| In recent years,with the rapid popularization of smart mobile devices,the mobile data traffic demand increases exponentially,but at the same time,it also brings more serious energy consumption problem.Therefore,the introduction of energy-efficient device-to-device technology in the cellular network,so as to achieve the purpose of reducing energy consumption while meeting the requirements of high rate is the future development trend of wireless mobile communication network.In addition,taking into account the full-duplex superior performance bring by the advanced self-interference cancellation technology,as well as full-duplex and device-to-device has the optimal matching with lower transmission power requirements,the combination of full-duplex technology and device-to-device technology will be very meaningful.Therefore,based on the background of green cellular networks,this paper takes the device-to-device technology as the research object,and combines the advanced full-duplex technology to discuss the optimal power allocation problem of the full-duplex device-to-device networks to maximize the system energy efficiency.The main research results of this paper are summarized as follows:The full-duplex device-to-device link share the uplink radio frequency resource with the cellular link,and each user belongs to both competition and cooperation relationship in cellular network.Based on this,we first propose a power allocation algorithm based on non-cooperative game theory,and then in consideration of different self-interference cancellation technologies,we use an iterative bisection-alternate optimization method to maximize the system energy efficiency while guaranteeing required signal-to-interference-plus-noise ratios and transmission power constraints.Simulation results show that the proposed method can obtain the optimal power allocation with lower complexity to improve the energy efficiency.In addition,the full-duplex mode can achieve higher energy efficiency than half-duplex mode when the distance between the device-to-device pair is short and the self-interference is eliminated to a certain extent.Considering that the device-to-device is a short-range direct communication,when the direct link is far away or the channel quality is poor,the device-to-device users often need higher energy consumption to obtain the communication quality guarantee.Therefore,on the basis of the full-duplex device-to-device networks,this paper introduces the relay to assist transmission,and establishes the power allocation optimization problem of the two-way relay-assisted full-duplex device-to-device networks to reduce the energy consumption so as to further improve the energy efficiency.According to the characteristics of the optimization problem,we turn the objective optimization problem into two subproblems to handle,and then propose a two-tier alternative iteration optimization algorithm to find the optimal power allocation and amplification gain to maximize the system energy efficiency while guaranteeing spectral efficiency requirements and maximum transmission power constraints.Simulation results show that the proposed algorithm is consistent with the results of exhaustive search but with lower complexity.And the highest energy efficiency can be achieved when the relay is located in the middle of the two full-duplex device-to-device users.In addition,the better self-interference cancellation technologies can make the energy efficiency of the two-way relay-assisted full-duplex device-to-device networks higher than that of the corresponding half duplex networks.The research results of this paper can provide theoretical support for the construction of the future 5G green cellular network,which has certain reference significance to improve the user experience and increase the energy efficiency. |
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