Energy Efficient Data Transmission In Wireless Network

With the evolution of wireless technology and the popularity of smart mobile terminals,mobile communication services are in an unprecedented deep change.The explosive growth of mobile data traffic,the interconnection of massive intelligent devices,and the emergence of new applications for new services have brought unlimited vitality and bright prospects for mobile communications.However,opportunities and challenges often coexist.The accompanying energy consumption is exponentially growing,which undoubtedly poses enormous challenges to the environment,resources,economy and user experience.Therefore,the green evolution of mobile communications is an inevitable choice.Green communication includes two levels of energy “throttle” and energy “open source”.Among them,energy “throttle” is to improve energy efficiency and reduce energy consumption of communication system;energy “open source”refers to collect clean energy and renewable energy from the environment by energy harvesting technology(EH)for communication systems,thereby reducing greenhouse gas emissions.This paper starts from the perspective of wireless resource allocation,and from the angle of energy“throttle” and “open source” to study the energy-efficient transmission mechanism.At the same time,it also reveals the trade-off between energy efficiency and delay,and the trade-off between average outage probability and EH related constraints.Firstly,we consider the energy-efficient data transmission problem with a non-first-in firstout(Non-FIFO)packet in a point-to-point additive white Gaussian noise(AWGN)channel under the feasibility constraints.This work is a special case of the extension of the existing energyefficient transmission of the same delay data stream to different delay type data streams.Specifically,there exists a data packet whose deadline is earlier than that of the packet arrives first.Therefore,the existing first-in-first-out(FIFO)transmission methods are no longer energy efficient.Firstly,a novel split-recoder strategy is proposed to convert the Non-FIFO data stream into a FIFO data stream,and the energy efficiency optimality of the strategy is proved.After the split-reorder operation,the original problem is equivalently converted into the problem of finding the optimal split factor.Then,based on the non-causal data arrival information,a low complexity offline transmission strategy is proposed to minimize the energy consumption of data transmission,and the optimality of the strategy is proved by exploiting the optimal properties.In addition,based on causal data arrival information and offline transmission strategy,a heuristic low-complexity online transmission strategy is proposed.Finally,the simulation results show that the proposed two transmission strategies have similar energy-saving performance and are significantly better than the corresponding existing transmission strategies.Secondly,as a generalization of the above and existing research work on delay,we consider the energy-efficient data transmission problem with multiple Non-FIFO packets in a point-topoint AWGN channel under the feasibility constraints.First,the necessary and sufficient conditions for the optimal transmission strategy are derived.Then,based on the non-causal data arrival information and the optimal properties,a low complexity offline ”non-idle” transmission strategy is proposed to minimize the energy consumption of data transmission,and the computational complexity of the strategy is analyzed and the optimality of the strategy is also proved.The offline transmission strategy includes rate allocation and sequence scheduling.Specifically,the maximum sub-interval rate in each iteration is the optimal transmission rate of the data packet contained in the sub-interval;the minimum deadline first sequence scheduling can determine the optimal transmission order.In addition,based on causal data arrival information and offline transmission strategy,a heuristic low complexity online transmission strategy is proposed and the computational complexity is analyzed.Finally,the simulation results show that the proposed two transmission strategies have similar energy-saving performance and are significantly better than the corresponding existing transmission strategies.Thirdly,we extend the second part of the research work to a more practical communication scenario,and consider the energy-efficient data transmission problem with multiple Non-FIFO packets in the point-to-point AWGN channel under the feasibility constraints and the non-ideal circuit power.This problem is a non-convex problem due to the presence of non-ideal circuit power.First,the original problem is transformed into a convex problem by the variable substitution,and the necessary and sufficient conditions for the optimal transmission strategy are derived.Then,based on the non-causal data arrival information and the optimal properties,a low complexity offline “intermitten” transmission strategy is proposed to minimize the energy consumption of data transmission,and the computational complexity analysis and the proof of the optimality are carried out.The offline transmission strategy includes rate allocation and sequence scheduling.Specifically,the larger rate of the maximum sub-interval rate and the maximum energy efficient rate in each iteration determine the optimal transmission rate of the data packets included in the sub-interval.In particular,when the optimal transmission rate is the maximum energy efficient rate,the data stream will take the form of an “intermittent” transmission.The optimal sequence scheduling is achieved by determining the packet transmission order according to the minimum deadline first principle.In addition,based on causal data arrival information and offline transmission strategy,a heuristic low complexity online transmission strategy is proposed and its computational complexity is also analyzed.Finally,the simulation results show that the proposed two transmission strategies have similar energy-saving performance and are significantly better than the corresponding existing transmission strategies.Finally,we consider the average outage probability minimization problem of underlay relay transmission with an EH source and an EH relay over a fading channel.Due to the interference threshold of the primary user and the limited battery capacity,this problem requires a joint consideration of the transmit power allocation and the energy overflow.First,we transform the original problem from a non-convex problem to a convex problem by using the upper bound approximation through the AM-GM inequality.Then,based on the perfect energy arrival information and channel distribution information,a low complexity two-stage offline transmission strategy is proposed to minimize the average outage probability of the secondary relay link.Specifically,in Phase I,a “best effort” method of transmitting power is proposed to achieve optimal energy overflow,which decouples the power allocation problem and the energy overflow problem,and the optimality of the strategy is also proved.Based on the optimal energy overflow strategy,in Stage II,the necessary and sufficient conditions for optimal power allocation are derived according to the KKT condition,and then a linear computational complexity transmission power allocation strategy is proposed according to the optimal properties,and its optimality is proved.Finally,the simulation results show that the proposed optimal transmission strategy has a significant performance gain compared to the baseline strategies.