Translated Abstract
With the wide use of wireless communications, various aspects are being researched to increase the channel capacity, to guarantee the quality and reliability of wireless communications. These novel technologies include cooperative communication technology and heterogeneous network technology. This thesis contains two parts. The first part designs a generalized physical layer anti-eavesdropping space-time network coding (GAE-STNC) scheme for cooperative communication systems. The second part works on the Inter-Cell Interference Coordination (ICIC) schemes used for heterogeneous networks in LTE-Advanced networks. The thesis proposes a theoretical way to analyze the ICIC schemes in heterogeneous networks which were mostly analyzed only by simulation. The authors work contains a variety of aspects in wireless communications, including physical layer coding, resource allocation, and algorithm design and system level simulation.Privacy and security issue has become a crucial concern in wireless communications. Recently, physical layer security has attracted much attention. The schemes based on mutual information can help to analyze the feasibility and limits of the secure communications from an information theory point of view but did not propose many practical schemes. This thesis proposes a generalized way of designing AE-STNC for cooperative communication networks from the prospective of physical layer. Based on the assumption of channel reciprocity, the basic idea is to exploit the channel state information (CSI) between the legitimate transmitters and the receiver, which is used to generate the secret key. In these schemes, we introduce an anti-eavesdropping matrix which is generated from the channel information. This random matrix introduces randomness to the transmitting signal. Due to the channel reciprocity assumption, the legitimate receive node can eliminate the randomness when decoding the received signal. However, the eavesdropping node can not eliminate the randomness even with perfect blind channel estimation. The eavesdroppers have a high decoding error rate, and the security can be guaranteed. Also, we give two specific design examples of the coding matrix which are both verified by the simulation results.In LTE-Advanced networks, the network topology used is heterogeneous networks, where the network nodes have different transmitting power. In heterogeneous networks, the interference situation is much worse than in traditional networks where only a single type of base-station is used. Thus, a variety of ICIC technologies are used in heterogeneous networks to overcome the fierce interference. In this thesis, we introduce the key aspects of heterogeneous networks briefly and explain the need of ICIC technology in heterogeneous networks. Due to the complexity of heterogeneous networks, the research was mostly done from the perspective of simulation. In this thesis, based on a simple model to analyze heterogeneous networks[38], we propose a theoretical way to calculate the parameters of ICIC schemes. In our methods, the fairness of different users is considered, not only the fairness between Pico cell center users and Pico cell edge users, but also the fairness between Pico cell users and Macro cell users. At last, the proposed schemes are validated by system level simulation results.Finally, the author’s work is summarized in the last section. In addition, some suggestions concerning these topics presented in the thesis are given.
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