On The Wireless Powered Buffer-aided Communication Networks And The Key Technologies

The rapid growth of mobile networks in terms of business scale and data traffic causes severe challenges for wireless communication technologies.On one hand,the most important core of wireless communication techniques is how to fully explore the potential of the network resources and information to design the high spectral/energy/cost-efficient communication systems.On the other hand,the energy supply of wireless devices becomes the bottleneck that restricts the network performance,and how to improve the energy sustainability of wireless devices and achieve the permanent information transmission is one of most important issues of the future networks.Recently,the potential of data buffer in the physical and MAC layers is unveiled that the buffer-aided communication system could either decrease the network energy consumption or improve the network spectral efficiency with a limited cost of transmission delay.Meanwhile,the radio frequency(RF)based energy harvesting technology,which could wirelessly power the network devices via RF signals,becomes an emerging method to prolong the lifetime of wireless devices and achieve the sustainable transmission,and attracts more and more research attentions.This thesis not only applies the RF energy harvesting technique to address the energy supply and sustainability issues of wireless devices,but also takes data/energy buffer into consideration to explore the network performance of wireless powered buffer-aided communication network.The goal is to design the energy sustainable and high efficient wireless communication systems.Firstly,to unveil the potential of buffer-aided communication systems,a buffer-aided cooperative network with multiple relays is investigated.The single-relay selection transmission scheme is usually adopted.While,it could not fully exploit the spatial gain of multiple relays and suffer some achievable rate loss.In this thesis,a buffer-aided collaborative relaying framework is proposed,in which all relays could simultaneously transmit their buffered data to the destination in the manner of non-orthogonal multiple access(NOMA).According to the achievable rate maximization problem under the data buffer stable constraint,the bufferenergy-aware adaptive(BEAA)scheduling scheme is proposed.Then the tradeoff between the average transmission delay and achievable rate is analyzed,and it is validated that the bufferaided communication system could improve the achievable rate with a cost of limited delay.Secondly,the effect of RF energy harvesting technology o the achieved performance is studied,and the network performance of wireless powered communication networks is analyzed.The effect of user deployment on the network fairness and throughput is unveiled,and a NOMA-based wireless powered scheduling scheme is proposed,which divides all users into the non-interference and interference groups,and allows the non-orthogonal energy transmission during the information transmission phases of interfered users.On one hand,from theview point of network fairness,a fairness-aware NOMA-based scheduling scheme is proposed,which sacrifices the rates of users with good channel conditions to improve those of users with poor channel conditions.The order statistic theory is exploited to analyze the network fairness performance and optimal user grouping policy.On the other hand,a throughput-optimal NOMA-based scheduling scheme is proposed,which could utilize the small rate loss of users with poor channels to obtain the large rate gain of users with good channels.Thirdly,the achievable rate of wireless powered buffer-aided relay network is analyzed.A buffer-aided time-switching based relaying(TSR)scheduling scheme is proposed,and the achievable rate and optimal time-switching parameter are derived.Considering the adaptive energy and time allocation,both the optimal adaptive and online buffer-energy-aware adaptive wireless powered buffer-aided relaying scheme are proposed.In the latter,the state information of channel/energy/buffer(CSI,ESI,BSI)is exploited to adaptively allocate the time slots and energy,and the tradeoff between the average transmission delay and achievable rate is derived.Finally,in order to further enhance the spectral efficiency,the successive relaying is incorporated into the wireless powered buffer-aided cooperative network.The scheduling schemes with and without data buffer and energy storage are proposed,and the corresponding achievable rate analysis unveils the joint effect of data buffer and energy storage.Based on the rate maximization problem under the data buffer stable constraints and energy storage sustainable constraints,the adaptive wireless powered buffer-aided successive relaying scheme is proposed,and the corresponding performance analysis validates the finite data buffer and energy storage length can be simultaneously guaranteed.Above all,the transmission scheme design and the achievable rate of the wireless powered buffer-aided communication networks are investigated.The effect of user deployment in the wireless powered communication networks is explored,the NOMA-based wireless powered communication scheduling schemes are proposed,which could simultaneously improve the network fairness and throughput.Meanwhile,the joint effect of both data buffer and energy storage on the wireless transmission scheme design and network performance are unveiled,and the potential of the buffer/energy state information on the resource allocation policy is demonstrated.The tradeoff among the transmission delay,energy consumption and achievable rate is derived.All simulation results validates that the achievable rate of wireless powered buffer-aided communication systems is enhanced,and the energy sustainability is guaranteed as well.