Wireless Transmission Optimization And Energy Conservation Of Mobile Terminal

With the explosive growth in mobile service,higher transmission bandwidth of wireless network becomes more and more important.Two kinds of existing raido access technologies,WiFi and Cellular,have become the most widely used communication technologies.With the feature of roaming and handover,cellular enables devices communicate with each other while on-the-move.As another popular wireless technology,WiFi transmits on both 2.4GHz and 5GHz bands based on IEEE802.11 standards.Cellular has the property of broaden coverage,high mobility and medium-low speed and WiFi can provide high speed data transmission services for short distances.They can be complemented each other.However,the sharp increase in transmission requirements of mobile network is usually accompanied by expansion in energy consumption.Unlike traditional PC devices,the mobile devices,such as smartphones and tablet computers,are limited by battery capacity,and hence the energy consumption problem becomes more prominent.Despite the factor of limited power capacity,there are multiple influencing factors for the matter.First,as a result of wireless communication own characteristic,the energy consumption of wireless transmission is very high.Especially for cellular network,devices have to keep a state at high potential to reduce latency,and hence resulting the "tail energy" which is a large part of transmission energy.And the channel fading and unsteabiness of signal caused by device moving will exacerbate the problem.Besides,improper scheduling strategy of applications also reduces energy efficiency.The problem of energy consumption in wireless network gets a lot of attention.The domestic and international research about energy saving and optimization of mobile terminals is mainly focused on two aspects.Some research is focused on optimization of communication protocol,such as reducing the "tail time".The other research uses the strategy of delay or prefetching to achieve the goal of energy saving.However,most research solves the problem from a single angle and ignores the coupling relation of upper applications and transmission,which can not guarantee user experience.Besides,there are few study about energy saving of link aggregation in heterogeneous wireless network.Focusing on wireless transmission optimization and energy saving of mobile terminal,this thesis has mainly done the following research.First,proposing a dynamic energy saving transmission strategy based on data flow analysis for traditional strategy with limited energy saving in mobile terminal.Instead of setting parameters statically,the strategy analyzes data flow real time with the help of neural networks and set the delay parameters dynamically.It takes different strategies according to the different applications to reduce the "tail energy" and guarantee user experience.The experiment results showed that the new strategy can save 20%energy further compared with traditional methods.Second,proposing an energy saving scheduling mechanism which facing sensitive network.Focusing on the wireless network jitter,the research analyzes transmission of single task and multiple tasks and proposes an optimum solution in theory.And on this basis,an online scheduling is presented to save energy.In the allowable range,the method chooses the optimal time slot to transmit according to the principle of avoiding "tail energy" as much as possible.In the experiment of multiple transmission in sensitive network,the proposed method can save up to 24%transmission energy.Third,presenting link aggregation middleware based on application layer in heterogeneous wireless network,which can improve transmission bandwidth without any modifications of existing protocol stack and network equipments.Then proposing a scheduling method with the consideration of energy cost characteristic of different network interfaces to reduce the energy consumption of multiple link transmission.The experiment results showed that the middleware can decrease 40%transmission time and save 16%energy consumption of dual interfaces compared with default method.Lastly,proposing a multi-devices energy saving transmission framework based on cooperative communication for the problem of limited saving effect in single device.By analyzing the data flow by random forest algorithm,mobile device migrates the"non-burst traffic" to other nearby devices,which then transmit data with an aggregation strategy.It reduces the transmission energy of the whole group with slight overhead of relay devices.In the large scale experiment,the results showed that it can save about 45%energy cost compared with traditional strategy for single device.From various aspects,these research significantly lowered transmission energy consumption of mobile terminal in wireless network and guaranteed the user experience while using applications.Besides,it tried to put forward preliminary discussion and attempt on the area of wireless communication,thus providing the basic supporting for mobile cloud computing.