| The rapid growth of user demand have posed a great challenge to the current wireless communication techniques.Wireless communication networks will make a higher requirement for channel capacity and spectral efficiency in the future.Traditional Half-Duplex Relay(HDR)collaboration needs to transmit and receive signals in mutually orthogonal time-domain or frequency-domain channels,resulting in a waste of network resources.The Full-Duplex Relay(FDR)technology allows simultaneous sending and receiving of signals at the same frequency,which can effectively improve channel capacity and spectral efficiency.But the technology of Full-Duplex Relay will produce additional self-interference problems,resulting in a more complex resource allocation in the relay networks.Based on this background,we focus on the optimal resource allocation of OFDM-based Full-Duplex Relay system under the conditions of residual self-interference in this dissertation.The main research contents of this thesis are as follows:(1)This thesis analyzes the performance of FDR networks under the conditions of residual self-interference and deduces the closed-form expressions of channel capacity and interrupt probability of FDR wireless networks under the Decode and Forward(DF)protocol.And the performance of half duplex and full duplex relay systems is simulated and compared.The results of simulation show that FDR systems have higher channel capacity and lower interrupt probability in the case of low self-interference.(2)We use the user information rate as QoS constraints,and an optimal resource allocation scheme based on QoS constraints(QCRA)of multi-user OFDM one-way FDR networks is proposed.Firstly,we propose a subcarrier allocation algorithm based on QoS constraints under the premise of equal power allocation.Then we propose an optimal subcarrier power allocation algorithm according to the SINR equilibrium condition of full-duplex DF protocol.The simulation results show that the QCRA scheme proposed in this thesis can improve the system throughput significantly.(3)We investigate the problem of resource allocation for multi-user OFDM two-way FDR networks under the condition of individual power constraints.First,we propose a joint optimal subcarrier and power allocation scheme(JOSPA)under the constraint of individual power constraint to ensure the maximizing total system throughput,and we obtain the optimal solution of the optimization problem by Lagrange duality and subgradient method.And then,we propose a layered sub-optimal resource allocation scheme(LSRA),which can reduce the complexity of the algorithm by relaxing the subcarrier allocation.The results of simulation show that the JOSPA scheme can significantly improve the system throughput in the full duplex relay system.At the same time,the LSRA scheme can approach the performance of JOSPA scheme while greatly reducing the complexity of the algorithm. |
