Cooperative Communications Of In-band Full Duplex Networks

The growth demands for data transmission rate and security are actuating the spec-tra efficiency of the wireless communication networks to be constantly improved,and prompting the confidentiality to be constantly enhanced.In-band full duplex(IBFD)tech-nology is one of the key technologies to meet these demands.When IBFD technology is adopted,the cooperative communications do not require any additional time-frequency resources for cooperation.Therefore,compared with the half-duplex technology,IBFD can improve the spectrum efficiency and enhance the con-fidentiality of the cooperative communications.This thesis focuses on the application and channel resource of the IBFD cooperative communications in public communication networks and secrecy communication networks,respectively.The main contributions are summarized as follows.First,an IBFD transmitter cooperative scheme is proposed to improve the achiev-able rate of cooperative multiple access(CMA)scheme by leveraging the amplify-and-forward protocol.We analyzes the accumulated additive white Gaussian noise and resid-ual self-interference(ANRI)caused by imperfect self-interference cancellation.Based on the analysis,the achievable rate regions are obtained by utilizing both the forward and backward decoding schemes at the receiver.A two-stage iterative algorithm is proposed to characterize these regions.The numerical results show that the maximal sum rates of the proposed schemes are about 0.54 bits/s/Hz higher than those of the noncooperative multiple access channel.Besides,when the power gains of the channels between the two transmitters are large and the power gains of the residual self-interference channels are small,the backward decoding outperforms the forward decoding.Second,we considers a decode-and-forward based three-phase CMA(3P-CMA)scheme where two IBFD transmitters simultaneously send their own messages to a common desti-nation.An algorithm is developed for computing the optimal power allocation to achieve the maximal network throughput subject to residual self-interference(RSI)at the non-ideal IBFD transmitters.The optimal power allocation is also shown to be a semi-closed form when the three-phases are constrained to be identical,i.e.,resulting in a one-phase CMA(1P-CMA)scheme.The theoretical and simulation results show that the throughput of the 3P-CMA scheme consistently exceeds that of the 1P-CMA scheme and time-division duplex(TDD)cooperative scheme.Besides,the optimal power allocation of the 1P-CMA scheme takes much less computation time,and its network throughout is close to that of the 3P-CMA scheme when the RSI power gain is small.Third,we considers the secure degree of freedom(SDo F)of a two-way multiple-input multiple-output Rayleigh block fading wiretap channel with two IBFD nodes exchanging messages simultaneously and wiretapped by a N_e-antennas eavesdropper.The channel state remains unchanged over a coherence interval T and is unknown to all terminals at the beginning of the coherence interval.By showing the expression of the optimal signal waveform and power allocation for the two IBFD nodes,which maximizes the SDo F,the upper-bound for the SDo F of the two-way wiretap channel is derived for large T and small N_e.Then,a constant-norm-signaling(CNS)scheme is presented to achieve this theoretical bound.Finally,we formulate an optimization problem of the SDo F achieved by the CNS scheme for general cases with arbitrary T and N_e,and solve this problem by exploring the monotonicity of the achievable SDo F.The theoretical results show that the optimal SDo F can be independent of coherence time T and becomes the product of the numbers of legitimate nodes’transmitter antennas(NLNTA)for large N_eand small NLNTA.The results also show that the SDo F of the considered two-way wiretap channel comes from two aspects:the first aspect is that there are not enough antennas at Eve?the second aspect is that more channel estimation cost is required at Eve,when the number of the antenna at Eve is large.