Research Of Resource Allocation Policy For Hybrid Power Supplied Wireless Networks

With the rapid development of wireless communication technologies and the increasing of wireless services,the amount of communication data and system energy consumption has increased drastically.In order to alleviate the problem of system energy consumption,most researchers pay attention to the energy management in hybrid power supplied wireless networks with energy harvesting.To provide high spectrum efficiency,orthogonal frequency division multiplexing(OFDM)technique is applied in wireless communication systems due to the ability of anti-fading.In addition,the system capacity of heterogeneous networks can be increased several times by macro-micro-cooperation and anti-fading ability,which is combined small cell and cellular networks.For this reason,small cell technology has been one of the key technologies in 5G networks.On the other hand,considering the complexity and uncertainty of wireless channels,how to optimize resource allocation and energy management under uncertain channels is also an important problem to reduce the cost and energy consumption of wireless communication systems.Therefore,in this thesis,the system of hybrid power supplied OFDM cellular networks is constructed,and the hybrid power supplied mode is further applied in small cell.Under the system models constructed for different communication networks,the resource allocation strategies are investigated in OFDM cellular networks with uncertain channel state information(CSI)and in small cell with certain CSI,respectively.Simultaneously,problem formulation and solution are obtained by using convex optimization and worst case methods.And proposed resource allocation schemes are simulated and analyzed.The main works are as follows:(1)In view of the condition with imperfect CSI,the model of uncertain CSI is constructed by worst case method in this thesis.The uncertain parameters are considered as bounded random variables,and the closed-form solution can be derived.Thus,by substituting the closed-form solution into the original problem,the robust optimization problem can be solved when the CSI is not completely known.(2)Under the condition that the CSI is not completely known,the problem of resource allocation and energy management scheme in hybrid power supplied OFDM cellular network is studied.Under the constraints of the basic communication rate requirements and renewable energy supply,the optimization problem is formulated,and the optimal allocation scheme and suboptimal allocation scheme are proposed,respectively.The optimal allocation scheme converts the mixed binary integer problem into a convex problem by time sharing technique.Suboptimal allocation converts the non-convex problem into a convex problem by using a low complexity suboptimal subcarrier assignment.Further,the resources are optimized through the convex optimization method and the worst case method,and the optimal closed-form solution can be obtained by using the Lagrange dual method.Based on the above,the sub-gradient iterative method is used for numerical simulation,the convergence and energy conversion efficiency of the proposed scheme in this thesis are analyzed,and four resource allocation schemes are compared.Numerical results show that the optimal scheme has the best performance in reducing the system cost,and suboptimal scheme performs is in the second.Moreover,the analysis of the robustness of the system shows that the proposed scheme can achieve a good trade-off between system cost and robustness under the uncertain CSI.(3)Under the condition with perfect CSI,the resource allocation and energy management scheme in hybrid power supplied small cell network are studied.Under the constraints of the basic communication rate of each mobile device and the interference between the small cell networks and the cellular networks,an optimization problem is formulated that minimizing the cost of the small cell network systems.By using the Lagrange dual method and the KKT conditions,the optimal closed-form solution can be obtained,and the optimal subcarrier and power allocation schemes are proposed.Simultaneously,in the process of numerical simulation,this thesis proposes an iterative algorithm with adaptive step size to improve the convergence speed of sub-gradient iterative algorithm.The simulation results show that the proposed optimal scheme can quickly converge.At the same time,the energy harvesting can significantly reduce the system cost.Moreover,the proposed optimal scheme is superior to the compared schemes in terms of cost reduction.