitimate receiver in virtually perfect secrecy without sharing a secret key with the legitimate receiver if the eavesdropper's channel is a degraded version of the main channel.In fact,It is unrealistic that the legitimate receiver's channel is better than the eavesdropper's channel.Specifically,the method to design a channel model that has better channel performances than those of eavesdroppers can be an important and waiting for addressed issue which can realize unconditional secrecy communication.Moreover,this problem will be addressed by this dissertation.To ensure the full diversity advantage at full rate over the MIMO channel,we analyze the extended orthogonal space-time block codes(EO-STBCs).To further increase the received signalto-noise ratio(SNR),we also analyze the EO-STBCs with 2-bit feedback scheme.In this dissertation,we first generalize the EO-STBCs and apply them to the two-way MIMO-WT channel.Then,Based on the generalized EO-STBCs,we first propose a simple partial feedback scheme.Based on the generalized EO-STBCs and the proposed partial feedback technique,the legitimate receiver(Bob)can be able to achieve a higher SNR.Therefore,the secrecy capacity using the proposed two-way MIMO wiretap channel can be greatly enlarged.