| In the future wireless communication network,different cellular networks and other communication systems will coexist for a long time,to meet the different needs of different terminal equipment.The rapid growth of massive connections has brought new challenges to the future wireless communication.The high-density deployment of wireless networks and the coexistence of multiple networks make the wireless interference environment very complex.And the effective scheduling and control of wireless resources become very difficult.How to improve the access capability of future wireless network with finite resources will be researchers’ problem and study direction.Backscatter communication is one of the key technologies to realize low power wireless communication system.The backscatter transmitter modulates the RF signal to sends data to receiver.There is a promising communication system,ambient backscatter communication.It can harvest energy from ambient RF source and modulate the RF signal to backscatter.It does not consume its own energy,and does not need to rely on fixed RF source.To some extent,it can realize the coexistence of multiple devices in time,space and frequency spectrum.So it can enhance the access capabilities of wireless network and has become a new field of concern for many scholars.The research of ambient backscatter communication will help to improve the access capability of wireless network.This paper is devoted to proposing the access selection,resource scheduling and transmission method in the multi-transmitter multi-receiver ambient backscatter communication.The main work includes the following three parts.Firstly,due to the communication demand of many receivers and transmitters in the communication network,a multi-transmitter multi-receiver ambient backscatter communication system is proposed.The system allows multiple transmitters communicate with multiple receivers simultaneously.The transmission protocol in system is based on FDM and TDM,which reduces the mutual interference between communication pairs.In order to solve the user association problem,priority-based access strategy is designed for proposed system.The strategy deals with link budget information to maximize the system communication capacity with power constraints.The simulation results show that the proposed access strategy has better convergence than baseline strategy.It achieves the optimal communication capacity and sub optimal bit rate.Moreover,it achieves low complexity,and the total time complexity is O(N),where N is the amount of receivers.In addition,when the receiver density is 0.02,the maximum capacity and bit rate of the whole simulation system is realized.Secondly,in order to solve the time resource allocation problem in the proposed multi-transmitter multi-receiver system,we firstly establish the corresponding model of time resources.The time resources in the system are time frame structure.Each frame includes several timeslots,and the time slot is the minimum allocation unit of time resources.Then,the action matrix of the time resource model is proposed.The elements in the matrix represent the corresponding actions of communication pairs under each time slot.The proposed action matrix is a good representation of the time resource scheduling strategy.Finally,genetic algorithm is introduced to formulate the optimal time resource scheduling strategy.The simulation results show that,the proposed time resource scheduling scheme based on genetic algorithm achieves the optimal throughput of the system in three dimensions:the number of communication pairs,the emission energy of RF source and the passive reflection rate.In addition,in these three dimensions,the performance of communication system with multiple communication pairs can be improved by 82%,64%and 47%respectively compared with single communication system,which shows the performance superiority of multi-transmitter multi-receiver ambient backscatter communication system.Thirdly,considering the differences of equipments in the environment.Different kinds of devices will have different QoS requirements.The QoS of the device is mainly consisted of the transmission rate,delay and priority,which are closely related to transmission.Therefore,we study how to formulate transmission control strategy to satisfy the QoS of the device and maximize the system energy efficiency.We propose a two-stage online auction transmission right scheme,which is mainly based on the basic idea of auction.Auction participants are communication pairs in the system.Auction items are the transmission rights in each stage of the system.Because of the existence of two communication modes,there will be 1 passive and 3 active transmission rights competition in each stage.The simulation results show that,the two-stage online auction transmission right scheme achieves the biggest energy efficiency in three compared methods,and meets the QoS requirements of all devices,and obtains the highest overall QoS score of the system. |
